Ti-based semiconductors the eco-friendly materials. Here, using n-tetrabutyl titanate and calcium acetate as raw materials, a dual- Z -scheme TiO 2 /CaTi 4 O 9 /CaTiO 3 heterojunction was facilely constructed via the solvothermal combination with calcination route. The obtained samples were intensively characterized by some physicochemical methods such as TG, XRD, FT-IR, SEM , TEM, XPS, UV–Vis DRS, PL , N 2 physisorption-desorption, and electrochemical tests. The optimum TiO 2 /CaTi 4 O 9 /CaTiO 3 photocatalyst fabricated at a solvothermal temperature of 160 °C and calcination temperature of 700 °C shows high efficiency for H 2 production, which was 11, 5, and 1.6 times higher than that of rutile-phase TiO 2 , CaTiO 3 and commercial P25(TiO 2 ), respectively. The Cr(VI) reduction rate over TiO 2 /CaTi 4 O 9 /CaTiO 3 was 3.3, 5.2, and 3.1 times higher than those of rutile-phase TiO 2 , CaTiO 3, and commercial P25, respectively. The superior photocatalytic performance is attributed to the strong redox ability of carriers excited by wide band gap semiconductors and the unique dual- Z -scheme which largely promotes carrier separation.
This study proposes a magnetic levitation fixed bed flocculation reactor as an effective method for the removal of Cr (VI). The research examines the effects of both single and dual polymer flocculants on the efficiency of the flocculation process. Initially, a magnetic levitation layer was established using a radial magnetic field in conjunction with stainless steel balls. Subsequently, polyaluminum chloride (PAC) and a non-ionic coagulant, polyacrylamide (NPAM), were introduced into the water to create a magnetic levitation fixed bed flocculation reactor. This reactor with the objective of purifying water contaminated with simulated Cr (VI). The results indicate that the incorporation of a reducing agent, specifically FeSO 4 , in conjunction with PAC and NPAM respectively, can achieve Cr (VI) removal rates exceeding 97% and turbidity removal rates exceeding 96%. The interaction between the cross-flow influent and the flocculating particles promotes the formation of micro-vortex flocculation.
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