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本文报道了广东的砖红壤和江西的红壤的电荷性质和在不同pH条件下对不同浓度的阴、阳离子的吸附,讨论了离子吸附与电荷性质的关系。砖红壤和红壤同时带有负电荷和正电荷(砖红壤的等电点在pH4.7左右),因而同时吸附阳离子和阴离子。阳离子的吸附取决于土壤的负电荷;阴离子的吸附取决于正电荷,而不是取决于静电荷。pH对离子吸附的影响,主要是pH变化的直接影响,其次是通过改变表面电荷所产生的间接影响。电解质浓度增加时离子吸附量增大,但相对吸附量(占溶液中离子数量的%)减小。红壤对SO_4~-离子的吸附量大于对Cl~-离子的吸附量。pH较高时Cl~-出现负吸附。土壤去除游离氧化铁后,只在pH很低时才吸附极少量Cl~-离子。吸附等量阳离子和阴离子时的pH称为等离子点。对1:2型电解质的等离子点高于1:1型者;1:2型电解质浓度增大时土壤的等离子点降低;1:1型电解质浓度增大时江西红壤的等离子点降低,而砖红壤者不变。在相同情况下,砖红壤的等离子点较江西红壤者为高。土壤去除游离氧化铁后等离子点显著下降。
In this paper, the charge properties of red brick in Guangdong and the red soil in Jiangxi and the adsorption of different concentrations of anion and cation under different pH conditions were discussed. The relationship between ion adsorption and charge properties was discussed. Both red and red soils have both negative and positive charges (the isoelectric point of the red soils is around pH 4.7), thus simultaneously adsorbing cations and anions. The adsorption of cations depends on the negative charge of the soil; the adsorption of anions depends on the positive charge and not on the electrostatic charge. The effect of pH on ion adsorption is mainly due to the direct effect of pH change, followed by the indirect effect of changing surface charges. When the electrolyte concentration increases, the amount of ion adsorption increases, but the relative adsorption amount (% of the amount of ions in the solution) decreases. The amount of SO_4 ~ - ion adsorbed by red soil was larger than that of Cl ~ - ion. Cl ~ - is negatively charged at higher pH. After the soil removes the free iron oxide, very little Cl ~ - ions are adsorbed only at very low pH. The pH at which the same amount of cations and anions are adsorbed is called the plasma point. The plasma point of 1: 2 type electrolyte was higher than that of 1: 1 type, while the plasma level of 1: 2 type electrolyte was decreased when the concentration of 1: 2 type electrolyte was increased. Red soil who do not change. Under the same conditions, the plasma point of red brick is higher than that of red soil in Jiangxi. Plasma removal of free iron oxide significantly decreased the plasma point.