Adsorption of Congo red from aqueous solution by surfactant-modifiedrice husk: Kinetic, isotherm and thermodynamic analysis

Abstract

In this present work, organo-modified rice husk (SMRH) adsorbent was prepared by using cetyltrimethyl ammonium bromide (CTAB) for removing Congo red (CR), a model anionic dye, from aqueous solution. The FTIR analysis indicated that CTAB was adsorbed onto the surface of rice husk. The adsorption was found to be favored at a lower pH. The amount of CR uptake was found to increase with increasing the initial CR concentration and contact time but decrease with increasing the amount of adsorbent. The equilibrium adsorption data were fitted well with the Langmuir model. The adsorption kinetics showed that CR adsorption onto SMRH followed the pseudo-second-order model. It was found that intra-particle diffusion was not the only rate-determining step. Thermodynamic studies revealed that CR adsorption onto SMRH was spontaneous and endothermic in nature.