Comparative studies on the adsorption of Au(III) from waste rinse water of semiconductor industry using various resins by ibnmalik

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Comparative studies on the adsorption of gold from waste rinse water (Au 178.3 mg/L and trace Cu, Ni, Zn, Sn,
etc) of the semiconductor manufacturing industry have been reported using nonionic Amberlite XAD-7HP,
strong base Bonlite BA304, and Purolite A-500. Batch and column studies were carried out to optimize various
process parameters such as contact time, acidity of solution, and resin dose for gold adsorption from waste
rinse water and elution to get a gold-enriched solution. The results showed that Bonlite BA304 and Purolite A-
500 resins could exchange gold easily at high acidity whereas Amberlite XAD-7HP adsorbs gold effectively at
low acidity (adjusted pH=0). Purolite A-500 was found to be the most suitable resin as it adsorbed 99.6% gold
at an A/R ratio of 8.33 and a sorption capacity of 53.6 mg gold/mL resin. The mixture of acetone and
hydrochloric acid at a volumetric ratio of 9.0 could elute gold loaded on Purolite A-500 resin to yield
10,497 mg gold/L. The adsorption behavior of gold on Amberlite XAD-7HP and Bonlite BA304 followed both
the Langmuir and Freundlich isotherms. In the case of the Purolite A-500 resin, it followed suitably a Langmuir
isotherm. Kinetic data for gold adsorption on the three resins followed a second-order rate.

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									                                                                       Hydrometallurgy 105 (2010) 161–167



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                                                                        Hydrometallurgy
                                               j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / h yd r o m e t




Comparative studies on the adsorption of Au(III) from waste rinse water of
semiconductor industry using various resins
Nghiem V. Nguyen a,b, Jinki Jeong b, Manis K. Jha c, Jae-chun Lee b,⁎, Kwadwo Osseo-Asare d,e
a
  Resources Recycling, University of Science and Technology, Daejeon 305-350, Republic of Korea
b
  Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 305-350, Republic of Korea
c
  Metal Extraction and Forming Division, National Metallurgical Laboratory (CSIR), Jamshedpur, India
d
  Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, USA
e
  Department of Energy and Mineral Engineering, Pennsylvania State University, University Park, PA 16802, USA




a r t i c l e          i n f o                          a b s t r a c t

Article history:                                        Comparative studies on the adsorption of gold from waste rinse water (Au 178.3 mg/L and trace Cu, Ni, Zn, Sn,
Received 2 July 2010                                    etc) of the semiconductor manufacturing industry have been reported using nonionic Amberlite XAD-7HP,
Received in revised form 14 July 2010                   strong base Bonlite BA304, and Purolite A-500. Batch and column studies were carried out to optimize various
Accepted 21 September 2010
                                                        process parameters such as contact time, acidity of solution, and resin dose for gold adsorption from waste
Available online 29 September 2010
                                                        rinse water and elution to get a gold-enriched solution. The results showed that Bonlite BA304 and Purolite A-
Keywords:
                                                        500 resins could exchange gold easily at high acidity whereas Amberlite XAD-7HP adsorbs gold effectively at
Gold recovery                                           low acidity (adjusted pH = 0). Purolite A-500 was found to be the most suitable resin as it adsorbed 99.6% gold
Adsorption                                              at an A/R ratio of 8.33 and a sorption capacity of 53.6 mg gold/mL resin. The mixture of acetone and
Waste water                                             hydrochloric acid at a volumetric ratio of 9.0 could elute gold loaded on Purolite A-500 resin to yield
IX resins                                               10,497 mg gold/L. The adsorption behavior of gold on Amberlite XAD-7HP and Bonlite BA304 followed both
Amberlite XAD-7HP                                       the Langmuir and Freundlich isotherms. In the case of the Purolite A-500 resin, it followed suitably a Langmuir
Purolite A-500                                          isotherm. Kinetic data for gold adsorption on the three resins followed a second-order rate.
Bonlite BA304
                                                                                                                               © 2010 Elsevier B.V. All rights reserved.




