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

Abstract

Because of its abundance and toxicity, heavy metals have become a serious
environmental problem. The presence of heavy metals, such as Cr(VI), in the
watercourses leads to numerous health problems in humans and animals. Cr(VI) is
highly toxic, even in low concentrations. Because of its carcinogenic, mutagenic and
teratogenic effects on human beings, Cr(VI) is considered one of the most critical
pollutants. Due to this, it is necessary to remove Cr(VI) from wastewater prior to its
discharge into the recipient.
This paper studied the possibility for application of bentonite as an adsorbent for
Cr(VI) from aqueous medium. The characterization of bentonite was determined with
chemical composition, specific surface, XRD method and FTIR. Optimal parameters
such as pH of solution, adsorbent weight, time of adsorption and temperature
were 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. Experimental
data were obtained by Freundlich and Langmuir isotherm adsorption models as well
as pseudo-first and pseudo-second order kinetics. Results were best described with
Freundlich isotherm adsorption model and pseudo-second order kinetics.