Obtaining activated-carbon from Zivzik (Siirt) pomegranate waste by chemical activation and model dye adsorption

Abstract

In this study, activated carbon, obtained from Zivzik Pomegrate (Siirt-TURKEY), has been used as adsorbent matter. The activated-carbon has been prepared with chemical activation using ZnC12. BET surface area has been measured as 1513.05 m2 /g. Methylene Blue and Crystal Violet have been used as dyestuffs. It has been investigated the effect of initial pH, initial dye concentration and temperature on adsorption. Four different initials concentrations have been used for both dyestuffs. It has been observed that the initial pH does not affect the adsorption capacity. The compatibility with four different adsorption isotherms has been investigated and it is approved that it fits the Langmuir adsorption isotherm. For both dyes; RL value, which is the dimensionless separation factor found using KL value from Langmuir parameters, was found to be 0.001. This result shows that the adsorption process is efficient. Also, it was seen that the correlation factor R2 for both dyes calculated from the graph drawn according to the Langmuir isotherm has a high value such as 0,999. Three different kinetic models (the pseudo first order model, the pseudo second order model and the Elovich equation) have been investigated by doing experimental studies at three different temperatures with different initial concentrations. Correlation coefficient R2 is; for Methylene Blue 0.99 and for Crystal Violet 0.99. Since the qe values calculated with the experimental qe values are compatible with each other, it was observed that our study is more suitable for the Pseudo 2nd Order Kinetic model. The entropy (ΔS ̊) values are 51.717 J/molK for Methylene Blue and 70.817 J/molK for Crystal Violet, respectively. The positive values of ΔS ̊reflect the affinity of adsorbent material towards Methylene Blue and Crystal Violet. In addition, it has been observed that adsorption is reversible and endothermic