Copper Adsorption on ZIF-8/Alumina Hollow Fiber Membrane: A Response Surface Methodology Analysis

Heavy metals from industries and agricultural sectors have become a prominent source to cause the contamination of groundwater and water bodies. The toxicity of heavy metals is a significant concern as excessive exposure to these chemicals may cause severe harm to humans and other life beings. In this study, the effects of independent variables on the adsorption of copper(II) ions on ZIF-8 membrane were determined using a three-factor three-level central composite design (CCD) by a response surface methodology (RSM) approach. The adsorption process was investigated using batch experiments. The independent variables include the initial concentration of copper(II) ions, the mass of ZIF-8 membrane and volume of copper solution. A quadratic model was developed to correlate the variables with the adsorption yield of copper(II) on ZIF-8. The optimum condition for maximum copper(II)ions removal was found as follows: initial concentration of 100 mg/L, adsorbent dose 29.93 mg and the solution volume of 40 mL. The adsorption mechanism of copper(II) onto the ZIF-8 membrane was best fitted to the Freundlich isotherm. The kinetic study concluded that the adsorption was best fitted to the pseudo-second-order model with a higher correlation coefficient. ZIF-8 membrane showed the promising adsorbent for copper(II) ions with the advantage of easier isolation from reaction mixtures than other powder form adsorbents.