Removal of methylene blue by natural and Ca and K-exchanged zeolite treated with hydrogen peroxide

A comparison was made of influence of physically adsorbed methylene blue (MB) dye on the physicochemical properties of Manisa-Akdere zeolite (natural zeolite) and zeolite modified with K and Ca (all samples treated with hydrogen peroxide before modification) using batch adsorption technique. After elementary characterization of this adsorbent, the effects were investigated of initial MB concentration, pH, contact time, stirring rate, adsorbent dosage and temperature on the selectivity and sensitivity of the removal process. A larger adsorption of the dye was observed for modified zeolite (42.7 mg/g) than for natural zeolite (28.6 mg/g) per gram of an adsorbent after all zeolite samples treated with hydrogen peroxide. Zeolite treated with H2O2 showed higher adsorption capacity than untreated zeolite samples. The Langmuir model (R2 values between 0.959 and 0.996) fitted the experimental data better than the Freundlich model (R2 values between 0.804 and 0.988). The adsorption process was found to be slightly influenced by adsorbent dosage, contact time and temperature. Optimum pH for adsorption of MB was found to be at 7. Adsorption equilibrium attained within 30 minutes. The sorption of MB increased slightly with rising temperature. In addition, adsorption values rose with modification Ca-Exchanged (after H2O2 treatment) > K-Exchanged (after H2O2 treatment) > Zeolite treated with H2O2 > Ca-Exchanged >K-Exchanged >Natural Zeolite.