Environmental Functional Materials最新文献

The heterogeneous activation of persulfate-based advanced oxidation processes (persulfate AOPs) has been defined as potential wastewater treatment methods due to their excellent chemical reactivity. However, the reaction mechanisms of these processes are extremely intricate because of the simultaneous participation of many substances from the solid, liquid, and even gas phases. The development of novel active catalysts is hindered due to divergent mechanisms and deficient research techniques. In this review, the up-to-date development of heterogeneous catalyst category, catalytic characteristics, and reaction mechanism are comprehensively discussed. Essentially, the detection of persulfate, the identification of reactive oxygen species, and the evolution and analysis of organic oxidation pathways are reviewed, highlighting the innovation integration experimental/theoretical protocol to reveal the reaction mechanism in a future study. Finally, the limitations and possible breakthrough directions of persulfate AOPs were discussed, including the further study of the internal reaction mechanism in persulfate AOPs, the requirement of reasonable evaluation of the treatment effect, and the feasibility of full-scale application.

Iron-based heterogeneous Fenton is a promising economic and eco-friendly technology in the degradation of organic pollutants, but the low conversion of ≡Fe³⁺ to ≡Fe²⁺ causes the low catalytic activity. Schwertmannite (Sch) formed via Fe(II) oxidation mediated by Acidithiobacillus ferrooxidans (A. ferrooxidans), resulting in the existence of low organic carbon (mainly from A. ferrooxidans cells) in Sch. Owing to magnetic inter-attraction between magnetosome-containing A. ferrooxidans and Fe₃O₄, A. ferrooxidans as organic carbon (OC) modified Fe₃O₄/Sch (namely Fe₃O₄/Sch/OC) was obtained by the introduction of Fe₃O₄ into synthetic process of Sch. Fe₃O₄/Sch/OC exhibited higher degradation efficiency (>95%) of antibiotics than Sch, Fe₃O₄ and Fe₃O₄/Sch, which was mainly ascribed to OC as electron donor and electron-transfer mediator for promoting ≡Fe²⁺ regeneration. Moreover, in situ H₂O₂ could be generated at a wide initial pH (3–9) via Fe₃O₄/Sch/OC-driven oxygen reduction reaction, and H₂O₂ was immediately activated to produce •OH for degrading organic pollutants (e.g., dyes, antibiotics). Considering the excellent arsenic (As) adsorption performance of Sch and the property of Fe₃O₄/Sch/OC to produce in situ H₂O₂, Fe₃O₄/Sch/OC-catalyzed in situ-generated H₂O₂ will be a promising strategy to synchronously remove antibiotics and As from livestock and poultry breeding wastewater.

Biochar, the product of anaerobic pyrolysis of biomass, has attracted immense interest not only as an adsorbent in agricultural and environmental remediation applications but also as a carbonaceous redox catalyst in air/water purification research. Various chemical approaches have been developed to modify biochar; however, most of them are costly because they require additional chemicals and a series of treatment steps, such as the dewatering the so-treated biochar and post-treatment removal of oxidant products. Recently, researchers, including the author of this article, developed a convenient and inexpensive method for enhancing adsorption of organic and inorganic compounds by subjecting the biochar to a brief thermal air oxidation (AO) step. In this review, the author outlines the basic mechanisms of thermal AO and critically examines the property changes of biochar after the thermal AO treatment. This review aims to improve the understanding of biochar after it is exposed to hot air (e.g., wildfires), provide a detailed discussion of scientific evidence, and offer major directions for future research concerning thermal AO and its applications. A comprehensive review of relevant literature indicates that the important factors governing the resultant biochar after thermal AO include the heat treatment temperature (HTT) at which biochar is made and the feedstocks of biochar. Biochar made from lignin-rich feedstocks such as coconut shells and nutshells is preferable for thermal AO treatment. Thermal reactions between molecular oxygen and biochar (1) improve surface oxygen functionality more effectively for biochar made at HTTs than for high-HTT biochar, (2) increase the surface area and porosity especially for high-HTT biochar; and (3) create new adsorption sites and/or relieve steric restrictions of organic molecules to micropores, thereby enhancing the adsorptivity of biochar.