Activated adsorption of dyes in a nutshell

In this study, walnut shell was activated with various acids, such as hydrochloric acid, sulphuric acid and phosphoric acid. Activated walnut shell was characterized by FTIR, SEM, TGA and BET surface area analysis. In the next step, activated walnut shells were investigated usability in removing of dye from aqueous solutions. For this purpose, methylene blue (MB) widely used was selected and adsorption studies were done with batch method. Effect on adsorption difference of parameters, such as pH, initial dye concentration, time and temperature was investigated. Adsorption isotherms were evaluated according to Langmuir, Freundlich and Dubinin-Radushkevich isotherm models. Adsorption kinetics data were evaluated according to pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models. From the results obtained, acid which is used to activate was observed to be highly effective in surface morphology of adsorbent and each acid was observed adding to different characteristic on adsorbent surface. Activated walnut shells greatly improves the removal of methylene blue, adsorption of MB onto activated walnut shells fit Langmuir adsorption isotherm, and the adsorption capacity of CK, of HCK, of SCK and of FCK was found to be as 9.73, 20.04, 19.61 and 38.46 mg/g respectively. Obtained results from kinetic studies, adsorption was determined to fit pseudo-second-order kinetic model and mechanism of adsorption was found to be as ion exchange mechanism. Obtained results from adsorption desorption studies five times repeated, the adsorption capacities of the activated walnut shell were not changed much, and they were observed to be reusable.