改性生物炭协同硫酸亚铁修复铬污染土壤

Modified Biochar with Ferrous Sulfate for Remediation of Chromium Contaminated Soil

以玉米秸秆为原料,在限氧和高温条件下制备成生物炭,并加入KOH溶液对玉米秸秆生物炭进行碱改性处理,利用FTIR、SEM和TGA等测试技术对材料进行表征,考察材料的理化性质,并通过稳定化实验,研究改性生物炭协同硫酸亚铁对铬污染土壤的修复效果。结果表明,改性后生物炭表面的含氧官能团得到强化,出现明显的孔隙管道结构,呈现蜂窝形状,且具有较强的热稳定性。由稳定化实验结果可知,改性生物炭协同硫酸亚铁对铬污染土壤有良好的稳定化效果。最佳的稳定化修复条件为5%投加比例的KBC和7 d的养护时间。土壤中总Cr和Cr(VI)浸出浓度、Cr(VI)含量分别为0.144 mg/L和0.135 mg/L,22.53 mg/kg,均满足《污水综合排放标准》(GB 8978—1996)中总Cr和Cr(VI)的浸出限值1.5 mg/L和0.5 mg/L以及《土壤环境质量建设用地土壤污染风险管控标准》(GB 36600—2018)中第一类用地筛选值30 mg/kg的限值要求。

With corn straw as raw material,under the condition of limited oxygen and high temperature preparation into biochar,and KOH solution was added to alkali-modified corn stover biochar.The materials were characterized by FTIR,SEM and TGA to investigate the physicochemical properties of the materials,and stabilization experiments were conducted to study the synergistic effect of modified biochar with ferrous surfate on chromium-contaminated soil.The results showed that the oxygen-containing functional groups on the surface of the modified biochar were strengthened,and an obvious pore-pipeline structure with a honeycomb shape appeared,and it had a strong thermal stability.From the results of stabilization experiments,it is clear that the modified biochar with ferrous sulfate has good stabilization effect on chromium-contaminated soil.The optimal stabilization remediation conditions were 5%of KBC at the dosage rate and 7 d of maintenance time.The leaching concentrations of total Cr and Cr(VI)and Cr(VI)in the soil were 0.144 mg/L and 0.135 mg/L and 22.53 mg/kg,respectively,which met the leaching limits of 1.5 mg/L and 0.5 mg/L for total Cr and Cr(VI)in the"Comprehensive Wastewater Discharge Standard"(GB 8978—1996)and the Soil Environmental Quality Construction Land Soil Pollution Risk Control Standards"(GB 36600—2018)in the first category of land screening value 30 mg/kg limit value requirements.