Search Results (20)

The existence of continually increasing refractory organic pollutants in water has always been a serious potential threat to human and environmental health due to their toxicity and persistence. Conventional water treatment technologies suffer from inherent limitations, including low degradation efficiency, secondary pollution issues, and high operational costs. Recently, molecular oxygen (O₂)-based advanced oxidation processes (O₂-AOPs) have attracted increasing attention as sustainable and efficient wastewater treatment technologies, as the abundant and environmentally benign oxidant in nature can be activated into reactive oxygen species (ROS), such as superoxide anions ($·{\mathrm{O}}_2^{-}$), hydroxyl radicals (·OH), and singlet oxygen (¹O₂), enabling the effective mineralization of refractory organic pollutants. This review presents a comprehensive summary of O₂-AOPs for water purification, specifically focusing on photocatalytic, electrocatalytic, thermocatalytic, and mechanocatalytic systems. Furthermore, we conduct a comprehensive analysis of the intrinsic reaction mechanisms associated with both free radical pathways and non-free radical pathways, which include processes involving singlet oxygen and high-valent metal-oxygen intermediates. Finally, we discuss the challenges and prospects associated with the degradation of typical organic pollutants, such as phenolic compounds, pharmaceuticals and personal care products (PPCPs), and organic dyes. Despite significant advancements in O₂-AOPs, several core challenges persist, including low efficiency in utilizing dissolved oxygen, insufficient catalyst stability, and unclear mechanisms of interfacial electron transfer. Future research should prioritize the precise regulation of material structures, a thorough analysis of reaction mechanisms, and the tailored development of reactors to facilitate the industrial application of this technology in water treatment. Overall, this review systematically outlines the current progress in technologies for removing organic pollutants using molecular oxygen, offering novel insights for mitigating organic pollution in water. Full article

The development of efficient spinel oxide catalysts for low-temperature oxidation of volatile organic compounds (VOCs) remains an important research objective. In this work, Ru was doped into a CoMn₂O₄ spinel to enhance its catalytic activity toward toluene oxidation and the underlying promotion mechanism of Ru doping was systematically investigated. The resulting Ru-CoMn₂O₄ catalyst showed remarkable performance, with T₉₀ reaching approximately 224 °C at a WHSV of 60,000 cm³ g⁻¹ h⁻¹ and nearly 100% CO₂ selectivity above 200 °C. Mechanism studies revealed that the reaction followed both Mars–van Krevelen (MvK) and Eley–Rideal (E–R) pathways. The reaction rates were strongly influenced by the oxidizing capacity of the catalyst, the abundance of highly valent surface species (namely Co³⁺, Mn⁴⁺, and Ru⁴⁺), adsorbed toluene, lattice oxygen, gaseous toluene, and adsorbed oxygen. With Ru doping, new Ru–O–Mn and Ru–O–Co chains formed in the CoMn₂O₄ spinel structure, leading to a moderate enhancement in oxidizing ability and a moderate increase in the concentration of highly valent surface species, adsorbed toluene, and lattice oxygen. Although a slight reduction in adsorbed oxygen was observed, Ru doping significantly boosted the overall toluene oxidation activity of CoMn₂O₄. In summary, Ru-CoMn₂O₄ represented a promising catalyst for the efficient oxidation of VOCs. Full article

Caproate is a valuable medium-chain fatty acid (MCFA) that is found to be extensively used in biofuel production, food preservation, and the pharmaceutical industries. Short-chain fatty acids (SCFAs) from waste streams can be upgraded sustainably through their biological synthesis via anaerobic chain elongation. However, caproate production is frequently limited in real-world systems due to low carbon conversion efficiency and a lack of electron donors. In this study, we developed a two-stage fermentation strategy employing yellow water—a high-strength organic wastewater from liquor manufacturing—as a novel substrate. During primary fermentation, Lactobacillus provided endogenous electron donors by converting the residual carbohydrates in the yellow water into lactic acid. Nano zero-valent iron (NZVI) was introduced to the secondary fermentation to enhance power reduction and electron flow, further promoting caproate biosynthesis. The caproate production increased significantly due to the synergistic action of lactic acid and NZVI, reaching a maximum concentration of 20.41 g·L⁻¹ and a conversion efficiency of 69.50%. This strategy enhances carbon recovery and electron transport kinetics while lowering dependency on expensive external donors like hydrogen or ethanol. Microbial community analysis using 16S rRNA sequencing revealed enrichment of chain-elongating bacteria such as Clostridium kluyveri. These findings demonstrate the feasibility of employing an integrated fermentation–electron management technique to valorize industrial yellow water into compounds with added value. This study offers a scalable and environmentally sound pathway for MCFA production from waste-derived resources. Full article

