Biosorption of methylene blue on chemically modified <i style="mso-bidi-font-style:normal">C<span style="mso-bidi-font-style:italic">haetophora</span></i> <i>Elegans </i>algae by carboxylic acids

Abstract

Chemical modification of <i>Chaetophora Elegans </i>algae with carboxylic acids were undertaken in order to improve the methylene blue adsorption. The modified algae with 1 M acetic and formic acid showed an increase in the maximum uptake, but the modified algae with 1M oxalic acid showed an important decrease in the uptake from 143 mg g^-1 to 20 mg g^-1. The type and concentration of acid used in the chemical modification (0.1 M -1 M) is the major parameter affecting the maximum uptake. The carboxylic acids having more than one –COOH lead to cross-linking effect and so to decrease in q_max. Langmuir-Freundlich isotherm model fitted better the isotherm adsorption data for modified and unmodified algae. Pseudo second order model was well in line with the experimental data. The adsorption rate constant (K₂) is higher for modified algae with acetic acid than that of raw algae. The maximum uptake is independent of isotherm adsorption temperature in the range studied.