Equilibrium studies and kinetics mechanism for the removal of basic and reactive dyes in both single and binary systems using EDTA modified rice husk

Abstract

The potential of using ethylenediamine tetraacetic acid modified rice husk (ERH) to remove different types of dyes, namely basic and reactive dyes were studied. Sorption characteristic of ERH showed that it was pH dependent. The kinetics of sorption for both dyes was rapid within the first 60 min regardless of its initial concentration. Using the pseudo-second order kinetics model, the predicted uptakes of Methylene Blue (MB) and Reactive Orange 16 (RO16) agreed closely with experimental values obtained. Three isotherm models were used to fit with equilibrium data, namely Langmuir, Freundlich and BET models. It was found that the equilibrium fitted well in Freundlich isotherm with higher regression coefficient value, R2. Thermodynamic parameters showed that the sorption of process of MB and RO16 are exothermic and endothermic, respectively. Decrease in sorbent particle size led to an increase in the sorption of dyes. The study revealed that ERH is suitable to use as a single sorbent to remove both MB and RO16 in all systems.