采用响应面法(Box-Behnken design,BBD)考察粟米糠吸附Pb2+的不同因素(pH值、Pb2+初始浓度、吸附剂浓度和吸附时间)对吸附过程的影响及交互效应,并通过等温吸附和表征分析研究吸附过程的热力学特征及其吸附机理.结果表明,pH值与Pb2+初始浓度和吸附剂浓度交互效应显著,Pb2+初始浓度与吸附时间的交互效应显著.使用等温吸附模型拟合吸附过程发现,Langmuir和Freundlich模型拟合结果较好,该过程为物理吸附与化学吸附共同作用,293、298、303、308 K条件下的粟米糠最大吸附量qm分别为10.33、10.56、11.10、11.22 mg·g-1,其对Pb2+吸附能力随温度上升而提高.对吸附热力学参数△G、△H与△S计算表明该过程为吸热的自发反应,随反应进行体系混乱度增加.SEM和FTIR分析表明,粟米糠吸附Pb2+前后表面形态发生明显改变,羟基、羧基、醇羟基等基团在粟米糠吸附Pb2+中起主要作用.
The Box-Behnken design (BBD) methodology including four factors:pH,initial Pb2+ concentration,adsorbent dosage and contact time was employed to study the adsorption process of Pb2+ from aqueous solution by millet chaff.The effects of four factors on the adsorption and intcractive effects between the factors were evaluated.The results indicated that the interactive effects between pH and initial Pb2+ concentration,pH and adsorbent dosage,and initial Pb2+ concentration and contact time were significant.The equilibrium adsorption analysis using different isotherm models showed that the processes of Pb2+ adsorption on millet chaff were dominated by chemical adsorption though physical adsorption phenomena were also observed.The maximum adsorption capacity qm of millet chaffwere found to be 10.33 mg·g-1,10.56 mg·g-1,11.10 mg·g-1 and 11.22 mg·g-1 at 293 K,298 K,303 K and 308 K,respectively,indicated that the adsorption capacity of millet chaff increased with the increase of temperature.Thermodynamic parameters such as △G,△H and △S were calculated and showed that the adsorption process was endothermic and spontaneous,while the entropy of the system increased.The SEM and FTIR spectra analysis indicated that surface morphology of millet chaff were significantly different after adsorption procedures,and the functional groups responsible for Pb2+ binding were hydroxyl,carboxyl,and alcoholic hydroxyl.
参考文献
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%