硫酸—甘氨酸共掺杂聚苯胺修饰电极去除废水中六价铬的实验研究

发布时间：2018-03-28 11:00

本文选题：电化学还原　切入点：吸附　出处：《湖南大学》2015年硕士论文

【摘要】：电化学还原技术通常依靠电极电子得失发挥还原作用,该技术无需添加额外还原试剂、污泥产量相对较少的洁净处理过程使其对生态环境的影响较小,因而已逐渐发展成为具有强大竞争力和应用前景的水处理方法之一。电化学还原技术也可应用于含Cr(Ⅵ)废水的处理过程,但其还原过程较慢的反应动力响应、较高的电流效率和能耗问题等均大大限制了该方法在废水处理方面的实际应用和推广。因此,采取有效手段在Cr(Ⅵ)的电化学还原过程中提高其相应的还原动力学反应速率以改善上述问题至关重要。本研究以通过电化学聚合法制备的硫酸-甘氨酸共掺杂聚苯胺修饰的网状玻璃碳(RVC/PANI-SA-GLY)电极作为电解槽阴极,成功构建了一个新颖的吸附-电化学还原体系以加快Cr(Ⅵ)的去除过程。本研究首先通过响应面法探寻了新型掺杂剂甘氨酸存在条件下的最优化聚苯胺聚合条件组成;之后在以硫酸掺杂聚苯胺修饰的网状玻璃碳(RVC/PANI-SA)电极、RVC电极为对比实验组的基础上,探究了电势、Cr(Ⅵ)初始浓度、初始p H和电流密度对RVC/PANI-SA-GLY电极电化学还原Cr(Ⅵ)过程的影响规律;通过傅里叶红外光谱及能谱分析技术对RVC/PANI-SA-GLY电极去除Cr(Ⅵ)的吸附-还原机理进行了验证和阐述;最后本研究对RVC/PANI-SA-GLY电极的电化学稳定性及可循环利用性能进行了评估。实验结果表明:最优化剂量甘氨酸的加入不仅能最大程度提高共掺杂聚苯胺的电化学聚合速度,同时在理论及实际过程中均一定程度上实现了甘氨酸对Cr(Ⅵ)阴离子吸附作用的最大化利用而提高了Cr(Ⅵ)的最终去除效率,CCD优化设计获得的最优化聚合条件为苯胺、硫酸、甘氨酸浓度分别为0.2 mol/L、0.85mol/L、0.93 mol/L;RVC/PANI-SA-GLY电极在Cr(Ⅵ)的电化学还原过程中展现出比RVC/PANI-SA电极和RVC电极更快的还原反应速率,而在与RVC/PANI-SA电极相比时RVC/PANI-SA-GLY电极上所掺杂甘氨酸的吸附作用更得以凸显,该作用对Cr(Ⅵ)去除效率的提高在更负电势、较低Cr(Ⅵ)初始浓度(5 mg/L、10mg/L)、非极酸溶液中(初始p H=2、3)及更高电流密度条件下尤为明显,最佳情况下(E=-0.8 V,C0=10 mg/L,p H=2,t=900 s)可取得高出RVC/PANI-SA电极7.84%的Cr(Ⅵ)去除效率并实现废水中Cr(Ⅵ)的完全去除;在较负的应用电势下(-0.6 V、-0.8 V),RVC/PANI-SA-GLY电极可相对大幅地提高Cr(Ⅵ)电化学还原过程的电流效率;傅里叶红外光谱及能谱分析结果揭示了RVC/PANI-SA-GLY电极潜在的吸附-还原机理,该机理可能与电极上甘氨酸质子化的氨基集团对HCrO_4~-的吸附作用有关,是导致更快还原反应速率产生的主要原因;RVC/PANI-SA-GLY电极的电化学稳定性相对令人满意,将其进行重复利用具有较高的可行性。RVC/PANI-SA-GLY电极处理废水过程的治理时间短、电流效率高等优势使其在含Cr(Ⅵ)废水尤其是低浓度含Cr(Ⅵ)废水处理方面具有良好的应用前景,是一种极具潜力的新型修饰电极。
[Abstract]:Electrochemical reduction techniques usually rely on electronic gain reduction electrode play, the technology without the need to add additional reagents, clean process less sludge production because of its smaller impact on the ecological environment, which has gradually become one of the water treatment method has strong competitiveness and application prospect. The electrochemical reduction technology can also be applied to Cr (VI) treatment process of wastewater, but the reaction dynamic process of slow response, application and promotion of high current efficiency and energy consumption are greatly limits the method in wastewater treatment. Therefore, taking effective measures in the Cr (VI) to improve the corresponding reduction reaction rate to improve the above problems is the electrochemical reduction process. In this study, through the mesh glass prepared by electrochemical polymerization sulfuric acid doped polyaniline modified glycine Carbon (RVC/PANI-SA-GLY) electrode as cathode, successfully constructed a novel adsorption electrochemical reduction system to speed up the process of removing Cr (VI). In this study, through the response surface method explores new doping agent under the condition of the existence of glycine optimization of polyaniline polymerization condition; after the reticulated vitreous carbon doped