investigation of kinetics and equilibrium isotherms of direct red 12b dye adsorption on hazelnut shells

in this work, efficiency and performance of hazelnut shells (hs) adsorbent was examined for the removal and recovery of direct red 12b (dr12b) from wastewater. the absorbance of dr12b was measured spectrophotometrically at λmax=523 nm before and after adsorption of dr12b. the maximum removal was 99.8% for 30 mg l –1 ofdr12b concentration on 0.3 gr hs adsorbent. acidic ph was favourable for the adsorption of dr12b. the influence of variables including ph, concentration dye, particle size, amount of adsorbent, temperature, in column method and kinetics, isotherm, contact time on the dye removal has been investigated in batch method by one at a time optimization method. the effect of foreign cations, anions and other dyes was investigated on removal efficiency. in order to investigate the efficiency of dr12b adsorption on the hs, pseudo-first-order, pseudo-second-order, elovich and intra-particle diffusion kinetic models were studied. the graphical correlation of various adsorption isotherm models like, langmuir, freundlich and tempkin have been carried out for this adsorbent .