Nanotechnology for Water Purification and Waste Treatment (PDF)

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					 Nanotechnology for
  Water Purification
and Waste Treatment
     Frontiers in Nanotechnology
US EPA Millennium Lecture Series
                     July 18, 2005
                  Washington D.C.


                Wei-xian Zhang
Acknowledgments
Research Team
Dr. C.B. Wang
Dr. H.L. Lien
Dr. Daniel Elliott
Dr. J. Cao
Y.P. Sun
Xiao-qin Li
Steve Spear
Yu Xue
Steph Kravitz
Patrick Clasen
Tim Marks            R829624
Jason Chen
Nanotechnology is…                                         C60
the art and science of manipulating matter               (~ 1 nm)
at the atomic or molecular scale
Size
A billionth (10-9) meter

Structure
                                                       Human
How things are put together -- arranged or
assembled.                                             (~1 m)

Novel properties
Novel and significantly changed
physical, chemical, and biological
properties
                                         Moon orbit
   The ultimate goal of                      (109 m)
nanotechnology is to build
 essentially anything from
  scratch, atom by atom
Nanoscale has already been with our
           profession …
   Nanoscale Materials:
   Ultrafine Water and Air Contaminants?
      H2 0            Hemoglobin           Virus        Microbial Cells     Protozoa
   (0.2 nm)             (7 nm)          (10-100nm)         (~1 µm)          (>2 µm)



    !                        !                !                     !       !
                                                                             Conventional filtration

                                                 Microfiltration


                      Ultrafiltration


         Reverse Osmosis



0.1 nm         1 nm           10 nm          100 nm                1 µm         10 µm           100 µm
                                             "                          "                  "

                                        Bacteriophage                PM 2.5              Pollens
                                           (80 nm)                 (aerosols)          (10-100 µm)

                                          Micropollutants
                               Nanopollutants
    A Research Framework for NanoEnvironTech

                Promote Applications
             reactive to existing problems
                           or
       proactive in preventing future problems.



                 Forecast Implications of
interactions of nanomaterials with the environment and
     possible risks that may be posed by the use of
                     nanotechnology.

                                       B.Karn, 2005, ACS
applications

       Sensors
       Treatment
       Remediation
       Green manufacturing
       Green energy


implications

      Natural nano processes
      Fate, transport, and transformation
      Lifecycle aspects
      Toxicology
      Exposure, bioavailability, and bioaccumulation
Nanotubes as SuperSorbent
SWNT for Dioxin Sorption
(Long & Yang, 2001, JACS)

  Sorbent    E (kJ/mol)   B (atm-1)

  SWNT          315       2.7x1052

 Activated      119       1.3x1018
  Carbon
  !-Al2O3       47.9      4.5x105
                      Nanocomposites

                        - Nanosorbents
                        - Nanoreactors
                            Pacific Northwest
                            National Laboratory




J. Am . Chem . Soc.
2002, 124,
11242−3
Sensing and Detection

Biological pathogens, heavy metals, organics, etc.




                                            IBM, Zurich
 Chad Mirkin, Northwestern
Nanocontact Sensor
N.J. Tao (Arizona State)




                 Atomic Scale!

                    Sensitivity:
   The electrodes are separated with an atomic-scale gap,
            so a few ions can be detected.
An Array of Atomic-Scale Gaps


                                        before




                                        after


Si3N4 / Au / SiO2 / Si   SEM images


                           N.J. Tao (Arizona State)
ES&T Feature Article
  March 1, 2003
ES&T, 2003, 37 (5),
   73A - 112A
                                                      Iron Nanoparticles
                                            for Water & Wastewater Treatment




       C2HCl 3               C2H6 + 3Cl -
                             5[H]
                        e-
Fe2+

                 <100 µm



                  Fe0

                                    Pd 0
         Advantages of Nano
         Remediants
Highly mobile

Highly Reactive

Shorter cleanup time & lower cost
A little history …

• Summer 1995 - original concepts

• July 1996 - Sodium borohydride method

• April 1997 - 1st paper (ES&T)

• Summer 2000 - 1st pilot test

• > 15 projects so far in U.S.
Nano Iron
 Effective reductant
 Widely used in PRBs

 Nontoxic

 Cheap




Key property - Efficient Electron Donor
    0                      2+            -
Fe         !           Fe       + 2e
                 ÷8


                                             N = 4096
                                             n = 2368

   N = 4096
   n = 1352




                                  ÷8




                                  N = 4096
                                  n = 3584




N: number of total atoms, n: number of surface atoms
27 Fe atoms - 26 (93.3%) on surface
1 nm     1 nm
       A Cube of 64 Fe atoms
       56 (87.5%) on surface
                                Surface Atoms




