一种改进的盐滴定法测定氧化锰矿物的电荷零点  

POINT OF ZERO CHARGE(PZC) OF MANGANESE OXIDES DETERMINED WITH AN IMPROVED SALT TITRATION METHOD

作　　者：陆泗进[1] 谭文峰[1] 刘凡[1] 冯雄汉[1] 

机构地区：[1]华中农业大学农业部亚热带农业资源与环境重点实验室

出　　处：《土壤学报》2006年第5期756-763,共8页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(No.40471071;40471070);教育部科学技术研究重点项目(No.104131)资助

摘　　要：以针铁矿为对照,采用电位滴定法(PT)、快速电位滴定法(RPT)、盐滴定法(ST)和改进的盐滴定法(IST)研究了几种氧化锰矿物的电荷零点(PZC)。结果表明:PT法测得酸性水钠锰矿、锰钾矿和钙锰矿的PZC分别为1.18、1.98和3.98,RPT法的结果分别为1.75、2.10和3.50。而ST法测得氧化锰矿物的ΔpH与横轴没有交点,但延长加入0.5 ml 2 mol L-1KCl溶液后的平衡时间至24 h,获得上述样品的PZC分别为0.98、1.72和3.31。经典ST法通过改进,可以测定氧化锰矿物的PZC,其方法简单,结果与PT、RPT法有可比性。Points of zero charge （PZC） of goethite as control and several ores of manganese oxides were determined with different methods, e.g. potentiometric titration （PT）, rapid potentiometric titration （RPT）, salt titration （ST） and the improved salt titration （IST） . Results showed PZC of birnessite, cryptomelane, todorokite was 1.18, 1.98 and 3.98 respectively with PT and 1.75, 2.10 and 3.50 respectively with RPT. With ST there was no point of intersection of ApH of manganese oxides and x-axis. However, when 0.5 ml 2 mol L^- 1 KCI was added into the solution and its equilibrium duration was set at 24 h, PZCs of the manganese oxides were determined to be 0.98, 1.72 and 3.31, respectively. The PZCs of goethite obtained with the PT and RPT methods were both 8.00 showing no difference between the two methods, and with the ST and IST methods were 8.31 and 8.41 respectively, showing a minor difference. After the ST method was improved, it could be used to determine PZC of manganese oxides. This method was reliable, simple and convenient compared with the PT and RPT methods.

关 键 词：电荷零点 盐滴定法 氧化锰矿物 

分 类 号：S153.1[农业科学—土壤学] S153.3[农业科学—农业基础科学]