有机膦酸防垢剂对CaCO_3溶液动电性质的影响

为了探讨有机膦酸防垢剂的防垢机理,将等量的CaCl2溶液和Na2CO3溶液混合,适时测定了加入不同有机膦酸防垢剂时CaCO3生成过程中的Zeta电位,并与加入EDTA的实验进行了比较.结果表明,CaCO3表面带有负电,反应刚开始时Zeta电位变化较快,30 min后趋于稳定;生成过程中加入有机膦酸防垢剂会使碳酸钙表面Zeta电位绝对值变小.最后,从配位化学及胶体化学的角度对实验结果进行了分析,认为加防垢剂后Zeta电位的变化对防垢作用有利.

Effect of phosphonic acid scale inhibitors on Zeta potential of calcium carbonate scale

The objective of the paper is to discuss the scale-inhibiting mechanism of phosphonic acids,First,CaCl_2 solution and Na_2CO_3 solution of the same molar concentration and the same volume are prepared separately.Then,the phosphonic acid solutions of different mass concentrations of different sorts are added into CaCl_2 solution,and the obtained solutions are separately mixed with Na_2CO_3 solution.In mixing,CaCO_3 is generated,and Zeta potential of CaCO_3 is measured.The Zeta potential is compared with that obtained when EDTA scale inhibitor solution is added.The measured results show that,the surface of CaCO_3 are electronegative;the Zeta potential varies quickly in the first 30 min of the reaction,and after then,it tends stable;adding phosphonic acid solutions in the process of CaCO_3 generation may make the absolute value of the Zeta potential on the surface of CaCO_3 little.The experimental results are analyzed based on coordinate chemistry and colloid chemistry,and it is held that the variation of the Zeta potential on the surface of CaCO_3 is favorable to scale inhibition after phosphonic acids are added.