Chen Bao-liang, Zhu Li-zhong, Tao Shu
Department of Environmental Sciences, Zhejiang University, Hangzhou 310028, China.
J Environ Sci (China). 2005;17(2):185-9.
The thermodynamic behavior of organic contaminants in soils is essential to develop remediation technologies and assess risk from alternative technologies. Thermodynamics of phenanthrene partition into four solids(three soils and a bentonite) from water were investigated. The thermodynamics parameters (deltaH, deltaG degrees, deltaS degrees) were calculated according to experimental data. The total sorption heats of phenanthrene to solids from water ranged from -7.93 to -17.1 kJ/mol, which were less exothermic than the condensation heat of phenanthrene-solid (i.e., -18.6 kJ/mol). The partition heats of phenanthrene dissolved into solid organic matter ranged from 23.1 to 32.2 kJ/mol, which were less endothermic than the aqueous dissolved heat of phenanthrene (i.e., 40.2 kJ/mol), and were more endothermic than the fusion heat of phenanthrene-solid (i.e., 18.6 kJ/mol). The standard free energy changes, deltaG degrees, are all negative which suggested that phenanthrene sorption into solid was a spontaneous process. The positive values of standard entropy changes, deltaS degrees, show a gain in entropy for the transfer of phenanthrene at the stated standard state. Due to solubility-enhancement of phenanthrene, the partition coefficients normalized by organic carbon contents decrease with increasing system temperature (i.e., ln Koc = -0.284 ln S + 9.82 (n = 4, r2 = 0.992)). The solubility of phenanthrene in solid organic matter increased with increasing temperatures. Transports of phenanthrene in different latitude locations and seasons would be predicted according to its sorption thermodynamics behavior.
土壤中有机污染物的热力学行为对于开发修复技术和评估替代技术的风险至关重要。研究了菲从水相分配到四种固体（三种土壤和一种膨润土）中的热力学。根据实验数据计算了热力学参数（ΔH、ΔG°、ΔS°）。菲从水相到固体的总吸附热范围为-7.93至-17.1 kJ/mol，比菲-固体的冷凝热（即-18.6 kJ/mol）放热少。菲溶解到固体有机质中的分配热范围为23.1至32.2 kJ/mol，比菲的水溶热（即40.2 kJ/mol）吸热少，且比菲-固体的熔化热（即18.6 kJ/mol）吸热多。标准自由能变化ΔG°均为负值，这表明菲吸附到固体中是一个自发过程。标准熵变ΔS°的正值表明在规定的标准状态下菲转移时熵增加。由于菲的溶解度增强，以有机碳含量归一化的分配系数随系统温度升高而降低（即ln Koc = -0.284 ln S + 9.82 （n = 4，r2 = 0.992））。菲在固体有机质中的溶解度随温度升高而增加。将根据菲的吸附热力学行为预测其在不同纬度位置和季节的迁移。
