Amino acid cysteine has been used as reducing mediator with the aim of improving dye degradation by homogeneous Fenton processes (Fe²⁺/H₂O₂ and Fe³⁺/H₂O₂). Through its known Fe³⁺-reducing activity, this amino acid can enhance the production of reactive oxygen species as HO^● (hydroxyl radical) and its pro-oxidant properties have been verified while decolorizing diverse dyes in the present work. Its presence enhanced decolorization of Methyl Orange, Phenol Red, Safranin T, Rhodamine B, Reactive Black 5 and Reactive Yellow 2, mainly in reactions initially containing Fe³⁺ as a catalyst (Fe³⁺-reactions). E.g. Fe³⁺/H₂O₂ and Fe³⁺/H₂O₂/cysteine systems decolorized 27% and 44% of Phenol Red after 60 min, respectively. A kinetic modeling analysis has revealed that 1^st-order and mainly 2^nd-order kinetic models were well fitted to both Fe²⁺- and Fe³⁺-reactions data. Improvements in reaction rate constants have been observed by adding cysteine. In experiments performed at varied temperatures, it was found a decrease in activation energy (Ea) due to cysteine addition while decolorizing Safranin T: Ea decreased from 104.6 to 88.9 kJ mol^-1 for Fe³⁺-reactions and from 81.0 to 52.2 kJ mol^-1 for Fe²⁺-reactions. Therefore, it was found that cysteine decreases the energy barrier so as to improve Fenton-based decolorization reactions.

氨基酸半胱氨酸已被用作还原介体，目的是通过均质的Fenton工艺（Fe ²⁺ / H ₂ O ₂和Fe ³⁺ / H ₂ O ₂）改善染料降解。通过其已知的还原Fe ^3+的活性，该氨基酸可以增强活性氧的生成，如HO ^●（羟基自由基），并且在本研究中使多种染料脱色的同时，还证实了其促氧化剂的特性。它的存在增强了甲基橙，苯酚红，番红花T，若丹明B，活性黑5和活性黄2的脱色，主要是在最初包含Fe ³⁺作为催化剂（Fe ³⁺-反应）。例如，Fe ³⁺ / H ₂ O ₂和Fe ³⁺ / H ₂ O ₂ /半胱氨酸体系在60分钟后分别使27％和44％的酚红脱色。动力学建模分析表明，1^日阶和主要2个^第二阶动力学模型较好地拟合到两个铁²⁺ -和Fe ³⁺ -reactions数据。通过添加半胱氨酸已观察到反应速率常数的改善。在不同温度下进行的实验中，发现由于半胱氨酸添加而使藏红素T：Ea脱色时活化能（Ea）降低从104.6降至88.9千焦耳摩尔^-1为铁³⁺ -reactions和从81.0到52.2千焦摩尔^-1为铁²⁺ -reactions。因此，发现半胱氨酸降低了能垒，从而改善了基于Fenton的脱色反应。