改性山竹壳钝化Cd、Cu、Zn复合污染土壤的研究

Study on passivation of soil polluted by Cd,Cu and Zn by modified mangosteen shell

以天然山竹壳(Man)为原料,采用KMnO_(4)氧化法制备得到改性山竹壳(Mn-Man),通过扫描电镜和红外光谱对Mn-Man进行了物化性质表征,研究了Mn-Man对水溶液中Cd^(2+)、Cu^(2+)、Zn^(2+)的吸附特征,在此基础上将Mn-Man投入重金属复合污染土壤中研究其钝化效果,分析了钝化前后土壤理化性质和重金属稳定性。结果表明:经KMnO_(4)改性后,Mn-Man表面形成粗糙多孔形貌,显著提高了其对金属离子的吸附能力;在pH<5时,静电作用对金属离子的吸附起主导作用,在pH>5时,沉淀作用开始对吸附产生重要影响,Mn-Man对金属离子的吸附顺序为Cu^(2+)>Cd^(2+)>Zn^(2+);经Mn-Man钝化后,污染土壤pH和肥力明显提高,有效促进重金属从活泼态向不活泼态转化,降低了重金属的TCLP浸出,表明Mn-Man可对重金属污染土壤进行有效修复。

Modified mangosteen shell(Mn-Man)was produced by using KMnO_(4) oxidation method with natural mangosteen shell(Man)as the raw materials.The physical and chemical properties of samples were analyzed with FE-SEM and FT-IR.The adsorption characteristics of Mn-Man on Cd^(2+),Cu^(2+)and Zn^(2+)in aqueous solution were studied.On this basis,the passivation effect of Mn-Man was studied in a heavy metal contaminated soil.The changes of soil physical and chemical properties associated with the heavy metal stability before and after passivation were analyzed.The results showed that the surface morphology of Mn-Man was rough and porous after modification by KMnO_(4).The adsorption capacity of Mn-Man to metal ions was significantly improved.The electrostatic action dominated the adsorption of metal ions with pH<5.The precipitation had an important effect on the adsorption with pH>5.The adsorption sequence of Mn-Man on metal ions was Cu^(2+)>Cd^(2+)>Zn^(2+).After Mn-Man passivation,pH and fertility of contaminated soil were significantly increased,which effectively promoted the transformation of heavy metals from active state to inactive state,and reduced the TCLP leaching of heavy metals,thus indicating that Mn-Man could effectively restore the contaminated soil by heavy metals.