摘要
研究了氧化、还原改性对活性炭吸附草甘膦的影响。以傅立叶红外光谱定性表面官能团变化,以扫描电镜观察表面形貌,以化学吸附分析仪测定后再通过测定样品的氮气吸附/脱附等温线计算比表面积和孔径。结果表明:(1)氧化改性使活性炭比表面积增大;还原改性使活性炭比表面积减小。还原阶段使先前氧化阶段中产生的孔道以及原有孔道均发生塌陷,导致还原改性活性炭比表面积减小。(2)在静态吸附的条件下,氧化改性和还原改性活性炭对草甘膦的吸附均为吸热反应。还原改性在活性炭表面产生的还原性官能团有利于活性炭对草甘膦的吸附,而氧化改性产生的氧化性官能团并不利于活性炭对草甘膦的吸附。(3)热力学参数的计算进一步表明,改性活性炭对草甘膦的吸附为吸热反应。
Seven modified active carbon was prepared through series of oxidation, and reduction process. The capability of modified active carbon for glyphosate adsorption was investigated. The modified active carbon was characterized by nitrogen adsorption isotherm method,SEM and FTIR. The results revealed that oxidative modification increased specific surface area and acid oxidation groups, reductive modification decreased specific surface area and in： creased unsaturated reduction groups. The adsorption capability of modified active carbon followed the sequence of CN5H〉CN1H〉CH〉CN5 〉CNI〉CKN〉CK. Adsorption isotherms of glyphosate onto Cn, CNIH and CNsn was better fitted by Langmuir equation than Freundlich equation,which was better for fitting the data of CN1 ,CN5 ,CK and CKH. The higher adsorption capacities found at a higher temperature was consistent with the positive AH for the endothermic adsorption process. The major force of the adsorption on CN5H. might be chemical force,that on CH and CN1H might be chemical force and hydrogen bond,on CN1 ,CN5 ,CK and CKH might be hydrogen bond and Van der Waals force.
出处
《环境污染与防治》
CAS
CSCD
北大核心
2009年第10期10-14,23,共6页
Environmental Pollution & Control
基金
国家科技支撑项目(No.2006BAC02A15)
江苏省环保科技重点项目(No.2007021)
关键词
草甘膦
吸附
活性炭改性
热力学
glyphosate
adsorption
modified activated carbon
thermodynamic
