几种酚类化合物在黄河水体沉积物上吸附行为的实验研究

Adsorptive Behaviors of Phenolic Compounds in Sediments of the Yellow River

采用现场采集河底表层沉积物及室内分析的方法,研究了邻硝基苯酚、对硝基苯酚、2,4-二硝基苯酚、2,4-二氯苯酚、五氯酚等酚类化合物在黄河水体沉积物上的吸附行为。结果表明,邻硝基苯酚等酚类化合物在黄河水体沉积物上的吸附量随pH值的增大而减小;随着离子强度的增加,对硝基苯酚和邻硝基苯酚在黄河水体沉积物上的吸附量增加;沉积物的有机质含量是影响酚类化合物吸附量大小的一个重要因素,即溶解分配过程在黄河水体沉积物吸附酚类化合物中起重要作用;当表面活性剂SDBS存在时,酚类化合物在黄河水体沉积物上的吸附以分配作用为主,SDBS在所测定的浓度范围内(小于CMC),酚类化合物的沉积物-水分配系数均增大,分配系数的增大倍数与它们的辛醇-水分配系数KOW成正相关。

Phenolic compounds, as chemically raw materials and key pollutants, have drawn more and more attention, because they may have potentially ecological risks and do harm to human health further through food chains. Due to its adsorptive behavior, sediment may have an obvious effects on phenolic compound's migration in water body based upon the recent researches. It is well documented that Baotou section of the Yellow River is a representative as the ultimate receiving body of industrial sewage, therefore, it is necessary and important that studying the contamination of phenolic compounds in the Baotou section of the Yellow River be urgent. In this paper, o-nitrophenol, p-nitrophenol, 2,4-dinitrophenol, 2,4-dichlorophenol and pentachlorophenol were chosen as target compounds. Taking the sediments from the clear reach in the Baotou Section of the Yellow River as the adsorbent, and the solutions containing the above-mentioned five phenolic compounds as the adsorbates, we tested the adsorption and affecting factors. According to the results, the adsorbability of each phenolic compounds were influenced by pH, ionic strength, and organic content and sodium dodecyl benzene sulfonate (SDBS) in the sediments studied. The adsorption capacity of each phenolic compound decreased with increasing pH ranging from 2 to 12. Taking NaCl as electrolyte, the adsorption capacity of o-nitrophenol and p-nitrophenol increased obviously with elevated ionic strength when pH at 7.3, while 2,4-dichlorophenol when pH at 11.3. However, the adsorption capacity of 2,4-dichlorophenol increased little when pH at 7.3. The adsorption capacity decreased after removing organic matter, indicating that the dissolving and partitioning process in the sediment is significant. The main way of adsorption was partition process, and the distribution coefficients of sediment-water became larger after adding SDBS which may reinforce the adsorption when the initial concentrations below the surfactant CMCs for SDBS and the adsorption capacity was directly relative to the distribution coefficient between capryl alcohol and water, respectively