Heterogeneous activation of peroxymonosulfate by supported cobalt catalysts for the degradation of 2,4-dichlorophenol in water: The effect of support, cobalt precursor, and UV radiation

In order to generate sulfate radicals (SRs) as oxidizing species for the degradation of 2,4-dichlorophenol (2,4-DCP) in water, we explored heterogeneous activation of peroxymonosulfate (PMS) by supported cobalt catalysts. More attention was given to the effect of support materials (Al₂O₃, SiO₂, TiO₂) and cobalt precursors (Co(NO₃)₂, CoCl₂, CoSO₄) on cobalt–support interaction, cobalt leaching, and reactivity of the catalysts. Especially, the feasibility of simultaneous generation of SRs and hydroxyl radicals (HRs) in PMS-Co/TiO₂ systems was first studied under ultraviolet (UV) radiation. Much lower cobalt leaching was observed in Co/Al₂O₃ and Co/TiO₂ systems than that of Co/SiO₂ most probably due to their relatively strong cobalt-support interaction. Co/TiO₂ catalyst prepared with Co(NO₃)₂, compared to CoCl₂ or CoSO₄ (where Cl⁻ and SO₄²⁻, respectively, were not completely removed upon heat treatment at 500 °C), showed strong cobalt–support interaction, and thereby exhibited negligible cobalt leaching. Under UV radiation, Co/TiO₂ at Co/Ti molar ratio of 0.001 showed significant improvement in the degradation of 2,4-DCP due to HRs. The effective generation of HRs in the system can be explained with Co(III)-mediated charge transfer from the photoinduced electrons to PMS, inducing facilitation of photoinduced electron-hole separation. However, high cobalt loading (i.e., Co/Ti molar ratio of 0.1) on TiO₂ surface exhibited negligible enhancement of 2,4-DCP transformation under UV radiation since the penetration of UV light to TiO₂ was prohibited by the cobalt.     

Iron–cobalt mixed oxide nanocatalysts: Heterogeneous peroxymonosulfate activation, cobalt leaching, and ferromagnetic properties for environmental applications

Sulfate radical-based advanced oxidation technologies (SR-AOTs) are attracting considerable attention due to the high oxidizing ability of SRs to degrade organic pollutants in aqueous environments. This study was carried out to respond to current concerns and challenges in SR-AOTs, including (i) need of heterogeneous activation of sulfate salts using transition metal oxides, (ii) nanoscaling of the metal oxide catalysts for high catalytic activity and promising properties with respect to leaching, and (iii) easy removal and recovery of the catalytic materials after their applications for water and wastewater treatments. In this study, we report a novel approach of using Fe–Co mixed oxide nanocatalysts for the heterogeneous activation of peroxymonosulfate (PMS) to generate SRs targeting the decomposition of 2,4-dichlorophenol, and especially focus on some synthesis parameters such as calcination temperature, Fe/Co contents, and TiO₂ support. The physicochemical properties of the catalysts were investigated using porosimetry, XRD, HR-TEM, H₂-TPR, and XPS. Ferromagnetic CoFe₂O₄ composites formed by thermal oxidation of a mixed phase of Fe and Co exhibited significant implications for the efficient and environmentally friendly activation of PMS, including (i) the cobalt species in CoFe₂O₄ are of Co(II), unlike Co₃O₄ showing some detrimental effects of Co(III) on the PMS activation, (ii) CoFe₂O₄ possesses suppressed Co leaching properties due to strong Fe–Co interactions (i.e. Fe–Co linkages), and (iii) Fe–Co catalysts in form of CoFe₂O₄ are easier to recover due to the unique ferromagnetic nature of CoFe₂O₄. In addition, the presence of Fe was found to be beneficial for enriching hydroxyl group content on the Fe–Co catalyst surface, which is believed to facilitate the formation of Co(II)-OH complexes that are vital for heterogeneous PMS activation.     