1. Introduction                                                                                    In general, the concentration of gold from various solutions varies
                                                                                               from 1 to 2000 ppm (Konishi et al., 2006). Several authors studied the
    Gold is an important metal used for several applications. In the                           recovery of gold using different techniques such as: precipitation
industry the most important use of gold is for the manufacturing of                            (Chmielewski et al., 1997), solvent extraction with dibutyl carbitol
electronic parts and devices such as cell phones, calculators, personal                        (DBC) (Byoung et al., 2008) or methyl isobutyl ketone (MIBK)
digital assistants, and global positioning system units. Generally, solid-                     (Marczenko and Kowalski, 1984), adsorption and ion exchange using
state electronic devices use very low voltages and currents which are                          activated carbon, various bio-derived adsorbents (e.g., persimmon
easily interrupted by corrosion or tarnish at the connector's contact                          tannin gel, neem leaf broth, tannin, and fugal biomass) and ion exchange
points. Gold is a highly efficient conductor that can carry these low                           resins (Ishikawa et al., 2002; Nakajima et al., 2003; Tasdelen et al., 2009).
voltage currents and remain free from corrosion. Electronic compo-                             Adsorption of metals using a solid resin is a proven technique for the
nents such as connectors, switches, relay contacts, soldered joints,                           purification and separation of metals from different aqueous solutions
connecting wires, and connection strips made of gold or coated with                            (Nguyen et al., 2009). In comparison to other techniques, the adsorption
this metal are highly reliable (Ming et al., 1999). During the processing                      or ion exchange technique is more suitable for the extraction of metals
and manufacturing of electronic parts and devices various steps such                           from a relatively dilute solution as it can be highly selective, less subject
as electroplating, etching, rinsing, and chemical and mechanical                               to sludge formation, easily regenerated, and more likely to be
polishing (CMP) are required. During these processing steps waste                              environmentally acceptable (Jha et al., 2008a). Some strong base resins
rinse water containing various valuable and precious metals is                                 such as Purolite A-500 (Rajasingam et al., 2006), Dowex 21K and Dowex
generated. Due to the presence of an appreciable amount of gold in                             G-55 (Zhang and Dreisinger, 2002) have been used for the adsorption of
these wastes, significant attention has been drawn to the recovery of                           gold due to the high capacity and fast loading rate. Nonionic Amberlite
this precious metal (Ishikawa et al., 2002; Nakajima et al., 2003).                            XAD-7 resin was used effectively for the recovery of gold from a waste
                                                                                               solution (Latif et al., 2003). Additionally, the resin can be eluted easily
                                                                                               and without loss of subsequent loading capacity (Harris et al., 1990).
    ⁎ Corresponding author. Tel.: +82 42 868 3613; fax: +82 42 868 3415.                           The present work is focused on the comparative studies for the
      E-mail address: jclee@kigam.re.kr (J. Lee).                                              adsorption of gold from waste rinse water of the Korean

0304-386X/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.hydromet.2010.09.003
162                                                         N.V. Nguyen et al. / Hydrometallurgy 105 (2010) 161–167


           Table 1                                                                        hydrochloric acid to remove any impurities and organics. Afterwards,
           Specifications of waste rinse water.                                            the resins were washed several times with deionized water to remove
               Elements                             Concentration (mg/L)                  excess acid and dried for 12 h in an oven at 50 °C.
               Au                                   178.30
               Cu                                   0.30                                  2.2. Methods
               Ni                                   0.96
               Zn                                   0.23
                                                                                              The experiments for the adsorption and elution of gold using the
               Sn                                   1.30
               Cl−                                  60,350 (1.7 M)                        various resins and mixture of eluents were carried out in batch and
               NO−3                                 359,600 (5.8 M)                       column scale. The batch experiments were carried out in a conical
               H+                                   7500 (7.5 M)                          flask using a shaking water bath under atmospheric conditions using
                                                                                          Amberlite XAD-7HP, Bonlite BA304 (gel strong base resin) and
                                                                                          Purolite A-500 (macroporous strong base resin). The theoretical
                                                                                          loading capacity of strong base resins was determined by titrating Cl−
semiconductor industry. After the gold electroplating of an electronic
                                                                                          using Mohr's method (Helfferich, 1962). To convert the strong base
device, the etching of plated material with a solution of reverse aqua
                                                                                          resins to chloride form completely, these were contacted with an
regia (HCl:HNO3 = 1:3) is performed to remove a portion of the
                                                                                          excess of 1.0 M of HCl. The resins were washed with deionized water
electroplated and the exposed seed layer of gold. Finally, water is used
                                                                                          to remove the acid and were then dried for 12 h. The exact amount of
to wash the etched material, resulting in waste rinse water containing
                                                                                          dry resin was contacted with a known amount of 3.0% Na2SO4 solution
gold(III) ion in [AuCl4]− complex with high chloride concentration.
                                                                                          for 10 h to elute chloride ions. The eluted chloride solutions were then
With the aim to select the best resin to be used in a continuous closed-
                                                                                          titrated by AgNO3 to determine the loading capacity of the resins. The
loop industrial process to recover gold generated during the
                                                                                          total loading capacity was found to be 1.22 eq/L and 1.27 eq/L for
manufacturing of electronic products, comparative studies were
                                                                                          Bonlite BA304 and Purolite A-500, respectively.
carried out using nonionic (Amberlite XAD-7HP) and strong base
                                                                                              After the gold adsorption, the resin was separated from the
resins (Bonlite BA304 and Purolite A-500). The effects of various
                                                                                          raffinate with a filter paper (Whatman no. 41). The gold adsorption
process parameters viz. contact time, the acidity of the solution, and
                                                                                          and elution experiments were also carried out in a column made of
the resin dose on gold adsorption were studied using all three resins.
                                                                                          Pyrex glass with a diameter of 10 mm and a length of 200 mm. The
From the loaded resins, gold is eluted to get a gold-enriched solution
                                                                                          flow rate of the solution in the column was controlled by the
using suitable elution solution. The pure gold metal could be obtained
                                                                                          adjustment of a stopcock. The bed volume (BV) was determined by
from the gold-enriched solution by electrowinning or precipitation.
                                                                                          adding a weighed amount of resin into a 25-mL cylinder and then
                                                                                          immersing the resin into water. After the adsorption of gold on the
2. Experimental                                                                           resins, the loaded resins were eluted by a mixture of acetone and
                                                                                          hydrochloric acid. The eluted solutions were then evaporated by
2.1. Materials                                                                            heating at 60 °C to release acetone. After that the near-dried samples
                                                                                          were added with hydrochloric acid and diluted with deionized water
    The original waste rinse water generated during the manufacturing                     before sampling and analysis. The aqueous raffinate and eluate were
of the semiconductor supplied by the Korean Semiconductor Company                         analyzed for gold content by atomic absorption spectroscopy
was used for experimental purposes. The composition of waste rinse                        (AAnalyst 400, PerkinElmer Inc., USA).
water used for experimental purposes is presented in Table 1. The waste
rinse water contained the following metals: 178.30-mg/L Au, 0.30-mg/L                     3. Results and discussion
Cu, 0.96-mg/L Ni, 0.23-mg/L Zn, and 1.30-mg/L Sn. The acidity of the
waste solution was titrated using sodium carbonate (Na2CO3), and the                      3.1. Effect of contact time
acid (H3O+) concentration was found to be 7500 mg/L. The Cl− anionic
content in the waste solution was determined by using the Volhard                            The effect of contact time on the adsorption of gold by the three
method of titration. Chemical reagents (sodium hydroxide, sodium                          resins was determined using 1 g of resin and 25 mL of the original
carbonate, potassium thiocyanate, silver nitrate, acetone, and nitric and                 waste solution in different stoppered flasks. The flasks were shaken at
hydrochloric acids) were of laboratory reagent grade.                                     140 rpm for different time intervals and at room temperature
    Purolite A-500 (macroporous strong base resin) was supplied by                        (temperature controller was fitted to the shaking machine). The
Purolite Company, Bonlite BA304 (gel strong base resin) by Born                           percentage adsorption is plotted against time in Fig. 1. For all three
Chemical Company and Amberlite XAD-7HP (nonionic resin) by                                resins a smooth curve leading to the equilibrium adsorption of gold
Rohm and Hass. The characteristic properties of all the three resins are                  complexes was obtained. With an increase in time from 2 to 30 min,
presented in Table 2. The resins were washed with 1.0 M of                                gold adsorption increased from 53.6%, 84.8% and 85.5% to 64.4%, 96.3%

