| As a new type of environment-friendly adsorbent,biomass carbon has a broad development prospect in the treatment and remediation of polluted water and soil,and has attracted much attention.However,biochar is susceptible to the influence of the external environment during long-term use,resulting in changes in its physicochemical properties,which in turn affects the effect of biochar on the adsorption of environmental pollutants and the remediation of polluted environments.In this paper,biochar with different charring temperatures was prepared by oxygen-limited warming method at different pyrolysis temperatures（250,350,500 and700°C）using corn straw as the biomass raw material,and different aging methods（alternate dry and wet aging,freeze-thaw cycle aging,simulated acid rain aging,microbial aging and alternate dry-wet and freeze-thaw aging）were used to simulate the aging process of biochar in natural environment.Characterization and adsorption experiments were used to investigate the effects of pyrolysis temperature and aging methods on the physicochemical properties and adsorption performance of biochar with tris（2-chloroisopropyl）phosphate（TCIPP）,and the adsorption mechanisms were investigated,and the main results were as follows:（1）The preparation temperature has a strong influence on the physicochemical properties of biochar.As the temperature of biochar increases,its total pore volume and specific surface area increase significantly,hydrophobicity and aromaticity increase significantly,and polarity decreases gradually;Boehm titration,FTIR and XPS analyses showed that the total amount of oxygenated acidic functional groups（-OH,C-OOH,O=C-O and-COOR）on the surface of biochar decreased significantly with the increase of charring temperature,and functional groups such as-OH,C=C/C=O and C-O-C were involved in the adsorption process of TCIPP on biochar.The adsorption results showed that the adsorption of TCIPP by biochar increased significantly with the increase of temperature from 0.8837 mg·g-1（CS250）to 2.2574 mg·g-1（CS700）.The adsorption of TCIPP by biochar is mainly surface adsorption.With the increase of biochar temperature,the pore filling,hydrophobic and P-πinteractions of biochar on TCIPP were significantly enhanced,while the hydrogen bonding was weakened.（2）Aging can significantly affect the specific surface area and surface morphology of biochar,the polarity index of biochar increased after aging,while the hydrophobicity and aromaticity decreased.The results of Boehm titration,FTIR and XPS of biochar after aging showed that the carbon content on the surface of biochar decreased significantly,while the oxygen content increased significantly,and the total number of oxygenated acidic functional groups on the surface were all significantly higher.The adsorption experiments showed that the aging effect on the performance of biochar adsorption of TCIPP was enhanced in the following order:microbial aging（80.59%）>freeze-thaw cycle aging（53.89%）>alternating wet-dry aging（51.73%）>alternating wet-dry and freeze-thaw aging（15.11%）>acid rain aging（-53.37%）.Adsorption of TCIPP by aged biochar is influenced by multiple mechanisms of action,the aging effect led to a significant decrease in the pore filling and hydrophobic effect of biochar on TCIPP and a significant increase in the P-πinteraction;the hydrogen bonding of biochar on TCIPP was weakened after alternating dry and wet aging,acid rain aging and freeze-thaw cycle aging,while the hydrogen bonding was enhanced after alternating dry-wet and freeze-thaw aging.（3）The experiments on the adsorption of TCIPP in soil by biochar showed that the adsorption capacity of TCIPP in soil showed an increasing trend with the increase of biochar addition ratio compared with the soil with 0%biochar mass ratio.Under the same conditions of biochar addition,biochar treated with alternate dry-wet-freeze-thaw aging had better adsorption effect on TCIPP,the sequence of adsorption is:CS700-DF>CS700>CK;and under different biochar addition conditions,the soil had the best adsorption performance on TCIPP when the mass ratio of biochar was 1%.（4）Overall,the aging effect has a greater impact on the physicochemical properties of biochar and can effectively improve the adsorption capacity of biochar for TCIPP in soil and water environment.In addition,when using biochar for long-term remediation of polluted soil and water,the effects of natural aging methods and aging time in different regions on the physicochemical properties and adsorption effects of biochar need to be considered comprehensively. |
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