Latest developments on application of heterogenous basic catalysts for an efficient and eco friendly synthesis of biodiesel: A review

Heterogeneous catalysts are now being tried extensively for biodiesel synthesis. These catalysts are poised to play an important role and are perspective catalysts in future for biodiesel production at industrial level. The review deals with a comprehensive list of these heterogeneous catalysts which has been reported recently. The mechanisms of these catalysts in the transesterification reaction have been discussed. The conditions for the reaction and optimized parameters along with preparation of the catalyst, and their leaching aspects are discussed. The heterogeneous basic catalyst discussed in the review includes oxides of magnesium and calcium; hydrotalcite/layered double hydroxide; alumina; and zeolites. Yield and conversion of biodiesel obtained from the triglycerides with various heterogeneous catalysts have been studied.     

多维度碳基负载金属催化剂活化PMS降解水中污染物的研究进展

碳基负载型催化材料凭借独特的负载结构、优异的化学稳定性和吸附特性等优势,在环境催化领域展现出广阔的应用前景,有望成为新一代绿色催化剂。研究不同维度的碳基负载金属材料与催化过一硫酸氢盐（PMS）降解污染物之间的相关性,对开发具有针对性应用的环境功能材料具有重要的指导意义。因此,本文从不同维度的碳基负载金属催化材料出发,综述了零维、一维、二维以及三维碳基负载金属催化剂活化PMS在水处理中的应用,探讨了碳基材料与其负载金属之间的相互作用、非金属元素掺杂对催化剂活性的影响以及PMS的活化机理。最后,对负载型环境催化材料未来的发展方向,如单原子催化、多反应中心体系和光电催化体系等新兴领域进行了分析和展望。     

Catalytic wet-air oxidation processes: A review

Environmental catalysis usually refers to end-of-the-pipe treatment processes that reduce the emissions of hazardous pollutants. Abatement of pollutants in aqueous streams by means of heterogeneous catalysts is an example of such process. This paper reviews the developments in the field of catalytic wet-air oxidation (CWAO). Catalysts are reviewed first, followed by mechanistic speculations and kinetics that have been proposed for the CWAO process. The process is discussed more in detail only in those cases where it is already commercialised or at least foreseen to be in the near future. Particular attention was given to the heterogeneously catalyzed wet-air oxidation of real industrial wastewaters (such as Kraft bleach plant effluents) in batch and continuous-flow oxidation reactors. Finally, the considerable potential of the CWAO process to ultimately destroy organic pollutants in industrial effluents and detoxify them by using novel titania-supported Ru catalysts is presented.     

Tailoring surface defects in Plasma Electrolytic Oxidation (PEO) treated 2-D black TiO2: Post-treatment role,and intensification by peroxymonosulfate activation in visible light-driven photocatalysis

Herein, we have developed a visible light-responsive black TiO₂ photocatalytic coating with controlled formation of oxygen vacancies (OV) and Ti³⁺ species, crucial for enhancing photocatalytic reactions. The rational control of these semiconductor defects was achieved through plasma electrolytic oxidation (PEO), followed by NaOH post-treatment. The coating's effectiveness was evaluated by tetracycline (TC) degradation. The surface defects function as traps, reducing electron/hole recombination and forming mid-gap/localized-donor states, narrowing the band gap. Rigorous material characterization confirmed unaffected morphology and PEO coating phases, while increasing the density of OVs and Ti³⁺ species. As a result, TC photo-degradation was ∼3.5 times higher compared to plain PEO coatings. The material demonstrated exceptional stability and efficiency, while it was successfully intensified via peroxymonosulfate (PMS) activation, leading to high synergies (2.10). Scavenger tests revealed the existence of both radical/non-radical pathways, indicating the prevailing photocatalytic mechanism and the key differences achieved through this novel process.     

Modeling the kinetics of a photochemical water treatment process by means of artificial neural networks

We have investigated the kinetics of the degradation of 2,4-dimethyl aniline (2,4-xylidine), chosen as a model pollutant, by the photochemically enhanced Fenton reaction. This process, which may be efficiently applied to the treatment of industrial waste waters, involves a series of complex reactions leading eventually to the mineralization of the organic pollutant. A model based on artificial neural networks has been developed for fitting the experimental data obtained in a laboratory batch reactor. The model can describe the evolution of the pollutant concentration during irradiation time under various conditions. It has been used for simulating the behavior of the reaction system in sensitivity studies aimed at optimizing the amounts of reactants employed in the process — an iron(II) salt and hydrogen peroxide. The results show that the process is much more sensitive to the iron(II) salt concentration than to the hydrogen peroxide concentration, a favorable condition in terms of economic feasibility.     

