Construction of multi-interface contact step-scheme photocatalyst is a promising pathway to achieve high-electron transfer efficiency for photodegradation Estrone and Congo red (CR). In this work, g-C 3 N 4 was selected as the main component, CeO 2 nanosheets with unique Ce 4+ →Ce 3+ conversion property and M-rGO were loaded on the surface of g-C 3 N 4 to construct magnetic photocatalyst, whose structure imparted reusability by magnetic retrieval and at the same time M-rGO acted as an efficient host for g-C 3 N 4 /CeO 2 composite photocatalyst. The photocatalytic performances were investigated with Estrone and CR, and the results showed that the composite photocatalyst g-C 3 N 4 /CeO 2 /M-rGO could degrade 71% of Estrone and 92% of CR. Free radical scavenger test showed that superoxide and hydroxyl radical species played a major role in the degradation. Furthermore, it was demonstrated that the magnetic photocatalyst g-C 3 N 4 /CeO 2 /M-rGO possessed strong antibacterial properties against Proteus mirabilis. A three-factor-three-level Box-Behnken design (BBD) was selected to optimize three greatly influential parameters: light irradiation time (min), the mass of photocatalyst (mg) and pollution concentration (ppm) by responding surface methodology. It was expected that the g-C 3 N 4 /CeO 2 /M-rGO can be used as a magnetic photocatalyst to achieve its valorization, which has very broad development prospects in the field of environmental remediation or catalysis.
Shi Zhou,Jing Yin,Qiang Ma,Baikerouzi Baihetiyaer,Jiaxue Sun,Ya Zhang,Yanji Jiang,Jun Wang,Xianqiang Yin
In this study, a type of montmorillonite-reduced graphene oxide aerogel (M−rGO) was successfully prepared by the sol–gel method and used for the effective removal of heavy metals (cadmium, Cd) and cationic dyes (methylene blue, MB) in wastewater. The chemical composition and micromorphology of the resulting M−rGO were characterized utilizing scanning electron microscopy and energy dispersive spectrometry, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, and X-ray diffraction. Furthermore, the effects of the initial concentration, adsorption time, and temperature on the static adsorption process were systematically studied. Equally important, the effects of the concentration, pH, ionic strength (IS), and pumping flow rate of contaminated solution on the dynamic removal of Cd and MB by M−rGO were investigated by a fixed-bed column experiment. The kinetics, isothermals, and thermodynamic adsorption experiment results showed that the Langmuir and pseudosecond-order models best suited the adsorption process in which physical adsorption and chemical adsorption act together. Functional groups containing O and C were involved in the adsorption of Cd and MB, and the hydrogen bonds, π-π, n-π interaction, and hydrophobic interaction between M−rGO and MB made important contributions to adsorption. The lower initial concentration, higher pH value, and slower pumping flow rate of the contaminated solution can effectively increase the dynamic adsorption capacity of Cd and MB on M−rGO. Contrary to that of Cd, the adsorption capacity of MB on M−rGO increased with IS. Both static adsorption and dynamic column experiments confirmed that the presence of Cd promoted the adsorption of MB, and MB inhibited the adsorption of Cd by M−rGO. In addition, the Cd/MB combined pollution wastewater experiment and the regeneration study showed that M−rGO could be a cost-effective and promising sorbent for Cd and MB wastewater treatment due to its high efficiency and excellent reusability.
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