Flower-like FeMoO4@1T-MoS2 micro-sphere for effectively cleaning binary dyes via photo-Fenton oxidation

1T/2H-MoS2-Decorated Carbon Felts as Excellent Co-Catalysts in Advanced Oxidation Processes for the Degradation of Organic Pollutants

The Fenton reaction is restricted by the sluggish Fe(II)/Fe(III) cycle and the low activation efficiency of oxidants. Herein, 1T/2H MoS2 nanoflowers with abundant defects and a multiphase structure, loaded on carbon felts (denoted as THMC), have been prepared to boost catalytic activity in Fenton-like oxidation. The defects and ultrathin nanosheets promote the adsorption of iron ions and pollutants, while the unsaturated S atoms and exposed Mo(IV) sites facilitate the conversion of Fe(III) to Fe(II). Additionally, the 1T phase accelerates electron transfer in Fe(II)/Fe(III) cycling, thereby synergistically enhancing catalytic activity in Fenton-like oxidation and improving the efficiency of pollutant elimination. Moreover, the loading of MoS2 nanoflowers on carbon felts not only overcomes the limitations of powder in separation and recycling but also offers robust stability for long-term applications. Thanks to these structural characteristics, the degradation efficiencies of rhodamine B and bisphenol A in the THMC cocatalyzed system reach 99.3% and 98.1%, respectively, and the corresponding rate constants (kobs) are 10.3 and 10.1 times higher than those of the traditional Fe2+-catalyzed system. Impressively, THMC still maintains excellent cocatalytic performance after 5 cycles and exhibits high degradation efficiencies across wide pH ranges. The cocatalytic system can efficiently eliminate a variety of organic pollutants and adapt to natural water samples. Furthermore, the performance of several MoS2 nanoflowers with varied phase structures and phase ratios has been investigated to probe the effect of phase structure. Interestingly, the kobs value of MoS2 with 52.4% 1T phase was 5.9 and 3.4 times higher than that of 5.6%-1T MoS2 in the degradation of RhB and BPA, respectively. Moreover, the cocatalytic performance of MoS2 could be further improved with an increase in the 1T phase to 66.6%. These observations reveal the significant role of phase effects on the cocatalytic activity of MoS2 in AOPs.

BiOBr/FeMoO4 composite achieves oxygen vacancy concentration adjustment to promote persulfate activation degradation of organic pollutants in saline water

The investigation about the mechanism of crystal plane regulation on the generation of oxygen vacancies remains a challenge. In this paper, BiOBr/FeMoO4 composites were synthesized by precise control of crystal plane growth, and it exhibited the enhanced concentration of oxygen vacancies due to lower formation energy of oxygen vacancies. The composite performs higher photo-Fenton-like ability for degrading oxytetracycline hydrochloride (OTC). Structural analyses and theoretical calculations reveal that crystal plane regulation induces significant changes in oxygen vacancy concentration. The BiOBr/FeMoO4/peroxydisulphate (PDS) /light system, which dominated by the non-radical pathway, degraded 96.8 % ± 1.0 % of OTC within 30 min. The activation mechanism of the system and the degradation pathway of OTC were elucidated. The intermediates in the degradation process of OTC were evaluated using liquid chromatograph-mass spectrometer (LC-MS), toxicity evaluation software tool (T.E.S.T) and soybean germination experiments. This work offers novel insights into the pivotal role of crystal plane directional regulation in the quantitative generation of oxygen vacancies.

Multiple interface coupling on natural tourmaline enables high-efficiency removal of antibiotic: Superior property and mechanism

Reasonably designing highly active, environmentally friendly, and cost-effective catalysts for efficient elimination of pollutants from water is desirable but challenging. Herein, an efficient heterogeneous photo-Fenton catalyst tourmaline (TM)/tungsten oxide (WO3-x) (named TW10) containing tungsten/boron/iron (W/B/Fe) synergistic active centers and 90% of cheap natural tourmaline (TM) mineral rich in Fe and B elements. The TW10 catalyst can quickly activate peroxymonosulfate (PMS) to generate massive active free radicals, which may induce the rapid and efficient degradation of tetracycline (TC). The TW10/PMS/Visible light system can effectively degrade up to 98.7% of tetracycline (TC) in actual waters (i.e. seawater, Yellow River, and Yangtze River water), and the catalytic degradation rates reach 1.65, 5.569, and 2.38 times higher than those of TM, WO3-x, and commercial P25 (Degussa, Germany), respectively. In addition, the catalyst can be recycled and reused multiple times. Electron spin resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS), and liquid chromatograph-mass spectrometer (LC-MS) analyses confirm that the synergistic catalytic effect of W/B/Fe sites on the TW10 catalyst accelerates the electron transfer between Fe(II) and Fe(III), as well as between W(V) and W(VI), and thus promotes the rapid degradation of TC. The catalytic reaction mechanism and degradation pathway of TC were explored. This work provides a feasible route for the design and development of new eco-friendly and efficient catalyst.

