Noble metal nanomaterials for water purification

Transcription

1 Now in the 52 nd year Noble metal nanomaterials for water purification T. Pradeep Department of Chemistry and Sophisticated Analytical Instrument Facility Indian Institute of Technology Madras Chennai , INDIA MRS-S Trilateral Conference on Energy, Water and Healthcare Singapore August 11-13, 2010

2 New materials Old materials 50 nm T. U.B. Rao and T. Pradeep, Angew. Chem. Int. Ed. 2010; JACS (under revision) 2010; Nanoscale 2010 (in press); Habeeb Muhammed et al. Chem. E. J. 2009; 2010 Faraday s gold preserved in Royal Institution. From the site,

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5 A B 1 nm 1 nm 4.8 nm 7.8 nm 0.1 µm 20 nm E. S. Shibu et al. Adv. Mater. 2008; Nano Res. 2009; Chem. Mater. 2009

6 Fluorescent superlattices E. S. Shibu et al, Adv. Mater. 2008; Nano Res. 2008, Chem. Mater.; 2009

7 P. R. Sajanlalal and T. Pradeep Nano Res. 2009; JPC C 2009; 2010

8 A B Intensity Au Ag Distance (nm) 1 µm 1 µm AuAg C D 500 nm 500 nm AuAg

9 For several of our concerns on water, such materials offer solutions There is indeed a need. Market is ripe. Solutions exist. What is the problem then?

10 One can look at India in many ways Political map

11 Groundwater depletion Low water Fluoride quality contamination (a) (b) (c) (d) (a) Satellite-based estimates of groundwater depletion in India, Matthew Rodell, Isabella Velicogna & James S. Famiglietti, Nature 460, (20 August 2009) (b) Environmental Atlas of India, Central Pollution Control Board ( org/pdf_map%20ga llery/ground%20wat er%20quality.pdf) (c) Census 2001 (d) India assessment 2002, Water Supply and Sanitation A WHO and UNICEF Joint Study. Lets us take a look at India from the perspective of (a) Ground water availability (b) Water quality (c) Population and (d) water contamination due to fluoride We have a problem; can nanotechnology help?

12 India has a long tradition in clean water Mohenjodaro - well Mohenjodaro the great bath

13 Gas hydrates to ozone chemistry

14 2 nm

15 Regulatory coverage of USEPA for safe drinking water has increased over 4 times since its inception, with revisions in regulations of many old contaminants Problems -1

16 Problems -2 Future of water purification: An enigma with some pointers 1 Candidate contaminant list Contaminants regulated by EPA r q p o n m g e c a l k j i h f d b Label for contaminants Number of contaminants (a): Halogenated organic (b): Metal (c): Organochlorine pesticide (d): Inorganic salt (e): Biological contaminant (f): Nuclear (g): Benzo derivative (h): Carbamate pesticide (i): Pesticides (others) (j): Unclassified (k): Triazine derivative pesticide (l): Organophosphorus pesticide (m): Organobromine pesticide (n): Non-metal (o): Nitrophenol derivative, (p): Dioxin, (q): Benzo and halogenated organic (r): Organometallics Category-wise distribution of contaminants regulated by USEPA and future contaminants Continued focus of USEPA regulatory activities on various other halogenated organics found in drinking water. The allowed concentration limits for a number of species may shift to subppb range. Source: and

17 Future of water purification: Shrinking limits for allowed concentration of contaminants in water Problems - 3 Concentration (in ppb) Lead Arsenic Year Changes in maximum allowable concentration for lead and arsenic in drinking water, based on WHO advisory

18 Nanotechnology holds the future for effectively removing many drinking water contaminants - Number of contaminants present in extremely low concentration range (< molecules per glass of water) are quite significant - Many of those contaminants contain C-Cl bond or are metallic in nature