Table 2
Characteristic properties of three resins.

  Properties                       Name of resin

                                   Amberlite XAD-7HP                                Bonlite BA304                        Purolite A-500

  Matrix                           Macroreticular aliphatic cross-linked polymer    Polystyrene–DVB                      Macroporous polystyrene cross linked with DVB
  Type                             Nonionic                                         Gel strong basic type I              Macroporous strong basic type I
  Physical form                    White translucent beads                          White/light yellow spherical beads   Faint light yellow spherical beads
  Functional group                 Nonionic                                         R–N+ (CH3)3–X-                       R–N+ (CH3)3–X-
  Capacity, Cl− form (eq/L)                                                         1.3                                  1.15
  Moisture content                 61%–69%                                          50%–60%                              53%–58%
  Specific gravity (g/mL)           1.06–1.08                                        1.26                                 1.08
  Harmonic mean size               0.56–0.71 mm                                     0.45–0.70 mm                         0.6–0.85 mm
  Uniformity coefficient            ≤ 2.0                                            ≤1.6                                 1.7
  Shipping weight (g/L)            655                                              660–710                              670–700
                                                                N.V. Nguyen et al. / Hydrometallurgy 105 (2010) 161–167                                                                                                             163


                                                                                              Table 3
                                                                                              Rate constants for the pseudo first- and second-order rates for the adsorption of gold on
                                                                                              resins.

                                                                                                Resin                                       Pseudo first order                           Pseudo second order

                                                                                                                                            k1                 qe (mg/g)   R2           k2            qe (mg/g)            R2

                                                                                                Amberlite XAD-7HP                           0.140              2.40        0.854        0.86          2.90                 0.99
                                                                                                Bonlite BA304                               0.094              1.98        0.835        0.67          4.34                 1.00
                                                                                                Purolite A-500                              0.098              2.52        0.920        0.78          4.33                 1.00

                                                                                              qe from the empirical data of Amberlite XAD7-HP = 2.87 mg/g; qe from the empirical
                                                                                              data of Purolite A-500 = 4.31 mg/g; qe from the empirical data of Bonlite BA = 4.3 mg/g.


                                                                                              presented in Table 3. The correlation coefficient R2 for the second-order
                                                                                              rate was found greater than the first order and the value of the rate
                                                                                              constant of the pseudo second-order sorption k2 was also found constant.
                                                                                              Thus, the second-order rate expression fits the data most satisfactorily.

