【摘要】 采用悬液Wien效应法研究了Na+、K+、NH4+、Ca2+、Zn2+和Cd2+阳离子与红壤黏粒间的相互作用及能量关系。结果表明,在试验条件下,红壤黏粒与阳离子Na+、K+、NH4+、Ca2+、Zn2+和Cd2+的平均结合自由能分别为:4.50、7.35、7.15、9.12、9.84和9.63 kJ mol-1。含Ca2+悬液的电导率随场强增加而递增最快,含Na+和NH4+悬液的电导率随场强增加而增加最慢,而含K+、Zn2+和Cd2+的悬液电导率的增速相近、介于其间。红壤悬液中不同阳离子的解离速率顺序为Ca2+>K+>Zn2+=Cd2+>Na+=NH4+。在低场强(15～80 kV cm-1)下,不同阳离子的平均吸附自由能ΔGad没有差异。在场强100 kV cm-1以上,二价阳离子的ΔGad明显大于单价阳离子,不同阳离子间ΔGad的大小顺序为NH4+≤Na+<K+<Cd2+<Zn2+<Ca2+。在场强150 kV cm-1时,红壤黏粒与阳离子Na+、K+、NH4+、Ca2+、Zn2+和Cd2+的平均吸附自由能分别为0.64、0.80、0.57、1.66、1.43和1.27 kJ mol-1,二价阳离子的平均吸附自由能约为单价离子的2.5～3倍。低场强(10～30 kVcm-1)时,红壤悬液中阳离子的平均解离度顺序为Na+>>K+=NH4+>Ca2+>Zn2+=Cd2+,Na+离子平均解离度的递增速率(场强增加1kV cm-1所引起的解离度增量)最大,为0.000 427 cm kV-1,其次是Ca2+离子,为0.000 221 cm kV-1,其余阳离子为0.000 12～0.000 14 cm kV-1。更多还原

【Abstract】 Investigation of interactions and energy relationships between cations(Na+,K+,NH+4,Ca2+,Zn2+,and Cd2+) and clay fraction of red soil with the aid of Wien effect in dilute suspensions.Results show that the mean Gibbs binding energies of the clay fraction of red soil with cations are 4.50,7.35,7.15,9.12,9.84,and 9.63 kJ mol-1 for Na+,K+,NH+4,Ca2+,Zn2+,and Cd2+,respectively,in the experimental condition.Electric conductivity increased very fast with field strength in the suspension containing Ca2+,at a similar rate in the suspension containing K+,Zn2+ or Cd2+,but very slowly in the suspensions containing Na+ or NH+4.In terms of releasing rate,the cations in the red soil suspension are in the order of Ca2+ > K+ > Zn2+ = Cd2+ > Na+ = NH+4.The mean Gibbs free adsorption energies,ΔGad,of the cations remained basically the same when the field strength was in the range of 15 to 80 kV cm-1,but when the field strength reached over 100 kV cm-1 ΔGad of the divalent cations were more obviously higher than of the monovalent cations,following an order of NH+4 ≤ Na+ < K+ < Cd2+ < Zn2+ < Ca2+.However,when the field strength got high up to 150 kV cm-1,ΔGad of the cations were 0.64,0.80,0.57,1.66,1.43,and 1.27 kJ mol-1 for Na+,K+,NH+4,Ca2+,Zn2+,and Cd2+,respectively,which shows that the mean Gibbs free adsorption energy of the divalent cations were about 2.5-3 times as much as that of the monovalent cations.The cations in the red soil suspensions at a low field strength ranging from 10 to 30 kV cm-1 showed a decreasing order of Na+ >> K+ = NH+4 > Ca2+ >Zn2+ = Cd2+ in mean dissociation degree.The increasing rate of mean dissociation degree,which is the increment of dissociation degree induced by the increment of 1 kV cm-1 in field strength,is the highest with Na+ being 0.000427 cm kV-1,the second with Ca2+ being 0.000221 cm kV-1,and the lowest with other cations in the range of 0.00012～0.00014 cm kV-1.更多还原