Low-price MnO2 loaded sepiolite for Cd2+ capture
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Cadmium ion (Cd2+) is one of the harmful metal ions in the wastewater and has attracted much attention for its removal. The current study proposes a low-cost adsorbent MnO2-sepiolite to capture Cd2+ from the aqueous solutions. The structure of the new MnO2-sepiolite adsorbent was characterized by using nitrogen adsorption–desorption isotherm, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The effects of MnO2-loading, pH and contact time of cadmium solution with the adsorbent were investigated with respect to the adsorption performance of MnO2-sepiolite. The Sips model was used to estimate the maximum adsorption capacity for capturing Cd2+ and the obtained results demonstrated that it reached 114.75 mg/g at pH 6 and T = 298 K, placing it in the top three most efficient adsorbents reported. Additionally, the experimental adsorption kinetic data was found in good agreement with the Avrami kinetic model. The obtained results also suggest that the MnO2-sepiolite still shows a high Cd2+ removal efficiency even after four adsorption–desorption cycles. A comparison between the cost of the proposed MnO2-sepiolites and other reported adsorbents for removing Cd2+ is provided and the results indicate that MnO2-sepiolite could be a very promising cost-effective adsorbent.
KeywordsSepiolite MnO2 Cadmium ion Adsorption Kinetics
The work was supported by National Natural Science Foundation of China (21506179, 21506181, 51608464), Hunan Province Science and Technology Project (2016JJ3113, 2016JJ5006, 2017JJ3291, 2018SK2027, 2018RS3088, 2019JJ40281), Research Foundation of Education Bureau of Hunan Province (17B255, 17B256), Hunan Key Laboratory of Environment Friendly Chemical Process Integration Technology, National & Local United Engineering Research Centre for Chemical Process Simulation and Intensification, National Department of Education Engineering Research Centre for Chemical Process Simulation, Optimization and Collaborative Innovation Center of New Chemical Technologies for Environmental Benignity and Efficient Resource Utilization and Xiangtan Science and Technology Project, China Scholarship Council (201707230001).
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