CHROMIUM(VI) REMOVAL FROM ELECTROPLATING WASTEWATER USING CHEMICALLY TREATED ZEOLITE

摘要

In this research, the technical feasibility of zeolite for Cr(VI) removal is investigated in batch and column studies using real and synthetic wastewater with initial Cr concentration of 8 and 10 mg/L, respectively. Chemical treatment of zeolite with NaCl is also conducted to improve its Cr removal performance. The removal performance of all types of zeolite is evaluated and statistically compared. Column regeneration for both types of zeolite is also performed using NaOH and their regeneration efficiency is evaluated. It is conclusively evident that chemical treatment of zeolite with NaCl significantly improves its Cr adsorption capacity. The results of batch studies show that the Cr adsorption capacities of NaCl–treated zeolite for real (5.97 mg/g) and synthetic Cr wastewater (6.66 mg/g) are relatively higher than those of asreceived zeolite for real (3.06 mg/g) and synthetic wastewater (3.55 mg/g), respectively. The Langmuir isotherm is found to be applicable for both types of zeolite. Similarly, the results of column studies also demonstrate that the Cr column capacities of NaCl-treated zeolite for real (6.18 mg/g) and synthetic wastewater (6.95 mg/g) are remarkably higher than those of as-received zeolite for real (3.82 mg/g) and synthetic wastewater (4.08 mg/g), respectively. It is important to note that the Cr adsorption capacities of zeolite vary, depending on the extent of chemical pretreatment and the initial concentration of chromium.