Removal of cationic, anionic and non-ionic dyes from aqueous solutions using Durio zibethinus husk

Abstract

Development of economical adsorbents from peanut hull, hazelnut shell, bottom ash and other waste materials to treat dyes in wastewater attracts a great interest in recent years. However, the adsorption capacities of these materials are still limited. Economical, locally available and highly effective adsorbents are still under investigation. The purpose of this study is to investigate the potential of Durio zibethinus husk (DZH) as a low‒cost adsorbent to remove cationic dye, Malachite Green (MG): anionic dyes, Congo Red (CR) and Reactive Blue 221 (RB 221): and non‒ionic dyes, Disperse blue 60 (DB 60) and Disperse violet 93 (DV 93) from aqueous solution. Adsorption studies were carried out under various parameters including adsorbent pre‒treatment, contact time, pH (2‒11), amount of adsorbent (0.25‒7.5 g/L), initial concentration (10‒200 mg/L) and temperature (30‒50 °C). Results revealed that the pre‒treatment of DZH and pH have significant effect on the removal of dyes. MG reached its maximum removal percentage of 76% using untreated DZH. However, maximum removal percentage of other dyes were obtained using treated DZH, i.e., 62,70,99 and 79% for CR, RB 221, DB 60 and DV 93, respectively. The adsorption data were correlated using Langmuir and Freundlich models, and the result showed that all dyes fitted well with the Langmuir model. The kinetic data were analyzed using pseudo ‒first‒and pseudo‒second‒order equations, and all dyes studied conformed to the pseudo‒second‒order kinetic model. The intraparticle diffusion model indicated that multiple stages were involved in the adsorption process. Negative value of ΔH for CR, RB 221 and DV 93 confirmed the exothermic nature of adsorption process, while the positive values for MG and DB 60 showed the endothermic adsorption in nature.