The feasibility of COD reduction of gas refinery wastewater through adsorption process using efficient Zeolite imidazolate frameworks (ZIF) has been investigated. In this work, the ZIF-8 adsorbent has been synthesized and characterized with the FT-IR, FE-SEM and BET analysis. The great capability of ZIF for COD adsorption has been confirmed owing to the unique properties of large specific surface area, ample nanochannels, and tunable pore properties which in turn benefits in appropriate pollutants adsorption. The influence of operating parameters of solution pH and ZIF-8 dosage within the constant time of 90 min were also evaluated and complete COD removal has been achieved with ZIF dosage of 8 ppm and pH=8.2. The results indicated that the electrostatic attraction is dominant mechanism for COD adsorption of gas refinery effluent via ZIF-8. The related adsorption behavior from two main aspects of equilibrium and kinetics has been studied via fitting the experimental data with models. Fitting the adsorption equilibrium data with Langmuir and Modified Langmuir-Freundlich models and the adsorption kinetic data with Pseudo-First order and Modified Pseudo n-order, the appropriate close to unity correlation coefficient and low amount of RMSE has been attained. The concluding results confirmed the potential of ZIF-8 adsorbent for complete COD removal of real effluent of gas refinery industries.
