Experimental Study On Passivation Of High-temperature Modified Biomass For Remediation Of Cd Contaminated Soil

The problem of cadmium pollution in farming soil has seriously endangered human health.Passivation of cadmium contaminated farming soil has been used to ensure food security.The objective of this study was to apply the final optimized passivation adsorption material to a cadmium-contaminated agricultural soil in a place in Henan Province.This study was mainly divided into three parts: high preparation of temperature modified biomass;selection of adsorption material by experiment in Cd solution;discussion of passive adsorption effect on exogenous cadmium contaminated soil.The conclusions are as follows:(1)The high temperature modification determined the rate of carbon yield of pyrolysis products.Different biomass pyrolysis reactions had different temperature points.The carbon production rate of high-temperature modified pyrolysis products was the basis for accounting the cost of the modified pyrolysis products.The higher the modified pyrolysis temperature,the higher the cost of production.It was better to choose pyrolysis products with higher carbon yield as much as possible for applications with the same effect.(2)When the pyrolysis temperature of orange peel reached 500 ℃for the same biomass,the pyrolysis products were alble to adsorb cadmium ions in the experimental solution.In addiition,the carbon production rate of orange peel was the highest at 500 ℃ under the same adsorption effect,and thus the most energy-saving from the economic point of view.Different kinds of biomass were the best pyrolysis products of orange peel at the same temperature.The pyrolysis reaction of orange peel was intense at 350 ℃,while the pyrolysis reaction of peanut shells was intense at 450 ℃.(3)The pyrolysis temperature modified by high temperature dominates the adsorption performance at a dosage of 2% the four passivation adsorption materials including CP-500,HS-500,CP-600 and HS-700.On the other hand,pyrolysis of biomass raw materials played a leading role at the same pyrolysis temperature.CP-500 has the best passivation performance for cadmium-contaminated soil at a dosage of 5%,.It is still CP-500 that had the best effect at the dosage of 10%.The larger the amount of passivation adsorbent which was added,the more obvious the passivation effect.(4)The effect of passivation depended on the characteristics of the biomass materials and the optimal temperature selected after high-temperature modification.In the case of the same dosage,the compounding result was better than the single HS-500,but also inferior to CP-500.The conclusions based on this experiment were not comparable between compounding and single passivating agent,because there are too few comparison data for compounding.