                                                                                              3.2. Effect of acidity
Fig. 1. Effect of contact time on the adsorption of gold by the three resins (A/R ratio,25
mL/g; aq. feed, 178.3 mg/L; agitation speed, 140 rpm; temperature, 25oC).
                                                                                                 As the acid concentration in the solution is one of the vital
                                                                                              parameters in the adsorption process, the effect of acidity on gold
and 96.7% for Amberlite XAD-7HP, Bonlite BA304 and Purolite A-500
                                                                                              adsorption by the three resins was investigated. The waste rinse water
resins, respectively. Subsequent increase in contact time had no effect
                                                                                              used for the experiment contained very high acidic content i.e. 7.5 M.
on the gold adsorption. Therefore, 30 min is a sufficient contact time
                                                                                              The pH of the waste rinse water was adjusted by the addition of NaOH.
to reach the adsorption reaction equilibrium for the three resins.
                                                                                              The results presented in Fig. 3 for the adsorption of gold using
Based on the obtained results for adsorption, orders of reaction were
                                                                                              Amberlite XAD-7HP showed that the gold adsorption increased
tested. The results presented in Fig. 2 indicate that the reaction
                                                                                              with decreasing the concentration of acid in the waste solution.
followed the second-order rate.
                                                                                              The dissociation of the gold chlorocomplex is the reason of this
    The pseudo second-order reaction is mostly concerned with the
                                                                                              phenomenon, which can be expressed as
amount of metal on the adsorbent's surface and the amount of metal
adsorbed at equilibrium (Nguyen et al., 2009). The pseudo second-                             HAuCl4 ↔ AuCl4 þ H :
                                                                                                                            –                   þ
                                                                                                                                                                                                                                    ð3Þ
order rate reaction was also analyzed by fitting the same data for gold
adsorption and may be presented by the following equation:                                       The adsorption of the gold complex on Amberlite XAD-7HP can
                                                                                              be proposed in Eqs. (4) and (5) to express the interaction between
dq              2
                                                                                              the protonated oxygen atom of the ester group C_O with gold
   = k2 ðqe −qÞ                                                                       ð1Þ
dt                                                                                            chlorocomplex.
where k2 = rate constant of pseudo second-order sorption (g/mg min).                             In the adsorption of gold from the solution of high acidic con-
Integrating and applying boundary conditions t = 0 and q = 0 to t = t                         centration, the equilibrium tends to shift toward the left side in Eq. (3);
and q = qe, Eq. (1) can be written in linear form as                                          therefore, gold is present in the aqueous solution as non-adsorbable
                                                                                              HAuCl4 species. The adsorption percentage of gold using Amberlite
t   1   1                                                                                     XAD-7HP reached 92.2% at solution pH= 0 (1.0 M H3O+). It should be
  =   +    t                                                                          ð2Þ
q   h   qe                                                                                    noted that Amberlite XAD-7HP resin is an aliphatic ester containing
                                                                                              the C_O group which might be degraded in a high acidic solution
where h = k2 q2 is the initial sorption rate.
                e                                                                             (Gopferich, 1996; Jung et al., 2006), causing the decrease of resin
    The plot of (t/q) against t for the previous equation should give a                       capacity and lifetime. Therefore, the waste solution was partly
linear relationship from which the constants k2 and correlation coefficient                    neutralized to an acidity of 1.0 M H3O+ by adding sodium hydroxide
R2 =1. The comparative results for the first- and second-order rates are                       throughout the gold adsorption experiments using Amberlite XAD-7HP.
                                                                                                 Fig. 3 indicates that the adsorption of gold by the strong base resins
               16
                                                                                              Bonlite BA304 and Purolite A-500 is not significantly affected by
                                                          y = 0.230x + 0.0791                 changes in acid concentration (1.0–7.5 M H3O+) in the solution.
                              y = 0.3441x + 0.1379
               14                                              2
                                                              R =1
                                  R2= 0.999
                                                                                                          CH3               CH3
                                                                                                                                                                                             CH3             CH3
               12                                                                                   CH2 C             CH2 C
                                                                                                                                                                                      CH2 C           CH2 C
                                                              y = 0.231x + 0.0683                         C       O         C       O
                                                                                                                                                                                             C    O          C   OH+
                                                                                                          O                 O
               10                                                    R2 = 1                                                                         +         nH +
                                                                                                                                                                                             O               O
                                                                                                          R
                                                                                                          O
                                                                                                                            R
                                                                                                                            O
                                                                                                                                                                                             R               R                  (4)
                                                                                                                                                                                             O               O
        t/qe




                8                                                                                         C       O         C       O
                                                                                                                                                                                             C    O          C   O
                                                                                                   CH2    C       CH2       C
                                                                                                                                                                                      CH2    C     CH2       C
                                                                                                          CH3               CH3
                6                                                                                                                           n                                                CH3             CH3
                                                                                                                                                                                                                                n


