Equilibrium and kinetics of biosorption of oxalic acid by wheat straw

Abstract

Biosorption equilibrium and kinetics of oxalic acid on wheat straw, Triticum aestivum, in an aqueous solution was investigated. Among the models tested, namely the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms, the biosorption equilibrium was best described by Freundlich model. It was also found the biosorption of oxalic acid by wheat straw followed second-order kinetics. The equilibrium amount of oxalic acid adsorbed onto the wheat straw increased with increasing the initial oxalic acid concentration and decreasing adsorbent weight. On the other hand, an increase of temperature decreased the biosorption of oxalic acid. Mean free energy of biosorption (10 kJ/mole) indicates that biosorotion of oxalic acid by wheat straw might follow a chemisorptions mechanism.