REMOVAL OF HEAVY METALS FROM WASTE WATER USING COPPER BASED METAL ORGANO FRAMEWORK

Abstract: The most challenge of this century is generation of wastewater which is released to the environment due to the industrial expansion. Industrial development has caused the release of various pollutants including heavy metals such as Cd, Pb and Cr into the environment. In this study hydrothermally synthesized copper diphenylamine metal organic framework has been tested for its efficiency to remove heavy metals from wastewater and its adsorption capacity was investigated by using iodine number analysis, characterized by using X-ray diffraction and Fourier transformer infrared spectroscopy. A waste water sample was collected from Gamo Gofa zone Arba Minch town from a car wash labajo. The removal efficiency of heavy metals by Cu-MOF was tested by optimizing the adsorption parameters such as adsorbent dosage, pH, initial metals concentration and adsorption time. The optimum pH is 6 for Cd2+ and Pb2+, 2 for Cr3+, optimum adsorbent dosage is 2.5 g for Cr3+ and Cd2+ ,1.5 g for Pb2+ and the equilibrium adsorption time is 60 minute for Pb2+, 80 minute for Cd2+ and Cr3+. The heavy metals concentration in wastewater before treated with as synthesized MOF was determined as 0.3027, 0.0098, 0.1021 mg/L for Cr(III), Cd(II) and Pb(II) respectively. After treated with as synthesized MOF the concentration of heavy metals reduced to 0.0015, 0.00024, 0.00016 mg/L and the removal efficiency recorded as 97.5 %, 99.5 % and 99.5 % for the respective metals. Equilibrium adsorption fitted Freunlich adsorption isotherm with adsorption capacity (KF) 0.114 L/g, 0.26 L/g, 0.575 L/g for Cd2+, Pb2+ and Cr3+ respectively. Favorable capacity of adsorbent/adsorbate system (n) was 1.26, 1.4, and 1.35 for Cd2+, Pb2+ and Cr3+ respectively. The kinetic process of Cd2+, Pb2+ and Cr3+ adsorption on to Cu-MOF were described by pseudo first and pseudo second order model from the optimized time of adsorption. The kinetic data obeyed pseudo second order for Cd2+ and Cr3+, pseudo first order for Pb2+. Based on the result obtained within the frame work of this study it concluded that the as synthesized metal organic framework is good adsorbent for removal of heavy metals ions like Cd2+, Pb2+ and Cr3+ from wastewater sample.