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International Journal of ChemTech Research
CODEN( USA): IJCRGG ISSN : 0974-4290
Vol.5, No.5, pp 2303-2308, July-Sept 2013
Nanotechnology in Waste Water Treatment: A Review
Prachi1*, Pranjali Gautam1, Deepa Madathil1, A. N. Brijesh Nair2
1School of Bio Sciences and Technology, 2School of Mechanical and Building
Sciences, VIT University, Vellore, Tamilnadu, India – 632014
*Corres.Author: prachi.11sep@gmail.com
Abstract: Nanoparticles have a great potential to be used in waste water treatment. Its unique characteristic
of having high surface area can be used efficiently for removing toxic metal ions, disease causing microbes,
organic and inorganic solutes from water. Various classes of nanomaterials are also proved to be efficient for
water treatment like metal-containing nanoparticles, carbonaceous nanomaterials, zeolites and dendrimers.
The paper reviews recent advances on different nanomaterials (nanostructured catalytic membranes,
nanosorbents, nanocatalysts, bioactive nanoparticles, biomimetic membrane and molecularly imprinted
polymers (MIPs)) with their application in waste water treatment. Nanotechnology has lead to various
efficient ways for treatment of waste water in a more precise and accurate way on both small and large scale.
Keywords: Nanoparticles, Polymers, Nanosorbents, Nanocatalyst, Water contamination.
Introduction
Water contamination is one of the major problems which the world is facing today. Water contamination not
only effect environment and human health, but it has also impacts on economic and social costs. There are
various ways used commercially and non- commercially to fight this problem which is advancing day by day
due to technological progress. Nanotechnology has also proved to be one of the finest and advance ways for
waste water treatment. There are various reasons behind the success of nanotechnology and scientists are still
working on further enhancement of its usage. Nanoparticles have very high absorbing, interacting and
reacting capabilities due to its small size with high proportion of atoms at surface. It can even be mixed with
aqueous suspensions and thus can behave as colloid. Nanoparticles can achieve energy conservation due to
its small size which can ultimately lead to cost savings. Nanoparticles have great advantage of treating water
in depths and any location which is generally left out by other conventional technologies.
Since water treatment by using nanoparticles has high technology demand, its usage cost should be managed
according to existing competition in market (Crane et al., 2012)1. There are various recent advances on
different nanomaterials (nanostructured catalytic membranes, nanosorbents, nanocatalysts, bioactive
nanoparticles, biomimetic membrane and molecularly imprinted polymers (MIPs)) for removing toxic metal
ions, disease causing microbes, organic and inorganic solutes from water.

Deepa Madathil et al /Int.J.ChemTech Res.2013,5(5) 2304
Nanosorbents
Nanosorbents have very high and specific sorption capacity having wide application in water purification,
remediation and treatment process. Commercialized nanosorbents are very few mainly from the U.S. and
Asia but research is on going on in large numbers targeting various specific contaminants in water. Few
advancements and applications of nanosorbents are given below.
Table 1: Different specialization of nanosorbents
S.No. Nanosorbent Specialization/Treatment
1. Carbon-based nanosorbents Water containing nickel ions (Ni2+). (high specific surface area,
excellent chemical resistance, mechanical strength, and good
adsorption capacity) (lee et al., 2012)2
2. CaptymerTM Contaminants (perchlorate, nitrate, bromide and uranium) branched
macromolecules forming globular micro particles (Aquanano, n.d.)3
3. Regenerable polymeric
nanosorbent
Many organic and inorganic contaminants in wastewater (Dunwell
Group, n.d.) 4
4. Nanoclays Hydrocarbons dyes and phosphorus (Carrado et al., 2009)5
5. Carbo-Iron The activated carbon for sorption while the elementary iron is
reactive and can reduce different contaminants (Helmholtz Centre
for Environmental Research, n.d.)6
6. Nano networks Complex three-dimensional networks caused by the ion beam
providing better efficiency (Dongqing et al., 2010)7
Magnetic nanosorbents also helps in treating waste water and is proved very interesting tool especially for
organic contaminants removal (Bull Mater, 2011)8. Since most of the contaminants are not of magnetic
nature filtration aids are needed to absorb which is generally followed by magnetic separation. The
nanosorbents used for magnetic separation are prepared by coating magnetic nanoparticles with specific
ligands presenting specific affinity (Apblett et al., 2001)9. Different methods like magnetic forces, cleaning
agents, ion exchangers and many more are used to remove nanosorbents from the site of treatment to avoid
unnecessary toxicity. Regenerated nanosorbents are always cost effective and promoted more for
commercialization.
