Adsorption performance and mechanism of heavy metals by manganese-loaded carbonized soil
In this study,a combination of permanganate pretreatment and oxygen-limited pyrolysis was used to treat and convert petroleum-contaminated soil(PCS)into carbonized soil loaded with manganese oxides(Mn-CS).Compared with the carbonized soil(CS)obtained by solo pyrolysis treatment,the Mn-CS is rough and porous,with higher specific surface area,micropore volume and lower leaching risk of soluble organic matter.The adsorption properties of Mn-CS for heavy metals can be well fitted by Langmuir isotherm model and pseudo-second-order kinetic model.The maximum theoretic adsorption capacity of Mn-CS for Pb2+,Cu2+,Zn2+and Cd2+is 420.54,81.19,79.73 and 26.40mg/g,respectively.The adoption processes are dominated by single-layer chemical adsorption.The heavy metals adsorbed by Mn-CS are mainly bound to Fe/Mn oxides,followed by bound to carbonate and organic matter.The adsorption mechanism includes surface complexation,coprecipitation and mineral binding/precipitation.Permanganate pretreatment significantly enhances the adsorption performance by increasing carbonate,manganese oxides and amorphous carbon on the surface of soil.Thus,the adsorption capacity of Mn-CS for heavy metals is synergistically improved.This study provided a new method to realize the value-added transformation of PCS,which is supposed to promote PCS treatment mode from up-to-standard remediation to resource utilization.
NETL
NSTL
万方数据
