Nowadays, with the
increasing demands of synthetic products, owing to considerable surge in
population in last three decades, environmental pollution has become a pressing problem of the word. The main
contributing factor behind it perhaps is a fundamental increase in
industrialization to fulfill the demand and supply balance. On one hand these
industries compensate the needs of people but on the other hand abruptly
polluting the environment by dumping their unprocessed waste in landfills, air
and water. This practice ultimately abrupt the supply of clean fresh water
drastically affects the marine life and massively contributes to water born diseases. Thus, conducting
research on cheap and efficient materials and techniques to clean the
contaminated water from hazardous contaminants is the need of the hour, as
water is the essential component of life for both terrestrial and aquatic
system.
In this regard various industries like textile,
metallurgy, pharmaceutical; dyes, fuel, leather, plastic, glass industry and
even food factories are adversely polluting the aquatic system. These
industries dump tons of poisonous chemicals, heavy metals and organic effluents
into groundwater which not only harms the quality of drinking
water but also responsible for deadly diseases like hepatitis and diarrhea. Thereby, it is mandatory to work on
precautions and solutions to save the fresh water which is only 3% of total
water assets on the globe and out of which only 1% is in domestic use.
A plethora of conventional techniques has been
used for the treatment of waste water using bulk materials such as solvent
extraction, adsorption, distillation, chlorination, filtration, precipitation,
coagulation and ion-exchange etc. These methods are usually less efficient in
complete decontamination of waste water because these contaminants when entered
and dissolved in water bodies are strenuous to remove. Another drawback of
using these techniques is the high cost of bulk material that is used to purify
the water. For instance, adsorption is the most effective method among all aforementioned
methods, but the adsorbents required in hundreds of grams
make it costly and not appropriate to use.
Nanotechnology is playing a crucial role in this regard, as nanoparticles
possess incredible and magnificent properties towards waste removal from water
owing to large specific surface area. High surface area of nano materials permits these to adsorb and remove large
quantities of contaminants from water as compared to same material when used in
bulk size. This is the basic reason that nano sized materials are used in minute quantities, making
this technology cost-effective and most efficient method for water
remediation.
Nanocatalyst are used in water treatment in photocatalytic as well as in catalytic thermal degradation reactions. The mechanism of these reactions starts with the adsorption of contaminant on nanocatalyst followed by the degradation of harmful waste reactants in water to other products which would not harm human health or marine life. Catalyst is recovered at the end through nano membranes or centrifuge techniques, thus, in this way can be used again and again.
Use of nano membranes is another cost-effective and reasonable method used in the treatment
of water in which membrane is once fitted, and it captures the contaminants of even nano range as waste water passed through it. Nano adsorbents are used to purify waste water in which the same principle of adsorption is used as for bulk material, the only difference is in the amount used
for both cases. Bulk material is used in grams but in nano range only milligrams of nanoparticles are used, making it more affordable and cheap to use
for general industrialists. Figure 1 shows schematic diagram of generally used nanotechnologies for the purification of water.
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