                4                                    Amberlite XAD-7HP
                                                                                                              CH3               CH3
                                                     Bonlite BA304                                                                                                                     CH3               CH3
                                                                                                     CH2 C                CH2 C
                2                                    Purolite A-500                                           C       O         C       OH+
                                                                                                                                                                                CH2 C            CH2 C
                                                                                                                                                                                       C     O           C   O H + A u C l4 -
                                                                                                              O                 O
                                                                                                                                                            n A u C l4 -               O                 O
                                                                                                                                                    +
                0
                    0   10      20       30          40       50        60      70
                                                                                                              R
                                                                                                              O
                                                                                                                                R
                                                                                                                                O
                                                                                                                                                                                        R                R                      (5)
                                                                                                                                                                                       O                 O
                                        Time (min)                                                            C       O         C       O
                                                                                                                                                                                       C     O           C   O
                                                                                                    CH2       C       CH2       C
                                                                                                                                                                                CH2    C         CH2     C
                                                                                                              CH3               CH3
                                                                                                                                                        n
Fig. 2. Fitting of the pseudo-second-order rate for gold adsorption on the three resins.                                                                                               CH3               CH3                        n
164                                                             N.V. Nguyen et al. / Hydrometallurgy 105 (2010) 161–167


                                                                                               and Purolite A-500 resins, respectively. It is observed that the amount
                                                                                               of gold adsorbed per unit mass increased with an increasing amount of
                                                                                               resin and adsorption density. As reported by several researchers,
                                                                                               increasing adsorbent doses provide a greater surface area or ion
                                                                                               exchange sites for a fixed initial solute concentration (Gode and
                                                                                               Pehlivan, 2006; Lin and Juang, 2007).

                                                                                               3.4. Loading capacity

                                                                                                   Studies were carried out to determine the loading capacity of all
                                                                                               three resins. A 1.0-g sample of each resin was contacted at room
                                                                                               temperature with 25 mL of waste rinse water for 30 min in a conical
                                                                                               flask fitted to a controlled shaker. In the case of Amberlite XAD-7HP,
                                                                                               the pH of the waste rinse water was adjusted to zero (acidity = 1.0 M
                                                                                               H3O+). The waste rinse water without pH adjustment was used for
                                                                                               gold adsorption using Bonlite BA304 and Purolite A-500 resins. The
                                                                                               repeated contacts with the same gold-loaded resin were made with
Fig. 3. Effect of acidity on the adsorption of gold. (A/R ratio, 25 mL/g; time, 30 mins; aq.   fresh waste rinse water until a maximum adsorption of gold was
feed, 178.3 mg/L; agitation speed, 140 rpm; temperature, 25oC).
                                                                                               achieved. In the first stage of contact, the adsorption of gold was found
                                                                                               to be 4.1, 4.27 and 4.25 mg gold/g resin with Amberlite XAD-7 HP,
                                                                                               Bonlite BA304 and Purolite A-500 respectively. In the subsequent
    These resins (Bonlite BA304 and Purolite A-500) contain the
                                                                                               stages of contact, the extraction of gold from the aqueous feed
functional group –N(CH3)3–Cl− which is very active at low pH (high
                                                                                               decreased, as the available site for the adsorption decreased in each
acidity) (Helfferich, 1962), giving an ionized group through dissoci-
                                                                                               subsequent contact. A cumulative adsorption at an aqueous to resin
ation. The ion exchange reaction can be expressed as
                                                                                               ratio of 25 in 15, 50 and 57 stages for Amberlite XAD-7HP, Bonlite
                                                                   þ       −
                                                                                               BA304 and Purolite A-500 resins was found to be 58.8 mg, 109.2 mg
R–NðCH3 Þ3 –Cl þ HAuCl4 ↔ R–NðCH3 Þ3 –AuCl4 þ H þ Cl :                                  ð6Þ    and 142.8 mg gold/g resin, respectively. The plot for the loading
                                                                                               capacity of resin for gold is presented in Fig. 5. The macroporous
                                                                                               strong base resin Purolite A-500 has the highest loading capacity in
                                                                                               comparison to XAD-7 HP and Bonlite BA304 resins.
3.3. Effect of resin dose
                                                                                               3.5. Adsorption isotherm
   The gold adsorption behavior of the resins Bonlite BA304 and
Purolite A-500 is not significantly affected by changes in acid con-
                                                                                                  Based on the data obtained from the above loading capacity
centration (1.0–7.5 M) of the solution; therefore, the effect of resin
                                                                                               experiments, the adsorption isotherms were plotted. The Langmuir
dose on gold adsorption was investigated without pH adjustment. In
                                                                                               and Freundlich models are well-known isotherms used to determine
the case of Amberlite XAD-7HP, the maximum adsorption was found at
                                                                                               adsorption phenomena. According to the Langmuir model the uptake
pH = 0, therefore the adsorption studies were carried out by adjusting
                                                                                               of metal ions occurs on a homogeneous surface by monolayer
the waste rinse water pH = 0. In all cases the maximum contact time
                                                                                               adsorption without any interaction between adsorbed ions. The
was maintained at 30 min. A solution volume of 25 mL was used and
                                                                                               model can be presented in linear form as follows:
the resin dose was varied from 0.1 to 3.0 g (8.33–250 mL aqueous
solution/g resin). The results in Fig. 4 indicate that the gold adsorption                     1     1     1     1
increased with an increasing resin dose. With an increase in resin dose                          =       ×    +                                                                  ð7Þ
                                                                                               q   k1 qm   Ce   qm
from 0.1 to 3.0 g, the gold adsorption increased from 51.8%, 63.4% and
62.9% to 94.3%, 98.7% and 99.6% for Amberlite XAD-7HP, Bonlite BA304                           where Ce = equilibrium concentration of metal in the solution (mg/mL),
                                                                                               q = amount of metal adsorbed on the resin at equilibrium (mg/g),




