LI Yue-xuan, LI Peng-fei, PAN Jie, LIU Yun, WANG Ping, DONG Yuan-hua. Study on the Corrosion of Coral Sand by Oxalic Acid.[J]. Journal of Ecology and Rural Environment, 2020, 36(7): 905-913. DOI: 10.19741/j.issn.1673-4831.2019.0229
    Citation: LI Yue-xuan, LI Peng-fei, PAN Jie, LIU Yun, WANG Ping, DONG Yuan-hua. Study on the Corrosion of Coral Sand by Oxalic Acid.[J]. Journal of Ecology and Rural Environment, 2020, 36(7): 905-913. DOI: 10.19741/j.issn.1673-4831.2019.0229

    Study on the Corrosion of Coral Sand by Oxalic Acid.

    • A vegetation ecosystem is essential to maintain a livable environment in a tropical reclamation land. In this paper, kinetics of coral corrosion in the presence of the different concentration of oxalic acid was studied. According to the kinetic model established, main factors affecting corrosion of coral sand were elucidated. The results show that Ca2+ and Mg2+ in the coral sand were rapidly dissolved during the beginning stage of the reaction, followed by the fixation of a large amount of Ca2+ by oxalate to form calcium oxalate precipitate. As the concentration of oxalic acid increased, the concentration of Ca2+ in the solution gradually decreased and the concentration of Mg2+ gradually increased. The maximum concentrations of Ca2+ and Mg2+ were 0.65 and 2.87 mmol·L-1, respectively. The corrosion kinetics of Mg2+ was fitting with Stumm model, indicating this process was mainly governed by diffusion. In addition, dissolution and loss of Ca2+ in coral sand was inhibited at high concentration of oxalic acid. The results of XRD and SEM show that the calcium oxalate precipitates formed by the reaction of high concentration oxalic acid are attached onto the surface of coral sands, and magnesian calcite is preferentially dissolved, followed by aragonite and calcite.
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