                                n
        n



   number of surface atoms 2n 2 + (n " 2)[n 2 " (n " 2)2 ]
D=                        =                3
                                                           #100
    total number of atoms                n
                  % Atoms on Surface
        100
         90
         80
         70
         60
D (%)




         50
         40
         30
         20
         10
          0
              1    10   100   1,000   10,000      100,000   1,000,000

                               nm


                                               Calculations for Fe
Methods of Synthesis
             Block
             materials




Top-down




            nanomaterials



Bottom-up


            Atoms or
            molecules
  Nano Iron for Remediation

• Materials Chemistry
  – Synthesis

• Environmental Chemistry
  – Contaminant degradation

• Geochemistry
  – Fate and transport
 Properties of Nano Fe

• Size range: 10-100 nm
• Mean Size: 60 ± 15 nm
• Specific surface area
  – 10-50 m2/g
• Zeta potential
  – 10 to -30 mV
  Properties of Nano Fe

Nominal Reaction Rate (Ω)
  0.1-1 mg TCE/g nanoFe/hour
  @ 22°C
  @ 1-100 mg/L TCE
  @ pH=7
Lindane (HCH, C6H6Cl6)
                 )
(Sample from Jacksonville, FL)
(5 g/L Fe)
Perchlorate (ClO4-)
(Sample from Phoenix, AZ)
Cr(VI)Reduction
COPR Samples from an industrial site in NJ
Aqueous Cr(VI) - 43.38 mg/L, Soil CrT - 7,725 mg/kg, pH = 11
       Cr(VI) Reduction/Immobilization

                Micro Fe        Nano Fe
                (~10 µm)        (~50 nm)

Rate             0.0063        0.157±0.018
               mgCr/m2/min    mgCr/m2/min


Capacity        1.53-1.75      84.0-109.3
               mg Cr/g Fe      mg Cr/g Fe
Carbon Tetrachloride (CT)
(CCl4, 14.5 mg/L, S. Charleston, WV)
Contaminant Degradation

Chlorinated Methanes    Cr(VI)
Chlorinated Ethenes     Pb(II)
Chlorinated Ethanes     Ni(II)
Chlorinated Benzenes    Cd(II)
PCBs                    Perchlorate
Lindane (HCHs)          As

> 100 compounds tested at Lehigh so far
Enhance Activity by Catalysts

             C2HCl 3               C2H6 + 3Cl -


                                   5[H]


                              e-
      Fe2+


                       <100 µm




                        Fe0




                                                  Pd 0
   Enhance Activity
by Porous Nanoparticles


           • Large surface area
           • Better hydraulics
           • High mobility
                 Synthesis of Porous
                   Nanoparticles
                   Self-assembling Template


                  MXn / M(OR)n

                                             Template
Preformed LC                                 Removal
(Liquid
crystal)
mesophase

MXn / M(OR)n
                            Mesostructured              Mesoporous
                            Hybrid network                 iron

  Surfactant (Template)
Template-directed Synthesis



                     0.4 mm
        Surface Areas

       Fe           SSA (m2/g)

Aldrich (~0.4 mm)     0.0012

 BASF (~1 µm)          1.5

 NanoFe (60 nm)       20-40

  Nanoporous         142-250
              Manipulate Nanoparticle
                     Mobility

 Nano Fe




                             Aquifer
                            Materials

Groundwater
   Flow
Dispersion


  Attachment




 Steric Repulsion




   Electrostatic
    Repulsion
               Dispersed
               Nanoparticle



Original
Nanoparticle
                                     Dispersion



                Fe
                          Fe
                                      Poly(vinyl alcohol-co-vinyl acetate-co-itaconic acid)
                     Fe
         Fe                     Fe
               Fe
                          Fe
                     Fe
          Fe
                               Fe
                     Fe




Iron Nanoparticle Aggregates
COSTS

        Iron Filings


          $0.5/kg


        <10 m2/kg


    <20 m2/dollar
COSTS
        Iron Filings     Nano Iron


           $0.5/kg        ~$25/kg


         <10 m2/kg      ~25,000 m2/kg


        <20 m2/dollar      ~1,000
                          m2/dollar
                COSTS

Iron Filings     Nano Iron       Porous Iron


   $0.5/kg        ~$25/kg          ~$50/kg


 <10 m2/kg      ~25,000 m2/kg   ~200,000 m2/kg


<20 m2/dollar      ~1,000          ~4,000
                  m2/dollar       m2/dollar
Conceptual Geologic and
 Hydrogeologic Model
             Field Applications
     (11 projects so far, >10 Planned for 04’)

