Mechanistic Insight into the Heterogeneous Electro-Fenton/Sulfite Process for Ultraefficient Degradation of Pollutants over a Wide pH Range

Abstract

Electro-Fenton (EF) has received widespread attention in terms of water decontamination in advanced oxidation processes but still has the bottlenecks of a narrow pH (∼3) application range and a slow rate of reduction of the iron ion to sustain high treatment efficiency. Herein, an iron–carbon catalyst was synthesized to develop a heterogeneous EF/sulfite (hetero-EF/sulfite) process, which expanded the pH application range to 7 and increased the rate constant of carbamazepine (CBZ) degradation 10.74 times compared with that of the hetero-EF process. The catalyst was systematically characterized; important process factors such as the applied current, initial pH, and CBZ, catalyst, and sulfite dosage were investigated, and a possible degradation mechanism and a possible pathway were proposed. The quenching experiments and electron paramagnetic resonance test revealed the existence of active species such as •OH, SO4 •–, O2 •–, 1O2, and their mutual transformation, in which •OH and O2 •– were dominant. This work also verified the suitability of the hetero-EF/sulfite for different pollutants, and its universal enhancement for different heterogeneous and homogeneous catalysts. This modified EF process expands the pH application range and enables the co-generation and transformation of free radicals, which has broad prospects for application in the effective degradation of organic pollutants for water purification.

Insights into Electrochemical Dehalogenation by Non-Noble Metal Single-Atom Cobalt with High Efficiency and Low Energy Consumption

“…The FLO removal (98.7%), defluorination efficiency (67.6%), and dechlorination efficiency (95.6%) of Co−N/C were higher than those of Pd/C (86.0, 41.8, and 87.3%), and the degradation rate constant of Co−N/C (0.0319 min −1 ) was 2.1 times that of Pd/C (0.0155 min −1 ) (Figures 2d,e and S11), confirming its dehalogenation performance was superior to Pd/C. To further assess the catalytic activity of Co−N/C, electric energy consumption (EEC) 38 and turnover frequency (TOF) 39 were calculated. As shown in Figure 2f, Co−N/C had a TOF value of 0.0208 min −1 , which was higher than the majority of other catalysts (0.0002−0.0127 min −1 ).…”

Molecular inspired electrocatalyst materials for environmental remediation

“…Fe( ii ) ions are then oxidized to produce hydroxyl radicals, as is shown in eqn (8). 136 O 2 + 2H + + 2e − ⇄ H 2 O 2 E ° = 0.68 V vs. SHEFe 2+ + H 2 O 2 → Fe 3+ + ˙OH + OH − …”

Electrospun TiO2/carbon composite nanofibers as effective (photo)electrodes for removal and transformation of recalcitrant water contaminants

“…Results from this work demonstrate the potential advantages of the proposed (photo)electrode architecture and design while avoiding complex systems or components (e.g., catalyst recovery, catalyst leaching, additional chemical and energy inputs). [38][39][40] The electrospun CNFs serve as a three-dimensional, low-resistance current collector and provide a high surface area for supporting and exposing embedded TiO 2 semiconductor particles for enhanced charge transport. TiO 2an earthabundant semiconductor that represents the industry standard for photocatalytic water treatment applications 41,42 was selected due to the extensive literature about its performance as a photocatalyst, particularly for pollutant transformation.…”