Kinetics of Cr(VI) adsorption from aqueous medium onto bentonite

Abstract

Because of its abundance and toxicity, heavy metals have become a seriousenvironmental problem. The presence of heavy metals, such as Cr(VI), in thewatercourses leads to numerous health problems in humans and animals. Cr(VI) ishighly toxic, even in low concentrations. Because of its carcinogenic, mutagenic andteratogenic effects on human beings, Cr(VI) is considered one of the most criticalpollutants. Due to this, it is necessary to remove Cr(VI) from wastewater prior to itsdischarge into the recipient.This paper studied the possibility for application of bentonite as an adsorbent forCr(VI) from aqueous medium. The characterization of bentonite was determined withchemical composition, specific surface, XRD method and FTIR. Optimal parameterssuch as pH of solution, adsorbent weight, time of adsorption and temperaturewere examined. Values of those parameters were: initial pH value of solution pH=2,adsorbent weight 2 g, time of adsorption 60 min, temperature 308 K. Experimentaldata were obtained by Freundlich and Langmuir isotherm adsorption models as wellas pseudo-first and pseudo-second order kinetics. Results were best described withFreundlich isotherm adsorption model and pseudo-second order kinetics.