药渣生物炭联合麦饭石对铜镉污染土壤修复研究

Study on Remediation of Cu and Cd in Contaminated Soil with the Combination of Biochar and Maifanite

期望以板蓝根药渣为原材料制备生物炭,用于修复重金属Cu、Cd污染土壤,实现以废治污。该研究探讨以板蓝根中药渣为原材料制备的生物炭联合天然麦饭石对重金属Cu、Cd污染土壤的钝化修复效果及作用机理,采用室内土壤培养试验,研究钝化剂施加量为2%土壤质量时,500℃下制备的药渣生物炭(BC500)、天然麦饭石(MS)和等质量的生物炭与麦饭石组合钝化剂(BC500+MS)共3种钝化剂处理对重金属Cu、Cd污染土壤p H、土壤养分、铜镉形态的影响。土壤培养30 d研究结果表明,3种钝化剂均能提高土壤pH、土壤养分;施加单一药渣生物炭对铜的钝化效果好于天然麦饭石,但天然麦饭石对镉的钝化比药渣生物炭的效果更优;采用修正BCR三步连续提取法提取不同处理的Cu、Cd形态,与对照值(CK)相比,BC500处理的弱酸可提取态Cu、Cd含量分别降低了9.00%和6.82%,残渣态Cu、Cd含量分别增加了16.08%和16.67%;MS处理的弱酸可提取态Cu含量较对照无变化,Cd的酸可提取态降低了17.05%,残渣态Cu、Cd含量分别增加7.75%和59.52%;BC500+MS处理的弱酸可提取态Cu、Cd含量分别降低4.44%和26.14%,残渣态Cu、Cd含量分别增加10.16%和78.57%。通过表征分析表明,生物炭对Cu、Cd污染土壤钝化机制是吸附固定和形成沉淀作用,麦饭石对Cu、Cd污染土壤钝化机制主要是吸附作用。

It is expected that biochar will be prepared from Radix Isatidis dregs as a raw material for the remediation of heavy metals Cu,Cd contaminated soil and to achieve pollution control with waste.This study discusses the passivation effect and mechanism of biochar and natural maifanite prepared from Radix Isatidis as raw materials for the heavy metals Cu and Cd polluted soils.In order to study the application effect of biochar(BC500),natural maifanite(MS)and equal quality biochar and maifanite combination passivator(BC500+MS)on the pH value,soil nutrients,and Cu and Cd forms of heavy metals,an indoor soil incubation experiment was performed and the rate of passivation agents were 2%of the soil quality.The results of soil incubation for 30 days showed that all three passivating agents could increase soil pH and soil nutrient;the application of a single dreg biochar had better passivation effects on copper than natural maifanite,but the passivation on cadmium by natural maifanite was better.Using the modified BCR three-step continuous extraction method to extract Cu and Cd forms of different treatments,compared to the control treatment(CK),BC500 treatment decreased the weak acid extractable content of Cu,Cd by 9.00%,6.82%,and increased the residual content by 16.08%,16.67%,respectively.The extractable Cu content of weak acid in MS treatment did not change compared with CK,the acid extractable state of Cd was reduced by 17.05%,the contents of residual Cu and Cd were increased by 7.75%and 59.52%,respectively.BC500+MS treatment decreased the weak acid extractable content of Cu,Cd by 4.44%,26.14%,and increased the residual content by 10.16%,78.57%,respectively.Characterization analysis results show that passivation mechanism of biochar on Cu,Cd in contaminated soils is adsorption and sedimentation,while maifanite is mainly adsorption.