摘要
以稻秆和稻壳为原料,在不同温度下(300、400、500、600、700℃)采用热裂解法制备生物炭,利用比表面积及孔径分析仪测定各生物炭比表面积,以傅里叶红外光谱图(FTIR)和Boehm滴定法分别定性和定量分析不同生物炭表面官能团的种类和数量,分析不同温度对不同原材料制备生物炭的表面官能团种类和数量的影响.结果表明,中、低温裂解条件(300、400、500℃)下,同温度稻壳生物炭(RC-H)比表面积显著高于稻秆生物炭(RC-S);高温裂解(600、700℃)条件下,同温度RC-S比表面积则更大.随裂解温度升高,两种原材料制备的生物炭比表面积均呈显著增大的趋势,其中稻秆在600℃下制备的RC-S比表面积最大,稻壳在700℃下制备的RC-H比表面积最大.FTIR分析结果显示,同一温度下两种材料制备的生物炭特征吸收峰基本相同,且表面基团种类大致相同,但RC-S较RC-H表面官能团更丰富,在热解过程中均形成了芳香环结构,且芳香化程度随裂解温度升高而增加.不同裂解温度下两种材料的生物炭表面官能团变化规律相似,主要表现为烷烃基随裂解温度升高而缺失,甲基(—CH3)和亚甲基(—CH2)逐渐消失,而芳香族化合物增加,芳香化程度增强.Bohem滴定结果表明,各裂解温度下RC-S的表面官能团总量和碱性官能团数量均高于RC-H,而各裂解温度下RC-S的酸性官能团含量均小于RC-H.随裂解温度升高,两种材料制备生物炭的表面官能团变化规律相似,表现为表面官能团总量均减少,酸性官能团含量降低,碱性官能团含量增加.
A series of biochars obtained from rice straw and rice husk were prepared under different pyrolysis temperatures of 300, 400, 500, 600 or 700 ℃ under the oxygen limited condition. The effects of materials and temperatures on the surface properties of biochars obtained from two materials under different temperatures were evaluated. BET specific surface area analyzer was used to characterize the BET specific surface area. Qualitative and quantitative analysis by Fourier-transform infrared spectroscopy （FTIR） and Boehm titration were used to estimate the species and amount of the surface functional groups of biochars. The results showed that the BET specific surface areas of the biochars made from rice husk （ named RC-H） of 300 ℃, 400 ℃ or 500 % was higher than that of the biochars made from rice straw （ named RC-S） at the same temperature. But the BET specific surface area of RC-S was higher than that of RC-H made at 600 ℃ or 700 ℃. With increasing pyrolysis temperature, the BET specific surface of both RC-S and RC-H increased obviously. RC-S with the highest surface area was obtained at 600 ℃ and RC-H at 700 ℃. The results of FTIR analysis indicated that the characteristic absorption peak of the biochars made from the two materials under the same pyrolysis temperature were the same, and there were no obvious differences between the species of functional groups, but the surface functional groups on RC-S were more abundant than RC-H made under the same pyrolysis temperature. Aromatic nucleus were formed during the pyrolysis process, and the degree of aromatics increased and stability enhanced with pyrolysis temperature. The change of the functional groups on the surface of the biochars made from the two materials with pyrolysis temperature was similar, which mainly showed that the alkyl group disappeared with the increasing temperature, methyl （-CH3 ） and methylene （-CH2 ） gradually disappeared, aromatic compounds increased and aromatic enhanced. The results of Bohem titration showed that the total quantities of surface functional groups and basic functional groups of RC-S were more than those of RC-H which made under different pyrolysis temperatures, but the quantities of acidic surface functional groups of RC-S were less than those of RC-H. With the increasing pyrolysis temperature, the change of the surface functional groups of the biochars made from the two materials was similar. The total quantities of surface functional groups and the contents of acidic surface functional groups decreased while the contents of the basic functional groups increased.
出处
《环境化学》
CAS
CSCD
北大核心
2016年第8期1663-1669,共7页
Environmental Chemistry
基金
国家自然科学基金(41161035和41461042)
江西省教育厅科技计划项目(GJJ14242)
江西省亚热带植物资源保护与利用重点实验室开放基金(YRD201412)资助~~
关键词
稻秆
稻壳
生物炭
裂解温度
表面官能团
rice straw, rice husk, biochars, pyrolysis temperature, surface functional groups.
