高岭石和硅／铝-氧化物对腐殖酸的吸附实验研究

矿物结合的腐殖质可改变矿物的表面性质,矿物对腐殖酸的吸附强度与矿物的吸附位性质、密度、荷电性及比表面积有关.若按比表面积计算,矿物对腐殖酸的吸附强度顺序为氢氧化铝>高岭石>石英;按单位质量计算,吸附强度顺序为高岭石>氢氧化铝>石英.研究表明,矿物表面活性受水溶液pH值的调控,且当pH值在4～7时,上述3种矿物对腐殖酸的吸附机理为石英主要表现为氢键作用;氢氧化铝主要表现为配体交换表面配位作用;高岭石表现为多种形式并存,包括氢键、配体交换表面配位和疏水性作用以及金属离子桥键作用.

An experimental study of the humic acid sorption on kaolinite and Si/Al-oxide minerals

Mineral_bound humic substances can modify the surfaces of minerals. The intensity of humic acid sorption on kaolinite, gibbsite and quartz is related to the nature and number of adsorption site of the minerals, the electricity and the specific surface. Calculated by the specific surface, the capability of minerals for humic acid sorption follows the sequence gibbsite>kaolinite>quartz; calculated by per unit mass of minerals, the sequence is kaolinite >gibbsite >quartz. It is thus considered that the mechanism of humic acid sorption on the minerals is affected significantly by pH value of the solution. Under the condition that pH values of the solution range from 4 to 7, the model for humic acid sorption on minerals can be described as follows: the hydrogen bonding is the main sorption form of quartz; the ligand exchange surface complexing is the main sorption form of gibbsite; and kaolinite is characterized by the existence of multiple sorption forms such as the hydrogen bonding, the ligand exchange surface complexing, the hydrophobic interaction and the cation bridging.