槐糖脂生物表面活性剂增效铬污染土壤电动修复实验研究

Electrokinetic Remediation of Chromium Contaminated Soil Enhanced by Addition of Sophorolipid Biosurfactant

将采集于青岛红星化工厂的铬污染土壤以槐糖脂生物表面活性剂为增效剂进行电动修复,考察槐糖脂浓度、电解液离子强度、电解液酸度对槐糖脂增效铬污染土壤电动修复效果的影响,其中,电解液离子强度和电解液酸度分别通过添加不同浓度的乙酸铵和乙酸来调节。结果表明:加入槐糖脂的电动修复体系中,电流强度显著增大,Cr^(6+)向阴极的迁移速率加快。与未添加槐糖脂的电动修复体系相比,Cr^(6+)和总Cr的去除率分别提高了134.8%和155.3%,这是由于槐糖脂对铬离子的络合增溶作用和竞争吸附作用,有效增加了土壤基质上的铬离子的解吸速率,进而增加其电迁移速率和去除效率。电解液离子强度和电解液酸度对铬去除率有显著影响。在电解液中含有0.1～1 mol·L^(-1)乙酸铵的修复体系中,Cr^(6+)和总Cr的去除率随电解液离子强度增大而增大;在添加乙酸浓度为0.01～1 mol·L^(-1)的范围内,随着添加的乙酸浓度的增大,阴极电解液pH值逐渐降低,在乙酸浓度为1 mol·L^(-1)的电动体系中,Cr^(6+)和总Cr的去除率相对于未添加乙酸的电动体系分别增加了38.3%和17.2%。

Chromium-contaminated soil(CCS), collected from Qingdao Red Star Chemical Plant, was remediated by electrokinetic techniques with addition of sophorolipid biosurfactant as enhancing reagent. The remediation effects of sophorolipid concentration, ionic strength, electrolyte acidity were also investigated. Ionic strength and acidity of electrolyte on efficiencies of electrokinetic remediation of the CCS were also investigated by the addition of different doses of ammonium acetate and acetic acid in the sophorolipid solution. Results showed that in the electrokinetic remediation system(ERS) with the addition of sophorolipid, the current intensity was significantly increased and the migration rate of chromium to cathode was accelerated. The removal efficiency of hexavalent chromium and total chromium was increased by 134.8% and 155.3%, respectively, compared with no addition of sophorolipid. Because of the complex solubilization and competitive adsorption of chromium ions by sophorolipids, the desorption rate of chromium ions on soil matrix was effectively increased, and the electro-migration rate and removal efficiency were further increased. The ion strength of electrolyte and the acidity of electrolyte have significant influence on the removal rate of chromium. In the ERS containing ammonium acetate with the concentrations from 0.1 to 1 mol·L-1, the removal efficiency of hexavalent chromium and total chromium were increased with the increase of the ionic strength of electrolyte. In the ERS, containing the acetic acid ranged from 0.01 to 1 mol·L-1, the pH value of catholyte gradually decreased with the increase of acetic acid concentration. In the ERS containing 1 mol·L-1 acetic acid, the removal efficiency of hexavalent chromium and total chromium were increased by 38.3% and 17.2%, respectively.