Elimination of cetyldimethylethylammonium ammonium bromide from water by almond shell based magnetic activated carbon/membrane hybrid processes

A composite material; Magnetite Carbon Nanocomposite (AMCNC), was synthesized using almond shell waste biomass following a co-precipitation method. The prepared nanocomposite was characterized using instrumental techniques such as BET/BJH surface area measurement, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis/differential thermal analysis (TG/DTA), determination of the point of zero charge and energy dispersive X-ray (EDX) analysis. The EDX, FTIR and XRD analysis revealed the presence of iron oxide on the surface of AMCNC, crystallinity and magnetic character. The BET surface area was 74.99 m² g⁻¹ and the BJH pore size distribution was 61.08 m² g⁻¹, total pore volume of 0.073 cm³ g⁻¹ and a pore diameter of 15.55 Å. The FTIR analysis of AMCNC identified surface functional groups like carboxylic acid, phenols, and ethereal groups along with a band at 580 cm⁻¹, corresponds to FeO linkage. The pH_pzc of the AMCNC was 7.7. The nanocomposite was used as sorbent for the remediation of cetyldimethylethylammonium bromide (CDEAB), a surfactant, from aquatic media. Effect of contact time, initial concentration of CDEAB, pH solution, AMCNC dosage, ionic strength, and temperature were evaluated. Regeneration study of the surfactant AMCNC was also performed. Fast adsorption occurred at initial few minutes and finally reached to equilibrium in 2 h with best fitting of the data recorded for Pseudo 2nd order kinetics model whereas the adsorption isotherm studies was well described by the Freundlich and Jovanovich models. The thermodynamic parameters revealed the process as exothermic and spontaneous. Improved permeate fluxes and the percentage retention of surfactant were observed for AMCNC/UF (magnetite carbon nanocomposite/ultrafiltration), AMCNC/NF (magnetite carbon nanocomposite/nanofiltration) and AMCNC/RO (magnetite carbon nanocomposite/reverse osmosis) hybrid processes. The fouling was minimized to considerable level for AMCNC/RO and AMCNC/NF operations which in turn could enhance the membranes efficacies in large scale commercial operations.