摘要
以桑树杆为主要原料,采用氧化和共沉淀法制备桑树杆活性炭/铁锰氧化物复合吸附剂,用扫描电镜、红外光谱、X射线衍射、XPS对其进行了表征,研究了其对Cr(Ⅵ)的吸附性能.探讨了溶液p H值、吸附时间等对吸附效果的影响.实验结果表明,桑树杆活性炭/铁锰氧化物复合吸附剂有羟基、羧基、羟基和内酯基官能团的存在;桑树杆活性炭/铁锰氧化物复合吸附剂上的铁锰分別以Fe_2O_3和Mn O2的形式存在;相比桑树杆生物炭,桑树杆活性炭/铁锰氧化物复合吸附剂对Cr(Ⅵ)的最大吸附量提高了33.02%;当溶液p H值为2时,吸附效果最好;准二级动力学模型对吸附过程的拟合效果最好,当初始浓度为20、50、100 mg·L^(-1)时,拟合的相关系数R^2分别为0.9998、0.9882、0.9829;25℃、35℃和45℃下,Langmuir等温吸附模型拟合的相关系数均为0.9999,对应的最大的吸附量分别为35.93、38.58、48.29 mg·g^(-1).Langmuir等温模型较Freundlich等温模型更适合对Cr(Ⅵ)吸附过程的拟合.热力学参数表明,吸附过程是自发的、吸热的.经过3次的解吸再生,复合吸附剂的再生利用效率为86.80%.
In this work,mulberry stem was used as a main material to prepare mulberry stem activated carbon / Fe-Mn oxide composite adsorbent through simultaneous oxidation and coprecipitation method. It studied the characterizations of composite adsorbent by SEM,FTIR,XRS,XPS and the performance of composite sorbent in removing Cr（ Ⅵ） from aqueous solution,and the effect of solution pH and adsorption time were investigated. Results showed that phenolic hydroxyl,carboxyl,hydroxyl and lactone functional groups exist in the composite adsorbent. Fe2O3 and Mn O2 exist on the surface of the composite adsorbent. Compared with mulberry stem biomass charcoal,the maximum adsorption capacity of Cr（ Ⅵ） on the mulberry stem activated carbon / Fe-Mn oxide composite adsorbent increased by 33. 02%. The estimated optimum pH of Cr（ Ⅵ） ionretention for the considered sorbents was 2. 0. The kinetic data were best described by pseudosecond-order model. The correlation coefficient R^2 of pseudo-second-order model was 0. 9998,0.9882 and 0. 9829 at temperature 25 ℃ for initial Cr（ Ⅵ） concentration of 20,50 and 100 mg·L^-1,correspondingly. At 25 ℃,35 ℃ and 45 ℃,the fitting correlation coefficient of Langmuir isotherm model was 0. 9999 and corresponding maximum adsorption update was 35. 93,38. 58,48. 29 mg·g^-1,respectively. Langmuir isotherm model was more suitable for the fitting of Cr（ Ⅵ） adsorption process than Freundlich isotherm model. Thermodynamic parameters depicted the endothermic nature of adsorption and the process is spontaneous. The regeneration efficiency of composite adsorbent is 86. 80% after three times of regeneration.
出处
《环境化学》
CAS
CSCD
北大核心
2016年第4期783-792,共10页
Environmental Chemistry
基金
国家自然科学基金(21367010)
"八桂学者"建设工程专项经费资助~~
关键词
桑杆
铁锰氧化物
Cr(Ⅵ)
吸附
mulberry stem
Fe-Mn oxide
hexavalent chromium
adsorption
