Removal of Aromatic Amines and Heavy Metals from Wastewater Using Nanoadsorbent

Abstract

Existence of water has led to evolution of life on our magnificent planet earth. But regrettably, quality of our water resources is declining continuously due to population explosion, industrialization, civilization, domestic activities and environmental changes. 5 10 billion tons of industrial effluents is generated annually worldwide, out of which maximum amount is dumped untreated into rivers, lakes and oceans leading to water pollution. More than seven hundred organic (azo-dyes, benzene, phenols, DDT, aromatic amines etc.) and inorganic pollutants (heavy metals like arsenic, cadmium, chromium, cyanide, fluoride, lead, mercury, selenium etc.) have been reported in water. Some of these pollutants like aromatic amines and heavy metals are alarming because of their highly toxic, mutagenic and carcinogenic nature and urgently need to be removed from wastewater. Chemical compounds with one or more aromatic rings along with amino substituents (-NH2, -NH- or nitrogen group(s)) are classified as aromatic amines. They are well known components in wide variety of wastewater including those from textile and dye processing industries, synthetic polymer industries, tanneries, oil refining processes and several other chemical process industries. Carcinogenic and mutagenic nature of aromatic amines are known since 1895 due to which twenty-two types of aromatic amines including 4-chloro-otoluidine (4-COT) and 4-Amino-bi-phenyl (4-ABP) above 30 mg/L in effluents have been restricted by European Union Standards (1907/2006), therefore need to be treated before discharge. On the other hand, heavy metals are the high atomic weight and high density (and#8776;5 times higher than water) elements present naturally in our ecosystem. Zinc is present in the earth s crust in abundance. However, its increasing concentration in wastewater as Zinc ion [(Zn (II)] owe to various commercial manufacturing units results to certain adverse diseases including skin irritations, vomiting, stomach cramps and anaemia. Chromium, contrarily is present in our su