腐殖酸对载木质素铁聚乙烯薄膜上砷释放行为的影响

Effect of humic acid on arsenic release behavior from polyethylenefilm loaded by ferric lignin

将吸附砷饱和后的载木质素铁聚乙烯薄膜固定于容器底部,采用静态批实验方法,添加不同质量浓度腐殖酸,研究溶液pH值、砷及铁离子质量浓度随时间的变化情况,考察环境温度的影响,分析薄膜上砷的释放行为.结果表明,添加腐殖酸能促使砷离子释放;当添加腐殖酸质量浓度为1,2和3 mg/L时,79 d内砷离子最大释放率分别为13.12%,15.87%和18.21%.实验温度范围内,温度变化对砷离子释放没有影响.光学显微镜测试表明腐殖酸引起的砷离子释放不会影响薄膜表面形貌;液相-有机碳联用测试仪(LC-OCD)和扫描电镜(SEM)测试表明腐殖酸在载木质素铁聚乙烯薄膜表面形成覆盖层,并且实验后薄膜表面的疏松孔增多.腐殖酸通过影响实验体系pH值、与薄膜上铁氧化物结合、占据有效吸附位点引起薄膜上砷离子的释放;而偏酸性溶液导致薄膜上少量铁离子的溶出,也促进了砷离子的释放.

Batches of static experiments were used to study the arsenic release from the polyethylene film loaded by ferric lignin after saturated with arsenic adsorption,which was fixed in a container.By adding different concentrations of humic acid,the changes of pH value,changes of arsenic and iron concentrations with time,and the effect of environmental temperature were investigated.The results showed that the addition of humic acid could promote the release of arsenic,and when the concentration of humic acid was 1,2 and 3 mg/L,the maximum arsenic release rate within 79 days was 13.12%,15.87%and 18.21%,respectively.While the temperature was 5,15,25 or 43℃examined in this work,changes of the temperature had no effect on arsenic release.Microscope images showed that arsenic release mediated by humic acid had no effect on the surface morphology of the film.LC-OCD and SEM results showed that there were covering layers formed by humic acid on the surface of film,of which the surface was looser.Therefore,humic acid mediated the release of arsenic on the film by changing the pH value of the experimental system,binding with iron oxides and occupying the effective adsorption sites on the film,while the acidity of the solution led to the dissolution of a small amount of iron ions on the film,which also promoted the release of arsenic.