Preparation, characterization and performance of zeolitic imidazolate framework-8 membrane on alumina hollow fiber for lead(II) removal

Abstract

Exposure to lead may cause severe health issues to human and life-beings. Therefore, the purpose of this study was to develop the zeolitic imidazolate framework-8 (ZIF-8) membrane on alumina hollow fiber for lead(II) removal in aqueous system. The first part of this study was to fabricate an alumina hollow fiber membrane as the support for the ZIF-8 membrane. The effects of alumina particle size on the morphology of alumina hollow fiber were determined by using several analyses including the porosity, surface roughness and mechanical strength. The performance of all the prepared membranes were determined using cross-flow filtration system. The results indicated that higher loading of fine particles produced alumina hollow fiber membrane with lower porosity and a higher ability to reject protein molecules. Three different preparation techniques were employed to determine the effects of the techniques on the growth of the ZIF-8 layer on the selected alumina support. The techniques include, in situ solvothermal method, combined in situ secondary growth, and layer-by-layer technique. The ZIF-8 membranes were characterized using several techniques including Fourier transform infrared spectrospcopy and X-ray diffractometer. A batch adsorption study was performed to evaluate the adsorption efficiency of the ZIF-8 membranes. Among all of the prepared membranes, the SC48 showed the highest performance for lead(II) adsorption with the ability to remove up to 67% of the lead(II) ions with the adsorption capacity of 115.38 mg/g. The cross-flow filtration test indicated that the SC48 exhibited the highest removal percentage, with the ability to remove up to 90% of lead(II) ions. Additionally, the regeneration study proved the reusability of the ZIF-8 membrane. The optimization study had shown that the optimum condition for removal of lead(II) ions using ZIF-8 membrane was at the initial concentration of 94.00 ppm, pH of 7.15, and operational pressure of 2.0 bar. Experimental test under optimized condition showed that lead(II) removal was at the average of 92.13% and the water permeation of 288.41 Lm-2h-1bar-1. The outcome of this study suggested that the ZIF-8 membrane had shown excellent performance as an adsorptive membrane for lead(II) removal and deserves further in-depth development.