Mwangi I W, Kinyua E M, Nthumbi R, Wanjau R N, Swaleh S, Ngila J C
Department of Chemistry, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya.
Department of Chemical Technology, University of Johannesburg, Doornfontein Campus, P.O Box 17011, Doornfontein 2028, Johannesburg, South Africa.
Heliyon. 2021 Apr 5;7(4):e06671. doi: 10.1016/j.heliyon.2021.e06671. eCollection 2021 Apr.
Availability of clean water is of concern due to pollution and diminishing supply pollution. However, purification is possible depending on the incorporated contaminants. Domestic wastewater contains dissolved organic matter and its remediation can be done by oxidation. The best oxidation can be achieved by electron transfer the same way metabolic processes occur. This study exploited the use of a film of iron (III) doped titanium dioxide applied on an electrode which was found to be effective. Natural light conditions generated electrons that migrated through the electrode leaving behind holes which oxidized the contaminants as the excess electrons were discharged at the cathode after passing through the casted proton exchange membrane (PEM) separating the two half cells of the prepared reactor. This electrochemical method has the advantage in that the organic pollutants are oxidized to carbon dioxide with no secondary pollutants and the inorganic pollutants into insoluble matter. The assembled cell was applied to purify both synthetic and real water samples of green leafy vegetable solution from the kitchen by clarification. The clarification process was monitored by UV-Vis using distilled water as a reference to compare the light that transmitted through a sample. It was observed that the electro-oxidation process took place showing a high potential 105 mV within the first 150 min followed by degradation at a high rate. The oxidation of the organic matter was confirmed by UV-Vis analysis as well as by cyclic voltametric analysis of iron released into the solution of the synthetic samples. The electro chemical treatment of the water was then applied to purify real water samples made from a sample of 4.5 g minced of green vegetables dispersed in one liter of water (4.5 g/l). The green leafy coloured solution was clarified after 154 h of continuous oxidation. The degradation process was confirmed to be independent of intermediates or other species present in solution as it was of first order reaction kinetics. The electrochemical oxidation of organic matter in water using iron (III) doped titanium dioxide coated graphite electrode has potential application on the purification of water.
由于污染和供应减少，清洁水的可得性令人担忧。然而，根据所含污染物的情况，净化是可行的。生活污水含有溶解的有机物，其修复可以通过氧化来完成。通过电子转移可以实现最佳氧化，就像代谢过程发生的方式一样。本研究利用了涂覆在电极上的铁（III）掺杂二氧化钛薄膜，发现其有效。自然光条件产生电子，这些电子通过电极迁移，留下空穴，当多余的电子通过分隔制备的反应器两个半电池的铸造质子交换膜（PEM）后在阴极放电时，空穴会氧化污染物。这种电化学方法的优点在于有机污染物被氧化成二氧化碳且无二次污染物，无机污染物则变成不溶物。组装的电池被应用于通过澄清来净化合成水样和来自厨房的绿叶蔬菜溶液的实际水样。澄清过程通过紫外可见分光光度计（UV-Vis）监测，以蒸馏水为参比来比较透过样品的光。观察到电氧化过程在前150分钟内呈现出105 mV的高电位，随后以高速率降解。通过UV-Vis分析以及对释放到合成样品溶液中的铁进行循环伏安分析，证实了有机物的氧化。然后将水的电化学处理应用于净化由4.5克切碎的绿色蔬菜分散在一升水中（4.5克/升）制成的实际水样。经过154小时的连续氧化后，绿叶色溶液变得澄清。降解过程被确认为与溶液中存在的中间体或其他物种无关，因为它符合一级反应动力学。使用铁（III）掺杂二氧化钛涂层石墨电极对水中有机物进行电化学氧化在水净化方面具有潜在应用。
