海藻酸钠改性纳米零价铁对底泥中Cd的稳定化研究

Immobilization of Cd in sediment using sodium alginate-modified nanoscale zero-valent iron

制备了海藻酸钠改性纳米零价铁(SA-nZVI),并对其结构进行表征。用制备的SA-nZVI和未改性的纳米零价铁(nZVI)修复Cd污染的底泥,通过重金属形态、酶活性、细菌群落多样性变化评价稳定化效果。结果表明,0.10%(质量分数)海藻酸钠溶液制备的SA-nZVI对底泥中Cd的稳定效果最好,随稳定化时间的延长,残渣态质量分数升高,弱酸提取态质量分数下降,30d后相比于不添加修复剂的对照组,残渣态质量分数升高了41.79百分点,弱酸提取态质量分数下降了23.18百分点。脲酶和过氧化氢酶的活性以及细菌群落多样性均支持0.10%海藻酸钠溶液制备的SA-nZVI对Cd的稳定化效果最好。从结构上进行解释,0.10%海藻酸钠溶液制备的SA-nZVI与nZVI相比,表面覆盖了一层海藻酸钠,分散性更好,不易被氧化。

Sodium alginate-modified nanoscale zero-valent iron(SA-nZVI)was prepared and characterized.The changes of the fraction of Cd,enzyme activities and bacterial community diversity were applied to evaluate the immobilization effect when SA-nZVI and unmodified zero-valent iron(nZVI)were used to repair Cd contaminated sediment.Results showed that0.10%(mass fraction)sodium alginate solution prepared SA-nZVI had the best immobilization effect.The mass fraction of residual Cd increased while weak acid extracted Cd decreased with immobilization time going.After30d,the mass fraction of residual Cd increased by41.79percentage points and the mass fraction of weak acid extracted Cd decreased by23.18percentage points compared with no repair agent treatment.Urease and catalase activities,as well as the bacterial community diversity all supported the above conclusion.0.10%sodium alginate solution prepared SA-nZVI had a cover of sodium alginate,leading to better dispersibility and oxidation resistance compared with nZVI,which explained the phenomenon in structure.