Environmental Functional Materials最新文献

Molybdenum disulfide (MoS₂) is an emerging class of heterogeneous catalyst in advanced oxidation processes (AOPs). Featuring a two-dimensional structure, good conductivity, photo-response, reductive capacity, and regulatable active sites, MoS₂ fulfills versatile functions in various AOPs systems, such as direct activation of peroxide, serving as a co-catalyst in Fe³⁺- and Cu²⁺-based Fenton/Fenton-like systems, photocatalytic oxidation, electrochemical oxidation, and piezoelectric oxidation. In this review, we summarize recent advances of MoS₂ in the AOPs applications. We systematically compare the dominant reactive oxygen species, and identify potential active sites (e.g., edges and vacancy defects) and the impact of the crystal structure (e.g., 1T phase). We also introduce some basic principles based on the structure-activity relationships to describe the intrinsic activation mechanisms. In addition, we discuss discrepancies in previous reports on MoS₂-based AOP systems. Finally, roadblocks are identified and future orientation is directed regarding catalyst design, system optimization, and practical applications.

Phosphorus (P) is an essential microelement for biota. Phosphate minerals obtained through subsurface mining are the main sources of P. Phosphate-bearing rocks are nonrenewable and reserves are limited, so overexploitation will cause a shortage of P. However, releasing large amounts of P into water bodies can cause eutrophication. The problems of availability of P and P-related pollution require long-term sustainable responses. Electrochemical P recovery methods have recently been found to offer promise for solving these problems. Here, we describe recent advances in electrochemical methods for removing and recovering P in various forms from aqueous systems and summarize the fundamentals and parameters affecting the methods. The review is not only limited to orthophosphate but also includes non-ortho P and phosphite, which are often overlooked. The economic viabilities of various methods are assessed and the constraints and prospects of the methods are summarized. Improving electrochemical methods will require interdisciplinary research in the fields of electrochemistry, chemical engineering, and environmental science.

Graphitic carbon nitride (g-C₃N₄), as an efficient semiconductor photocatalyst with an excellent tunable bandgap, a high physicochemical stability and a proper optical performance, has shown its non-negligible potential in multifarious photocatalytic reactions, such as hydrogen (H₂) evolution, carbon dioxide (CO₂) reduction, hydrogen peroxide (H₂O₂) production, pollutants degradation and so on. However, considering the solar light transfer efficiency, the accurate reaction mechanisms as well as the limitations of various reactions, is g-C₃N₄ more suitable for reduction or oxidation reactions? In this perspective, we think g-C₃N₄ might be more suitable for photocatalytic reduction reactions since the performances of single oxidation reactions maybe not ideal and sometimes the electrons are still essential during such a process.

To understand the role of phosphorus doping in Co and Ni-loaded carbon nitride photocatalysts, four P-doped samples are prepared using different strategies. Morphological characterization shows that Co and Ni single atoms were prepared using a concurrent P annealing process in the presence of carbon nitride and CoNi layered double hydroxides (PA-4). In addition, structural characterization indicates that the introduced P can etch CoNi soft-templates and be doped into the coordination environment. The PA-4 structure is believed to enhance the photogenerated charge carrier transfer. The as-prepared PA-4 samples exhibit better photocatalytic activity for nefazodone (Nefa) degradation in water (99.9% within 40 ​min) than other P-doped samples. Quenching experiments indicate that O₂^•−, •OH, and photogenerated electrons and holes contribute to the degradation of Nefa. Analysis of the intermediate products suggests that the degradation routes primarily involve hydroxylation reactions, N-dealkylation reactions, and piperazine cracking. The findings provide an alternative strategy for the preparation of P-doped Co and Ni-loaded carbon nitride photocatalysts for contaminant degradation and elucidate the role of P doping.

