Role of activated carbon from natural adsorbent for removal of textile dyes: effect of pH, kinetic and adsorbent mass

In the present work, we have investigated the sorption efficiency of the treated activated carbon from walnut shell(ACW) towards Direct Red 81 (DR81) and Direct Blue 71 (DB71) for the removal from aqueous solution. Thesorption study of ACW at the solid-liquid interface was investigated using kinetic, sorption isotherms, pH effectand amount of adsorbent. Experimental data were analyzed by Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherms. Langmuir isotherm model (R2 =0.9664 and R2 =0.9484) fitted the equilibrium datathe best other isotherms for DR81 and DB7I. According to the results maximum adsorption occurred in acidic pH.The results showed that the sorption processes of DR81 and DB71 on ACW are in good agreement with pseudosecondorder kinetic. Maximum amount of adsorbent for adsorption of mentioned dyes was 1 gr.