Adsorption of Cr (VI) ions by low cost Adsorbents: A Review

ABSTRACT

Chromium is the industrial effluent is a major concern for the environment. Elimination of heavy metal ions form industrial effluents to allowable limit before discharging them into environment is most important for protection and conservation of our resources and ecosystem. Chromium is one of the metal ions which occur in trivalent and hexavalent forms. Cr(VI) is more toxic and highly soluble than Cr(III). Cr(VI) causes cancer in digestive tract and lungs.  So, it is essential to remove Cr(VI) from industrial wastewater before disposal. This paper reviews, the potential of various low-cost adsorbents for the removal of Cr(VI) ions from industrial effluent. Various conventional methods for heavy metal removal such as chemical precipitation, ion exchange, reverse osmosis, electroplating, ultra-filtration, non-filtration, Coagulation, flocculation have been applied. Since in previous years However these methods have several disadvantages such as high reagent requirement, unpredictable metal ion removal, generation of toxic sludge etc. Adsorption process being very simple, economical, effective and versatile has become the most preferred methods for removal of toxic contaminants from wastewater. This paper reviews the use of various readily available natural materials as adsorbents of Cr(VI) metal ion from industrial wastewater. various low cost adsorbents reviewed includes acacia Niloticalleaf, Rice husk, saw dust, baggasof sugarcane, Rice straw, rice bran, hyacinth roots, neem bark, saw dust of teakwood origin, neem leaves and coconut shell, Elacagnusangystifolio fruit charcoal, jujuble fruit charcoal marble waste powder.

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