Phosphorus recovery from wastewater is important for protecting the aquatic environment and achieving sustainable development. However, as a typical phosphorus adsorbent, nanoscale magnesium oxide (MgO) exhibits aggregation and limited adsorption ability. Herein, melamine foam (MF) was selected as a self-sacrifice template to prepare an oxygen-vacancy-rich MgO/MF phosphate adsorbent with high dispersion and a multistage pore structure. Density-functional theory calculations reveal that the phosphate preferentially adsorbed on the hollow sites rather than top sites of MgO when there were oxygen vacancies, which improved the intrinsic adsorption ability of MgO/MF. The MgO/MF adsorbent exhibited excellent phosphorus removal from water within a wide pH range of 2–12; the maximum adsorption capacity of phosphate was as high as 1226 ​mg/g. The adsorption capacity of the MgO/MF adsorbent after phosphate adsorption was reactivated to ca. 100%. After six adsorption cycles, MgO/MF with a high phosphate content of 117.5 ​mg ​P/g is a potential high-quality fertilizer. This work provides a promising strategy for constructing an efficient adsorbent for wastewater treatment and resource recovery.

Peroxymonosulfate (PMS)-based advanced oxidation technologies are among the most promising strategies for degrading refractory organic pollutants in water. Recently, carbon nitride (CN) materials have been widely reported for the preparation of PMS activators owing to their unique molecular structures. With the advancement of this research, it is not only the activation ability of CN materials that is considered, but also their inherent photocatalytic performance in the activation system, which further improves the degradation efficiency of organic pollutants and at the same time makes the whole oxidation processes more variable and complex. In this review, we summarize recent work on the activation of PMS with CN. Firstly, in terms of improving the activation performance of PMS at the interface of CN materials, function-imparting strategies and the corresponding catalytic mechanisms of non-metallic and metal-containing CN materials are discussed. Then, the potential photochemical properties of CN materials are highlighted, the synergistic-gain principle for activation reactions at the material interface are discussed, and methods for controlling the optical properties of CN, including regulation of its intrinsic optical properties, the grafting exogenous optical materials, and the construction of heterostructures are reviewed. Finally, the CN-modification strategies and the PMS-activation mechanisms are discussed, and the possible directions and future prospects for this field of research in view of its current uncertainties and bottlenecks are presented.

The economical and effective capture of radioactive iodine has always been an important field of research in the reprocessing of spent fuel. In this work, we successfully prepared a novel bismuth-modified all-silica beta zeolite material (Bi@Si-BEA) though a modified incipient wetness impregnation method. A series of iodine sorption and desorption experiments and characterization methods (PXRD, SEM, TEM, TG, XPS, FTIR, ²⁹Si NMR, Raman, PDF, and DFT calculation) were performed to reveal the structural characteristics and the mechanism of iodine capture of Bi@Si-BEA. The results showed that the sorption mechanism generally involved the preferential enrichment of iodine molecules in the 12-ring channels of the Si-BEA, for which the adsorption energy was −0.23 ​eV. The enriched iodine molecules subsequently reacted with the active bismuth sites (Bi⁰ and β-Bi₂O₃) on the surface of Si-BEA to form bismuth iodine compounds (BiI₃ and BiOI), thereby achieving immobilization of iodine through strong chemical interactions. Through a combination of physical and chemical effects, Bi@Si-BEA could reach a sorption capacity of 600 ​mg/g, of which the chemisorption accounts for approximately 350 ​mg/g, in approximately 2 ​h. In addition, we explored the effects of different loadings of bismuth and experimental temperatures on the iodine sorption performance and scaled up the preparation of Bi@Si-BEA.

Metal–organic frameworks (MOFs) are ideal adsorbents because of their porous structure, ultra-large specific surface area, abundant active sites, and specific surface charge. Recently, light-response MOFs have received considerable research interests regarding their potential applications in environmental remediation, medical treatment, and artificial intelligence. This review systematically summarizes the recent progress of light-response MOFs and MOF-based composites for light-response adsorption/desorption. The fabrication strategies of light-response MOFs, including in situ synthesis, post-synthesis modification, and introduction of guest molecules, are presented. The mechanisms of light-induced structural change and light-responsive adsorption/desorption are summarized. The prospects for further development of light-response MOFs are discussed. The facile regeneration of light-response MOF-based adsorbents by light irradiation is highly promising for energy saving, environmental friendliness, and sustainability.