摘要
土壤水分是动植物生长发育的基础,而在土壤中添加生物炭可以提高土壤的持水性能.生物炭影响土壤水分的机制除了通过影响土壤结构外,还与生物炭自身的结构和性质有关.本研究分别选取小麦、玉米和水稻秸秆,在300℃、500℃和700℃条件下限氧热解制得生物炭.通过对生物炭元素组成、比表面和红外光谱分析测定,对其表面结构、孔径和表面官能团等理化性质进行了表征,同时用重量法对生物炭的吸湿性进行测定.通过对生物炭理化性质的分析,初步探讨了热解温度对生物炭吸湿性的影响.结果表明,随着热解温度的上升,3种秸秆类生物炭都逐渐向芳构化趋势发展,极性、亲水性逐渐减弱.相同热解温度下玉米秆炭的BET比表面积最大,而微孔体积和平均孔径的大小为稻秆炭>玉米秆炭>麦秆炭.当热解温度升高时,BET比表面积和微孔体积迅速上升,平均孔径则逐渐减小.FTIR图谱表征表明,不同原料制得的生物炭在相同热解温度下的表面官能团种类相近.原料和热解温度对生物炭的吸湿性影响显著,相同热解温度下玉米秆炭的吸湿效果最好,300℃的玉米秆炭可达到的最大吸湿量为5.68%.300℃和700℃的热解温度更有利于生物炭吸收水分.不同的湿度会影响生物炭的吸湿量,300℃的玉米秆炭在70%湿度下的吸湿量要比50%时高2.18%.
Soil moisture is crucial for the growth and development of plants and animals.The addition of biochar to soil has potential to improve soil water retention.The influence mechanisms of biochar to soil water retention is confirmed by the unique characteristics and structures of biochar,besides biochar affected the soil structure.Herein,wheat,corn,and rice straw were used to produce biochars at pyrolysis temperatures of 300℃,500℃,and 700℃,respectively.Through element composition analysis,specific surface measurement,and infrared spectroscopy,the physicochemical properties of biochars such as surface structure,pore size and surface functional groups were characterized.Meanwhile,the hygroscopicity of biochars were determined by weight method.The effect of pyrolysis temperature on the hygroscopicity of biochar was studied by analyzing the physicochemical properties of biochar.The results showed that the three kinds of straw biochars underwent aromatization process,and the polarity and hydrophilicity gradually decreased with the increasing pyrolysis temperature.The BET specific surface area of corn straw biochar was the largest,while the micropore volume and average pore size were in order of rice straw biochar>corn straw biochar>wheat straw biochar under the same pyrolysis temperature.When the pyrolysis temperature rose,the BET specific surface area and the micropore volume started to rise rapidly,and the average pore size gradually decreased.The FTIR characterization showed that the surface functional groups of biochars prepared from the different biomasses at the same pyrolysis temperature were similar.Biomass and pyrolysis temperature had a significant influence on the hygroscopicity of biochars.The water absorption effect of corn straw biochar was the best at the same pyrolysis temperature and the maximum water absorption of corn straw biochar at 300℃was 5.68%.300℃and 700℃pyrolysis temperature were more favorable for biochars to absorb water.Different humidities affected the moisture absorption of biochars and the moisture absorption of corn straw biochar at 300℃at 70%humidity was 2.18%higher than that at 50%.
作者
赵越
赵保卫
刘辉
李刘军
张鑫
ZHAO Yue;ZHAO Baowei;LIU Hui;LI Liujun;ZHANG Xin(Faculty of Environmental and Municipal Engineering,Lanzhou Jiaotong University,Lanzhou,730000,China)
出处
《环境化学》
CAS
CSCD
北大核心
2020年第7期2005-2012,共8页
Environmental Chemistry
基金
国家自然科学基金(51766008,21467013,21167007)资助
关键词
生物炭
热解温度
理化性质
吸湿性
biochar
pyrolysis temperature
physicochemical properties
hygroscopicity