Synergistic effect of photothermal and magnetic hyperthermia for in situ activation of Fenton reaction in tumor microenvironment for chemodynamic therapy

Traditional cancer treatments are ineffective and cause severe adverse effects. Thus, the development of chemodynamic therapy (CDT) has the potential for in situ catalysis of endogenous molecules into highly toxic species, which would then effectively destroy cancer cells. However, the shortage of high-performance nanomaterials hinders the broad clinical application of this approach. In present study, an effective therapeutic platform was developed using a simple hydrothermal method for the in-situ activation of the Fenton reaction within the tumor microenvironment (TME) to generate substantial quantities of •OH and ultimately destroy cancer cells, which could be further synergistically increased by photothermal therapy (PHT) and magnetic hyperthermia (MHT) aided by FeMoO4 nanorods (NRs). The produced FeMoO4 NRs were used as MHT/PHT and Fenton catalysts. The photothermal conversion efficiency of the FeMoO4 NRs was 31.75 %. In vitro and \ experiments demonstrated that the synergistic combination of MHT/PHT/CDT notably improved anticancer efficacy. This work reveals the significant efficacy of CDT aided by both photothermal and magnetic hyperthermia and offers a feasible strategy for the use of iron-based nanoparticles in the field of biomedical applications.

Ultrasound-assisted adsorption of organic dyes in real water samples using zirconium (IV)-based metal-organic frameworks UiO-66-NH2 as an adsorbent

The utilization of dye adsorption through metal-organic frameworks represents an eco-friendly and highly effective approach in real water treatment. Here, ultrasound assisted adsorption approach was employed for the remediation of three dyes including methylene blue (MB), malachite green (MG), and congo red (CR) from real water samples using zirconium(IV)-based adsorbent (UiO-66-NH2). The adsorbent was characterized for structural, elemental, thermal and morphological features through XRD, XPS, FTIR, thermogravimetric analysis, SEM, BET , and Raman spectroscopy. The adsorption capacity of adsorbent to uptake the pollutants in aqueous solutions was investigated under different experimental conditions such as amount of UiO-66-NH2 at various contact durations, temperatures, pH levels, and initial dye loading amounts. The maximum removal of dyes under optimal conditions was found to be 938, 587, and 623 mg g-1 towardMB, MG, and CR, respectively. The adsorption of the studied dyes on the adsorbent surface was found to be a monolayer and endothermic process. The probable mechanism for the adsorption was chemisorption and follows pseudo-second-order kinetics. From the findings of regeneration studies, it was deduced that the adsorbent can be effectively used for three consecutive cycles without any momentous loss in its adsorption efficacy. Furthermore, UiO-66-NH2 with ultrasound-assisted adsorption might help to safeguard the environment and to develop new strategies for sustainability of natural resources.

Efficient microbial cellulose/Fe3O4 nanocomposite for photocatalytic degradation by advanced oxidation process of textile dyes

Fenton-type advanced oxidative processes (AOP) have been employed to treat textile dyes in aqueous solution and industrial effluent. The work focused on assisting the limitations still presented by the Fenton process regarding the use of suspended iron catalysts. Soon, a nanocomposite of bacterial cellulose (BC) and magnetite (Fe₃O₄) was developed. It has proven to be superior to those available in the literature, exhibiting purely catalytic properties and high reusability. Its successful production was verified through analytical characterization, while its catalytic potential was investigated in the treatment of different textile matrices. In initial tests, the photo-Fenton process irradiated and catalyzed by sunlight and BC/Fe₃O₄ discolored 92.19% of an aqueous mixture of four textile dyes. To improve the efficiency, the design of experiments technique evaluated the influence of the variables pH, [H₂O₂], and the number of BC/Fe₃O₄ membranes. 99.82% of degradation was obtained under optimized conditions using pH 5, 150 mg L^-1 of H₂O₂, and 11 composite membranes. Reaction kinetics followed a pseudo-first-order model, effectively reducing the organic matter (COD = 83.24% and BOD = 88.13%). The composite showed low iron leaching (1.60 ± 0.08 mg L^-1) and high stability. It was recovered and reused for 15 consecutive cycles, keeping the treatment efficiency at over 90%. As for the industrial wastewater, the photo-Fenton/sunlight/BC/Fe₃O₄ system showed better results when combined with the physical-chemical coagulation/flocculation process previously used in the industry's WWTP. Together they reduced COD by 77.77%, also meeting the color standards (DFZ scale) for the wavelengths of 476 nm (<3 m^-1), 525 nm (<5 m^-1), and 620 nm (<7 m^-1). Thus, the results obtained demonstrated that employing the BC/Fe₃O₄ composite as an iron catalyst is a suitable alternative to materials employed in suspension. This is mainly due to the high catalytic activity and power of reuse, which will reduce treatment costs.

