摘要:
采用沉降试验研究高岭石在不同pH及钙镁离子浓度下的分散行为,并结合Zeta电位分析及EDLVO理论计算进一步研究了高岭石颗粒间的相互作用.试验结果表明,pH的升高可促进高岭石的分散,而钙镁离子的加入可促进高岭石的凝聚;结合Zeta电位结果可知,pH的升高会降低表面电位,而钙镁离子加入会使表面电位升高.电位绝对值越大,颗粒间排斥力越大,易于分散.碱性条件下钙镁离子在矿物表面形成氢氧化物沉淀,导致高岭石表面的Zeta电位升高,破坏悬浮液的稳定性.EDLVO理论计算结果与沉降试验和Zeta电位试验的结果一致,可以对高岭石的分散行为进行理论解释.
关键词:
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高岭石
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钙镁离子
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分散
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EDLVO
Abstract:
To study the effect of solution pH, calcium and magnesium ions on dispersion of kaolinite, sedimentation test, zeta potential measurement and EDLVO theory calculation were adopted to explain the interaction between kaolinite particles.The results showed that pH increase promoted kaolinite dispersion, but the addition of calcium and magnesium ions accelerated the kaolinite agglomeration.Zeta potential analysis indicated that surface potential of kaolinite decreased with the solution pH increase.While the addition of calcium and magnesium ions could increase its surface potential.Electrostatic repulsion was proportional to the absolute value of zeta potential.Meanwhile, a strong electrostatic repulsion benefited the dispersion behavior of kaolinite.In alkaline medium, calcium and magnesium ions generated hydroxide precipitation on the kaolinite surface, increasing the zeta potential of kaolinite surface and thus destroying the stability of suspension.The results of EDLVO theory calculations were consistent with the results of sedimentation tests and zeta potential measurements, which could give theoretical explanations to the dispersion of kaolinite.
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