Characterization of ZSM-5 zeolite and its application in the removal of Co2+ from aqueous solutions

ZSM-5 zeolite is characterized by XRD, FTIR and acid-base titration in detail. The results show that the main sorption sites are chemical bounds XNa, chemical bounds YOH and chemical bounds YO- in all pH ranges. The sorption of Co2+ on ZSM-5 zeolite is strongly dependent on pH value and ionic strength under ambient conditions. The sorption edges of Co2+ on ZSM-5 zeolite in 0.01 mol/L NaClO4 is modeled using a quasi-mechanistic sorption model (1-site protolysis non electrostatic surface complexation and cation exchange (1-SPNE SC/CE) model). The Co2+ sorption edges could be modeled in the pH range about 3 to 7 using cation exchange reactions for Co2+/Na+ and three surface complexation reactions on the sorption sites forming chemical bounds X2Co, chemical bounds YOCo+ and chemical bounds YOHCo2+ complexes appear successively with increasing of pH values. (authors)