可溶性有机质对芘在泥炭和高岭土上吸附和解吸的影响

为掌握可溶性有机质(DOM)对憎水性有机污染物吸附和解吸行为的影响,本研究选取四环多环芳烃——芘作为目标污染物,通过批平衡实验研究了不同分子量组分DOM对芘在泥炭和高岭土上吸附和解吸的影响.结果表明,吸附和解吸数据均可以用Freundlich模型很好地拟合(R²>0.93).DOM的添加抑制了泥炭对芘的吸附,并且分子量越大的DOM产生的抑制效应越明显,主要是由于DOM与芘分子的竞争、增溶作用及泥炭表面微孔的堵塞引起的.与之相反,DOM促进了芘在高岭土上的吸附,DOM分子量越大,促进效应越强,这是由于DOM与芘分子之间通过累积吸附或共吸附增加高岭土对芘的吸附.DOM促进了芘在泥炭和高岭土上的解吸,并且促进效应随分子量的增加而增强.此外,芘在泥炭和高岭土上的解吸均存在迟滞现象,均在低浓度时表现出更明显的效应.DOM_bulk和DOM_(>14000 Da)增加了芘在泥炭上的解吸迟滞现象,但降低了其在高岭土上的解吸迟滞现象.

Effects of dissolved organic matter on the adsorption and desorption of pyrene on peat and kaolin

In order to understand the effects of dissolved organic matter(DOM)on the adsorption and desorption properties of hydrophobic organic pollutants,a typical polycyclic aromatic hydrocarbon compound pyrene(tetracyclic)was selected as the target pollutant in this study.Batch experiments were conducted to investigate the effects of different fractions of DOM on the adsorption and desorption characteristics of pyrene on peat and kaolin.The results indicated that the adsorption and desorption data were well fitted by Freundlich Model(R2>0.93).The addition of DOM inhibited the adsorption of pyrene on peat and the inhibition effects were more significant with the increase of molecular weight DOM,which caused by the competitive effects between DOM and pyrene,solubilization of pyrene,and the blocking of micro-pores on peat surface.On the contrary,DOM enhanced the adsorption of pyrene on kaolin via accumulated adsorption and co-adsorption.The higher the molecular weight of DOM,the more significant the promotion effects presented.DOM increased the desorption of pyrene on both peat and kaolin and the desorption capacity enhanced with increasing molecular weight of DOM.Besides that,desorption hysteresis was observed for the desorption of pyrene from peat and kaolin,DOMbulk and DOM>14000Da enhanced the desorption hysteresis of pyrene from peat whereas inhibited that from kaolin.