Effect of two Fe-modified hydrochar carbons on the curing efficiency and morphology of chromium in soil
In this work,zero-valent iron(ZVI)or pyrite loaded hydrochar was prepared by mechanical ball-milling method,respectively.Through soil extraction experiment and soil column leaching experiment,the changes of chromium(Cr)content in soil after adding different materials were compared.The cumulative release of Cr in leaching solution and the longitudinal migration behavior of Cr in soil column were analyzed.The results showed that compared with other materials,both ZVI modified hydrochar(ZBC)and pyrite modified hydrochar(HBC)had excellent effect on the immobilization of Cr in soil.Under low dosage(5 g·kg-1),ZBC and HBC reduced the total Cr concentration in soil leaching solution by 35.8％and 39.6％,respectively.While the increase of available iron(Fe)content in soil was less than 0.1％,which solved the problem of excessive increase of Fe content in soil caused by ZVI and pyrite.In soil column leaching experiments,compared with CK(control group without modified hydrochar),the total Cr content in ZBC and HBC leaching solution decreased by 27.3％and 39.3％,respectively.The total Cr content in the unpolluted soil at the bottom of the soil column decreased by 31.4％and 56.3％,respectively,and the concentration of Cr(Ⅵ)decreased by 51.7％and 44.4％,respectively.The characterization result proves that Cr in soil can be adsorbed by ZBC and HBC.Cr(Ⅵ)can be reduced to Cr(Ⅲ)and fixed in soil by Fe load on hydrochar.The presence of FeS2 in HBC effectively participates in the reduction of Cr(Ⅵ).In general,HBC has better effect on the immobilization of Cr in soil,which can provide ideas and exploration for the application of hydrochar in remediation of heavy metal contaminated soil.
chromiumremediation of contaminated soilhydrocharzero-valent ironpyrite
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