Removal of Orange G dye using peanut shells activated carbon: a green synthesis approach

Abstract

The use of activated carbon (AC) to remove heavy metals and dyestuffs from heavy industry waste is widely preferred. In this study, a novel adsorbent AC obtained from peanut shell (PS)s by the green chemical activation (sodium thiosulphate and potassium chloride) method was used in the adsorbing process of Orange G (OG) from aqueous solutions. The surface area of the activated carbon was determined as 930.1 m(2) g(-1). Several parameters, such as pH, dye concentration, adsorbent amount, and temperature, were investigated in relation to the adsorption process. Isotherm, kinetic and thermodynamic analyses were performed using experimental adsorption data. Accordingly, the most appropriate isotherm model which described the system was the Langmuir isotherm (R-2 = 0.999), and the most efficient kinetic model was pseudo-second order (R-2 = 0.999). It was discovered that the adsorbent with a maximum adsorption capacity (q(max)) of 294.12 mg g(-1) is suitable for sustainable OG adsorption (R-L = 0.044). The standard free energy ( increment G degrees) values of the system were between -7.5 and -10.6 kJ mol(-1) and negative increment G degrees values increased in the negative direction, revealing that the adsorption process takes place by spontaneous physical adsorption. It was found that the adsorption process with positive enthalpy ( increment H degrees) (14.5 kJ mol(-1)) was endothermic and with positive entropy ( increment S degrees) (57.9 J mol(-1) K-1) value increased the disorder at the solid-liquid interface.