Cation-π induced surface cleavage of organic pollutants with ⋅OH formation from H2O for water treatment

Abstract

Summary High energy consumption is impedimental for eliminating refractory organic pollutants in water by applying advanced oxidation processes (AOPs). Herein, we develop a novel process for destructing these organics in chemical conjuncted Fe 0 -Fe y C z /Fe x , graphited ZIF-8, and rGO air-saturated aqueous suspension without additional energy. In this process, a strong Fe-π interaction occurs on the composite surface, causing the surface potential energy ∼310.97 to 663.96 kJ/mol. The electrons for the adsorbed group of pollutants are found to delocalize to around the iron species and could be trapped by O 2 in aqueous suspension , producing ⋅ OH, H, and adsorbed organic cation radicals, which are hydrolyzed or hydrogenated to intermediate. The target pollutants undergo surface cleavage and convert H 2 O to ⋅ OH, consuming chemical adsorption energy (∼2.852–9.793 kJ/mol), much lower than that of AOPs. Our findings provide a novel technology for water purification and bring new insights into pollutant oxidation chemistry.

Preferential Destruction of Micropollutants in Water through a Self-Purification Process with Dissolved Organic Carbon Polar Complexation

“…However, opposite phenomena appeared on Fe 0 -Fe y C z /Fe x -GZIF-8. Moreover, according to our previous research, 20 in the N 2 -saturated suspension with Fe 3+ addition, Fe 0 -Fe y C z /Fe x -GZIF-8-rGO exhibited the same catalytic activity as that under the air-saturated condition, while no significant oxidation was observed under the N 2 -saturated condition. The results indicated that O 2 mainly served as an electron acceptor for maintaining pollutant degradation.…”

“…The surface microelectric field stability of Fe 0 -Fe y C z /Fe x -GZIF-8-rGO was measured by Tafel polarization before and after the reaction with BPA with a reference of unstable Fe 0 -Fe y C z /Fe x -GZIF-8. 20 The corrosion current density of Fe 0 -Fe y C z /Fe x -GZIF-8-rGO was 10.99 μA/cm 2 , which decreased to 4.67 μA/cm 2 after reaction with BPA, while the value of Fe 0 -Fe y C z /Fe x -GZIF-8 was 20.82 μA/cm 2 , and it significantly increased to 120 μA/cm 2 in the BPA-adsorbed Fe 0 -Fe y C z /Fe x -GZIF-8 sample (Figure 1b,c). Correspondingly, the corrosion potentials of Fe 0 -Fe y C z /Fe x -GZIF-8-rGO exhibited a positive shift from −0.620 to −0.439 V after the reaction, indicating corrosion inhibition.…”

“…Thus, on the catalyst surface, a strong Fe(Zn)−π electrostatic interaction occurred, resulting in the electron-rich area around the Fe species and the electron-poor area around the aromatic rings of GZIF-8 and rGO. 20,21 By the strong surface electrostatic force, most of the refractory organic pollutants in ultrapure water were almost completely destroyed and mineralized without additional energy through their surface complexation and cleavage, meanwhile converting H 2 O to • OH for water purification. Our findings indicate that both complexation and cleavage of reactants on the catalyst surface were crucial to driving the water-purification reaction for the developed technology.…”

Insights into singlet oxygen generation and electron-transfer process induced by a single-atom Cu catalyst with saturated Cu-N4 sites

“…In recent decades, emerging micropollutants in water have posed a serious threat to the ecological environment and human health, even at trace concentrations (ng L −1 −μg L −1 ) ( Schulze et al., 2019 ). Owing to the generation of powerful oxidizing radicals (e.g., hydroxyl radical ⋅ OH and sulfate radical SO 4 ⋅− ), persulfate-mediated advanced oxidation processes (AOPs) are regarded as efficient technologies for water purification ( Wang et al., 2021a ; Zhang et al., 2021 ). However, in actual water with complex chemical compositions, radicals are inevitably consumed by natural organic matter (NOM) and inorganic substrates (e.g., HCO 3 − and Cl − ), hindering the degradation of target pollutant and increasing the toxicity caused by halogenated byproducts ( Yang et al., 2021 ).…”

“…), persulfate-mediated advanced oxidation processes (AOPs) are regarded as efficient technologies for water purification (Wang et al, 2021a;Zhang et al, 2021). However, in actual water with complex chemical compositions, radicals are inevitably consumed by natural organic matter (NOM) and inorganic substrates (e.g., HCO 3…”