Studied On Physicochemical Properties Of Biochar And Activated Carbon And Their Applications

Biochar has an expansive application prospect in environmental system and agriculture due to the high carbon content, stability and adsorption capacities. The research on physicochemical properties and application of biochar is very important for increasing utilization ratio of pyrolysis products, promoting environmental and economic benefits. In this research, biochars were created from switchgrass, oak and larch using both fast pyrolysis and slow pyrolysis, various methods were selected for characterization of biochars; then activated with steam to obtained activated carbon and the impact of feedstock and conditios on physicochemical properties of biochar was studied; focused on the influence of specific surface area, surface chemical properties on phenol and heavy metal (copper and zinc) adsorption properties, and explored the mechanism of reaction via FTIR; finally, studied on the interaction between biochar/activated carbon and arbuscular mycorrhizal fungi with heavy metal ions together, and the effect on leeks growth and heavy metal ions absorbed from soil.The main conclusion and innovation points are as follows:(1) Compared to biochar obtained from woody material, the biochar generated from switchgrass was with lower surface area but higher concentration of surface functional groups; fast pyrolysis was not suitable for creating biochar with developed pore structure, the specific surface area usually lower than10m2/g, the temperature had more severe influence on physicochemical properties of biochar;(2) Steam activation was helpful in increasing surface area, especially the micro-pore surface area, but with reduction of concentrion of surface function groups; after activation, the adsorption capacities of fast pyrolysis biochar was greatly increased to more than28.50mg/g which was almost the same as slow pyrolysis biochar (<700℃);(3) First investigated that phenol adsorption onto fast pyrolysis biochar was accompanied with chemical reaction, which was stable and nonreversible, whereas for slow pyrolysis biochar and activated carbon it was physical process, which was unstable and reversible;(4) In the particular range, heavy metal adsorption properties of biochar was reduced as pH increasing; copper and zinc adsorption properties was restricted due to the competition between two kind of metal ions, increasing concentration of copper resulted in great reduction of zinc adsorption capacity, however, increasing concentration of zinc had less influence on copper adsorptioin;(5) First investigated biochar/activated carbon or arbuscular mycorrhizal fungi existed could reduce the toxicity of heavy metal ions, and promoted growth of leeks; while if biochar/activated carbon and arbuscular mycorrhizal fungi existed together, resulted in reduction of leeks growth; exist of biochar/activated carbon reduced the population and colonization of fungi and fast pyrolysis biochars were accompanied with the most serious inbibitional effect, which were lower than3%.