外源有机酸添加对风化煤矸石污染释放及重金属有效性的影响

Effects of Organic Acid on the Release of Contaminant and Heavy Metal Availabilities of Weathered Coal Gangue

为评价不同类型有机酸对风化煤矸石污染释放的影响,通过在风化煤矸石中添加不同种类的外源有机酸(腐殖酸、柠檬酸、草酸、水杨酸)进行处理,分析稳定7d后煤矸石浸出液的特征污染组分及TCLP提取态重金属含量。结果表明:对照处理组的风化煤矸石浸出液具有典型的酸性矿山废水特征。添加少量柠檬酸、草酸和水杨酸能显著(p<0.05)降低风化煤矸石浸出液的pH和Eh值、明显增加浸出液的盐度、亚铁、总铁和硫酸盐含量,然而腐殖酸处理对浸出液pH、EC、Eh无明显影响,且可降低浸出液硫酸盐含量。少量外源有机酸添加均能不同程度促进风化煤矸石中Fe、Mn、Cu、Zn元素溶出,其中水杨酸处理对4种金属元素的溶出量较大。然而4种外源有机酸处理则能有效抑制Pb溶出,其中柠檬酸、水杨酸处理抑制效果最明显。有机酸添加对风化煤矸石的重金属有效性影响表现为4种外源有机酸处理均能明显增加风化煤矸石中Mn元素的有效性,降低Zn元素的有效性,但对Fe元素的有效性影响不明显。4种外源有机酸添加对煤矸石中Cu元素有效性具有不同程度的影响,其中腐殖酸、草酸处理能明显降低Cu元素有效性,而柠檬酸和水杨酸处理则明显增加Cu的有效性。

Effect of different organic acids on contaminant release from weathered coal gangue was studied by adding different kinds of organic acids（humic acid,citric acid,oxalic acid,and salicylic acid）.Pollution contents of leaching solution and TCLP extractable heavy metal contents of the medium were tested after stabilition for 7day.Results show that the weathered coal gangue leaching liquid has typical characteristics of acid mine drainage.Addition of a small amount of citric acid,oxalic acid and salicylic acid can significantly（p0.05）reduce the leaching solution of pH and Eh value and increase obviously the salinity of the leaching solution,ferrous and total iron content.However,humic acid treatment has no effect on pH,EC,Eh and can reduce the content of sulfate in leaching solution.The addition of a small amount of organic acids can promote the dissolution of Fe,Mn,Cu,and Zn in different degrees from weathered coal gangue,and salicylic acid treatment can promote four kinds of metal dissolution at the highest degree.However,four kinds of organic acid can effectively restrain Pb dissolution,and the inhibiting effect of citric acid and salicylic acid treatment is the most obvious.Four kinds of exogenous organic acid treatment can significantly increase the availability of Mn and reduce the availability of Zn,but the effect of organic acids on Fe is not obvious.Different kinds of organic acids have different effects on the availability of Cu.Humic acid and oxalic acid treatment can obviously reduce Cu validity,however,citric acid and salicylic acid have the opposite effect.