【作者】 马杰；

【导师】 韩润平；

【作者基本信息】 郑州大学 ， 环境科学， 2021， 硕士

【摘要】 通过改性农林废弃物花生壳(PS)可以提高其对污染物的吸附性能。本文以花生壳为原材料,利用聚乙烯亚胺(PEI)、FeCl3·6H2O、β-环糊精(β-CD)与柠檬酸(CA)进一步改性,制得吸附剂PEI-PS、Fe-PEI-PS和β-CD-PS,研究其对六价铬(Cr(VI))、2,4-二氯苯氧乙酸(2,4-D)、铅离子(Pb2+)和双酚S(BPS)的吸附性能。采用扫描电镜(SEM)、红外光谱图分(FTIR)、元素分析、X射线荧光分析(XRF)、比表面积分析(BET)、热重分析(TG)、等电点等表征方法对吸附剂改性前后进行表征,结果表明三种吸附剂改性成功。PEI-PS对Cr(VI)的吸附研究结果表明,pH为2时吸附量最大,盐的存在不利于吸附。吸附等温线符合 Langmuir、Freundlich、Temkin 和 Koble-Corrigan 模型。吸附动力学符合Pseudo-second-order和Elovich模型。该吸附是自发、熵减的放热反应。Thomas、The Clark和The Yoon-Nelson模型可以用来描述动态吸附过程。复合试剂0.1 moL·L-1NaCl+0.1 moL.L-1 NaOH可以进行解吸再生。Fe-PEI-PS对2,4-D的吸附研究结果表明,Fe-PEI-PS对2,4-D的吸附在pH为3～8时基本保持不变,盐的存在利于吸附。吸附等温线符合Langmuir和Koble-Corrigan模型,Pseudo-second-order kinetic模型可以描述动力学吸附过程。热力学研究表明,该吸附反应是自发、熵减的放热反应。Thomas、Yan和The Yoon-Nelson模型可描述该动态吸附过程。0.1 moL·L-1 NaCl可以对Fe-PEI-PS进行多次解吸再生。β-CD-PS对Pb2+和BPS的吸附研究结果表明,酸性条件不利于Pb2+的吸附,BPS的吸附在pH为2～7时基本保持不变,碱性条件不利于吸附。盐的存在对Pb2+是负影响,对BPS的吸附没影响。Langmuir和Koble-Corrigan模型可以预测Pb2+的平衡吸附过程;Temkin和Koble-Corrigan模型可以描述BPS的平衡吸附过程。Pseudo-first-order kinetic和Elovich模型符合Pb2+的动力学吸附过程;BPS的吸附过程符合Pseudo-second-order kinetic模型。热力学研究表明,Pb2+的吸附是自发、熵增的吸热反应,BPS的吸附是自发、熵减的放热反应。Yan和The Adams-Bohartmodel模型可以很好描述Pb2+的动态吸附过程,BPS的吸附过程符合Yan模型。0.1 mol·L-1 HNO3可以对吸附过Pb2+的吸附剂进行多次解吸再生,75%C2H5OH对吸附过BPS的吸附剂有比较好的解吸再生效果。研究结果为花生壳的有效利用提供依据。更多还原

【Abstract】 Peanut shell(PS)as agricultural byproduct can be developed to remove pollutants from environment.In this study,PS was modified to improve its adsorption capacity toward pollutants for solution.Polyethyleneimine(PEI),FeCl3·6H2O,β-cyclodextrin(β-CD)and citric acid(CA)were selected as modified agents to obtain the adsorbent PEI-PS,Fe-PEI-PS and P-CD-PS,respectively while adsorption properties of hexavalent chromium(Cr(VI)),2,4-dichlorophenoxyacetic acid(2,4-D),lead ions(Pb2+)and bisphenol sulfide(BPS)were performed.Scanning electron microscopy(SEM),infrared spectroscopy(FTIR),elemental analysis,X-ray photoelectron spectroscopy(XPS),etct were used to characterize the adsorbent before and after modification,and the results showed that the three adsorbents were successfully prepared.The results of the adsorption of Cr(VI)by PEI-PS showed that there is in favor of Cr(VI)adsorption at pH 2 while there is not conducive to adsorption with common salts coexisted in solution.The adsorption isotherm conformed to the four models of Langmuir,Freundlich,Temkin and Koble-Corrigan while the adsorption kinetic process conformed to the Pseudo-second-order kinetic model and Elovich model.This adsorption was an exothermic reaction with spontaneous and entropy reduction.Thomas,The Clark and The Yoon-Nelson models can be used to describe the kineitc adsorption process.0.1 moL·L-1 NaCl+0.1 moL·L-1 NaOH can be used as desorption agent.The results of the adsorption of 2,4-D by Fe-PEI-PS indicated that Fe-PEI-PS has a wide range of 2,4-D adsorption within pH 3～8.The presence of salts has a negative effect on the adsorption.The equilibrium results were well predicted by Langmuir model and Koble-Corrigan model while the pseudo-second-order models can describe the kinetic adsorption process.Thermodynamic studies showed that the adsorption process was an exothermic reaction with spontaneous and entropy reduction.The column adsorption process was consistent with Thomas,Yan and The Yoon-Nelson models.0.1 moL·L-1 NaCl can regenerate the spent Fe-PEI-PS multiple times.The results of β-CD-PS adsorption on Pb2+ and BPS showed that acidic conditions were not conducive to the adsorption of Pb2+,and the adsorption of BPS remained basically unchanged within pH 2～7 while alkaline conditions were not in favor of BPS adsorption.The presence of salt had a negative effect on Pb2+ adsorption,but had no effect on BPS adsorption.Langmuir and Koble-Conrigan models showed a high fitting degree for the adsorption process of Pb2+,and the adsorption process of BPS conformed to the Temkin and Koble-Corrigan models.The adsorption process of Pb2+was fitted with Pseudo-first-order and Elovich model,while the BPS adsorption was consistent with the model of Pseudo-second-order kinetic model.Thermodynamic studies showed that the adsorption of Pb2+ was an endothermic reaction with spontaneous and entropy increase.The adsorption of BPS was an exothermic reaction with spontaneous and entropy reduction.Yan model and The Adams-Bohart model can well describe the dynamic adsorption process of Pb2+.The dynamic adsorption process of BPS was fitted with Yan model.The β-CD-PS adsorbed by Pb2+can be regenerated using 0.1 mol·L1HNO3 while75%C2H5OH had a better desorption and regeneration effect on BPSloaded β-CD-PS.The modified peanut shell is promising to effectively remove some pollutants from solution.更多还原