Nanocatalysts
Nanocatalysts are also widely used in water treatment as it increases the catalytic activity at the surface due
its special characteristics of having higher surface area with shape dependent properties .It enhances the
reactivity and degradation of contaminants. The commonly used catalytic nanoparticles are semiconductor
materials, zero-valence metal and bimetallic nanoparticles for degradation of environmental contaminants
such as PCBs (polychlorinated biphenyls), azo dyes, halogenated aliphatic, organochlorine pesticides,
halogenated herbicides, and nitro aromatics (Xin et al., 2011)10. The catalytic activity has been proved on
laboratory scale for various contaminants. Since hydrogen is used in making active catalyst in large scale by
redox reactions, there is need in reducing its consumption and maintain hydrogen economy by directly
making catalysts in metallic form.
Silver (Ag) nanocatalyst, AgCCA catalyst, N-doped TiO2 and ZrO2 nanoparticles catalysts have been made
which is highly efficient for degradation of microbial contaminants in water and are reusable as well (Shalini
et al., 2012)11. TiO2-AGS composite is very efficient for Cr (VI) remediation in waste water due to the
modification done in TiO2 nanoparticles leading to absorption band shift from UV light activity to natural
light degradation. Specific interactions between hydrogen and the Pd based nanoparticles were proved (Kan
et al., 2012)12. Waste waters with specific contaminants like traces of halogenated organic compounds
(HOCs) can be selectively biodegraded using advanced nanocatalytic activities. The contaminants (HOCs)
are first converted into organic compounds using nano-sized Pd catalysts which are followed by its

biodegradation in treatment plant. The nanocatalyst can be recycled back and reused due its property of
having ferromagnetism which helps it to be easily separated.
The reductants for the reaction can be Hydrogen or Formic acid depending on the level of contamination
(Hildebrand et al., 2008)13.It has also been found that the nanocatalyst of silver and amidoxime fibres which
is made by coordination interactions can be reactivated many times using simple tetrahydrofuran treatment
and thus can be used efficiently for degradation of organic dyes (Zhi-Chuan Wua et al., 2010)14.
Palladium incorporated ZnO nanoparticles were found to be having very high photocatytic activity for
removal of E.coli from water which was studied through several analytical studies done using different
concentrations of Pd in ZnO nanoparticles (Khalil et al., 2011)15.
Nano-WO3 having photo-catalytic activity for E.coli disinfection in water showed increased activity when
used in conjunction with 355 nm pulse laser which is synthesized by sol–gel method (Khalil et al., 2009)16.
In situ remediation by using Palladium nanoparticles (PdNPs) as catalyst for the reduction of Cr (VI) to Cr
(III) has been studied (Marcells et al., 2009)17.Another approach for enhancing the effect is by combining
nanosorbents with a catalyst for the combined sorption and degradation of contaminants. Nanocatalysis has
proved to very efficient in water treatment.
Nanostructured catalytic membranes (NCMS)
Nanostructured catalytic membranes are widely used for water contamination treatment. It offers several
advantages like high uniformity of catalytic sites, capability of optimization, limiting contact time of catalyst,
allowing sequential reactions and ease in industrial scale up.
Several functions which include decomposition of organic pollutants, inactivation of microorganisms, anti-bio
fouling action, and physical separation of water contaminants are performed by nanostructured TiO2
films and membranes under UV and visible-light irradiation (Hyeok et al., 2009)18.The N-doped “nut-like”
ZnO nanostructured material forming multifunctional membrane is very efficient in removing water
contaminants by enhancing photo degradation activity under visible light irradiation. It also showed
antibacterial activity and helped in producing clean water with constant high flux benefiting the water
purification field (Hongwei et al., 2012)19.
Various studies have been done regarding immobilization of metallic nanoparticles in membrane (such as
cellulose acetate, polyvinylidene fluoride (PVDF), polysulfone, chitosan, etc.) for effective degradation and
dechlorination of toxic contaminants which offers several advantages like high reactivity, organic
partitioning, prevention of nanoparticles, lack of agglomeration and reduction of surface passivation (Jian et
al., 2009)20.
Nanocomposites films have been prepared from polyetherimide and palladium acetate and specific
interactions between hydrogen and the Pd based nanoparticles have been studied proving the efficiency in
water treatment. The metal nanoparticles were generated within the matrix by annealing the precursor film
under different conditions using both in situ and ex situ method. This provides opportunities to design
materials having tunable properties (Clémenson et al., 2010)21.
With the advancement in nanotechnology several novel nanostructured catalytic membranes has been
synthesized with increased permeability, selectivity, and resistance to fouling. The techniques include
bottom-up approaches and hybrid processes for enabling its multi functionality (Volodymyr et al., 2009)22.
Bioactive nanoparticles
Water pollution has caused lots of infectious diseases due to various contaminating pathogens. Many of the
microorganisms acting as pathogens are antibiotic resistance and so it’s very difficult to remove them from
water. Recently the concept of bioactive nanoparticles has emerged which has given the alternative of new
chlorine –free biocides (2008)23.
