Preparation of PMDA@CS/PVA composite membranes and their sorption for Cu(II), Co(II), and Ni(II) in water: Experimental and statistical physics exploration

A series of new PMDA@CS/PVA composite membranes were fabricated by the crosslinking of pyromellitic dianhydride (PMDA) with chitosan (CS) and poly(vinyl alcohol) (PVA) in the presence of glutaraldehyde (GA) as a crosslinking agent. While, their adsorptions for Cu(II), Co(II), and Ni(II) in a single- and multiple mixed solutions were investigated. It was found that the incorporation of PMDA in the membranes can significantly enhance the adsorption capacity of membranes for these metals. The fitting of kinetic modeling s showed that the sorption manner of Cu(II), Co(II) and Ni(II) on the membranes obeyed the quasi-2nd kinetic modeling, indicating that it was dominated by chemisorption. The kinetic rate constants K 2 of membranes A-E for Cu(II), Co(II), and Ni(II) were in the region of 0.005–0.02, 0.026–0.082, and 0.002–0.053 [g/(h·mg)], respectively. The fitting of sorption isotherm modeling followed the Langmuir isotherm equation and the maximal Langmuir adsorption capacities for Cu(II), Co(II), and Ni(II) could reach 36.466, 32.119, and 30.916 mg/g, respectively. In addition, in the multi-component solutions, these membranes exhibited better selection for Cu(II) in Cu(II), Co(II), and Ni(II) mixed solutions. Moreover, it can be recycled five times when an EDTA was used as a de-sorbent. The exploration based on statistical physics principle confirmed that the adsorption of these membranes for Cu(II) is a mono-ion manner. These findings suggest that PMDA@CS/PVA composite membranes are promising sorbents for the removal of toxic metal ions from waste vehicle power batteries or metal-bearing wastewater.