19 Permissible contamination molecules Time Permissible contamination reaches limits of detection

20 Important milestones in the history of water purification ( ) Year 1804 Milestone Setup of world's first city-wide municipal water treatment plant (Scotland, sand-filter technology) 1810 Discovery of chlorine as a disinfectant (Humphrey Davy) 1852 Formulation of Metropolis Water Act (England) 1879 Formulation of Germ Theory (Louis Pasteur) 1902 Use of Chlorine as disinfectant in drinking water supply (calcium hypo chlorite, Belgium) 1906 Use of ozone as disinfectant (France) 1908 Use of Chlorine as disinfectant in municipal supply, New Jersey 1914 Federal regulation of drinking water quality (USPHS) 1916 Use of UV treatment in municipal supplies 1935 Discovery of synthetic ion exchange resin (Adams, Holmes) 1948 Nobel Prize to Paul Hermann Müller (insecticidal properties of DDT) 1959 Discovery of synthetic reverse osmosis membrane (Yuster, Loeb, Sourirajan) 1962 Publishing of Silent Spring, first report on harmful effects of DDT (Rachel Carson) 1965 World's first commercial RO plant launched 1974 Reports on carcinogenic by-products of disinfection with chlorine Formulation of Safe Drinking Water Act (USEPA) 1975 Development of carbon block for drinking water purification 1994 Report on use Zerovalent Iron for degradation of halogenated organics (Gillham, Hannesin) 1997 Report on use Zerovalent Iron nanoparticles for degradation of halogenated organics (Wang, Zhang) 1998 Drinking Water Directive applied in EU 2000 Adoption of Millennium Declaration during the UN Millennium Summit (UN Millennium Development Goals) 2003 Report on use Noble metal nanoparticles for degradation of pesticides (Nair, Tom, Pradeep) Last globally big invention in water purification There is a gap and technology is waiting 2004 Stockholm Convention, banning the use of persistent organic pollutants 2007 Launch of world's first nanotechnology based domestic water purifier (Pradeep, Eureka Forbes Limited) Credits to several governments, organizations and individuals, we have moved ahead. The journey of pure water for all calls for next big innovation. Source: Multiple sources from internet

21 Chapter by T. Pradeep and Anshup

22 Illustration of metal adsorption on nanoparticle surface (ZVI surface) TEM image of Fe nanoparticle and Cartoon representation of chemistry at Fe nanoparticle, Iron Nanoparticles: the Core-Shell Structure and Unique Properties for Ni(II) Sequestration, Xiao-qin Li and Wei-xian Zhang, Langmuir 2006, XPS wide-scan survey of iron nanoparticles after exposure to a metal salt containing solution, Sequestration of Metal Cations with Zerovalent Iron Nanoparticless A Study with High Resolution X-ray Photoelectron Spectroscopy (HR-XPS), Xiao-qin Li and Wei-xian Zhang, J. Phys. Chem. C 2007, Cartoon representation of chemistry at Fe nanoparticle surface (left) and metal ion removal efficiency for different adsorbents, Iron Nanoparticles: the Core-Shell Structure and Unique Properties for Ni(II) Sequestration, Xiao-qin Li and Wei-xian Zhang, Langmuir 2006,

23 All inclusive affordable water purifier using nanomaterials Microbes Organics Heavy metals Anions Not purification alone Sensing End of life indicators Visual inspection Salinity Affordable? < 5 paise per litre at point of use Green Water based synthesis, maximum temperature ~ 65 o C, scalable locally, back to nature after use

24 (L) Silver nanoparticles coated on activated alumina (R) Photograph of a pesticide filter device using supported nanoparticles (WQA certified) Noble metal nanoparticles: removal of pesticides from water A.S. Nair, T. Pradeep, Curr. Sci. 84 (2003) 1560 Absorbance a o p b A Wavelength (nm) B Variation of the UV-visible absorption spectrum of silver nanoparticles upon the addition of CCl 4 [V] CP [mv] (a) Time 2 (min) 4 Time (min) Gas chromatogram of chlorpyrifos solution (L) and after treatment with silver nanoparticles (R) 0 A.S. Nair, R.T. Tom, V.R. Rajeev Kumar, C. Subramaniam, T. Pradeep, Cosmos 3, (2007) 103 (b) Indian patent 2004 June 2007

25 Product is marketed now Cartridges are recovered after use A pesticide test kit has been developed > 25 ppb

26 Noble metal nanoparticles: removal of heavy metals from water T. Pradeep et al (unpublished) (a) 0.10 Absorbance 0.05 (viii) (ix) (i) (ii) Wavelength (nm) (b) (b) 5 μm (a) UV-vis absorption spectra of silver nanoparticles (i) before Hg 2+ treatment (ii-ix) after Hg 2+ treatment. (b) Large area SEM image of the Ag-Hg bimetallic nanoparticles (a) (b) (c) 2 μm Ag Si Hg Si (a) SEM image of an Ag-Hg alloy nanoparticle, (b) elemental image of Ag and (c) elemental image of Hg overlaid on Si (Si is from ITO substrate).

