Study On Remediation Of Heavy Metal Contaminated Soil Using Iron Sulfide Nanoparticles

The deterioration of the environment increasingly threatens the existence of mankindwith the acceleration of the urbanization process as well as the development of agriculture andindustry. And soil, which serves as the anchor and primary nutrient base for plants, is on a badcondition. Naturally, soil heavy metal contamination has been one of the global focusingissues for a long time.This paper reviewed the current situation of soil heavy metal contamination, andsummed up the main points of the previous researchers. According to the review, only byanalyzing from both sides of total contents and chemical species, can it be objectively toassess the heavy metal contamination. So, the accumulating condition as well as the migratoryand direct perniciousness of heavy metals can be reflected from these two assess methods.Experiments were carried out to measure the heavy metal (Zn、Cu、Ni、Cr、Pb、Cd)total concentrations of the soil samples from Yingcheng of Hubei, Dangtu of Anhui,Zhucheng of Shandong, Duyun of Guizhou in the study. The results suggested that the heavymetal total content is severely over standard, but the concentration of biologically activespecies is much lower with a weak direct perniciousness in Yingcheng of Hubei, Dangtu ofAnhui, Zhucheng of Shandong soils. On the contrary, test on the soil samples from Duyun ofGuizhou farmland and mine tailing area showed an over-standard heavy metal concentrationof both total content and biologically active species, which has a high direct perniciousness,especially Zn and Cd.The forms of heavy metal will transform with the changes of some environmental factors.To verify the variation law and influence factors of the heavy metal migration andtransformation, Static leaching tests and column leaching tests were conducted with differentexperiment condition with the medium of modeling rainwater, real rainwater and pure water.Conclusion can be drawn that soil pH and base cations are the main factors of heavy metalreleasing, which will pose a potential threaten to the environment by boosting thetransformation from noble to active forms.To explore new methods of soil heavy metal remediation, iron sulfide powder and ironsulfide nanoparticles were invested through a series of submergence tests and leaching tests.The submergence tests showed that both the powders and the nanoparticles can repair soilspolluted by Zn and Cr, but the latter showed a better result of reparation. For leaching tests,iron sulfide nanoparticles has an advantage on the reparation of Cd and Cu polluted soil,which mainly because that the nanoparticles can accelerate the transformation from noble toactive forms, While the powders were at an average level. In the last conclusion, the ironsulfide nanoparticles were obviously superior to the iron sulfide powders, and it is the ironsulfide nanoparticles that is the potential remediation material of soil heavy metal pollution.