Thus, the reduction of Fe 3+ to Fe 2+ greatly limits the treatment performance of the Fenton reaction for pollutants degradation. As a result, Fe 3+ is massively accumulated from the oxidation of Fe 2+ in the Fenton reaction system since Fe 2+ regeneration from Fe 3+ is very slow ( Qiang et al., 2003). Besides, most of the Fenton reagents are added at once while over-dosage of either H 2O 2 or iron ions would lead to side reactions ( Eq. The increased salt content probably makes this wastewater unacceptable for natural environments or poses significant pressure on the subsequent reverse osmosis unit ( Wang et al., 2014 Fang et al., 2018). In addition, the employment of iron salt inevitably increases water salinity ( Li et al., 2013). In addition, massive alkaline reagents were also consumed for the subsequent neutralization of the treated solution. However, working in such acidic pH requires the addition of a large amount of acid. The addition of concentrated acid reagent is indispensable to adjust the solution pH to ∼3.0, that is the optimum condition for the Fenton reaction. However, the Fenton process has some drawbacks, which greatly hamper its industrial application ( Babuponnusami and Muthukumar, 2014 Gao et al., 2020). 2), maintaining the continuous Fenton reaction ( Babuponnusami and Muthukumar, 2014 Bello et al., 2019). The second stage is characterized by a slow reaction between Fe 3+ and H 2O 2 for the regeneration of Fe 2+ ( Eq. 1), most of the pollutant degradation is achieved in this stage. OH from the homogeneous reaction between Fe 2+ and H 2O 2 ( Eq.The first stage is characterized by the rapid formation of The Fenton reaction mainly proceeds via two steps ( Neyens and Baeyens, 2003 Moreira et al., 2017 Gao et al., 2020). Among various AOPs, the conventional Fenton reaction process has been most widely applied for the treatment of wastewater streams because it exhibits the advantages of fast reaction rates, mild operating conditions, and simplicity to control ( Bello et al., 2019). OH, E 0 = 2.80 V/SHE) was generated in situ and found to be capable of degrading any refractory organic molecules present in the aqueous solution until total mineralization at the kinetic constant values as high as 10 8∼10 10 M −1s −1 ( Andreozzi et al., 1999 Oturan and Aaron, 2014 Gao et al., 2018).Over the past few decades, advanced oxidation processes (AOPs) have attracted increasing interests for wastewater treatment since the highly oxidative hydroxyl radical ( Generally, this combined system was eco-friendly, energy-efficient, and has the potential of being a promising technology for the removal of bio-refractory organic pollutants from wastewaters. In this case, the conductivity just slightly increased from 4.35 to 4.37 mS/cm, minimizing the increase of water salinity, as compared with the conventional Fenton process. Meanwhile, a COD and TOC removal efficiency of 79 and 60% was obtained, respectively. It was found that when a potential of 1.2 V/SCE was applied on the iron cathode, 98% of p-nitrophenol was removed in the combined system after 30 min with continuously adding 200 mg/L of H 2O 2. In an ICEF system, an iron plate was used as the cathode to inhibit the release of iron ions and promote the reduction of Fe 3+ to Fe 2+. In a pH-regulation divided electrolysis system, the desired pH for an effective Fenton reaction and for a neutral treated media could be obtained by H 2O splitting into H + and OH − at the anode and cathode, respectively. In this work, a novel eco-friendly iron cathode electrochemical Fenton (ICEF) system coupled with a pH-regulation divided electrolysis cell was developed. The high consumption of salt reagents and strict pH control are still bottlenecks for the full-scale application of the Fenton reaction. 2Shengli Oilfield Testing and Evaluation Research Co., Ltd., SINOPEC, Dongying, China.1Technical Test Center of Sinopec Shengli OilField, Dongying, China.Xiaohui Wang 1,2* Jingang Zhao 1,2 Chunyan Song 1,2 Xian Shi 1,2 Haipeng Du 1,2
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