27 Noble metal nanomaterials: detection of toxic species M. Mulvihill, A. Tao, K. Benjauthrit, J. Arnold, P. Yang, Angew. Chem. Int. Ed. 47 (2008) 6456 K.P. Lisha, Anshup, T. Pradeep, J. Environ. Sci. Health B. (in press) (a) SERS Intensity Raman Shift (cm -1 ) (b) SERS Intensity PVP BT HDT MDA Raman Shift (cm -1 ) (c) SERS Intensity As III + As V As V Raman Shift (cm -1 ) SERS spectra of arsenate ion (1X10-6 M) on (a) LB films of silver nanocrystals (b) LB arrays of silver octahedra coated with various organic species. BT: benzenethiol, HDT: hexadecanethiol, MDA: mercaptodecanoic acid. (c) SERS-based speciation of arsenate and arsenite ions (18 ppb) (A) a b c d e f Au a+na 2 SO 4 b+50 ppb b+100 ppb b+500 ppb CP CP CP a b c d e f b+1 ppm CP (B) a b c 0.1 c b 0 a nm 50 nm (c) 50 nm (C) Wavelength (nm) Colorimetric detection of chlorpyrifos using the gold nanoparticle-na 2 SO 4 system Absorbance d f e

28 Conclusions from our studies (a) (b) (c) 10 1/nm 2.45 Å 100 nm 50 nm 5 nm 1. Bulk materials used for water purification can be made efficient MnO 2 Lisha et al. Chem. Eng. J. 2010, 160, 432.

29 A B E 30 µm 5 µm C D Si Au Si Hg 2. Nanomaterials have much larger capacity for scavenging SEM images of mercury treated gold nanoparticles. (A) Large area image, (B) magnified image of few particles, (C) elemental map of Au, (D) elemental map of Hg and (E) EDAX spectrum of mercury treated gold nanoparticles. Inset is the composition table. Lisha et al. Gold Bulletin. 2009, 42, 144.

30 3. Monolayer makes a difference in metal ion removal M. S. Bootharaju and T. Pradeep, J. Phys. Chem. C 2010, 114, 8328.

31 A B Ag(111) 50 nm 5 nm 4. Size of core makes a difference Sumesh et al. Submitted.

32 Concentration (ppb)1500 1:6 1: Volume passed (L) Sumesh et al. Submitted.

33 5. Graphene offers a number of possibilities

34 1.0 GRP MnO 2 A 1.0 GRP Au B Absorbance 0.5 KMnO 4 GRP GRP+0.01 mm KMnO 4 GRP mm KMnO 4 GRP+0.05 mm KMnO 4 GRP+0.1 mm KMnO 4 GRP+0.3 mm KMnO 4 KMnO 4 Absorbance 0.5 GRP GRP+0.01 mm Au 3+ GRP mm Au 3+ GRP+0.05 mm Au 3+ GRP+0.1 mm Au Wavelength (nm) Wavelength (nm) 1.0 GRP Ag GRP C 1.0 D Absorbance 0.5 GRP GRP+0.01 mm Ag + GRP mm Ag + GRP+0.05 mm Ag + GRP+0.1 mm Ag + Absorbance 0.5 GRP GRP+0.01 mm Pt 2+ GRP mm Pt 2+ GRP+0.05 mm Pt Wavelength (nm) Wavelength (nm) Figure: UV/Vis spectra of RGO upon the addition of metal ions. A) KMnO 4, B) Au 3+, C) Ag +, and D) Pt 2+. Absorption at 270 nm for RGO and the changes due to the formation of MnO 2, Au, Ag and Pt nanoparticles can be seen. Spectral changes are marked. Pt nanoparticles do not show a distinct Plasmon absorption Sreeprasad et al. Submitted

35 A B 0.2 µm 50 nm 5 nm Figure: TEM images of RGO-MnO 2 (0.05 mm) showing at various magnifications nanoparticles attached to RGO. Folded RGO sheets are marked with arrows in A. Sreeprasad et al. Submitted

36 Figure: TEM images of RGO-Ag (0.05 mm) showing well dispersed nanoparticles over a RGO sheet Sreeprasad et al. Submitted

37 Figure: Concentration dependent TEM images of RGO-MnO2.A1) 0.01 mm, A2) mm and A3) 0.05 mm and RGO-Ag B1) 0.01 mm, B2) mm and B3) 0.05 mm. Insets in all figures show the lattice resolved images taken from the same sample. All scale bars in the inset correspond to 5 nm. Sreeprasad et al. Submitted

38 A B Intensity (a.u) GO G G+0.01 mm KMnO 4 G mm KMnO 4 G+0.05 mm KMnO 4 G mm KMnO 4 G+0.1 mm KMnO Intensity (a.u) GO G G+0.01 mm AgNO 3 G mm AgNO 3 G+0.05 mm AgNO 3 G mm AgNO Wavenumber (cm -1 ) G+0.1 mm AgNO 3 Wavenumber(cm -1 ) Figure: Raman spectra of A) RGO-MnO 2 composite and B) RGO-Ag composite, at different loading of MnO 2 and Ag. Peak positions are marked. Sreeprasad et al. Submitted

