| With the icreasing of heavy metal contamination,the treatment and remediation of heavy metals contaminated water and soil increasingly becomes a hot environment issue.The aim of this research to study the adsorption effect of the compound amendment(M-H)prepared by Modified flu gases desulfurization residue(MF)and humic acid(HA)on Pb and Cd,and the restoration of Pb and Cd contaminated soil.The effects of dosage of M-H,p H of solution,initial concentration of heavy metal ions and adsorption temperature were studied by static adsorption experiment.The results showed that the temperature at 25°C,the initial concentration of lead was 800 mg/L,the pH was 3.0,the dosage of M-H was 3 g/L,the removal rate of lead were above 90%,and when the dosage of M-H was 1.5g/L,the removal rate of cadmium was above 80%.In general,the effect of M-H on the removal of lead and cadmium was better than the addition of MF and HA alone.The adsorption capacity of lead and cadmium were increasing with the rising of temperature.The adsorption process of lead in accordance with the Freundlich model,and the adsorption process of cadmium was more consistent with the Langmuir model.It can be seen from the thermodynamic analysis that the reaction process of the adsorption of lead and cadmium by M-H wad endothermic reaction,and higer temperature is more conducive to sorption.The application of M-H can significantly improve the pH value of soil and reduced the availabile Pb and Cd concentration.The concentrations of available Pb and Cd in soil reduced by 82.75% and 48.15% at the addition rate was 1.5 g/kg,respectively.The correlation analysis showed that the concentrations of Pb and Cd in soil were significantly negatively correlated with soil pH(p<0.01).The addition of M-H can significantly reduce the exchangeable content of heavy metals in soil and changed to more stable forms.On the whole,the amount of the exchangeable Pb content decreased by 56.25% and the residue state Pb increased by 9.20% with application amount was 1.5 g/kg of M-H.The exchangeable fraction Cd was reduced by 21.90%,and the Fe-Mn oxides combined fractio Cd,the organic matter-bound fraction Cd and the residual Cd increased by 19.53%,11.76% and 58.40% respectively.At the same time,the application of M-H increased the content of soil effective K,Ca,Mg and Si,and the soil organic matter content was also significantly improved.However,the application of MF only can increase the content of mineral nutrients,and organic matter of soil was supplemented by adding HA,which had little effect on the mineral nutrients in the soil.The addition of M-H reduced the adsorption of heavy metals by pakchoi,and promoted the growth of pakchoi.The correlation analysis showed that the concentrations of Pb in pakchoi were significantly positively related to the available concentrations of Pb in soil.The available Pb in soil was the main reason that can influence the ad sorption of Pb by pakchoi.In addition,the combination of compound amendment can improve soil pH,increase the content of effective mineral elements and organic matter content,and improve the soil quality and provide sufficient nutrition for the growth of pakchoi. |
PDF Full Text Request