Mechanochemical Remediation Of Petroleum Hydrocarbon Contaminated Soil

Petroleum is an important resource.With the rapid development of society,petroleum and its derivatives are used more and more in all walks of life,but it also causes very serious soil pollution.Petroleum hydrocarbons are a mixture of alkanes,polycyclic aromatic hydrocarbons and other organic substances.Once released into the soil,petroleum hydrocarbons are extremely easy to be adsorbed by the organic matter in the soil.With the effects of volatilization,oxidation,biodecomposition,toxic accumulation and food chain,it will cause serious harm to the environment and human life.Therefore,it is of practical significance to explore effective petroleum hydrocarbon contaminated soil remediation technology for the control and treatment of petroleum hydrocarbon pollution.This study on physical and chemical method to repair oil chemical pollution easily residues toxic and harmful substances in the soil and waste water,waste gas,adopts the Mechanochemical method（MC）of different types of mechanized method processing of petroleum hydrocarbon contaminated soil,ball grinding parameters and grinding aid on the effects of the repair analysis mechanization research method to repair effects on soil properties,using modern characterization methods on soil physical and chemical properties were analyzed before and after repair,reveal the mechanization research method to repair the mechanism of petroleum hydrocarbon contaminated soil and its environmental effects.The main conclusions are as follows:（1）Mechanochemical remediation of the straight-chain alkanes in soil and its effects on soil propertiesUsing typical petroleum hydrocarbon n-hexadecane as a characteristic pollutant,batch experiments were used to study the mechanochemical method for remediation effects and influencing factors of simulated petroleum hydrocarbon-contaminated soil;GC/MS was used to analyze the degradation products of n-hexadecane in the soil.XRD,FTIR,SEM and BET were used to characterize the soil samples before and after treatment to reveal the mechanism of mechanochemical method for remediation of petroleum-contaminated soil.The results show that at a ball mill speed of 500 r·min^-1,a ball-to-material ratio of 35:1,a large,medium,and small steel ball ratio of 2:5:3,and a dosage of n-hexadecane of 0.5μL·g^-1,the degradation rate of n-hexadecane reached95.86%after ball milling for 4 h.After ball milling,the surface of soil particles became rough,and the quartz content with better grinding aid is significantly increased.Compared with the tested soil before treatment,no short chain alkane was detected after milling treatment,indicating that n-hexadecane degradation was more thorough.Soil adsorption capacity have been significantly improved,so it is difficult to completely remove residual low-concentration petroleum hydrocarbons.The mechanochemical method shows advantages of rapidness,efficiency and completeness in remediation of petroleum hydrocarbons contaminated soil,thus has excellent application potential.（2）Mechanochemical remediation of the straight-chain alkanes in soil and its effects on soil propertiesThe planetary ball mill was used to study the remediation efficiency of mechanochemical method on diesel-contaminated soil,and the degradation products of hydrocarbon components of diesel were analyzed by GC/MS.Analysis,using SEM,XRD,BET,FTIR and TGA methods to characterize soil samples under different treatment conditions.The results show that the removal rate of total petroleum hydrocarbon（TPH）in the soil can reach more than 95%within 0.5–4 h by MC treatment.With the increase of initial TPH concentration and ball-soil ratio,the TPH removal rate increases.The order of difficulty in the degradation of diesel components after MC treatment is as follows:alkane<olefin<cycloalkane<aromatic compounds.After 4 hours of ball milling,no toxic and harmful residues were detected.After ball milling,the soil particle size became smaller,the surface became rougher,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 Gradual rupture or deformation can form an electron-rich region on the soil surface or promote higher activity of the soil,which is the main mechanism of mechanochemical degradation of total petroleum hydrocarbons.Secondly,the main functional groups of soil organic matter are destroyed,the nano-scale pore capacity is reduced,the adsorption capacity of soil components is reduced,and the effectiveness of diesel is increased,which also contribute to the desorption and mechanochemical degradation of diesel.As the milling time increased,the soil organic carbon（SOC）content increased first and then decreased,but both were higher than before treatment.It can be seen that the MC treatment can quickly and completely degrade diesel in the soil,and is beneficial to increase the soil organic carbon content,and has good application potential for the repair of petroleum hydrocarbon contaminated soil.（3）Remediation of actual oily soil by mechanochemical method and its environmental effectsTaking the surrounding soil of a chemical plant as the experimental object,the removal rate of total petroleum hydrocarbons（TPH）in the actual oily soil and its influencing factors were studied by MC treatment.The GC/MS was used to identify and analyze the degradation process of TPH components in soil,and the soil samples under different treatment conditions were characterized by raman and TOC methods.the biological toxicity and bioavailability of soil samples were studied the remediation mechanism of the actual oily soil.The results showed that MC treatment could rapidly and thoroughly degrade the petroleum hydrocarbons in the soil in a relatively short time.When the initial TPH concentration in the oil-contaminated soil was 17256.25 mg·kg^-1,the milling speed was 500 r·min^-1,the ball-material ratio was 30:1,and the ratio of large,medium and small steel balls was 2:5:3,the TPH degradation rate of the oil-contaminated soil reached 92.25%after 8 h of ball-milling.The soil organic carbon content decreased slightly after MC treatment,and the soluble organic pollutants and inorganic pollutants in the soil increased first and then decreased with the increase of ball milling time.Biological toxicity showed that after mc treatment,soil organic matter decreased,soil structure was destroyed,and inorganic substances contained in soil particles were released in large quantities.Soil bioavailability showed that the soil was activated after long time ball milling,and the bioavailability was greatly enhanced,which was beneficial to biological reproduction.Oil contaminated soil contains organic pollutants such as alkanes,alcohols,lipids and aromatic hydrocarbons.Macromolecular alkanes or olefins(C₂₁H₄₄,C₂₆H₅₄,C₃₅H₇₀ and their isomers)are formed in the MC process.After treated by MC for 8 h,TPH in the soil was almost completely degraded.MC treatment can quickly and thoroughly degrade the TPH content in oily soil,which has a good application potential.