兰炭基改良剂协助微波修复萘污染土壤

Bluecoke-based Conditioner-assisted Microwave Remediation of Naphthalene Contaminated Soil

微波热修复技术是一种极具潜力的土壤处理技术,能高效去除土壤中的有机污染物。文章以兰炭末为基体、KHCO_(3)为土壤改良组分,制备了兼顾微波吸波和土壤改良的兰炭基土壤改良剂,并将其应用于微波修复多环芳烃模型化合物(萘)污染土壤。研究了改良剂类型和工艺条件(修复时间、微波功率、兰炭基土壤改良剂添加量和萘初始浓度)对污染土壤微波修复升温特性和萘去除率的影响,分析了最优微波修复条件下的产物特性。结果表明,兰炭基改良剂对污染土壤的修复效果优于兰炭和KHCO_(3)改良剂。微波修复萘污染土壤的最佳处理条件为处理时间20 min,微波功率700 W,兰炭基改良剂添加量4%和萘初始浓度1%。在此最佳工艺条件下,污染土壤修复最高温度可达474.46℃,萘去除率达到96.32%。修复后土壤中总钾和速效钾质量分数分别增加了0.12 g/kg和0.20 g/kg,土壤颗粒明显变小,片层和团粒结构增多,但其无机矿物和表面官能团组成并未发生明显变化。污染物萘在微波修复过程中未发生分解,主要以气化、CO_(2)和水蒸气的“裹挟”方式从污染土壤中分离出来。

Microwave thermal remediation technology is a potential soil treatment technology that can efficiently remove organic pollutants from soil.Bluecoke powder and KHCO_(3)were respectively used as a carbon matrix and an ameliorant,which were employed to prepare bluecoke-based conditioner with the characteristics of microwave absorption and fertility improvement of soil.The prepared bluecoke-based conditioner was applied to microwave remediation of polycyclic aromatic hydrocarbons model compound(naphthalene,NAP)contaminated soil.The effects of type of conditioner and process conditions(treatment time,microwave power,addition of bluecoke-based conditioner,and initial content of NAP)on the temperature-rising characteristics of microwave remediation and removal rate of NAP were investigated.The remediation product under the optimal microwave remediation conditions were analyzed.The results showed that the removal effect of NAP of bluecoke-based conditioner was better than that of bluecoke and KHCO_(3)conditioner in microwave remediation.The optimal conditions of microwave remediation were 20 min of irradiation time,700 W of microwave power,4%of bluecoke-based conditioner,1%of initial content of NAP,and 4%of moisture content in soil.Under these optimal conditions,the maximum remediation temperature reached 474.46℃,and the removal rate of NAP was the maximal of 96.32%.The mass fraction of total potassium and available potassium in remediation soil increased by 0.12 g/kg and 0.20g/kg,respectively.The size of soil particles obviously decreased,the content of lamellar and aggregate structure in soil increased,while the inorganic minerals and surface functional groups in soil were not obviously changed.The pollutant NA did not decompose during the microwave remediation,and it was mainly separated from the contaminated soil by gasification and“entrainment”of H_(2)O and CO_(2).