Selective Removal of Emerging Organic Contaminants from Water Using Electrogenerated Fe(IV) and Fe(V) under Near-Neutral Conditions

Abstract

Fe(IV) and Fe(V) are promising oxidants for the selective removal of emerging organic contaminants (EOCs) from water under near-neutral conditions. The Fe(III)-assisted electrochemical oxidation system with a BDD anode (Fe(III)–EOS–BDD system) has been employed to generate Fe(VI), while the generation and contributions of Fe(IV) and Fe(V) have been largely ignored. Thus, we examined the feasibility and involved mechanisms of the selective degradation of EOCs in the Fe(III)–EOS–BDD system under near-neutral conditions. It was found that Fe(III) application selectively accelerated the electro-oxidation of phenolic and sulfonamide organics and made the oxidation system be resistant to interference from Cl–, HCO3 –, and humic acid. Several lines of evidence indicated that EOCs were decomposed via direct electron-transfer process on the BDD anode and by Fe(IV) and Fe(V) but not Fe(VI), besides HO•. Fe(VI) was not generated until the exhaustion of EOCs. Furthermore, the overall contributions of Fe(IV) and Fe(V) to the oxidation of phenolic and sulfonamide organics were over 45%. Our results also revealed that Fe(III) was oxidized primarily by HO• to Fe(IV) and Fe(V) in the Fe(III)–EOS–BDD system. This study advances the understanding of the roles of Fe(IV) and Fe(V) in the Fe(III)–EOS–BDD system and provides an alternative for utilizing Fe(IV) and Fe(V) under near-neutral conditions.

Electrochemical Synthesis of Ferrate (VI): Factors Influencing Synthesis and Current Research Trends

“…The use of ultrasound facilitated the diffusion and transfer of iron powder material loaded onto inorganic electrode surfaces. Wang [72] studied the combined use of BDD electrodes and Fe(III) for electrochemical selective oxidation and degradation of organic compounds (EOCs), demonstrating that the generation of Fe(IV) and Fe(V) has little impact on the degradation of organic substances. Fe(VI) generation only happened after the complete degradation of organic substances, as shown in Figure 1.…”

Carbon nanotubes as a nanocatalyst and nanoreactor for the efficient treatment of pharmaceutical wastewater via CaSO3 activation

“…For the past few years, advanced oxidation processes have been comprehensively used in the decontamination of groundwater and soil because of their high-efficiency and eco-friendliness. [1][2][3][4][5] As a consequence, multiple oxidants, particularly persulfates, [6][7][8][9][10] have been employed in advanced oxidation processes to produce reactive oxygen species (including SO 4 • − and HO•) for degrading organic pollutants [11][12][13][14][15][16][17] due to their high redox potential, wide range of pH application, and ultra-high degradation rate. [18][19][20][21][22] However, these heavily used persulfates could cause potential chronic diseases due to their high stability and toxicity.…”