机械化学法修复柴油污染土壤的效率、产物及影响

针对常规污染土壤修复处理方法存在有毒降解产物、容易产生二次污染等问题，本研究采用行星球磨仪研究了机械化学法（MC）对柴油污染土壤的修复效能，利用GC/MS对柴油烃组分的降解产物进行分析，并采用SEM、XRD、BET、FTIR和TGA等方法对不同处理条件下的土壤样品进行表征.结果表明，MC处理在0.5~4.0 h内对土壤中总石油烃（TPH）的去除率可达95%以上.随着初始TPH浓度和球土质量比的升高，TPH去除率随之提高.采用MC处理后柴油组分降解难度顺序如下：烷烃<烯烃<环烷烃<芳香族化合物.在球磨处理4 h后，未检出有毒有害残留物质.球磨后土壤粒径变小，表面变粗糙，粘土矿物中的硅氧四面体暴露在土壤表面，矿物结构的结晶度逐渐降低，晶体结构逐渐破裂或变形，可在土壤表面形成富电子区域或促使土壤具有更高的反应活性，这是机械化学法高效降解柴油的主要机制.其次，土壤有机质的主要官能团受到破坏，纳米级孔隙容量降低，从而降低了土壤组分的吸附能力，增加了柴油的有效性，也有助于柴油的解吸和机械化学降解.此外，随着球磨时间的增加，土壤有机碳（SOC）含量先增加后下降，但均高于处理前.可见，MC处理可以快速彻底降解土壤中的柴油，且有利于增加土壤有机碳含量，对于石油烃污染土壤修复具有较好的应用潜力.

Remediation of diesel-contaminated soil by mechanochemical treatment: Efficiency,products and impacts

Aiming at the problems including toxic degradation products and secondary pollution in conventional treatment methods,the planetary ball mill was used to study the remediation efficiency of diesel-contaminated soil by mechanochemical method (MC). The degradation products of diesel were analyzed by GC/MS. The SEM,XRD,BET,FTIR and TGA were used to characterize soil samples under different treatment conditions. The results showed that the removal rate of total petroleum hydrocarbon (TPH) in the soil can reach more than 95% within 0.5~4.0 h by MC treatment. With the increase of initial TPH concentration and ball-to-soil ratio,the TPH removal rate increases. The degradation difficulty order of diesel components by MC treatment is as follows:alkane < olefin < cycloalkane < aromatic compounds. After 4 hours of ball milling,no toxic and harmful residual product was detected. After ball milling,the soil particle size became smaller,the surface became rougher,and the silica tetrahedron in the clay mineral was exposed on the soil surface. The crystallinity of the mineral structure gradually decreased,and the crystal structure gradually ruptured or deformed,which can form an electron-rich region on the soil surface or promote higher activity of the soil. It may be the main mechanism of total petroleum hydrocarbons degradation by MC treatment. Secondly,the main functional groups of soil organic matter are destroyed,the nano-scale pore capacity became shrink,which may reduce the adsorption capacity of soil components,increase the availability of diesel in soil,and thus also contributes to the desorption and degradation of diesel. As the milling time increased,the soil organic carbon (SOC) content increased first and then decreased,but both were higher than that before treatment. MC treatment can quickly and completely degrade diesel in the soil,and increase the soil organic carbon content,so it has good application potential for remediation of soil contaminated by petroleum hydrocarbon.