Activated carbon, zeolite, and ceramics immobilized TiO2 photocatalysts for the enhanced sequential uptake of dyes and Cd2+ ions

The post-reaction separation in heterogeneous catalysis always remained a point of concern for nanoparticle application in an aqueous medium. This study corroborates the immobilization of TiO2 nanoparticles (NPs) on various solid supports such as activated carbon (AC), zeolite (Z), and ceramics (CCTO) materials. Economically viable and facile impregnation methods were employed to obtain a high mass yield (up to 95%) of immobilized TiO2 NPs. The characterizations of tailored materials were performed by using XRD, BET, UV-Vis DRS, SEM, and pH of the point of zero charges (pHpzc) analyses. The immobilization of TiO2 NPs significantly altered the physicochemical properties and ultimately enhanced the photocatalytic activities under ordinary compact fluorescent light (CFL). To investigate the photocatalytic performance of immobilized materials, model dyes e.g., Methyl Orange (MO) and Methylene Blue (MB) were considered in addition to the heavy metal ions i.e., Cd2+. The immobilization of TiO2 on solid supports revealed better performance for all tshree systems; whereby the AC@TiO2 exhibited higher efficiency as compared to the counterparts i.e., Z@TiO2 and CCTO@TiO2. In binary solutions (MB:Cd2+ and MO:Cd2+), the synergistic effect of the photo-generated positive hole scavenger (MB) and electron trapper (Cd2+) further enhances the removal efficiencies. The regeneration studies showed similar performance as that of the fresh samples, whereby the photocatalytic efficiencies were found to decrease for the consecutive cycles.