Fig. 4. Effect of resin dose on the adsorption of gold. (time, 30 mins; aq. feed, 178.3 mg/    Fig. 5. Adsorption isotherm of resins for the adsorption of gold. (A/R ratio, 25 mL/g;
L; agitation speed, 140 rpm; temperature, 25oC).                                               time, 30 mins; aq. feed, 178.3 mg/L; agitation speed, 140 rpm; temperature, 25oC).
                                                                       N.V. Nguyen et al. / Hydrometallurgy 105 (2010) 161–167                                                         165

            0.30                                                                                     Table 4
                                                                                                     Constants and correlation coefficients of the Langmuir and Freundlich isotherm for the
                                                                y = 2.0507x − 0.0081
                                                                                                     adsorption of gold using the three resins.
            0.25                                                  R2 = 0.983
                                                                                                       Resin                     Langmuir isotherm             Freundlich isotherm
                        y = 3.1761x − 0.0128
            0.20
                                2
                               R = 0.889                                                                                         k1       qm         R2        kf       n         R2
                                                                                                                                          (mg/g)
                                                                 y = 1.9397x − 0.0068
                                                                                                       Amberlite XAD-7HP         0.0040    78.12     0.889     0.524    1.044     0.927
     1/qe




            0.15                                                         2
                                                                        R = 0.990                      Bonlite BA304             0.0039   123.40     0.983     0.352    0.860     0.980
                                                                                                       Purolite A-500            0.0035   147.05     0.990     1.022    0.980     0.936

            0.10

                                                           Amberlite XAD-7HP
            0.05                                           Bonlite BA304
                                                                                                     to that obtained from theoretical calculation. Therefore, the Langmuir
                                                           Purolite A-500
                                                                                                     adsorption isotherm provides a suitable representation of these
            0.00                                                                                     adsorption data. In the case of Amberlite XAD-7HP and Bonlite
               0.00     0.02        0.04    0.06        0.08      0.10         0.12    0.14          BA304 resins, the correlation coefficient R2 is quite similar for both of
                                                   1/Ce                                              the isotherms. Adsorption data that follow both Langmuir and
                                                                                                     Freundlich isotherms have also been reported by several authors
      Fig. 6. Langmuir isotherm for the adsorption of gold by the three resins.                      (Jha et al., 2008b; Xiong et al., 2009).

kl = equilibrium constant related to the affinity of the binding sites for                            3.6. Determination of breakthrough curve
the metals or the Langmuir constant, and qm = the resin capacity
(maximum possible amount of metallic ion adsorbed per unit mass of                                       The tests for the determination of the breakthrough curve for gold
adsorbent, mg/g).                                                                                    adsorption using the resins Amberlite XAD-7HP, Bonlite BA304 and
    The Freundlich model assumes that the uptake or adsorption of                                    Purolite A-500 were carried out in a column. The breakthrough curve
metal ions occurs on a heterogeneous surface by monolayer                                            for the adsorption of gold takes place when the concentration of gold
adsorption. The model can be described as follows:                                                   in the raffinate begins to increase significantly until it finally reaches
                                                                                                     the same concentration of gold as in the feed waste rinse water. After
            1=n
q = kf C e                                                                                    ð8Þ    this point, no more adsorption takes place. The breakthrough curve is
                                                                                                     considered as the time of completion of the adsorption cycle in a
               1                                                                                     continuous process used for industrial applications (Kose and Ozturk,
log q =          log Ce + log kf                                                              ð9Þ
               n                                                                                     2008). The resin was packed in the column (bed volume,
                                                                                                     BV = 5.0 mL). The flow rate for the waste rinse water as feed solution
where kf and n are Freundlich constants for adsorption capacity and                                  was maintained at 0.88 mL/min. The ratio between concentration of
adsorption intensity, respectively. Ce = equilibrium concentration of                                gold in the raffinate and feed solution (Ce/Co) increased after 90 and
metal in solution (mg/L), and q = amount of metal adsorbed on the                                    95 BV of waste solution passed through the columns containing the
resin at equilibrium (mg/g).                                                                         strong base resins Bonite BA304 and Purolite A-500. The increase in
    The plots ‘(1/Ce) vs. (1/q)’ and ‘log(Ce) vs. log(q)’ were examined to                           the ratio Ce/Co could be explained by the condition that the active sites
validate the experimental data with Langmuir and Freundlich                                          on the resin were decreased. The breakthrough curves for all three
isotherms, as presented in Figs. 6 and 7, respectively. The correlation                              resins are presented in Fig. 8. The corresponding breakthrough
coefficients of the Langmuir and Freundlich isotherms for gold                                        capacity and sorption capacity of the three resins are shown in
adsorption on the three resins are presented in Table 4. For the                                     Table 5. Among the three resins used, Purolite A-500 was found to be
Purolite A-500 resin, the R2 value for the Langmuir model is much                                    the most effective resin for the adsorption of gold from waste rinse
closer to 1 compared with the Freundlich model and the maximum                                       water as its breakthrough capacity and sorption capacity were found
capacity of the resin derived from the experimental data is very close                               to be 16.5 mg and 53.6 mg Au/mL resin, respectively.


