Design and Preparation of Magnetically-Oriented Poly(styr-co-MMA)-3MPS Capped Fe(ZnO) Hybrid Microspheres for Ion Exchange Removal of Toxic Pollutants from Wastewater

In this work, polymeric microspheres derived from polystyrene-co-methyl methacrylate embedded with magnetic ZnO nanoparticles (poly(styrene-co-MMA)-3MPS-Fe (ZnO)) were synthesized using the suspension polymerization method. The surfaces of polymeric Fe(ZnO) microspheres were improved by functionalization with amino and sulphonate groups. The physicochemical analysis indicated a large number of positively charged (anion exchange) groups (91 mmol/g) on the amine-modified polymeric microsphere (MFZPI) and a large number of negatively charged (cation exchange) groups (90 mmol/g) on the sulphonate-modified polymeric microsphere (SMFZPI)—revealing ambivalent character of obtained sorbent. The characterization of the synthesized compounds using various analytical techniques such as TGA, FTIR, XRD, SEM/EDX, UV-VIS and VSM indicated that synthesized microspheres were thermally stable, semi-crystalline in structure with hollow irregular morphology, optically active in UV region and slightly magnetic in nature. Due to the introduction of groups having ion exchange properties, these modified poly(styrene-co-MMA)-3MPS-Fe(ZnO) microspheres were used for the ion exchange sorptive removal of Cr(III) and fluorescein from aqueous matrix. The equilibrium sorption capacity of Cr(III) was 16.79 mg/g whereas of fluorescein was 12.03 mg/g under optimized conditions. Therefore, SMFZPI was found to be a promising sorbent for both cationic heavy metals and anionic dyes due to the presence of both acidic and basic groups. The mathematical modelling revealed that the sorption phenomenon followed pseudo-second-order kinetics with Freundlich equilibrium isotherm, indicating multilayer chemisorption of the pollutants on the synthesized ion exchange sorbents. This work establishes the utilization of polymeric magnetic ZnO-based ion exchange sorbents to effectively remove harmful toxins from wastewater.