Characterization of the physical and chemical structures of biochar under simulated aging condition
Biochars added into the soil are agedas time goes on under the influence of the environment such as long-term precipitation leaching or acid rain caused by greenhouse effect.The change of physic-chemical properties and structure are the new problems which have attracted wide attention.The aim of this study was to investigate the aging process of peanut shells biochar by washing and acidification.The physic-chemical properties and structure of biochar and aged biochar were characterized by elemental analysis,scanning electron microscopy (SEM),X-ray diffraction spectroscopy (XRD) and Fourier-transformed infrared spectroscopy (FTIR).The results showed that:the pH of biochar declined after the two treatment,and the acidified biochar (AB) dropped more than washed biochar (WB).Moreover,the O/C and (O+N)/C ratio of WB decreased by 8.89％ and 10.42％,but the ratios of AB increased by 11.11％ and 14.58％,respectively.These suggest that aging process changed the hydrophilicity and polarity of the biochar.In addition,compared with primary biochar (PB),the total content of alkaline elements of WB and AB was reduced by 26.53％ and 88.76％ respectively,indicating that more alkaline elements were released after the biochar aging.Compared with PB,the surface of the washed biochar was smoother and the microporous structure remained intactly.However,the surface of biochar was rough and microporous structure was disrupted severely after acidification.The content of the crystal structure of Al2SiO5 and SiO2was decreased obviously during aging process.Compared with PB,the characteristic peaks at 1166,1082 cm-1 appeared due to the aging process of the washed biochar,and the characteristic peaks at 1705,1622 and 1546 cm-1 appeared and the characteristic peaks at 466 cm-1 disappeared due to the aging process of the acidified biochar.Meanwhile the relative absorbance of other peaks was reduced indicating that the amount of oxygen functional groups increased in the process of aging.At the same time,the other functional groups became less and the content of crystal was reduced.Therefore,under a certain environment,during the aging process of biochar,some elements were released and their contents were reduced,which lead to the destruction of the material structure.
NETL
NSTL
万方数据
维普
