Production of chemically and microwave activated hazelnut husk as an adsorbent for dye contaminated wastewaters

Abstract

Adsorption has traditionally been evaluated as an economical and easily applicable process for treating certain wastewaters, such as ones including dyes and heavy metals. Even though adsorbent materials specifically produced for the purpose of wastewater treatment commercially exist, the production cost may create an economic burden on wastewater treatment processes. Agricultural wastes can be valorized as adsorbents in adsorption processes. The adsorption capacity of these wastes can be improved via pre-treatment methods such as chemical application and microwave irradiation. This study investigated the potential applicability of hazelnut husk as an adsorbent for methylene blue (MB) dye. To this purpose, the husk was activated by sequential chemical or water and microwave applications. Structural analysis on the produced adsorbent was performed by Fourier transform infrared spectrophotometry (FTIR) and field emission scanning electron microscopy (FE-SEM). Isotherm (Langmuir, Freundlich, Temkin and Harkins-Jura isotherms) and kinetic (pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion kinetic models) behaviours of adsorption were also evaluated. The results indicated that MB could be removed by 92-94% considering all adsorbents produced. Further isotherm and kinetic studies revealed that MB adsorption was both physically and chemically induced, and the reaction followed the pseudo-second-order kinetic model (R2>0.99).