Remediation of potentially toxic elements from aqueous solutions utilizing mixed matrix membranes (MMMs) based on polyethersulfone and functionalized mesoporous arrangements

The recent increase in world industrial activities has resulted in higher wastewater discharge containing potentially toxic species (PTEs) into the aquatic environment. This study aimed to evaluate the PES/mesomaterial-based mixed matrix membranes (MMMs) adsorption capacities for PTEs (Cd²⁺, Cr⁶⁺, Ni²⁺, and Pb²⁺) in different aqueous systems using a Doehlert design method. The MCM-41 synthesis was performed via the hydrothermal method and modified via the grafting method (NH₂-MCM-41 and SH-MCM-41). The MMMs were obtained by the phase inversion method. PTEs quantification was performed by inductively coupled plasma optical emission spectrometry (ICP OES). Preliminary adsorption results showed no significant differences between the membrane adsorption capacities for the PTEs studied. The in-depth study using the PES/SH-MCM-41-based MMMs (MMM-S) showed a significant influence of the independent variable X₂ (initial PTEs concentration) in the MMM-S adsorption capacities. Contrary, pH, contact time and amount of SH-MCM-41 into the MMMs does not significantly affect the adsorption process. Also, maximum adsorption capacity values of PTEs were observed in batch adsorption systems with an initial PTEs concentration of 0.332 mmol L⁻¹, at pH 5, under agitation (300 rpm) for 39 min and using a MMM synthesized with 6% of SH-MCM-41. In the permeation system, the MMM-S2 presented the best performance with the lowest permeability rates and the highest removal percentage of PTEs.