Preparation Of Functional Biochars And Its Effect On Remediation Of Lead Contaminated Soil

In this paper,the common agricultural waste rice straw and pig manure in Zhejiang Province were used as raw materials to produce biochar through hydrothermal high-temperature and high-pressure reactor and programmable tubular carbonization furnace.The physical and chemical properties of biochar prepared under two process conditions The differences of the process parameters on the biochar quality under different process conditions were analyzed.Revealed the intrinsic relationship between pyrolysis temperature and biochar properties.In view of the current situation of soil heavy metal lead pollution in our country,the biochar adsorption process,adsorption rate and adsorption capacity of lead in solution were discussed.The adsorption mechanism of lead by biochar prepared under two process conditions.Based on the physico-chemical properties of biochar and the adsorption of lead by biochar,pig manure biochar was selected as a remediation agent for heavy metal contaminated soils.The effects of biochar on heavy metals in soils after addition of biochar were discussed.Plant absorption of heavy metals interference effect.The results provide some support for the biodegradation of biochar in heavy metal contaminated soils.(1)The results of elemental analysis showed that as the pyrolysis temperature increased,the yield of biochar decreased,the C content,ash content and pH increased,and the H/C,O/C and(O+N),Pyrolytic biochar has more stability than hydrothermal carbon.By infrared spectroscopy analysis,biochar is rich in carboxyl,phenolic hydroxyl and other oxygen functional groups on the surface.The XRD shows that two main components of biochar are silica and calcium carbonate,of which the pig manure biochar is more similar in crystallographic structure to calcite and albite.The crystal structure of straw biochar is dominated by potassium chloride and calcite.Biomass raw materials and process parameters directly affect the composition and physical and chemical properties of biochar(2)By biochar adsorption kinetics study found that with the increase of solution pH,the adsorption of Pb2+ by biochar increased.And the maximum amount of adsorption at pH 5.5.The adsorption kinetics of Pb2+ by biochar accords with the pseudo-second-order kinetic equation.Adsorption process includes rapid reaction process and slow adsorption equilibrium two parts.The RSP700 pyrolysis has the highest adsorption rate and the RSP300 has the smallest adsorption rate.Straw biochar and pig manure biochar prepared by pyrolysis at high temperature are more in accordance with the Langmuir isotherm equation.Biochar adsorption capacities and adsorption capacities of biochar prepared at low temperature were lower than that of biochar prepared at high temperature.(3)Plant ryegrass in leaded soils and observe the change in available lead in the soil by applying biochar.After applying biochar,the pH of the soil increased to a certain extent.The EC value increases with the addition of biochar.This shows that the addition of biochar can effectively improve the inorganic mineral elements in the soil.Pig manure biochar can increase the content of available phosphorus and available potassium in the soil.The addition of biochar reduced the available heavy metals in the soil and improved soil quality.