裂解温度和酸处理对生物炭中持久性自由基产生的影响  

Effect of pyrolysis temperature and acid treatment on the generation of free radicals in biochars

作　　者：赵力 陈建[1] 李浩[1] 梁妮[1] 张朋超 ZHAO Li;CHEN Jian;LI Hao;LIANG Ni;ZHANG Pengchao(Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming, 650500, Chin)

机构地区：[1]昆明理工大学环境科学与工程学院,昆明650500

出　　处：《环境化学》2017年第11期2472-2478,共7页Environmental Chemistry

基　　金：国家自然科学基金(41473116);云南省应用基础研究计划(20137FZ004);云南省人才培养项目(KKSY201622013)资助~~

摘　　要：本研究利用电子顺磁共振波谱(electron paramagnetic resonance,EPR)和激光显微拉曼光谱分别测定不同裂解温度(200、300、500、700℃)和酸处理(HCl和HCl-HF)生物炭样品的自由基信号和化学键振动特征,以期探究不同裂解温度和酸处理对生物炭上自由基的影响机制.EPR结果表明,自由基信号随裂解温度的升高呈现先增强(200—500℃)后降低(700℃)的趋势,随酸洗程度的增加而增强(200℃除外).拉曼结果表明,生物炭的D峰峰面积(AD)和自由基强度随裂解温度的变化趋势一致,这显示低氧条件下的裂解过程会伴随着生物炭碳层结构的缺陷形成以及C—C键的断裂,从而形成以氧为中心的自由基(2.0044≤g因子值≤2.0049);AD随酸洗程度的增加而增加(200℃除外),这与自由基酸洗后信号增强的现象相一致.另外,酸洗后自由基信号的增加率远大于碳含量的增加率,这可能归因于酸洗会使有机—无机复合体的C—O—C和COOH上的C—O键的断裂而生成新的自由基.In this study, electron paramagnetic resonance（ EPR） and laser micro-Raman spectrometry were employed to detect free radicals and chemical bond vibration of pre-and postacid-washed（ HCl and HCl-HF treated） biochars produced at different pyrolysis temperatures（ 200,300,500,700 ℃）. The effects of pyrolysis temperature and acid treatment on free radical generation in biochars were evaluated. EPR results showed that the intensity of free radicals increased in pyrolysis temperature range of 200 ℃ to 500 ℃ but decreased at 700 ℃. Increased degree of acid-washing also elevated the intensity of free radicals（ except for 200 ℃）. Raman spectroscopic results indicated that the peak area for D（ AD） and intensity of free radical for biochars changed analogously along with the pyrolysis temperature. This reflected that charring process under low oxygen condition was accompanied with defects on carbon lattice structure and breaking of C—C bonds resulting in oxygen-centered free radicals generation（ 2.0040≤g factor≤2.0049）. Enhanced degree of acid-washing（ except for 200 ℃） also augmented AD,which is consistent with the observation of increased intensity of free radicals after acid-washing. In addition,the rate of free radical signal increase was significantly higher than that of C content after acid-washing. These findings indicated that acid-washing could lead to the breaking of C—O bonds from C—O—C and COOH on organic-mineral complexes and the generation of new free radicals.

关 键 词：生物炭 裂解温度 酸洗 自由基 

分 类 号：X505[环境科学与工程—环境工程]