sulfate polyaniline modified electrode (RVC/PANI-SA), RVC based electrode as the comparison group, to explore the potential of Cr (VI) initial concentration, the initial P H and current density on the reduction of Cr (VI) RVC/PANI-SA-GLY electrode electrochemical process were studied by spectral analysis; the removal of Cr on RVC/PANI-SA-GLY electrode technique and Fourier transform infrared spectroscopy (to VI) reduction mechanism of adsorption was verified and discussed; finally the electrochemical stability of RVC/PANI-SA-GLY electrode and recycling performance was evaluated. The experimental results Show that the optimization can not only improve the total dose of glycine doped polyaniline electrochemical polymerization velocity maximum, while achieving a glycine on Cr in the theory and practical process are to a certain extent (VI) increased Cr maximum use of anion adsorption (VI) the final removal efficiency of CCD, optimization design for the polymerization conditions for aniline, sulfuric acid, glycine concentration were 0.2 mol/L, 0.93 0.85mol/L, mol/L; RVC/PANI-SA-GLY electrode in Cr (VI) show a faster reaction rate than the RVC/PANI-SA and RVC electrodes on the electrochemical reduction process, and the adsorption of RVC/PANI-SA-GLY in comparison with RVC/PANI-SA electrode electrode doped glycine is more prominent and the effect on Cr (VI) removal efficiency in a more negative potential, low initial concentration of Cr (VI) (5 mg/L, 10mg/L), non polar acid solution (initial P H=2, 3) and higher current density condition is particularly evident, the best condition (E=-0.8 V, C0=10 mg/L, P H=2, t=900 s) can achieve higher RVC/PANI-SA 7.84% electrode Cr (VI) and the removal efficiency of Cr in wastewater (VI) were completely removed; in the application of potential more negative (under -0.6 V -0.8, V, Cr) RVC/PANI-SA-GLY electrode can improve the relative greatly (VI) the current efficiency of electrochemical reduction process; spectrum analysis results reveal the mechanism of reduction of adsorption and RVC/PANI-SA-GLY electrode potential and Fourier transform infrared spectroscopy, the mechanism may be related to the adsorption on the electrode and the amino group of glycine proton HCrO_4~-, is the leading the reason for the faster reaction rate generated; electrochemical stability of RVC/PANI-SA-GLY electrode is relatively satisfactory, the repeated use of.RVC/PANI-SA-GLY has the high feasibility of wastewater treatment process of electrode treatment time is short, electric The advantages of high flow efficiency make it have good application prospects in the treatment of wastewater containing Cr (VI), especially low concentration of Cr (VI), and it is a potential new modified electrode.

【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

【参考文献】