草酸对珊瑚砂的溶蚀作用及其机制研究  

Study on the Corrosion of Coral Sand by Oxalic Acid

作　　者：李越煊 李鹏飞 潘杰 刘云[2,3] 王萍 董元华[2,3] LI Yue-xuan;LI Peng-fei;PAN Jie;LIU Yun;WANG Ping;DONG Yuan-hua(School of Chemical and Biological Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]兰州交通大学化学与生物工程学院,甘肃兰州730070 [2]中国科学院南京土壤研究所土壤环境与污染修复重点实验室,江苏南京210008 [3]中国科学院大学,北京100049

出　　处：《生态与农村环境学报》2020年第7期905-913,共9页Journal of Ecology and Rural Environment

基　　金：国家重点研发计划(2016YFC0501309-4);国家自然科学基金面上项目(21477137)。

摘　　要：营造热带吹填陆域的宜居生态环境,构建植被生态系统必不可少,其中,研究植被分泌小分子有机酸对岛礁母质珊瑚砂的风化作用对于岛礁生态建设至关重要。通过研究不同浓度草酸对珊瑚砂的溶蚀动力学,建立动力学模型,研究珊瑚砂溶蚀的主要影响因素,探讨草酸对珊瑚砂的溶蚀机制。结果表明,在不同草酸溶液中,反应初始阶段珊瑚砂中Ca^2+、Mg^2+迅速溶出,随后大量Ca^2+被草酸固定生成草酸钙沉淀。随着草酸浓度的增加,溶液中Ca^2+浓度逐渐降低,Mg^2+浓度逐渐升高,c(Ca^2+)最大值为0.65 mmol·L^-1,c(Mg^2+)最大值为2.87 mmol·L^-1。通过Mg^2+溶出动力学拟合发现其溶出动力学符合Stumm模型,主要受扩散过程的影响。此外,高浓度草酸会抑制珊瑚砂中Ca^2+的溶解流失。XRD和SEM分析结果表明,高浓度草酸与珊瑚砂反应生成草酸钙沉淀相互胶连附着在珊瑚砂表面,且溶蚀过程中优先溶蚀珊瑚砂组分中镁方解石,其次是文石和方解石。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 Ca ^2+and Mg ^2+in the coral sand were rapidly dissolved during the beginning stage of the reaction,followed by the fixation of a large amount of Ca ^2+by oxalate to form calcium oxalate precipitate.As the concentration of oxalic acid increased,the concentration of Ca ^2+in the solution gradually decreased and the concentration of Mg ^2+gradually increased.The maximum concentrations of Ca ^2+and Mg ^2+were 0.65 and 2.87 mmol·L^-1,respectively.The corrosion kinetics of Mg ^2+was fitting with Stumm model,indicating this process was mainly governed by diffusion.In addition,dissolution and loss of Ca ^2+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.

关 键 词：珊瑚砂 草酸 溶蚀 动力学 草酸钙 

分 类 号：X13[环境科学与工程—环境科学] P579[天文地球—矿物学]