Adsorption of dyestuff in household-scale dyeing onto rice husk

Abstract

As the direct discharge of dying wastewater into the environment has harmful effects, there is a growing interest in using low–cost and waste materials to adsorb dyes. The main objective of this study was to investigate the adsorption of a commercial synthetic dye in household–scale dyeing onto rice husk using batch process. The effects of adsorption such as contact time, initial dye concentration and temperature were evaluated. The rice husk was characterized by Fourier transform infrared spectrophotometer (FTIR), BET surface area and scanning electron microscopy (SEM). The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. It was found that the Langmuir isotherm provided a good model and the maximum monolayer adsorption capacity values were 14.9, 15.6 and 16.9 mg/g at 20, 30 and 40°C, respectively. The kinetic experimental data were fitted well by pseudo–second order model at all temperatures. The thermodynamic investigation indicated that the adsorption of dye was spontaneous and endothermic.