Propane is a typical volatile organic compound (VOC) in coal chemical processing and petroleum refining. However, coexisting SO₂ significantly impairs its catalytic oxidative removal, potentially causing catalyst poisoning and deactivation. This study systematically elucidated the inhibitory effects of SO₂ on the catalytic oxidation of propane over the Ru@CoMn₂O₄ catalyst system. Under continuous exposure to 30 ppm SO₂, propane conversion plummeted by 30% within two hours. Mechanistic studies revealed that SO₂ selectively bound to high-valent Mn sites rather than preferentially interacting with Co sites, leading to the formation of MnSO₄ particles. These particles were directly corroborated by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. After four hours of exposure to SO₂, roughly 11.8 mole percent of manganese in the catalyst was converted into MnSO₄. These deposits physically blocked active sites, reduced specific surface area, and disrupted redox cycling. As a result, their combined effects diminished performance progressively, ultimately leading to complete deactivation. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) confirmed that SO₂ suppressed C=C bond oxidation in propane intermediates, thereby directly limiting conversion efficiency. Combining qualitative and quantitative methods, we characterized SO₂-induced poisoning during propane oxidation. This work provides guidelines and strategies for designing anti-sulfur catalysts at the elemental scale for the catalytic combustion of low-carbon alkanes. Full article

Non-noble metals catalyzed carbonylative reactions serve as straightforward and sustainable methods for the synthesis of functionalized carbonyl-containing compounds. Herein, a low-valent-tungsten-catalyzed reaction that enables the coupling of aryl iodides and alcohols or phenols was disclosed, employing the readily available W(CO)₆ as the effective catalyst and PPh₃ as ligand. Under the optimal reaction conditions, aryl iodides smoothly underwent carbonylative coupling reactions with alcohols or phenols, processing the feature of broad substrate scope and good functional groups tolerance. Furthermore, this conversion can be carried out on a gram scale, showcasing significant promise in the synthesis of pharmaceutical or biologically active compounds. Full article

The synthesis, isolation, and characterisation of well-defined low-valent actinide complexes are reviewed with a main focus on compounds featuring uranium and thorium metal centres in formal oxidation states ≤ +3. The importance of the ligand environment in enabling access to these highly reactive species, as well as its influence on ground state electronic configurations and their reactivity, are emphasised. Furthermore, we highlight cyclic voltammetry (C.V.) studies as a more widely used method that can guide the synthesis of these highly reducing species. Full article

A virtual screening, a process based on computational chemistry that involves the rapid evaluation of a large number of compounds to identify those with the most promising characteristics, is presented. This screening found concordance in the fluorescent heterocyclic compounds with isosteres of similar reactivity, determining that rhodamine B (RhB) meets the necessary criteria for its use. Furthermore, with the values calculated in silico, it is considered to be a compound with low adsorption and oral bioavailability, so its degradation was evaluated by advanced oxidation processes (POAs), such as the catalytic process with titanium dioxide (TiO₂), hydrogen peroxide (H₂O₂), and presence or absence of dissolved oxygen (O₂), in which the concentration of RhB and amount of TiO₂ were varied, and the photo-Fenton process with an ultraviolet light emitting diode (UV-LED), zero-valent iron (ZVI) and H₂O₂, in which the amount of ZVI and H₂O₂ were varied. The results indicate that the catalytic process achieves a removal of 95.11% compared to 80.42% in the photo-Fenton process, concluding that the greater the amount of ZVI in the solution, the greater the degradation of RhB and that the residual amount of iron (II) (Fe²⁺) ions in the solution is less than 0.3 mg/L without causing secondary contamination. These results highlight the efficacy and feasibility of POAs for the removal of dyes such as RhB, which offers a promising solution for the remediation of contaminated waters. Full article