Visible-light-driven iron-based heterogeneous photo-Fenton catalysts for wastewater decontamination: A review of recent advances

Visible-light-driven heterogeneous photo-Fenton process has emerged as the most promising Fenton-derived technology for wastewater decontamination, owing to its prominent superiorities including the potential utilization of clean energy (solar light), and acceleration of ≡Fe(II)/≡Fe(III) dynamic cycle. As the core constituent, catalysts play a pivotal role in the photocatalytic activation of H₂O₂ to yield reactive oxidative species (ROS). To date, all types of iron-based heterogeneous photo-Fenton catalysts (Fe-HPFCs) have been extensively reported by the scientific community, and exhibited satisfactory catalytic performance towards pollutants decomposition, sometimes even exceeding the homogeneous counterparts (Fe(II)/H₂O₂). However, the relevant reviews on Fe-HPFCs, especially from the viewpoint of catalyst-self design are extremely limited. Therefore, this state-of-the-art review focuses on the available Fe-HPFCs in literatures, and gives their classification based on their self-characteristics and modification strategies for the first time. Two classes of representative Fe-HPFCs, conventional inorganic semiconductors of Fe-containing minerals and newly emerging Fe-based metal-organic frameworks (Fe-MOFs) are comprehensively summarized. Moreover, three universal strategies including (i) transition metal (TMs) doping, (ii) construction of heterojunctions with other semiconductors or plasmonic materials, and (iii) combination with supporters were proposed to tackle their inherent defects, viz., inferior light-harvesting capacity, fast recombination of photogenerated carriers, slow mass transfer and low exposure and uneven dispersion of active sites. Lastly, a critical emphasis was also made on the challenges and prospects of Fe-HPFCs in wastewater treatment, providing valuable guidance to researchers for the reasonable construction of high-performance Fe-HPFCs.

Two Cu(i) coordination polymers based on a new benzimidazolyl-tetrazolyl heterotopic ligand for visible-light-driven photocatalytic dye degradation

Two Cu(i) CPs based on a new heterotopic tripodal ligand were constructed and their visible-light-driven photocatalytic performance were studied.

Protonated g-C3N4 coated Co9S8 heterojunction for photocatalytic H2O2 production

Photocatalytic H₂O₂ production is an eco-friendly technique because only H₂O, molecular O₂ and light are involved. However, it still confronts the challenges of the unsatisfactory productivity of H₂O₂ and the dependence on organic electron donors or high purity O₂, which restrict the practical application. Herein, we construct a type-II heterojunction of the protonated g-C₃N₄ coated Co₉S₈ semiconductor for photocatalytic H₂O₂ production. The ultrathin g-C₃N₄ uniformly spreads on the surface of the dispersed Co₉S₈ nanosheets by a two-step method of protonation and dip-coating, and exhibits improved photogenerated electrons transportability and e^--h⁺ pairs separation ability. The photocatalytic system can achieve a considerable productivity of H₂O₂ to 2.17 mM for 5 h in alkaline medium in the absence of the organic electron donors and pure O₂. The optimal photocatalyst also obtains the highest apparent quantum yield (AQY) of 18.10% under 450 nm of light irradiation, as well as a good reusability. The contribution of the type-II heterojunction is that the migrations of electrons and holes within the interface between g-C₃N₄ and Co₉S₈ matrix promote the separation of photocarriers, and another channel is also opened for H₂O₂ generation. The accumulated electrons in conduction band (CB) of Co₉S₈ contribute to the major channel of two-electron reduction of O₂ for H₂O₂ production. Meanwhile, the electrons in CB of g-C₃N₄ participate in the single electron reduction of O₂ as an auxiliary channel to enhance the H₂O₂ production.