               2.5

                                                 y = 1.022x + 0.0096
                                                     R2 = 0.936
               2.0

                                y = 1.1674x − 0.4525
                                      2
                                     R = 0.980
               1.5
      log qe




                                                                 y = 0.9575x − 0.2807
                                                                        R2 = 0.927
               1.0



               0.5                                         Amberlite XAD-7HP
                                                           Bonlite BA304
                                                           Purolite A-500
               0.0
                 0.0       0.5             1.0            1.5            2.0           2.5
                                                 log Ce
                                                                                                     Fig. 8. Breakthrough curves of the three resins for gold adsorption. (bed volume BV,
    Fig. 7. Freundlich isotherm for the adsorption of gold using the three resins.                   5mL; flow rate, 0.88 mL/min).
166                                                           N.V. Nguyen et al. / Hydrometallurgy 105 (2010) 161–167


Table 5
Column performance of the three resins.

                                                  Name of resin

                                                  Amberlite       Bonlite      Purolite
                                                  XAD-7HP         BA304        A-500

  Breakthrough capacity (mg Au/mL resin)           0.35           15.84        16.52
  Sorption capacity (mg Au/mL resin)              11.90           41.17        53.60




3.7. Batch elution test

    The elution experiments were carried out to desorb gold from the
gold-loaded resins. Varying concentration (0.5 to 3.0 M) of hydro-
chloric acid was used. The flasks were shaken for 30 min maximum at
140 rpm and at room temperature (via a temperature controller fitted
to the shaking machine). The result presented in Fig. 9 indicates that
                                                                                             Fig. 10. Elution of gold from the loaded resin using varying mixture concentrations of
hydrochloric acid is not a suitable reagent for the elution of gold as it
                                                                                             hydrochloric acid and acetone (time, 30 mins; hydrochloric acid, 1M; agitation speed,
eluted negligible amounts of gold. Harris et al., 1990 suggested the use                     140 rpm; temperature, 25oC).
of a mixture of acetone and diluted hydrochloric acid for gold elution
from a metal-loaded resin. Rajasingam et al. (2006) used a mixture of
water and dipolar aprotic solvents i.e. acetone + water, dimethylsulf-
oxide + water and N-methyl-2-yrrolidone + water for the elution of
gold from loaded Purolite A-500. The reason for the effective elution
was due to the enhanced activity of Cl− species in dipolar aprotic
solvents, which promotes the formation of metal chloro-complexes
and subsequently increases the selective elution of gold from an anion
exchange resin (Jayasinghe et al., 2005). Therefore, further studies on
the elution of gold from the loaded resins were carried out using a
mixture of acetone and 1.0 M of hydrochloric acid. The result
presented in Fig. 10 indicates that the elution of gold increased with
increasing acetone/acid ratio for all the three resins. With increase in
acetone/acid volumetric ratio from 1.0 to 9.0, the gold elution
increased from 43.3%, 13.8% and 3.3% to 98.1%, 67.8% and 85.3% for
Amberlite XAD-7HP, Bonlite BA304 and Purolite A-500 resins,
respectively.

3.8. Elution in column
                                                                                             Fig. 11. Enrichment of gold using mixtures of acetone and hydrochloric acid (bed
                                                                                             volume BV, 5mL; acetone/acid ratio, 9; flow rate, 0.88 mL/min).
   The elution of gold from the gold-loaded resin was carried out in a
column with the mixture of acetone and hydrochloric acid in column.
The volumetric ratio between acetone and hydrochloric acid was 9.0                           Bonlite BA304, and Purolite A-500 resins. The corresponding gold
and the flow rate was 0.88 mL/min. The results presented in Fig. 11                           concentration in the eluted solution were 7240 mg, 6325 mg and
indicate that the elution could be achieved by up to 98.9%, 68.8%, and                       10,497 mg gold/L, respectively, which are 40, 35 and 59 times more in
88.6% of gold, respectively from the gold-loaded Amberlite XAD-7HP,                          comparison with the concentration in waste rinse water used for the
                                                                                             experiments. Pure gold metal or salt could be obtained from the gold-
                                                                                             enriched solution by acetone evaporation, followed by the electro-
                     3.0
                                                                                             winning of gold or gold precipitation using hydrazine.

