Recycling coir pith, an agricultural solid waste, for the removal of procion orange from wastewater

Batch adsorption experiments were carried out for the removal of procion orange from its aqueous solution using coir pith carbon. This study examines adsorption kinetic parameters on coir pith carbon. The effect of process parameters like contact time, concentration of dye, temperature and pH on the extent of procion orange adsorption from solution has been investigated. In order to develop an effective and accurate design model for removal of dye, adsorption kinetics and equilibrium data are essential basic requirements. Kinetic study showed that the adsorption of dye on coir pith carbon was a gradual process. Lagergren first-order, second-order, Bangham's and intra-particle diffusion model were used to fit the experimental data. Results of the kinetic studies show that the adsorption reaction is second-order kinetic model with respect to dye solution concentration. Equilibrium isotherms were analyzed by Langmuir, Freundlich, Dubnin–Radushkevich, and Tempkin isotherms. The adsorption equilibrium data obeyed Langmuir, Dubnin–Radushkevich, and Tempkin isotherms. The adsorption capacity was found to be 2.6 mg/g of carbon. Increase of temperature increased adsorption. Acidic pH was favorable for the adsorption of dye. Studies on pH effect and desorption show that chemisorption seems to play a major role in the adsorption process.