39 A 1 A 2 A 3 B 1 B 2 B 3 C 1 C 2 C 3 Figure: XPS spectra of samples containing 1) mm, 2) 0.05 mm and 3) 0.1 mm KMnO 4. A) C 1s, B) O 1s, and C) Mn 2p regions. Sreeprasad et al. Submitted

40 A B Intensity C (d) (c) (b) (a) D Wavenumber (cm -1 ) Figure: SEM Images of A) Ch-RGO-Ag@RS, B) Ch-RGO-MnO inset in A shows an SEM image of bare sand particles before coating.c) Raman spectrum of (a) RS, (b) Ch, C) Ch-RGO- MnO and (d) Ch-RGO-Ag@RS. D) Photograph of RS, Ch-RGO-MnO and Ch-RGO- Ag@RS showing the color change. Sreeprasad et al. Submitted

41 A B Kd ( L/g) 2000 Kd ( L/g) RGO GO AC RGO- MnO2 Adsorbents RGO- Ag AC- MnO2 AC-Ag 0 RS Ch Ch-RGO- Ag@RS Adsorbents Ch-RGO- MnO2@RS Ch@RS C 1 RGO-MnO2 D Groundwater Distilled water 0.8 RGO-Ag RG0 100 Hg(II) ccon. ( mg/l) 0.6 GO Ch-RGO-Ag@RS Time (min) Hg(II) removed (%) Ch-RGO- Ag@RS Ch-RGO- MnO2@RS RGO-MnO2 Adsorbents RGO-Ag Figure: A) Comparison of Kd values obtained for the adsorption of Hg(II) of unsupported RGO composites with different materials examined. B) Comparison of Kd values obtained for the adsorption of Hg(II) of supported RGO composite with RS, Ch, Ch@RS. C) Kinetics of Hg(II) adsorption by various adsorbents (temperature = 30 2oC; ph = 7 0.2, initial Hg(II) conc. = 1 mg/l). D) Performance comparison of RGO composites for removing Hg(II) from distilled water and real water (initial Hg(II) conc. = ~ 1 mg/l. Sreeprasad et al. Submitted

42 A 10 B q t (mg/g) P- RGO-Ag E - RGO P - RGO E - GO P - GO E - RGO-Ag E - RGO-Mn P - RGO-Mn Time (min) q t (mg/g) E - Ch-RGO-MnO2@RS P - Ch-RGO-MnO2@RS E - Ch-RGO-Ag@RS P - Ch-RGO-Ag@RS Time (min) Figure: Pseudo-first-order kinetic plots with experimental data for adsorption of Hg(II) by GO, RGO and various RGO composites (E experimental, P predicted) A).unsupported and B) supported form. Sreeprasad et al. Submitted

43 6. Halogen and silver free antimicrobial media (A) SEM and (B) TEM images at various magnifications of virus removal media, and [A (d) ] shows the UV-vis spectra of various virus removal compositions

44 350 nm 550 nm 550 nm 640 nm TUB Rao and T Pradeep, Angew. Chem. Int. Ed Habeeb Muhammed et al Chem. Eur.J.2009; 2010

45 White light RT UV light T

46 Current developments Purifiers for specific areas local issues seasonal problems All inclusive solutions Local manufacture Sustainability Nanomaterial toxicity Community involvement NGOs

47 Ongoing field trials Ongoing field trials of fluoride treatment unit (domestic unit) at Kotlapalli, Anantapur, Andhra Pradesh Date: August 07, 2010

48 Several new technologies Nanotubes Dendrimers Magnetic particles Membranes Self organised structures Capacitive deionization E. F. Schumacher Pure water can be affordable..

49 A technology solution may appear to you in one of these forms Aquasure Supreme 1800 Aquasure Supreme 3000 Aquasure Royal 3000 Forbes Futura Aquasure Mobile Water purifier Aquasure Storage 4-in-1 Aquasure Storage UV Pureit Tata Swach Genzon Water Aquasure Steel Kenstar

50 For ultimate nanotechnology solutions, more work is needed Crystallographic structure of the aquaporin 1 (AQP1) channel Schematic depiction of water movement through the narrow selectivity filter of the aquaporin channel

51 On collaboration New sensors for ultralow sensing in water Visual displays Sustainable purification technologies; combining solar, membrane and materials Water harvesting Aquaporins On water nations can indeed come together!

52 IIT Madras Nano Mission, Department of Science and Technology World Gold Council Well-meaning individuals, Companies IGCAR Field trials Thank you all Noble metal nanoparticles for water purification: A critical review, T. Pradeep and Anshup, Invited Feature, Thin Solid Films, 517 (2009)

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