Abstract

KINETICS, THERMODYNAMICS AND ISOTHERM ANALYSIS ON THE REMOVAL OF Cr(VI) ION ONTO PONCS.

S. Sumithra, S. Arivoli* and M. Hema

ABSTRACT

The presence of hexavalent chromium Cr(VI) in wastewater is a potential hazard to aquatic animals and humans. There are various mechanisms proposed, kinetic models used and adsorption isotherms employed for the efficient removal of hexavalent chromium from industrial and municipal wastewaters using biosorbent. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. Metal removal treatment systems using natural materials are cheap because of the low cost of sorbent materials used and may represent a practical replacement to conventional processes. The objective of this study is to assess the uptake of hexavalent chromium from aqueous solutions onto Posidonia Oceanica raw and chemically modified nano carbon. The Biosorption data of hexavalent chromium by Posidonia Oceanica nano carbon, which was raw PONC and chemically modified by sulphuric acid, has been used for kinetic studies based on fractional power, Elovich, pseudo-first order, pseudo-second order and intraparticle diffusion rate expressions. Isotherm models, Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Hurkins-Jura, Halsay, Radlich-Peterson, Jovanovic and BET isotherm models are tested for their applicability. The time-dependent Cr(VI) biosorption data were well-described by fractional power and Elovich kinetic model. Among the multi-parameter models, the BET isotherm model produces the best fit. Comparing our results with other previous work, shows the value of materials developed from Posidonia Oceanica and allows us to offer them as adsorbent materials.

Keywords: Posidonia Oceanica Nano Carbon (PONC), Hexavalent chromium, Biosorption, Kinetics, Equilibrium models.