高岭石的胶体稳定性与其电荷零点的关系

THE STABILITY OF KAOLINITE COLLOID AS A FUNCTION OF ITS ZERO POINT OF CHARGE(ZPC)

高岭石的胶体稳定性与其表面电荷性质有密切关系。高岭石既带有正电荷又带有负电荷,高岭石与腐殖酸复合可增加负电荷,降低电荷零点,增加粒间斥能,提高了它的胶体稳定性。

The stability of kaolinite colloid is closely related to the chracteristics ofits surface charge.The surface of colloidal particles of kaolinite is negativelyand positively charged. The increase of negative charge in kaolinite may enh-ance the stability of kaolinite colloid. Generally, the methods of increasingnegative charge are to raise pH, and add phosphate or organic matter. Howe-ver, raising pH and adding phosphate will destroy the kaolinite, so the additionof organic matter is preferable, as it may be easily removed by oxidation. Theincrease of negative charge in kaolinite will lower its zero point of charge(from 3.2 down to 2.7 pH). We have calculated the repulsive energy(△E) incolloidal particles of kaolinite by means of zero point of charge, indicating thestability of kaolinite as a function of zero point of charge. In addition, the qu-antity extracted of kaolinite colloid under the action of humic acid is a directline of evidence.