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The synergic persulfate-sodium dodecyl sulfate effect during the electro-oxidation of caffeine using active and non-active anodes.
Chemosphere ( IF 8.8 ) Pub Date : 2020-03-30 , DOI: 10.1016/j.chemosphere.2020.126599
Florymar Escalona-Durán 1 , Djalma Ribeiro da Silva 1 , Carlos A Martínez-Huitle 2 , Paola Villegas-Guzman 3
Affiliation  

It has previously been established during the elimination of organic matter that the addition of sodium dodecyl sulfate in solution is an important condition in the electrochemical oxidation approach that allows to increase the production of persulfate, enhancing the efficacy of the treatment. This outcome was observed when using the anodic oxidation with boron doped diamond (BDD), the extra production of persulfate was achieved after the SDS-sulfate released in solution and it reacts with hydroxyl radicals electrogenerated at BDD surface. However, this effect was not already tested by using active anodes. For this reason, the effect of sodium dodecyl sulfate (SDS) during the electrochemical treatment of caffeine was investigated by comparing non-active and active anodes performances. A significant decrease on the oxidation efficiency of caffeine was observed by using Ti/IrO2-Ta2O5 anode at high current density when SDS was added to the solution. Conversely, at BDD anode, the presence of SDS enhanced the degradation efficiency, depending on the applied current density. This behavior is mainly due to the degradation of SDS molecules, which allows to increase the amount of sulfate in solution, promoting the production of persulfate via the mechanism involving hydroxyl radicals when BDD is used. Meanwhile, no oxidation improvements were observed when Ti/IrO2-Ta2O5 anode was employed, limiting the caffeine oxidation. Results clearly showed that the surfactant concentration had little influence on the degradation efficiency, but this result is satisfactory for the BDD system, since it demonstrates that effluents with complex matrices containing surfactants could be effectively degraded using the electrooxidation technique. Degradation mechanisms were explained by electrochemical measurements (polarization curves) as well as the kinetic analysis. Costs and energy consumption were also evaluated.

中文翻译:

使用活性和非活性阳极对咖啡因进行电氧化过程中的过硫酸盐-十二烷基硫酸钠的协同作用。

先前已经确定,在消除有机物的过程中,在溶液中添加十二烷基硫酸钠是电化学氧化方法中的重要条件,该条件允许增加过硫酸盐的产生,从而提高治疗效果。当使用掺杂硼的金刚石(BDD)进行阳极氧化时,观察到了这种结果,在溶液中释放SDS-硫酸盐后,过硫酸盐产生了额外的过硫酸盐,并且它与BDD表面电生成的羟基自由基反应。但是,尚未通过使用有源阳极来测试这种效果。因此,通过比较非活性和活性阳极性能,研究了十二烷基硫酸钠(SDS)在咖啡因电化学处理过程中的作用。当在溶液中添加SDS时,在高电流密度下使用Ti / IrO2-Ta2O5阳极可观察到咖啡因的氧化效率显着下降。相反,在BDD阳极,SDS的存在会提高降解效率,具体取决于施加的电流密度。这种行为主要是由于SDS分子的降解,这使溶液中硫酸盐的含量增加,从而在使用BDD时通过涉及羟基的机理促进了过硫酸盐的产生。同时,当使用Ti / IrO2-Ta2O5阳极时,未观察到氧化改善,限制了咖啡因的氧化。结果清楚地表明,表面活性剂浓度对降解效率的影响很小,但这对于BDD体系是令人满意的,因为它表明使用电氧化技术可以有效降解含有表面活性剂的复杂基质的废水。通过电化学测量(极化曲线)以及动力学分析解释了降解机理。还评估了成本和能耗。
更新日期:2020-03-30
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