不同Ca^(2+)浓度及pH值溶液中高岭石颗粒表面Zeta电位模拟

Zeta potential simulation of kaolinite particle surface in different Ca^(2+) concentration and pH value suspension

高岭石颗粒因表面荷电稳定分散在煤泥水中难以沉降,水溶液中Ca2+浓度及pH值对高岭石颗粒表面Zeta电位影响较大.基于高岭石不同断面的不同荷电机理,选择高岭石不同断面的晶胞数为权重,得到了颗粒表面总Zeta电位模型,并进行了模拟计算,利用拟合对该模型进行校正.采用电泳法测定了不同Ca2+浓度及不同pH值下高岭石颗粒的Zeta电位,并与模拟值进行了比较,结果表明:当溶液中Ca2+浓度大于等于25mg/L时,模型能够有效的预测高岭石表面的Zeta电位,最大偏差为1.368mV;当溶液中Ca2+浓度小于25mg/L的溶液中,由于Helm-holtz内层负电荷吸附量变化,预测精度降低.当溶液中pH值小于等于9时,模型能够有效的预测高岭石表面的Zeta电位,模型的最大偏差为1.368mV;当溶液中pH值大于等于9时,由于Ca2+的羟基络合吸附量增大,预测精度降低.

It is difficult to settle down kaolinite particles in the coal slime water due to their stable surface charge.The Ca2＋ concentration and pH value has a comparatively large effect on kaolinite surface Zeta potential in aqueous solution.Based on the different charge mechanism on different fracture surface of kaolinite,the total-surface Zeta potential model was established by the crystal cell number of different kaolinite fracture surface as weight,and adjusted by the fitting.The kaolinite surface Zeta potentials was simulated by the model above.The kaolinite surface Zeta potentials was also measured by the electrophoresis method.The results show that the model could effectively predict kaolinite surface Zeta potential when the Ca2＋ concentrations is more than 25 mg/L and the pH less then 9.The maximum deviation is 1.368 mV.The prediction accuracy reduced when Ca2＋ concentration is less than 25 mg/L because of increasing of negative charge on the kaolinite surface.The prediction accuracy reduced when pH value is more than 9 because of Ca2＋ complexion adsorption.