Adsorption and regeneration performances of the modified zeolite for high-concentration ammonium in real coal chemical wastewater

Abstract

In view of the practical problems of high energy consumption, high treatment cost and complicated operation caused by the current high-concentration ammonia nitrogen removal method in coal chemical wastewater, such as the steaming ammonia and stripping method, the natural zeolite was modified to investigate the adsorption and chemical regeneration performance of the modified zeolite on the high concentration of ammonia nitrogen in coal chemical wastewater. The results showed that the specific surface area of zeolite increased from 18.541 m2/g to 32.198 m2/g after the synergistic modification processes by heat treatment at 300 ℃ and brine leaching in 1.5 mol/L NaCl solution. Compared with the natural zeolite, the adsorption capacity increased by 74% and the removal efficiency of NH4+ also reached to 88.94%. The adsorption kinetic and isotherm analysis showed that the adsorption process of high-concentration NH4+ by modified zeolite in coal chemical wastewater was consistent with the chemical multilayer adsorption process. In addition, 0.100 mol/L NaClO solution had the best regeneration effect for the modified zeolite, with the regeneration rate as high as 94.5%, and the regenerated NH4+ was converted into non-toxic and harmless N2, which realized the prospects of high-efficiency and sustainable regeneration of zeolite without secondary pollution.

Keywords

• coal chemical wastewater
• zeolite
• nh4+
• modification
• adsorption
• regeneration