预处理过程中酸对黏土矿物的影响——基于标准矿物的XRD分析  

Effects of Different Pretreatment Processes on Measurement Results of Clay Minerals by X-ray Diffraction

作　　者：李秋玲 乔淑卿 方习生 石学法 LI Qiuling;QIAO Shuqing;FANG Xisheng;SHI Xuefa(College of Oceanography,Hohai University,Nanjing 210098,China;Key Laboratory of Marine Geology and Metallogeny,First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China;Laboratory for Marine Geology,Laoshan Laboratory,Qingdao 266061,China)

机构地区：[1]河海大学海洋学院,江苏南京210098 [2]自然资源部第一海洋研究所海洋地质与成矿作用重点实验室,山东青岛266061 [3]崂山实验室海洋地质过程与环境功能实验室,山东青岛266061

出　　处：《海洋科学进展》2023年第4期610-621,共12页Advances in Marine Science

基　　金：国家自然科学基金项目(42006199、42149902和42049902)。

摘　　要：鉴定沉积物中黏土矿物的常用方法是X射线衍射(X-ray diffraction,XRD)分析。但不同的预处理方法会导致测试结果存在较大差异,例如,在去除样品中有机质和碳酸盐时,不同的试剂浓度、试剂种类以及反应条件等会导致实验结果不同。研究各种预处理方法对黏土矿物XRD分析结果的影响程度,对改进黏土矿物测试方法、提高数据分析准确度具有重要意义。本文对钙蒙脱石(STx-1b)、铁绿泥石(CCa-2)、高岭石(KGa-1b)和伊利石(IMt-2)四种标准黏土矿物样品,进行了不同种类、不同浓度的酸和H2O_(2)处理的对比实验,并采用XRD分析评估各种处理方法对不同黏土矿物的影响。结果显示,质量分数为10%和30%的H2O_(2)处理对4种黏土矿物均不会产生影响;HCl处理会不同程度地破坏蒙脱石的晶体结构,随着HCl摩尔浓度由0.1、0.5 mol/L增大至1.0 mol/L,蒙脱石晶体结构被破坏的程度逐渐加大。因此,使用HCl除碳酸盐时,建议浓度不要超过0.5 mol/L;质量分数为10%的CH3COOH处理对4种黏土矿物的晶体结构均不会产生破坏,但可能因有机酸分子黏附在矿物晶体(尤其是蒙脱石)表面使衍射峰强度升高,这在实际应用中可能会造成蒙脱石相对含量计算结果偏高。Removal of organic matter and carbonate is one of the important steps in the pretreatment of X-ray diffraction(XRD)measurement of clay minerals,and the different reagent concentrations,reagent types and reaction conditions may lead to different experimental results.To improve the accuracy of clay mineral analysis data,it is important to clarify the influence of various processing methods on clay minerals.In this study,we conducted comparative a series of experiments on four standard clay mineral samples(montmorillonite,chlorite,kaolinite,and illite)treated with different types and concentrations of acids and hydrogen peroxide under different reaction conditions,and evaluated the effects of various treatments on different clay minerals by XRD analysis.The results showed that hydrogen peroxide treatment at concentrations of 10%and 30%did not affect any of the four clay minerals;hydrochloric acid treatment would destroy the crystal structure of montmorillonite to different degrees,and the destruction of the crystal structure of montmorillonite gradually increased with the concentration of hydrochloric acid from 0.1,0.5 to 1 mol/L.Therefore,we suggested that when using hydrochloric acid to remove carbonate,the concentration should not exceed 0.5 mol/L.The treatment with acetic acid at a concentration of 10%does not damage the crystal structure of any of the four clay minerals,and yet the intensity of the diffraction peaks may be significantly increased by the adhesion of organic acid molecules to the mineral crystal surfaces,especially for montmorillonite,which may lead to a high calculation of the relative content of montmorillonite in practical applications.tive content of montmorillonite in practical applications.

关 键 词：蒙脱石 HCL 醋酸 X射线衍射 

分 类 号：P736.4[天文地球—海洋地质]