Silver nanoparticles (AgNPs) can be synthesized extracellularly by bacteria Bacillus cereus which is having
very high antibacterial potential. The silver resistant strain was exposed to different concentrations of silver

salt (AgNO3) and studied with the help of various analytical instruments like High Resolution Transmission
Electron Micrography (HRTEM), X-ray diffraction (XRD) and Energy Dispersive spectroscopy (EDS)
(Prakash et al., 2011)24.
MgO nanoparticles and Cellulose acetate (CA) fibres with embedded Ag nanoparticles are very effective
biocides against Gram-positive bacteria, Gram-negative bacteria and bacterial spores (Nora et al., 2005)25.
Current and emerging nanotechnology approaches for the detection of microbial pathogens will aid microbial
and pathogen detection as well as diagnostics.
Biomimetic membrane for water treatment
Biomimetic membranes are developed by Albuquerque-based Sandia National Laboratories and the
University of New Mexico. It represents a new and advanced way for water purification based on its specific
design and fabrication (2011)26.
The invention uses self-assembly and atomic layer deposition tuned nanopores which generally gives high-flux
desalination. The membranes remove impurities like salt and others from water with applied pressure
powered by electrical energy. The nonporous bio mimetic design enables high salt rejection and faster water
flow at lower driving pressures generally used is around 5.5 bars. The process basically uses reverse osmosis
principle with doubled efficiency due to its low pressure requirement.
Tremendous improvement was found in water purification with cost effectiveness due to this innovative
functionalization which combines use of nano-fabrication techniques and inspiration from protein channels
in biological membranes. Some of the molecular design principles of natural porous systems were
transcribed into robust synthetic porous membranes.
The technology uses pressure driven water filtration. Some of the advantages of this technique are
advancements, reduced cost, better water flux and improved efficiency with high salt rejection (Jeffrey et al.,
2011)27. A biomimetic membrane can be prepared by vesicle fusion on a dense water-permeable support,
such as an NF membrane. The process uses electrostatic stiching principle by maximizing attraction and
minimizing repulsion between head groups. Biomimetic membrane should have high permeability and
selectivity with chemical stability (Kaufman et al., 2011)28. Chemical stability can be provided using various
synthetic biomimetic analogues like of aquaporins, carbon nanotubes etc. Many more advancements are
expected from this technology in coming years.
Molecularly imprinted polymers (MIPs)
Molecularly imprinted polymers have recently emerged as one of very fine techniques for various biological,
pharmaceutical and environmental applications. The high selectivity of the polymers is due to its synthetic
procedure where a template molecule is linked to suitable monomer(s) having functional groups by covalent,
semi covalent or non-covalent bonds providing subsequent specific binding sites to the MIPs. The left
imprint after the removal of template from polymer helps in recognizing properties of the MIP and are
generally called binding sites.
Molecular imprinting is basically a process of free radical polymerization of a functional monomer and a
cross linker. It works very selectively and has great potential to act as absorbents. It has been used for
detection and treatment of water pollutants even at very low concentrations (Caro et al, 2006)29.
Molecularly imprinted materials can be also used in combination with catalysts forming novel composite
adsorbent or catalyst systems. The use of MIPs is advantageous over commonly used sorbents due to nature
of being or performing selective extraction .MIP nanoparticles are encapsulated in nanofibres using
electrospinning method that can be used for various pollution control applications including water treatment
(Costas Kiparissides, 2010)30.
Molecularly imprinted nanospheres (nano MIPs) are also developed for the specific adsorption of micro
pollutants from hospital waste water by using mini-emulsion polymerization technique which is very
complex but can run in a single reaction chamber resulting in particles with size( 50 nm-500 nm). Magnetic

core can be introduced to allow the final separation of the nano MIPs and more important of the recognized
pollutants from waste water (Tino et al, 2009)31.
Conclusion
Nanotechnologies have made great improvements for handling water contamination problems and will
clearly make further advancements in future. Nanotechnology based treatment has offered very effective,
efficient, durable and eco friendly approaches. These methods are more cost-effective, less time and energy
consuming with very less waste generations than conventional bulk materials based methods. However
certain precautions are to be taken to avoid any threat to human health or environment due to the
nanoparticles.
The technology should be cost effective and friendly with ease in establishment and use. BCC research has
concluded, in a report from 2011-12, that the total market for emerging nanotechnology products used in
water treatment, including nanosorbents, will be only around €80 million in 2015. One can see that the large
scale commercialisation of nanosorbents is to be expected only after some additional 10 years of applied
research (Boehm, 2009)32.For the success of proper commercialization of nanotechnology based water
treatment several technical, economical and social challenges has to be tackled properly.
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