Environmental Functional Materials最新文献

It has been a pressing challenge to treat saline wastewater with advanced oxidation techniques due to the inhibition of reactive oxygen species in the actual wastewater by co-existing ions. Herein, we synthesized TCPP@UiO-66(Hf) catalysts enriched with deletion linker defects by doping meso-tetra (4-carboxyphenyl) porphine (H₂TCPP) in UiO-66(Hf) to modulate its performance for the removal of ofloxacin (OFL) from complex aqueous environment. TCPP@UiO-66(Hf)-250 promoted the removal efficiency of OFL from 13.4% to more than 96%. The adsorption and photocatalytic properties of TCPP@UiO-66(Hf)-250 with defects were significantly enhanced in various anionic environments. The electron-donating role of coexisting anions was investigated with SO₄²⁻ as a representative. Quenching tests and electron paramagnetic resonance (EPR) revealed that in the TCPP@UiO-66(Hf)-250/Na₂SO₄/visible light (TCPP@UiO-66(Hf)-250/Na₂SO₄/VIS) system, O₂^∙− and ¹O₂ dominated the removal of OFL with increasing levels. And SO₄^∙− was generated after the addition of SO₄²⁻, confirming the electron-donating role of sulfate in the photocatalytic system. The TCPP@UiO-66(Hf)-250/visible light (TCPP@UiO-66(Hf)-250/VIS) system maintained excellent OFL removal efficiency over a broad pH range of aqueous solutions, in high co-existing ion concentrations and actual aqueous matrices, and exhibited good performance in cycling tests. It demonstrates that the coexisting anions play an electron-donating role in the photocatalytic system and further reveals the synergistic mechanism between the photocatalyst and coexisting anions, which offers the possibility of contaminant removal in highly saline water.

Petroleum and its refined products enter the marine environment during the extraction process, causing serious pollution. Herein, a bifunctional Fe–N₂ single-atom embedded in nitrogen-doped porous carbon photocatalyst (FC) was fabricated for the efficient removal of marine petroleum pollutants. The combination of highly dispersed Fe–N₂ active sites, large surface area, high porosity, and good conductivity results in excellent photocatalytic activities. The FC catalyst exhibited a 96.7% degradation rate in the oxidative removal of bisphenol A (BPA) and a 63.4% reduction of Cr(VI) within 1 ​h, whereas the reaction equilibrium rate constants of 0.0132 ​min⁻¹ and 0.0505 ​min⁻¹ were reached, respectively. FC with good stability and reusability could reach 88.3% and 53.5% removal rate of BPA and Cr(VI) after 5 cycles. Radical quenching experiments and electron spin resonance (ESR) confirmed that ‧OH and e⁻ were the most driving active species for photo-oxidation and reduction, respectively. Besides, the FC catalyst was applied to an actual seawater system and the simulation results showed a good removal rate (82.7% of BPA and 50.9% of Cr(VI) within 1 ​h). The BPA oxidation pathway in the system was proposed and the toxicity of each intermediate was accessed. This work offers a new way to construct single-atom functionalized carbon-based catalysts for marine pollution control.

Enzyme immobilization, due to its higher effective density in a limited micro space, can effectively improve the removal efficiency for some recalcitrant compounds. Metal–organic frameworks (MOFs) have been identified as having attractive properties for the immobilization of enzymes, such as high surface area, large internal pore volumes and easily adjustable pore size. In the present study, a new immobilization carrier was synthesized through the modification of zeolitic imidazole framework-8 (ZIF-8) by 2-aminobenzimidazole, which was employed for enzymes immobilization for the first time. The immobilized bio-enzyme was extracted from trichloromethane (TCM) degrader Stenotrophomonas sp. GYH, and identified through label-free quantitative proteomics. Based on the metabolites detection and molecular docking, a proper degradation pathway for TCM was proposed, in which some key enzymes were tagged with the specific role. XRD, BET, and FTIR analyses proved that ZIF-8-NH₂ was proper as the immobilization carrier. The bio-enzyme@ZIF-8-NH₂ prepared under the best immobilized conditions had a similar relative enzyme activity to that of free enzyme (the Michaelis kinetic constant K_m was 3.86 and 3.78 ​min⁻¹), but it had better pH and temperature adaptability (pH 5−9 and temperature 10−50 ​°C), better storage stability (83% and 40% of the initial enzyme activity at 30 ​d) and so on. The density functional theory (DFT) results show that the ZIF-8-NH₂ carrier has a better TCM and CO₂ adsorption energy, which is consistent with the fact that the bio-enzyme@ZIF-8-NH₂ had better TCM degradation efficiency and less CO₂ emission to the surroundings.

The solar-driven photocatalytic process has been evolved as a promising technology for both hexavalent chromium reduction and organic pollutants oxidation. Although both reactions are based on the same principle of photoinduced interfacial charge transfer, different catalysts and reaction conditions are required in two processes. This review revealed the scientific advances in dual-functional photocatalytic processes that enable simultaneous hexavalent chromium reduction and organics oxidation. Firstly, the basic principles of dual-functional photocatalysis are briefly discussed whereby the key concept of the system is the simultaneous oxidation of organic pollutants via photogenerated holes and reduction of hexavalent chromium via photogenerated electrons. Then, advances in dual-functional photocatalysis for the simultaneous removal of hexavalent chromium and organics are presented and discussed in terms of catalysts classification, including TiO₂-based, bismuth-based and g-C₃N₄-based catalysts. Finally, the prospects, challenges and new perspectives of feasible solutions for dual-functional photocatalytic catalysts design are presented. Overall, this paper provides new insights on the modulation strategies and conformational relationships of dual-functional materials for researchers in the field of photocatalysis, which is beneficial for the practical applications of dual-functional materials in environmental remediation.

