Pd-Catalytic In Situ Generation of H₂O₂ from H₂ and O₂ Produced by Water Electrolysis for the Efficient Electro-Fenton Degradation of Rhodamine B

Abstract

A novel electro-Fenton process was developed for wastewater treatment using a modified divided electrolytic system in which H2O2 was generated in situ from electro-generated H2 and O2 in the presence of Pd/C catalyst. Appropriate pH conditions were obtained by the excessive H+ produced at the anode. The performance of the novel process was assessed by Rhodamine B (RhB) degradation in an aqueous solution. Experimental results showed that the accumulation of H2O2 occurred when the pH decreased and time elapsed. The maximum concentration of H2O2 reached 53.1 mg/L within 120 min at pH 2 and a current of 100 mA. Upon the formation of the Fenton reagent by the addition of Fe2+, RhB degraded completely within 30 min at pH 2 with a pseudo first order rate constant of 0.109 ± 0.009 min(-1). An insignificant decline in H2O2 generation and RhB degradation was found after six repetitions. RhB degradation was achieved by the chemisorption of H2O2 on the Pd/C surface, which subsequently decomposed into •OH upon catalysis by Pd0 and Fe2+. The catalytic decomposition of H2O2 to •OH by Fe2+ was more powerful than that by Pd0, which was responsible for the high efficiency of this novel electro-Fenton process.

Preparation and characterization of a novel KOH activated graphite felt cathode for the electro-Fenton process

“…After immersion in 1.0 mol L −1 NaOH aqueous solution under mechanical stirring for 3 h to make GF more hydrophilic, it was washed with deionized water and then immersed in 6.0 mol L −1 KOH aqueous solution under mechanical stirring and heating until KOH crystals were separated out. After that, GF was mixed with KOH crystals and heated in a tube furnace at different temperatures (700, 800, 900, and 1000 • C) for 1 h or at 900 • C for different time (15,30,60, and 90 min). The temperature was increased to the objective point at a heating rate of 4 • C min −1 from room temperature.…”

“…Their DMP degradation percentage and the corresponding apparent rate constant (k), based on pseudo first-order reaction [43], at RGF and AGF treated at different temperatures for 1 h (700, 800, and 900 • C) and different time (15,30, and 60 min) at 900 • C, are given in Fig. 2.…”

“…As known, the electrocatalytic mechanism and kinetics is heavily dependent on the electrode materials [14]. Accordingly, the efficiency of H 2 O 2 generation is directly related to the types and properties of the cathode materials for ORR [15]. Thus, to improve the ORR activity of cathode materials to in-situ electrochemically generate H 2 O 2 is the key step in the EF technology.…”

Optimization and control of Electro-Fenton process by pH inflection points: A case of treating acrylic fiber manufacturing wastewater

“…Similarly, pH curves II and VII both had their corresponding pH IPs at 5 min, respectively. In Fenton reaction system, pH variation has been reported to be highly dependent on the reagents and intermediates involved in the Fenton chain-reactions, such as Å OH, hydroxide ion, and hydrogen ion [24]. In EF reactors, the electrode reactions such as water electrolysis also play an important role [1].…”

Fenton degradation of 4-chlorophenol using H2O2in situ generated by Zn-CNTs/O2 system

“…4 Moreover, the application of in situ generated H 2 O 2 has been found to be potentially safer and more economical than that of bulk commercial H 2 O 2 . 5 Various methods have been used for the in situ generation of H 2 O 2 for the Fenton oxidation of organic pollutants, such as electroFenton, [6][7][8] photo-Fenton, 9,10 and bio-Fenton processes 11,12 etc. However, these processes require the use of a high concentration of electrolyte or electrical energy or luminous energy or nutrient substances, which limits their application in wastewater treatment.…”