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研究了以醇水混合液为底液,分别以盐(NaCl,Na_2SO_4),碱(NaOH,KOH)和酸(H_2SO_4,HClO_4)为支持电解质时,对硝基甲苯在Cu,Ag,Pt,Pb电极上电化学还原的循环伏安行为,从而选择出以Cu电极,H_2SO_4为支持电解质作为较理想的体系.对于该体系,用循环伏安法研究了浓度、扫描速度、搅拌强度与峰电流、峰电势的关系.结果表明,对硝基甲苯电化学还原的峰电势大约在(-0.5V,vs.SCE)处,且其还原与扩散有关;采用恒电压稳态极化法,测出稳态极化曲线,得到电势与ln((Id-I)/I)(I:电流,I_d:极限电流)成线性关系.从而确认该体系中对硝基甲苯电化学还原的电极过程为动力学和扩散混合控制过程;初步确认Ti~(4+)/Ti~(3+)电对对于对硝基甲苯在该体系中电化学还原具有一定的催化活性.探讨了在硝基苯的苯环上的不同位置接入不同的自由基后,对于硝基的电化学还原的影响,表明在苯环上接入吸电子基后,有利于它的电化学还原,而接入供电性基因后则不利于它的电化学还原,特别是在硝基的邻位和对位上接入时,这种效应特别明显.讨论了p~H值对于对硝基甲苯电化学还原的影响,表明在一定范围内,当p~H值较低时,有利于它的电化学还原.
The effects of salt (NaCl, Na_2SO_4), alkali (NaOH, KOH) and acid (H_2SO_4, HClO_4) on the electrolyte were studied in the presence of Cu, Ag, Pt and Pb The cyclic voltammetry of electrochemical reduction on the electrode was chosen to select the Cu electrode and H_2SO_4 as supporting electrolyte as the ideal system.Using cyclic voltammetry, the concentration, scanning speed, stirring intensity and peak current, The results showed that the peak potential of p-nitrotoluene was about (-0.5V, vs.SCE), and the reduction and diffusion were related. The steady-state polarization (I-current, I_d: the limiting current) linear relationship between the resulting potential to confirm the electrochemical reduction of p-nitrotoluene electrode system for the kinetics And diffusion-controlled mixing process. The catalytic activity of Ti ~ (4 +) / Ti ~ (3+) for p-nitrotoluene in this system was confirmed to be certain. On different positions on the access to different free radicals, the electrochemical reduction of the nitro group, indicating that access to electron-withdrawing groups in the benzene ring, Which is conducive to its electrochemical reduction, and access to power gene is not conducive to its electrochemical reduction, especially in the ortho and para nitro access, this effect is particularly evident.It is discussed p ~ The effect of H value on the electrochemical reduction of p-nitrotoluene shows that it is beneficial to electrochemical reduction of p ~ H value in a certain range.