比较三种稳定剂对FeS纳米颗粒的稳定效果及对水土中镉的固定与去除性能的影响

Comparing three stabilizers for stabilizing FeS nanoparticles:Performance and effects on immobilization of cadmium in water and soil

本研究评估了三种多糖稳定剂(羧甲基纤维素钠(CMC)、羧甲基淀粉钠(CMS)和一种水溶性淀粉)用于稳定FeS纳米颗粒的有效性,并测试了相应稳定化纳米颗粒在水和土壤中固定Cd^(2+)的性能。使用0.010 wt%CMC、0.025 wt%CMS或0.065 wt%淀粉可获得完全稳定的FeS纳米颗粒(100 mg/L FeS)。CMC-FeS表现出较高的zeta负电位,淀粉-FeS保持中性,而CMS-FeS则表现出中等负电位。CMCFeS对Cd^(2+)的吸附速率最快,吸附容量也最高。当用100 mg/L CMC-FeS或CMS-FeS处理一种含Cd土壤(58.3 mg/kg Cd)后,Cd的TCLP浸出率分别降低了88.4%和68.0%。CMC-FeS和CMS-FeS均可在模型土壤中运移,显示出其在土壤中原位固定Cd^(2+)方面的潜力。土壤穿透曲线实验表明,CMC-FeS在4.5个孔体积,CMS-FeS在约25个孔体积处几乎完全穿透。柱实验结果表明,当用55个孔体积的CMC-FeS或CMS-FeS悬浮液(100 mg/L)处理该含Cd土壤后,Cd的水浸出率分别降低了98.2%和98.0%。根据目标污染物、材料在土壤中的传输特性和材料成本,可找到这三种稳定剂在土壤修复中的最佳应用。

In this study,we evaluated effectiveness of three polysaccharide stabilizers(sodium carboxymethyl cellulose(CMC),sodium carboxymethyl starch(CMS),and a water-soluble starch)for stabilizing FeS nanoparticles,and tested the stabilized nanoparticles for immobilization of Cd^(2+)in water and soil.Fully stabilized FeS nanoparticles(100 mg/L FeS)were obtained using 0.010 wt%CMC,0.025 wt%CMS,or 0.065 wt%starch.CMC-FeS showed a highly negative zeta potential,starch-FeS remained neutral,whereas CMS-FeS displayed a moderately negative potential.CMC-FeS showed the fastest sorption rate and highest sorption capacity for Cd^(2+).When a Cd-laden soil(58.3 mg/kg Cd)was amended with 100 mg/L CMC-FeS or CMS-FeS,the TCLP-leachable Cd was reduced by 88.4%and 68.0%,respectively.Both CMC-FeS and CMS-FeS were transportable through a model soil and showed high potential for in-situ immobilization of Cd^(2+)in soil.Nearly complete breakthrough occurred at 4.5 pore volumes(PVs)for CMC-FeS and about 25 PVs for CMS-FeS.When the Cd-laden soil was treated with 55 PVs of CMC-FeS and CMS-FeS suspensions(100 mg/L),the water-leachable soluble Cd was reduced by 98.2%and 98.0%,respectively.The three stabilizers may find their best uses in soil remediation according to the target contaminants,transport properties in soil,and material cost.