nanotechnology in waste water treatment
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Nanotechnology in wastewater treatment
Nanotechnology in wastewater treatmentPresented by , Guided by, ANOOPA ANN THOMAS Dr .MARY LUBI C GCANECH010
Water, Water every where but not a drop to drink! Over 75% of the earth surface is covered in water 97.5% of this water is salt water, leaving 2.5% as fresh water.
Nearly 70% of the fresh water is frozen in the icecaps of Antartica and Greenland; most of the remainder is present as soil moisture or as groundwater not accessible to human use.
Less than 1% of the worlds freshwater is accessible for direct human uses.
What we need?????
Why wastewater treatment???
Depleting water resources
Climate change resulting in prolonged droughts and floods.
CONVENTIONAL WASTEWATER TREATMENT METHODS
Coagulation Chlorination Flocculation Lime softening Ozonation Membrane separation processes etc....
Why research is still going on?????
Day to day Change in wastewater composition Requirement of stable methods Requirement of economical methods Requirement of effective methods Search for reliable methods
UNSOLVED TECHNOLOGY PROBLEMS......Mercury contamination, Minamata, Japan, 1956Microbial contamination, Zimbabwe, 2009Pesticide contamination, Kerala, 2001Fluoride contamination, India, 2003
What is nanotechnology??
The creation of functional materials ,devices and systems through control of matter on the nanometer length scale (1-100nm), and exploitation of novel phenomenon and properties (physical, chemical and biological ) at that length scale.
NANOPARTICLES IN WASTEWATER TREATMENT Dendrimers Metal nanoparticles Zeolites Carbonaceous nanomaterials
Size 1-20 nm Globular shape Structure 3 regions Dendrimers differs in structure Presence of interior voids
Eg: PAMAM (Polyamidoamine) dendrimers Ethylene Diamine (EDA) core and terminal NH2 groups can recover Cu ( II ) ions from aqueous solutions. Cu (II), Ni (II) and Cr (III) can be removed.
Metal nanoparticles Magnesia nanoparticles (5-100 nm): Effective biocide against gram positive and gram negative bacteria and bacterial spores
Gold nanoparticles (20-100nm): Palladium coated nanoparticles are effective catalyst for removing TCE (Trichloroethane) from groundwater.
Silver nanoparticles (1-40nm) : acts as an anti-microbial, anti-biotic and anti- fungal agent
Zeolites Zeolite nanoparticles are prepared by laser- induced fragmentation. An effective sorbent and ion exchange media for metal ions.
Porous structure Can accommodate variety of cations Na+,K+,Ca2+,Mg2+ etc....... These ions can be readily exchanged NaP1 zeolites (Na6Al6Si10O32.. 12H2O) have a high density of Na+ ion- exchange sites.Experiments have reported the successful use of synthetic NaP1 zeolites to remove Cr (III), Ni (II), Zn (II), Cu (II) and Cd (II) from wastewater.
High capacity selective sorbents for organic solutes Shows antibacterial properties Includes polymers like azidated polyvinyl chloride, PEG polymer, Polyethylene mine (PEI) etc... Polymers are poly cationic agents
HOW IT SHOWS ANTIBACTERIAL ACTIVITY????
Occurrence of new micro contaminants is a challenge to mankind. Nanoparticles have the ability to penetrate into the cell cytoplasm. Positively charged materials are absorbed on negatively charged cell surfaces. Disruption of cell membranes
MECHANISMS OF REMOVING POLLUTANTS
Nanosorption Nanofiltration Photocatalysis
Nanoparticles have larger surface area. It can be enhanced with various reactive groups to increase their chemical affinity towards target compounds. Activated carbon is the widely used adsorbent in conventional methods. Higher efficiency with the use of CNTs and metal based nanosorbents
Major drawbacks of activated carbon Contains a significant number of micropores inaccessible to bulky organic molecules. Low affinity for low molecular weight polar organic compounds.
Carbon nanotubes (CNTs) & Metal nanosorbents
From planar sheet of graphite (Graphene) Available surface area for adsorption on individual CNTs is their external surfaces. Hydrophobicity of graphitic surface. Peng (2005) discovered Cerium oxide supported CNTs are effective sorbents for arsenic . Nanomaterials can remove heavy metals. Metal based nanosorbents are used for the removal of arsenic.
NANOFILTRATION A pressure driven membrane separation process. Falls between ultrafiltration and reverse osmosis. Low pressure membrane process (7-30 bar) Nanofiltration membrane has pore size 1-5 nm Higher flux rate Allows the transmission of monovalent ions but multivalent ions are largely retained.
Nanofiltration membranes have been shown to remove Turbidity Microorganisms Inorganic ions (Ca , Na) Nitrates and arsenic from groundwater Organic pollutants Carbon nanotube filters Nanoceramic filters
PHOTOCATALYSIS An advanced oxidation process Major barrier for its wide application is slow kinetics TiO2 is the most widely used photocatalyst Ti exists naturally in three different forms rutile, anatase, brookite. Anatase is most often used in photocatalysis
Steps involved in degradation of organic compounds
External diffusion of reactant to photocatalyst surface. Adsorption of contaminant. Reaction of adsorbed organic compound with photo-excited photocatalyst. Desorption of reaction products. Mass transfer of reaction product to bulk water.
How it works ???
ADVANTAGES OVER CONVENTIONAL METHODS
Efficient Reliable High capacity Regenerative Stable
Scale up is difficult High cost
CONCLUSION The unique properties of nanomaterials and their convergence with current treatment technologies present great opportunities to revolutionize water and wastewater treatment.
REFERENCES: Sayan Bhattacharya, Indranil Saha, Anirudda Mukhopadhyay, Dhrubajyoti Chattopadhyay,Uday Chand Gosh and Debashis Charrerjee (2013), Role of nanotechnology in water treatment and purification: Potential applications and implications, International Journal of Chemical Science and Technology, ISSN 2249-8532
M. T. Amin, A. A. Alazba, and U.Manzoor (2014), A Review of Removal of Pollutants from Water/Waste water Using Different Types of Nanomaterials, Journal of Advances in Materials Science and Engineering, Volume 2014,Article ID: 825910
Karishma K. Chorawala, Mehali J. Mehta (2015),Applications of Nanotechnology in Wastewater Treatment, International Journal of Innovative and Emerging Research in Engineering, Volume 2,Issue 1,ISSN:2394-5394
4. Bernd Nowak (2008), Pollution Prevention and Treatment Using Nanotechnology, Volume 2, Environmental Aspects, Edited by Harald Krug, ISBN: 978-3-527-31735-6
5. Xiaolei Qu, Pedro J.J. Alvarez, Qilin Li (2013),Application of nano technology in water and wastewater treatment, SciVerse Science Direct, ISSN 3931-3946
6. Dhermendra K. Tiwari, J. Behari and Prasenjit Sen (2008),Applications of Nanoparticles in Waste Water Treatment, World Applied Sciences Journal 3 (3) 417-433,2008,ISSN 1818-4952
7. D.M Johnson, D.R. Hokanson, Q. Zhang, K.D.Czupinski and J.Tang (2008), Feasibility of water purification technology in rural areas of developing countries ,Journal of Environmental Management,Vol.88,no.3,pp.416-427
Quotes!!!!The wars of the twenty-first century will be fought over water Ismail Serageldin
THANK YOU ALL!!!!