                     2.5                                                                     4. Conclusions

                     2.0                                                                         The main goal of this study was the assessment of the performance
                                                                                             of nonionic and strong base resins in order to recover gold from the
       Elution (%)




                                                      Amberlite XAD-7HP
                                                      Bonlite BA304                          waste rinse water of semiconductor industries. The experimental
                     1.5
                                                      Purolie A-500                          results showed that all the three resins are effective for the recovery of
                                                                                             gold (III) from the waste solution. The strong base resins (Bonlite
                     1.0                                                                     BA304 and Purolite A-500) had high adsorption efficiency at high
                                                                                             acidity of solution whereas the nonionic resin (Amberlite XAD-7HP)
                     0.5                                                                     was only effective for the adsorption of gold at low acidity. The elution
                                                                                             efficiency of Purolite A-500 was higher than the Bonlite BA304 resin.
                                                                                             The gold loaded on Amberlite XAD-7HP was easily eluted by a mixture
                     0.0                                                                     of acetone and hydrochloric acid. The gold was eluted from the gold-
                       0.0   0.5   1.0    1.5      2.0      2.5      3.0      3.5
                                                                                             loaded Purolite A-500 resin to yield a gold-enriched solution
                                    HCl concentration (M)
                                                                                             containing 10,497 mg gold/L. The adsorption equilibria of gold on
Fig. 9. Elution of gold from the loaded resin using varying concentrations of hydrochloric   Amberlite XAD-7HP and Bonlite BA304 followed both the Langmuir
acid (time, 30 mins; agitation speed, 140 rpm; temperature, 25oC).                           and Freundlich isotherms; but in the case of Purolite A-500 resin, the
                                                                N.V. Nguyen et al. / Hydrometallurgy 105 (2010) 161–167                                                                167


adsorption data were better represented by the Langmuir isotherm.                              Jayasinghe, N.S., Lucien, F.P., Tran, T., 2005. Ion-exchange equilibria for [Au(CN)2]–/Cl–
                                                                                                    and [Au(CN)2]–/SCN– on Purolite A500 in mixed solvents at 303 K. Ind. Eng. Chem.
The kinetics of gold adsorption on the three resins was found to follow                             Res. 44, 7496–7504.
a second-order rate. From the overall results, the Purolite A-500 resin                        Jha, M.K., Upadhyay, R.R., Lee, J.-C., Kumar, V., 2008a. Treatment of rayon waste effluent
seems promising for the recovery of gold from waste rinse water. A                                  for the removal of Zn and Ca using Indian BSR resin. Desalination 228, 97–107.
                                                                                               Jha, M.K., Nguyen, N.V., Lee, J.-C., Jeong, J., Yoo, J.M., 2008b. Adsorption of copper from
pure gold metal or salt could be obtained from a gold-enriched                                      the sulphate solution of low copper contents using the cationic resin Amberlite IR
solution by acetone evaporation, followed by the electrowinning of                                  120. J. Hazard. Mater. 164, 948–953.
gold or precipitation by hydrazine.                                                            Jung, J.H., Ree, M.H., Kim, H.S., 2006. Acid- and base-catalyzed hydrolyses of aliphatic
                                                                                                    polycarbonates and polyesters. Catal. Today 115, 283–287.
                                                                                               Konishi, Y., Tsukiyama, T., Ohno, K., Saitoh, N., Nomura, T., Nagamine, S., 2006.
Acknowledgments                                                                                     Intracellular recovery of gold by microbial reduction of AuCl− ions using the
                                                                                                                                                                         4
                                                                                                    anaerobic bacterium Shewanella algae. Hydrometallurgy 81, 24–29.
                                                                                               Kose, E.T., Ozturk, N., 2008. Boron removal from aqueous solutions by ion-exchange
   This paper is based on work supported by the Korea Institute of
                                                                                                    resin: column sorption–elution studies. J. Hazard. Mater. 152, 744–749.
Energy Technology Evaluation and Planning (KETEP) under the                                    Latif, E.E., Mustafa, S., Buyuksekerci, E.B., 2003. Separation of gold, palladium and
project entitled "Development of Technology for the Recycling of                                    platinum from metallurgical samples using an Amberlite XAD-7 resin column prior
Valuable Metals from End-of-Life Small Electric & Electronic                                        to their atomic absorption spectrometric determinations. Anal. Sci. 19, 1621–1624.
                                                                                               Lin, L.C., Juang, R.S., 2007. Ion-exchange kinetics of Cu(II) and Zn(II) from aqueous
Equipment".                                                                                         solutions with two chelating resins. Chem. Eng. J. 132, 205–213.
                                                                                               Marczenko, Z., Kowalski, T., 1984. The extraction of gold(III) from nitric acid medium.
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