摘要:
With the increase in industrialization worldwide, industries such as electroplating, leather tanning, textile, paints and pigments discharge toxic effluent, which contains Cr(VI) and organic matter like phenol (Gupta et al. 2015; Song et al. 2009). Both chromium and phenol are used in tanneries in the tanning process for the manufacturing of leather (Munz et al. 2009; Srivastava et al. 2007). Simultaneous removal of Cr(VI) and phenol is a matter of concern for the industries such as tanneries, photographic-film production, preservation of wood, manufacturing of car, petroleum refining and agricultural production because Cr(VI) and organic pollutants like Phenol, naphthalene are discharged simultaneously from the waste effluent of these industries. Two stable oxidation states of chromium such as trivalent [Cr(III)] & hexavalent [Cr(VI)] are found in the environment. Cr(VI) is in the form of chromate (CrO 4 2- ) or dichromate (Cr 2 O 7 2- ) ions while Cr(III) is in the form of oxides, hydroxides or sulphates and less mobile than Cr(VI) but it can be oxidized to Cr(VI) (Thinh et al. 2013). Cr(III) is hazardous to the plants and living beings only at higher concentration and less toxic to animals or living beings while Cr(VI) is mutagenic and carcinogenic to the living organism. Cr(VI) enters into the human body causes epigastric pain, nausea, vomiting, severe diarrhea, corrosion of the skin, respiratory tract and lung carcinoma. Hence, removal of Cr(VI) from industrial effluents becomes necessary before its discharge to main water sources. Among the various harmful and toxic organic compounds like dyes, pesticides and fluorine, phenol is most toxic to the environment. Phenol is a weak biodegradable and toxic aromatic compound and consumption of phenol causes various diseases such as gastrointestinal disorder, lung damage, liver disease, kidney disease, heart attack and finally death of living beings (Chaudhary et al. 2014). WHO (world health organization) sets the maxi