Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate rep...Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate reparative adsorption for Cr（VI） from the polluted Xiangjiang River water. A comparative X-ray analysis shows that the degree of crystallization in the imprinted polymer was significantly weakened, the area of the non-crystalline region was larger. There were more adsorption sites in the imprinted polymer, and the adsorption capacity towards Cr（VI） was increased. The adsorption capacity of the imprinted polymer towards Cr（VI） increased with time and reaches saturation after 8 h. The optimal adsorption time was 4-8 h after the adsorption starting and the optimal pH value for the solution was in the range of 4.5-7.5. When the chitosan reaches saturation, the adsorption capacity achieves a state of equilibrium, and the maximum Cr（VI） extraction rate reaches 33.7%. Moreover, the adsorption capacity of the imprinted polymer towards Cr（VI） increases with increasing chitosan concentration. In this situation, the Cr（VI） extraction rate shows little variation, and the maximum removal rate can reach 98.3%. Furthermore, the Cr（VI） extraction rate increases with an increase in the degree of deacetylation in the chatoyant and chitosan, with the best adsorption effect corresponding to 90% deacetylation. Fitting the adsorption data to the quasi first- and second-order kinetic models yields correlation coefficients of 0.9013 and 0.9875, respectively. The corresponding rate constants for the two models are 0.0091 min-1 and 7.129 g/（mg.min）, respectively. Hence, the adsorption using Cr（VI）-imprinted chitosan is more consistent with the second-order kinetics. Comparing the data to Freundlich and Langrnuir adsorption isotherms shows that the latter has a better linear fit and a maximum adsorption capacity of 15.784 mg/g.展开更多
六价铬Cr(VI)的不稳定性使其成为RoHS(限定有害物质,Restriction of Hazardous Substances)符合性测试的难点之一.采用分光光度法对塑料中痕量Cr(VI)进行检测,着重研究Cr(VI)萃取与显色中的过程参数与干扰因素的影响,并建立了一套试样...六价铬Cr(VI)的不稳定性使其成为RoHS(限定有害物质,Restriction of Hazardous Substances)符合性测试的难点之一.采用分光光度法对塑料中痕量Cr(VI)进行检测,着重研究Cr(VI)萃取与显色中的过程参数与干扰因素的影响,并建立了一套试样制备、萃取、显色等标准程序.研究表明,采用混合碱萃取法可对Cr(VI)进行有效提取,同时消除Cr(III)的干扰,通过排除共存离子影响,优化萃取、显色、标定过程中pH值、温度和时间等参数,可使试样和加标溶液的回复率保持在90%～110%之间,RSD<1%,校准在低浓度范围(0～500μg/L)呈良好线性关系.提出的方法和检测程序具有较高的精确度和灵敏度,而且操作简单、快速,为信息产业应对RoHS符合性测试提供了较好的技术支持.展开更多
Ionic liquid (IL) trihexyl (tetradecyl) phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104) was impregnated on XAD-7 resin. The solvent impreganated resin (SIR) was prepared and applied in Cr(VI) removal....Ionic liquid (IL) trihexyl (tetradecyl) phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104) was impregnated on XAD-7 resin. The solvent impreganated resin (SIR) was prepared and applied in Cr(VI) removal. The morphology and the thermal stability of the resins were explored. The effects of equilibrium time and initial pH value on Cr(VI) adsorption were investigated. Adsorption isotherm, separation and desorption of the SIR, and selectivity of SIR were also explored. The results show that Cyphos IL 104 exists in the inner XAD-7 resin, and the optimum pH value range of the SIR for Cr(VI) extraction is 0 to 2. When NaOH used as desorption solution, the Cr(VI) can be effectively desorbed from the SIR.展开更多
将普通和磷酸改性后的核桃壳对Cr(VI)的吸附作用进行对比。实验结果表明,由于改性核桃壳表面结构孔隙率更大,有利于增强对Cr(VI)的吸附作用,当控制温度为35℃,吸附剂用量为0.80 g,吸附时间为120min,吸附50 m L Cr(VI)浓度为20 mg/L的水...将普通和磷酸改性后的核桃壳对Cr(VI)的吸附作用进行对比。实验结果表明,由于改性核桃壳表面结构孔隙率更大,有利于增强对Cr(VI)的吸附作用,当控制温度为35℃,吸附剂用量为0.80 g,吸附时间为120min,吸附50 m L Cr(VI)浓度为20 mg/L的水样时,Cr(VI)的去除率可以达到99.4%。对吸附等温线和动力学模型拟合后表明,Langmuir吸附等温模型能更好地反映改性核桃壳对Cr(VI)的吸附过程;且普通和改性核桃壳对Cr(VI)的吸附过程均符合拟二级动力学方程。展开更多
