【摘要】 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SO₄^-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。更多还原

【Abstract】 In order to study the adsorption of cations and anions by red soils in relation to the electric charge of the soil, electrolyte solutions of KCl, NH₄Cl and K₂SO₄ in concentrations of 0.001, 0.01 and 0.1N were equilibrated with soil samples at different pH. Two soil samples were used for the study, one was red earth with a permanent negative charge of 7.4 m.e. per 100 gms. and a positive charge of 2.8 m.e. per 100 gms. at pH 2 and the other was a lateritic soil with a permanent negative charge of 3.3 m.e. per 100 gms. and a positive charge of 5.8 m.e. per 100 gms. （iso-electrie point at about pH 4.7）The pH at which a soil showed neither positive adsorption nor negative adsorption for Cl^- ions was called the point of zero adsorption of the soil under the specified conditions. This point was thought to be closely related to the relative magnitude of the effective positive charge density and the effective negative charge density of the soil. It was shown that the point of zero adsorption for the lateritic soil was higher than that for the red earth. The point decreased with the decrease of ion concentration for the red earth, whereas ion concentration had no remarkable effect on the lateritie soil.The pH at which a soil adsorbed equal amounts of cations and anions was called the iso-ionic point of the soil. Besides the electric charge of the adsorbent, this point was also strongly affected by the valence type and the concentration of electrolytes. The iso-ionic point for 1:2 type electrolyte was higher than that for 1:1 type electrolyte. In the former case the point decreased with the inerease of concentration, while in the latter case the point practically unchanged irrespective of the change in concentration for the lateritic soil although for the red earth the point decreased with the increase of concentration too.The removal of free iron oxides from the soil resulted in the decreases of both the point of zero adsorption and the iso-ionic point as a consequence of the decrease of positive charge.It was found that although both the electric charge and the adsorption of cations or anions were strongly affected by the pH of the solution, the effected extent were different. When expressed as the ratio of adsorbed cations to the amount of negative charge or the ratio of adsorbed anions to the amount of positive charge of adsorbent, the former increased with the increase of pH and the latter increased with the decrease of pH. It thus seems to imply that besides the change of electric charge of the soil, pH also plays an important direct effect on ion adsorption.更多还原