In recent years, with increasingly scarce land resources, incineration technology has gradually become the mainstream disposal method of household hazardous waste. The exhaust gas of incineration contains both NO_x and chlorine-containing volatile organic compounds (CVOCs), which will cause air pollution and serious harm to human health. The synergetic purification of NO_x and CVOCs has huge ecological environment and economic benefits. Therefore, it is necessary to design a dual-effect catalyst to eliminate NO_x and CVOCs simultaneously. In this work, we prepared CeO₂-based catalysts doped with different metal cations by co-precipitation method. The physical and chemical properties of the catalysts were characterized by a variety of characterization methods. The catalytic activity of the catalysts for the synergistic oxidation of chlorobenzene and reduction of NO_x was evaluated, and the reaction mechanism was explored. We found that Cr–Ce sample showed good synergistic catalytic activity and stability. The strong redox performance of Cr species not only improved the NO_x reduction and CVOC oxidation capacity of CeO₂, but also solved the problem of chlorination poisoning of pure CeO₂.

Large amounts of various (in)organic pollutants and CO₂ are released into the environment with the fast development of agriculture and industry, which results in the environmental pollution and climate change, thereby causes great threat to human society. The efficient capture and conversion of CO₂ are critical to against the greenhouse effect, whereas the elimination of pollutants from environment is important to human health and ecosystem. The COFs (covalent organic frameworks) have attracted multidisciplinary research interests because of their outstanding physicochemical properties such as high surface areas, tunable porous structures, abundant active sites and functional groups. Herein the application of COFs in CO₂ capture and conversion, the sorption-photocatalytic degradation of organic pollutants, and the sorption-catalytic reduction-solidification of heavy metals/radionuclides were reviewed and compared. The interaction mechanisms of COFs with the pollutant molecules were discussed from the macroscopic sorption results, microscopic spectroscopy analysis, and theoretical calculations. The adsorption capacity was mainly related to the surface areas, functional groups and active sites, whereas the photocatalytic activity was mainly dominated by •O₂⁻ and •OH active species. The COFs exhibited high sorption capacity and catalytic activity in CO₂ capture and conversion, and removal of pollutants. However, there are still some main challenges of COFs in real applications: 1) the high and selective capture and conversion of CO₂ with low cost and reusability; 2) the high visible light absorption and photocatalytic activity for organic molecule degradation; 3) the high sorption of target pollutants with high selectivity and reusability; 4) the high reduction ability for the in-situ solidification of target metals/radionuclides under complex conditions; and 5) the high selective extraction of radionuclides from complicated solutions such as seawater or salt lake. In the end, the perspectives and difficulties for COFs real applications were described.

The threaten of ubiquitous antibiotics to human and ecosystem makes it urgent to seek efficient treatment technologies. Peroxymonosulfate (PMS)-based advanced oxidation processes have revealed wide prospects for wastewater treatment via controllable PMS activation for desired ROS generation. Herein, a novel TiO₂ photoelectrode decorated with atomically distributed Mn (SA-MnTiO₂) was designed via a modified molten salt method (MSM) for photo-electro-catalytic (PEC) activation of PMS. The electron transfer in reduction-/oxidation-state Mn(II)/Mn(III)/Mn(IV) cycles facilitated the cleavage of intramolecular O–O bonds in PMS to preferentially generate hydroxyl radical (HO•). Almost complete degradation of norfloxacin (NOR) was occurred with optimal SA-Mn_0.6TiO₂ within 15 ​min, exhibiting high turnover frequency (0.066 min⁻¹). Around 74.8% of total organic carbon was eliminated with a low specific energy consumption of 0.94 ​kW ​h/g. The key operational parameters during actual wastewater treatment were inspected for SA-Mn_0.6TiO₂/PMS system, suggesting the satisfactory stability for practical applications.

The efficiency and stability of photocatalytic oxidation techniques in the treatment of volatile organic compounds (VOCs) in the air are affected by the adsorption performance at the reaction interface and the photogenerated electron–hole separation efficiency. Carbon-loaded porous TiO₂ with an internal hydrophobic interface was prepared by finely controlling the calcination time and temperature of a titanium-based metal–organic framework (MIL-125). The carbon load in the porous TiO₂ presents a gradient from the pore surface to the interior. The formed hydrophobic interface in the channel avoids competitive adsorption between gas-phase toluene and H₂O and effectively improves photogenerated electron transfer. Experiments and comprehensive analysis by using techniques such as thermogravimetric analysis, Raman spectroscopy, and ultraviolet diffuse-reflectance spectroscopy clarified the mechanism of gradient carbon formation in the porous TiO₂, in which the organic ligands in MIL-125 are carbonized during calcination because of the low oxygen content of the pores. The sample prepared by pyrolyzing MIL-125 at 400 ​°C for 1 ​h showed the best activity in the photocatalytic degradation of toluene; the activity was twice that achieved with the commercial photocatalyst P25. Surface photovoltage spectroscopy and photoelectrochemical measurements proved that the gradient carbon load enhances photogenerated electron transfer in the porous TiO₂. In-situ diffuse-reflectance infrared Fourier-transform spectroscopy was used to investigate the processes of photocatalytic degradation of toluene, in which the generation of C–H-containing intermediates is a crucial step. This research provides a novel concept for the future design and modification of photocatalyst structures for the effective photocatalytic degradation of VOCs.