Mixed-valent Ba₂Mn²⁺Mn₂³⁺(SeO₃)₆ crystallizes in a monoclinic P2₁/c structure and has honeycomb layers of Mn³⁺ ions alternating with triangular layers of Mn²⁺ ions. We established the key parameters governing its magnetic structure by magnetization M and specific heat C_p measurements. The title compound exhibits a close succession of a short-range correlation order at T_corr = 10.1 ± 0.1 K and a long-range Néel order at T_N = 5.7 ± 0.1 K, and exhibits a metamagnetic phase transition at T < T_N with hysteresis most pronounced at low temperatures. The causes for these observations were found using the spin exchange parameters evaluated by density functional theory calculations. The title compound represents a unique case in which uniform chains of integer spin Mn³⁺ (S = 2) ions interact with those of half-integer spin Mn²⁺ (S = 5/2) ions. Full article

Two diphenyl formamidine ligands, four dirhodium(II,II) complexes, and three axially modified low-valent dirhodium(II,II) metallodendrimers were synthesized and evaluated as anticancer agents against the A2780, A2780cis, and OVCAR-3 human ovarian cancer cell lines. The dirhodium(II,II) complexes show moderate cytotoxic activity in the tested tumor cell lines, with acetate and methyl-substituted formamidinate compounds displaying increased cytotoxicity that is relative to cisplatin in the A2780cis cisplatin resistant cell line. Additionally, methyl- and fluoro-substituted formamidinate complexes showed comparable and increased cytotoxic activity in the OVCAR-3 cell line when compared to cisplatin. The low-valent metallodendrimers show some activity, but a general decrease in cytotoxicity was observed when compared to the precursor complexes in all but one case, which is where the more active acetate-derived metallodendrimer showed a lower IC₅₀ value in the OVCAR-3 cell line in comparison with the dirhodium(II,II) tetraacetate. Full article

Pretreatment with the addition of metals to anaerobic digestion in biogas production is crucial to address improper degradation of organic compounds with low methane production. Biogas production from a combination of cassava pulp and cassava wastewater in the batch system under the variation of alkaline and heat conditions as a pretreatment was investigated with the zero-valent iron (ZVI) addition after the pretreatment. It was found that alkaline pretreatment at pH 10 with the heat at 100 °C for 30 min combined with 50 g of ZVI kg of TVS⁻¹ showed the highest methane production up to 4.18 m³ CH₄ kg TVS⁻¹. Nevertheless, chemical oxygen demand (COD) and volatile fatty acid (VFA) removals were slightly reduced when ZVI was added to the system. Furthermore, application in the continuous system showed increased COD and VFA removals after applying alkaline and heat pretreatments. On the other hand, additional ZVI in the substrate after the pretreatments in the continuous system increased the methane production from 0.58 to 0.90 and 0.19 to 0.24 of CH₄ m³ kg TVS⁻¹ in 20 and 60 days of hydraulic retention times (HRTs), respectively. Thus, a suitable combination of alkaline and heat pretreatments with ZVI is essential for increasing methane production in batch and continuous systems. Full article

Interest in the third-row transition metal osmium and its compounds as potential anticancer agents has grown in recent years. Here, we synthesized the osmium(VI) nitrido complex Na[Os^VI(N)(tpm)₂] (tpm = [5-(Thien-2-yl)-1H-pyrazol-3-yl]methanol), which exhibited a greater inhibitory effect on the cell viabilities of the cervical, ovarian, and breast cancer cell lines compared with cisplatin. Proteomics analysis revealed that Na[Os^VI(N)(tpm)₂] modulates the expression of protein-transportation-associated, DNA-metabolism-associated, and oxidative-stress-associated proteins in HepG2 cells. Perturbation of protein expression activity by the complex in cancer cells affects the functions of the mitochondria, resulting in high levels of cellular oxidative stress and low rates of cell survival. Moreover, it caused G2/M phase cell cycle arrest and caspase-mediated apoptosis of HepG2 cells. This study reveals a new high-valent osmium complex as an anticancer agent candidate modulating protein homeostasis. Full article

