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赤铁矿胶体是可变电荷土壤的重要组成部分,其相互作用深刻影响可变电荷土壤团聚体的形成、稳定与分散,从而深刻影响土壤结构状态与物质迁移过程的发生.通常的土壤pH(pH<8)条件下,赤铁矿带净正电荷,其凝聚由溶液中的阴离子引发.目前,阴离子引发土壤胶体凝聚的相关研究鲜见报道.本研究以赤铁矿为试验材料,在pH=4的酸性条件下研究了NaCl溶液中Cl-引发赤铁矿凝聚的动力学特征.研究发现:1)NaCl溶液中,赤铁矿胶体的临界聚沉浓度为99.2mmol/L.2)NaCl溶液中,赤铁矿胶体的凝聚活化能与NaCl浓度间满足如下指数关系:ΔE=RTln{[0.35f0/(0.44f0-8.66)]}.3)当NaCl浓度小于99.2mmol/L时,赤铁矿胶体发生慢速的反应控制凝聚,即表现出RLCA凝聚机制;当NaCl浓度高于99.2mmol/L时,赤铁矿胶体发生快速的扩散控制凝聚,即表现出DLCA凝聚机制.本研究发现的带正电荷赤铁矿胶体的凝聚动力学规律对于进一步探索可变电荷土壤团聚体的形成与分散机制具有一定参考价值.
Hematite colloids are an important part of variable charge soils and their interaction deeply affects the formation, stabilization and dispersion of variable charge soil aggregates, which will profoundly affect soil structure and material migration. (pH <8), the net positive charge of hematite belt and its agglomeration are induced by the anions in the solution.At present, there are few reports about the anionic coagulation induced by soil colloids.In this study, hematite was used as the experimental material, = 4, the kinetic characteristics of Cl-induced hematite agglomeration in NaCl solution were studied.The results showed that: 1) the critical concentration of hematite colloid in NaCl solution was 99.2mmol / L.2) NaCl Solution, the cohesion activation energy of hematite colloid and the NaCl concentration satisfy the following exponential relationship: ΔE = RTln {[0.35f0 / (0.44f0-8.66)]}. 3) When the NaCl concentration is less than 99.2mmol / L, red The slow reaction of iron colloids controls the aggregation, that is, the aggregation mechanism of RLCA. When NaCl concentration is higher than 99.2mmol / L, hematite colloids rapidly diffuse and control the aggregation, that is, the aggregation mechanism of DLCA is found. Of the positively charged hematite colloidal kinetic law of aggregation Formation and dispersion mechanism further variable charge soil aggregates having a certain reference value.