Most countries worldwide face the problem related to clean and safe water. The major source of contamination of water bodies includes the discharges of wastes from various domestic and industrial sources (heavy metal ions, dyes, and pharmaceuticals). To overcome those problems, various water purification methods such as coagulation, flocculation, adsorption, membrane separation, biological, and electrochemical methods have been engaged. Adsorption using nano-biosorbents based on chitin, chitosan and modified chitosan, cellulose, alginate, micro algal has emerged as a better alternative for the removal of contaminants from drinking and wastewater treatment. The main advantages of these nano-biosorbents include its biodegradability and eco-friendliness, which have attracted researchers to this field.
TopIntroduction
Nanotechnology is a newly emerging branch of science that deals with the study of matter that is in the range of 1-100 nm. Materials in nanometer scale possess specific physical, chemical and biological properties that differs from properties of bulk. (Ealias & Saravanakumar., 2017) Potential application of nanotechnology includes its use in catalysis, scientific tools, electronics, biomedical application, environmental remediation and many industrial applications. (Pangiet al., 2003) (Pal et al., 2011) (Jeevanandam et al., 2018) Recently, reports have been found which explains the use of nanotechnology in solving various social problems that are persisting in various developing countries. Clean and safe water is one of the major problems faced by many countries worldwide. (Fleischer & Grunwald, 2008) Release of effluents (heavy metal ions, dyes and pharmaceuticals) from industries is the prime source of contamination of water bodies. (Mallampati et al., 2015) These pollutants are often very stable and non-biodegradable. They often gets accumulated in the living tissues. (Gokila et al., 2017) Once it is accumulated, its removal becomes a cumbersome process. [Castro et al., 2014) To overcome this problem various water purification methods such as coagulation, flocculation, adsorption, membrane separation, biological, and electrochemical methods have been employed, out of which adsorption using bio adsorbents has emerged a better alternative. (Ouyang et al., 2018) (Crini, 2006)
Advantages of Bio Sorbents: (Crini, 2006)
TopMaterials And Methods
Different bio sorbents such as rice husk, banana peels, sugarcane bagasse, tomato peels, orange peels, eggshells, tea waste, kiwi peels, pine bark, and other peels have been used for the removal of heavy metals, dyes and organic molecular pollutants. (Mallampati et al., 2015)Most of the household vegetable wastes contains polar functional groups such as -OH, -NH2, -COOH which helps in the process of adsorption. (Feng et al., 2011) (Negi et al., 2012) After initial reports on bio sorbents, to make the process of adsorption more effective and efficient it has been replaced by nano adsorbents. Nano adsorbents possess unique physical and chemical properties, which take account of its high chemical activity and adsorption capacity at its surface. (Kyzas & Matis (2015) These nano adsorbents are widely used to solve the problems related to water. Nano adsorbents remove the toxic substances via ion exchange, ion precipitation and adsorption. (Lata & Samadder., 2016)
Some of the commonly used nano adsorbents are as follows: (Lata & Samadder., 2016)
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Iron oxides/hydroxides nanoparticles
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Alumina nanoparticles
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Copper oxide nanoparticles
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Titanium dioxide nanoparticles
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Zinc oxide nanoparticles
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Mixed metal oxide (MMO's) nanoparticles
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Carbon nano tubes
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Nano-biosorbents
In this chapter, our interest lies with the use of nano-biosorbents for the removal of toxic substances form water.