基金Project(41271332)supported by the National Natural Science Foundation of ChinaProject(2010YBB186)supported by the Social Science Foundation of Hunan Province,Chian
文摘Methacrylic acid was used together with a molecular imprinting technique to modify chitosan. In addition, the adsorption kinetics and adsorption isotherms were recorded and the results were analyzed to investigate reparative adsorption for Cr（VI） from the polluted Xiangjiang River water. A comparative X-ray analysis shows that the degree of crystallization in the imprinted polymer was significantly weakened, the area of the non-crystalline region was larger. There were more adsorption sites in the imprinted polymer, and the adsorption capacity towards Cr（VI） was increased. The adsorption capacity of the imprinted polymer towards Cr（VI） increased with time and reaches saturation after 8 h. The optimal adsorption time was 4-8 h after the adsorption starting and the optimal pH value for the solution was in the range of 4.5-7.5. When the chitosan reaches saturation, the adsorption capacity achieves a state of equilibrium, and the maximum Cr（VI） extraction rate reaches 33.7%. Moreover, the adsorption capacity of the imprinted polymer towards Cr（VI） increases with increasing chitosan concentration. In this situation, the Cr（VI） extraction rate shows little variation, and the maximum removal rate can reach 98.3%. Furthermore, the Cr（VI） extraction rate increases with an increase in the degree of deacetylation in the chatoyant and chitosan, with the best adsorption effect corresponding to 90% deacetylation. Fitting the adsorption data to the quasi first- and second-order kinetic models yields correlation coefficients of 0.9013 and 0.9875, respectively. The corresponding rate constants for the two models are 0.0091 min-1 and 7.129 g/（mg.min）, respectively. Hence, the adsorption using Cr（VI）-imprinted chitosan is more consistent with the second-order kinetics. Comparing the data to Freundlich and Langrnuir adsorption isotherms shows that the latter has a better linear fit and a maximum adsorption capacity of 15.784 mg/g.
文摘六价铬Cr(VI)的不稳定性使其成为RoHS(限定有害物质,Restriction of Hazardous Substances)符合性测试的难点之一.采用分光光度法对塑料中痕量Cr(VI)进行检测,着重研究Cr(VI)萃取与显色中的过程参数与干扰因素的影响,并建立了一套试样制备、萃取、显色等标准程序.研究表明,采用混合碱萃取法可对Cr(VI)进行有效提取,同时消除Cr(III)的干扰,通过排除共存离子影响,优化萃取、显色、标定过程中pH值、温度和时间等参数,可使试样和加标溶液的回复率保持在90%～110%之间,RSD<1%,校准在低浓度范围(0～500μg/L)呈良好线性关系.提出的方法和检测程序具有较高的精确度和灵敏度,而且操作简单、快速,为信息产业应对RoHS符合性测试提供了较好的技术支持.
基金Project (51174184) sponsored by the National Natural Science Foundation of ChinaProject (2012CBA01202) supported by the National Basic Research Program of ChinaProject (KGZD-EW-201-1) supported by the Key Research Program of the Chinese Academy of Sciences
文摘Ionic liquid (IL) trihexyl (tetradecyl) phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104) was impregnated on XAD-7 resin. The solvent impreganated resin (SIR) was prepared and applied in Cr(VI) removal. The morphology and the thermal stability of the resins were explored. The effects of equilibrium time and initial pH value on Cr(VI) adsorption were investigated. Adsorption isotherm, separation and desorption of the SIR, and selectivity of SIR were also explored. The results show that Cyphos IL 104 exists in the inner XAD-7 resin, and the optimum pH value range of the SIR for Cr(VI) extraction is 0 to 2. When NaOH used as desorption solution, the Cr(VI) can be effectively desorbed from the SIR.
文摘将普通和磷酸改性后的核桃壳对Cr(VI)的吸附作用进行对比。实验结果表明,由于改性核桃壳表面结构孔隙率更大,有利于增强对Cr(VI)的吸附作用,当控制温度为35℃,吸附剂用量为0.80 g,吸附时间为120min,吸附50 m L Cr(VI)浓度为20 mg/L的水样时,Cr(VI)的去除率可以达到99.4%。对吸附等温线和动力学模型拟合后表明,Langmuir吸附等温模型能更好地反映改性核桃壳对Cr(VI)的吸附过程;且普通和改性核桃壳对Cr(VI)的吸附过程均符合拟二级动力学方程。
