Nanotechnology in water pollution treatment
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Water pollution and scarcity are increasingly pressing issues that could surpass concerns over oil. Nanotechnology offers a potential solution by enabling efficient removal of toxic contaminants from water. The document outlines various sources and health impacts of water pollution, as well as conventional treatment methods and their limitations. It then describes how scientists in India developed a nanotechnology-based treatment using nano-silica-silver composite that can purify water and remove pathogens simultaneously without chemicals. Nanoscale zero-valent iron is also discussed as another nanotechnology approach for heavy metal removal through redox, cementation, adsorption and precipitation processes.
Nanotechnology in water pollution treatment
- 1. Bara’a fouad abdul ameer
- 2. Introduction: While everybody talks about oil prices, water scarcity and water pollution are two increasingly pressing problems that could easily and quickly surpass the oil issue. Renewable energy sources can substitute for fossil fuels – but freshwater can't be replaced . Water is the most essential substance for all life on earth and a precious resource for human civilization. This makes the ability to remove toxic contaminants from aquatic environments rapidly, efficiently, and within reasonable costs an important technological challenge . Nanotechnology could play an important role in this regard . Nanotechnology is a field of applied science, focused on the design, synthesis, characterization and application of materials and devices on the nanoscale.
- 3. Sources of water pollution: 1- water used for domestic, commercial and other purposes, such as schools, hotels and restaurants. 2- Water industrial uses. 3- rainwater. 4- leaking water from several sources, particularly groundwater. This water contains several solid and dissolved elements in the form of pollutants: stuck materials , organic materials biodegradable ,live pathogens ,plant nutrients (nitrogen, phosphorus, potassium ),organic materials resistant to degradation ,. heavy metals , soluble metal salts.
- 4. Diseases caused by contaminated water: Malaria, Cholera, Typhoid, Cystitis, Nephritis Gastroenteritis, Viral hepatitis, Skin diseases (hardened lesions), Goiter.
- 5. Water pollution treatment methods: Conventional practices adopted for water purification – which can be classified into physical, chemical and biological methods – suffer from certain limitations such as high cost, low adsorption capacity, generation of toxic sludge, etc. These technologies – which include coagulation, flocculation, reverse osmosis, membrane separation, oxidation and ozonation, adsorption – are expensive or inadequate to remove dye. Adsorption with activated carbons, which is a cheap and effective method, has been demonstrated to remove dye from wastewater. But this approach is not suitable for industrial wastewater treatment because activated carbon can only be used once and then it is commonly disposed of in landfills. Moreover, removal of pathogens from treated water requires additional processes like chlorination, ozonation, etc., which increases the cost of treatment.
- 6. Solution : A possible solution to tackle this problem has been demonstrated by scientists in India. They developed nanotechnology-based water purification using nano-silica-silver composite material as antifouling, antimicrobial and dye adsorptive material. Using this process, pathogenic bacteria and dye present in contaminated water can be treated simultaneously without using any chemicals, high-temperature, pressure or electricity.
- 7. Schematic illustration of the in situ synthesis (A) of silver nanoparticles on nano-silica support (NSAgNP) by protein extract, (B) immobilization of protein coated silver nanoparticles on nano-silica support by the ‘post- deposition’ route.
- 8. Scheme of the removal of heavy metals with the humic acid coated Fe3O4 magnetic nanoparticles.
- 9. *zero-valent iron, were directed towards the depollution of waste water It proved to be particularly suitable for the decontamination of halogenated organic compounds, the presence of zinc is mainly from industrial pollution. Nanoscale zero-valent iron (nZVI) has been investigated as a new tool for the reduction of contaminated water. The heavy metal removal by nZVI generally involves redox, cementation, adsorption and precipitation. The nZVI is the core-shell structure: a single particle composed of a dense core surrounded by a thin amorphous shell exhibiting markedly less density than the interior core. When nanoscale iron particles are exposed to water media, they will obtain hydroxide groups and consequently an apparent surface stoichiometry in proximity to FeOOH is formed.
- 10. . The FeOOH-shell could enhance the adsorption. The H+ inhibited the formation of iron (oxy)hydroxide, resulting in the low removal extent of Zn2+ by nZVI. Accordingly, the high removal extent of Zn2+ by nZVI might be caused by adsorption and co-precipitation, which was proved by the effects of DO and pH. The formation of FeOOH on the surface of nZVI could be the main factor of Zn2+ removal because of its high adsorption affinity for aqueous solutes. The structure of nZVI during reaction.
- 11. Treated water uses: Treated water can be used in several purposes, either directly or indirectly. In general, the re-use of treated water by various sectors ratio are as follows: 1. Agricultural purposes 60% . 2. Industrial purposes 30% . 3. Other purposes finance groundwater 10%.