Calcined sugar scum as a low-cost adsorbent for dye removal from aqueous solution: equilibrium, kinetic and modeling

Abstract

Sugar-refining process in sugar industry produces a high amount of waste that can be used as secondary source material. This waste was calcined and used as low-cost adsorbent for the removal of methylene blue (MB) and methyl orange (MO) as models for cationic and anionic dyes. The kinetic and equilibrium adsorption have been investigated to determine the adsorption mechanisms and the adsorption capacities. The pseudo-first order, the pseudo-second order and the intraparticle diffusion models were used to examine the adsorption kinetic. Adsorption isotherm was modeled using Langmuir and Freundlich models. MB adsorption process can be best described by the pseudo-first order and Langmuir isotherm models while MO adsorption process was best fitted to the Langmuir isotherm with a monolayer maximum adsorption capacity of 40.28 mg/g. Moreover, both pseudo-first order and pseudo-second order models were appropriate to describe the adsorption process of MO. The percentage removal of the calcined sugar scum powder (CSSP) was found greater than 98% and 87% for MB and MO, respectively. The results showed that (CSSP) is a powerful adsorbent for the removal of cationic and anionic dyes.