High concentrations of antibiotics have been identified in aqueous media, which has diminished the quality of water resources. These compounds are usually highly toxic and have low biodegradability, and there have been reports about their mutagenic or carcinogenic effects. The aim of this study was to apply zero-valent iron-oxide nanoparticles in the presence of hydrogen peroxide and the sonolysis process for the removal of the amoxicillin antibiotic from aqueous media. In this study, zero-valent iron nanoparticles were prepared by an iron chloride reduction method in the presence of sodium borohydride (NaBH₄), and the obtained nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating-sample magnetometry (VSM). Then, using a Fenton-like process, synthetic wastewater containing 100 to 500 mg/L amoxicillin antibiotic was investigated, and the effects of different parameters, such as the frequency (1 and 2 kHz), contact time (15 to 120 min), the concentration of hydrogen peroxide (0.3%, 0.5%, and 6%), the dose of zero-valent iron nanoparticles (0.05, 0.1, 0.5 g/L), and pH (3, 5, 10) were thoroughly studied. A pH of 3, hydrogen peroxide concentration of 3%, ultrasonic-wave frequency of 130 kHz, zero-valent iron nanoparticles of 0.5 g/L, and contaminant concentration of 100 mg/L were obtained as the optimal conditions of the combined US/H2O2/nZVI process. Under the optimal conditions of the combined process of zero-valent iron nanoparticles and hydrogen peroxide in the presence of ultrasonic waves, a 99.7% removal efficiency of amoxicillin was achieved in 120 min. The results show that the combined US/H2O2/nZVI process could be successfully used to remove environmental contaminants, including antibiotics such as amoxicillin, with a high removal percentage. Full article

Trialkyl and triaryl phosphines are important classes of ligands in the field of catalysis and materials research. The wide usability of these low-valent phosphines has led to the design and development of new synthesis routes for a variety of phosphines. In the present work, we report the synthesis and characterization of some mixed arylalkyl tertiary phosphines via the Grignard approach. A new asymmetric phosphine is characterized extensively by multi-spectroscopic techniques. IR and UV–Vis spectra of some selected compounds are also compared and discussed. Density functional theory (DFT)-calculated results support the formation of the new compounds. Full article

Reduction of nitrobenzene with NaBH₄ using zero-valent iron nanoparticles (ZVI-NPs) and NiCl₂∙6H₂O incorporated in organically modified hybrid silica matrices as ZVI@ORMOSIL and Ni(II)@ORMOSIL catalysts is proposed as a remediation strategy. Ni(II)@ORMOSIL is prepared by ion-exchanging H⁺ of the ORMOSIL matrix with Ni^II. Ni(II)@ORMOSIL is a pre-catalyst that undergoes reduction by NaBH₄ by an in-situ reaction and promotes nitrobenzene reduction by the unconsumed NaBH₄, leading to sparing use of the catalyst. Ni(II)@ORMOSIL undergoes color change from green to black in this process, returning to a green hue after washing and drying. Nitrobenzene reductions were examined in aqueous acetonitrile solvent mixtures, and the reduction cascade produced the reaction end-products with catalytic implications. Plausible mechanisms of ZVI@ORMOSIL and Ni(II)@ORMOSIL catalyzed reductions of nitrobenzene are discussed. This work is the first to report M(II)@ORMOSIL pre-catalysts for in-situ reduction of nitrobenzene, and expands the scope of the ORMOSIL series of catalysts for the reduction of polluting compounds. This approach enables the development of catalysts that use very low concentrations of transition metal cations. Full article

Increasing environmental pollution causes the search for new methods of purification. Currently, the remediation potential of nanoparticles is increasingly being studied. Unfortunately, there is still a lack of data on the impact of these compounds on living organisms, including plants. This study was designed to test the effects of nanoFER 25 and nanoFER 25S iron on Lolium westerwoldicum Breakw. After cultivation of plants in a soil contaminated with nanoparticles, the biometric parameters, content of polyphenols, flavonoids, chlorophyll changes, carotenoids, anthocyanins, superoxide dismutase, catalase and pyrogallol peroxidase were studied. The conducted experiment showed that nano zero-valent iron (nZVI) is slightly taken from the soil to the plants. The iron passes to the root but there is no further transport up the plant. The content of polyphenols and flavonoids in aboveground parts of plants decreases with a simultaneous increase in roots compared to the control sample. The chlorophyll content in the leaves is strongly related to the concentration of the contaminant. Similarly, the enzyme activity of the antioxidant system in the whole plant is strongly related to the concentration of the pollutant. The amount of vegetable pigments in the leaves increases for low concentrations of contamination and then decreases at higher levels of contamination. The study has shown that both types of nanoFER are not indifferent to the plants’ growth. Full article