            Flowmeter
                                   Nanoparticle
                                   Suspension
                                   (400 L)



 Building

                                                                     3.0 m
Groundwater
Flow
       Injection                                                     6.0 m
       Well                     PZ-1           PZ-2           PZ-3
                        1.5 m          1.5 m          1.5 m
Conceptual Model
The Nano Fe Slurry
     (1-2 g/L)
Test Set-up
ORP 2/4/02



Before                           Oxidative
Nano Fe                          Environment
Application




              +100 to + 400 mV
              ORP 2/11/02



Right after
Nano Fe
Application




               0 to + 400 mV
               ORP 2/19/02




1 week after
Nano Fe
Application



                -200 to + 400 mV
                ORP 3/4/02




3 weeks after
Nano Fe                             Reducing
Application                         Environment



                 -500 to + 400 mV
                                          Sampling Results
                                            TCE - MW-4
 Injection of 11 kg of                                         No Additional Treatment
     BNP (2 Days)                                              Passive In-Situ Treatment
                        20,000                                                                                      100%


     18,000
 Pre-treatment                                                                                                      90%
Concentrations
                        16,000                                                                                      80%


                        14,000                                                                                      70%




                                                                                                                           Percent Reduction [%]
 Concentration [ug/l]




                        12,000                                                                                      60%


                        10,000                                                                                      50%


                         8,000                                                                                      40%


                         6,000                                                                                      30%


                         4,000                                                                                      20%


                         2,000                                                                                      10%


                            0                                                                                       0%
                                 -5   5     15            25                 35            45             55   65
                                                               Time [days]



                                             TCE [ug/l]                                         TCE [%]
     Sampling Results
TCE and cis-1,2-DCE at MW-4
 Injection of 11 kg of                                                  No Additional Treatment
     BNP (2 Days)                                                       Passive In-Situ Treatment
                        20,000                                                                                                   100%


     18,000
 Pre-treatment                                                                                                                   90%
Concentrations
                        16,000                                                                                                   80%


                        14,000                                                                                                   70%




                                                                                                                                        Percent Reduction [%]
 Concentration [ug/l]




                        12,000                                                                                                   60%


                        10,000                                                                                                   50%


                         8,000                                                                                                   40%


                         6,000                                                                                                   30%


                         4,000                                                                                                   20%


                         2,000                                                                                                   10%


                            0                                                                                                    0%
                                 -5   5                15          25                 35             45        55           65
                                                                        Time [days]



                                          TCE [ug/l]        cis-1,2-DCE [ug/l]             TCE [%]        cis-1,2-DCE [%]
                                  Comparison:
                           Bioremediation - and Nano Fe
                0.14
                                                                                                                                                                                                                                        Re-bioaugmented day 125
                                                                                                                                                                                                                                                                                                          TCE
                0.12
                                                                                                                                                                                                                                                                        Re-bioaugmented day 182
                                                                                                                                                                                                                                                                                                          cis-DCE
                 0.1
                                                                                                                                                                                                                                                                                                          VC
mmol / bottle




                0.08


                0.06
                            TCE                                                                                                                                                                                                                 DCE
                                                                                                                                                                                                                                                                                                          ethene



                0.04                                                                                                                                                                                                                                                                              Ethene
                0.02


                  0
                       0                                                                                                                           50                                                                                  100                        150                      200      250
                                                                                                                                                                                                                                              time (in days)



                                           60 Days                                                                                                                                                                                                                       Bioremediation
                            TCE Concentrations




                                                                                                                                   –
                                                                                                           No Additional Injections Passive In-Situ BNP Treatment
                              Pre-Treatment




                                                        15,000                                                                                                                                      100%
                                                                    Injection of 11 kg of BNP (2 days)




                                                        12,000                                                                                                                                      90%

                                                                                                           1-Day Response to
                                                                                                             BNP Injection
                                                                                                                                                                                                           TCE Percent Reduction [%]
                             TCE Concentration [ug/l]




                                                         9,000                                                                                                                                      80%




                                                         6,000                                                                                                                                      70%




                                                         3,000                                                                                                                                      60%




                                                            0                                                                                                                                        50%
                                                            -5.00                                        5.00            15.00           25.00         35.00          45.00           55.00      65.00
                                                                                                                                            Date and Time


                                                                                                                BNP-4 TCE Concentrations [ug/l]                BNP-3 TCE Concentrations [ug/l]
                                                                                                                BNP-4 TCE Reduction [%]                        BNP-3 TCE Reduction [%]




                                                                                                                                                                                              Nano Fe
                                                                                                                                                                                60 Days
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