The Research On Remediation Of Heavy Metal Contaminated Soils By D-Gluconic Acid

Among the pollutants in soil, heavy metal often results in long-term soil contamination. It not only may accumulate in organism, but also may easily recycle in the food chain. So it directly threatens humanity's grain security. This makes it of great significance to study soil heavy contamination.Taking the soil leeward Zhuzhou meltery as research object, D-gluconic acid were tested for their ability to remove heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) from soil. Batch equilibrium experiments were performed under variation of fundamental process parameters, i.e. pH value, sugar acid concentration, batch solution volume and solid: liquid ratio.A BCR sequential extraction procedure, detailed elsewhere, was used to divide the metals into mobile, Fe-Mn oxide bound, organically bound and residual fraction. The following soil characteristics were determined: texture: 34% sand,49% silt, 17% clay; 87.2g/kg organic matter, 156g/kg carbonate content; pH 6.3; 290mmol/kg CEC; Total heavy metal content: Pb1014.9mg/kg, Zn1014.9 mg/kg, Cu 268.5 mg/kg, Cd 40.1 mg/kg, Cr 114.6mg/kg and Ni 64.7mg/kg.The extractability of heavy metals was low under near-neutral and slightly basic pH conditions. It increased drastically between pH12.0 and 13.0. Pb and Cu were preferentially extracted metals. Compared with the extraction efficiency of pH adequate pure sodium hydroxide solutions, the sugar acids enhanced the solubilization of Pb and Cr especially. The metal depletion from soil was the highest when applying 20 or 50g/L solutions of the chelating agents. Under strongly basic conditions solid: liquid ratios of 1:10 or 1:20 were proofed to be advantageous. Following metal extraction degrees were achieved with strongly alkaline D-gluconic acid solutions: Ni 43%,Cr 60%, Cd 50%, Zn70%, Pb 80% and Cu 84%。...