等离子体预处理聚四氟乙烯接枝改性提高粘接性能的研究进展

由于碳氟原子间强烈的结合力和氟原子的保护作用,使聚四氟乙烯(PTFE)具有优异的耐高温性能和极强的化学惰性,故其在苛刻环境中得到广泛应用。为了提高PTFE与其他物质的粘接性能,必须对其进行接枝改性。详细介绍了等离子体预处理PTFE的接枝改性技术,包括改性方法的特点、影响因素、接枝后的表征和应用情况等。     

活化过碳酸盐及过氧碳酸氢盐在水处理领域中的研究进展

近年来,活化过碳酸盐（SPC）和过氧碳酸氢盐（PMC）高级氧化体系在水处理中的应用受到了学者们的广泛关注。本文通过调研大量国内外文献,系统总结了目前活化SPC体系及活化PMC体系在水处理中的应用,梳理了在SPC体系中常见的活化剂,如铁基材料、生物炭及金属复合体系等,在PMC体系常见的过渡金属离子以及金属复合物活化剂等,对比分析了活化SPC及活化PMC体系降解污染物的影响因素及其反应机理,影响因素包括溶液初始pH、氧化剂、活化剂、污染物浓度以及共存离子等,在SPC和PMC体系中添加活化剂均会促进HO·的生成,并对污染物的降解发挥作用,最后对未来相关研究的发展趋势提出了建议,可进一步探究活化SPC和PMC体系对水体的修复性能以及利用其进行实际水处理时的稳定性和安全性,厘清体系中产生的自由基对水体中污染物的去除机制。     

A simplified model for catalyzed isobutane autoxidation: implications for the mechanism of catalysis by halogenated porphyrin complexes

A simple kinetic model shows that a radical-chain mechanism can account for the high activity and selectivity found for oxidation of isobutane tot-butanol catalyzed by highly halogenated metalloporphyrins.     

Photochemistry and photophysics of poly(organophosphazenes) and related compounds: A review. I. Monomolecular processes

In this review we report an outline of the synthesis, UV-Vis spectral characterization, and light-induced reactivity in monomolecular processes of poly(organophosphazenes). The photoreactivity of phosphazene polymers, both in solution and in solid state, strongly depends on the nature of the chromophore attached to the phosphorus atoms of the inorganic –P=N – backbone. In fact, polyphosphazenes not bearing mobile hydrogen atoms in the side moieties undergo, in the first excited singlet state, homolytic eleavage of the bonds connecting the substituents to the inorganic backbone: free radicals of the substituents and phosphazene macroradicals are formed. Moreover, for polyphosphazenes containing labile hydrogens in the side groups, C–H bond scission takes place with the formation of free hydrogens and radicals located in the phosphazene substituents. From these species degradation or crosslinking of the macromolecules will follow according to the experimental conditions.This review is in three parts. Parts II and III will appear sequentially in the next two issues of this journal.     

催化焚烧处理挥发性有机物技术进展

本文介绍了国内外有关挥发性有机物（VOCs）及其联合工艺的应用情况及最新进展,并对国内VOC治理技术开发方向提出了自己的看法。     

An efficient green route for hexamethylene-1,6-diisocyanate synthesis by thermal decomposition of hexamethylene-1,6-dicarbamate over Co3O4/ZSM-5 catalyst:An indirect utilization of CO2

The utilization of CO2 as rawmaterial for chemical synthesis has the potential for substantial economic and green benefits. Thermal decomposition of hexamethylene-1,6-dicarbamate (HDC) is a promising approach for indirect utilization of CO2 to produce hexamethylene-1,6-diisocyanate (HDI). In this work, a green route was developed for the synthesis of HDI by thermal decomposition of HDC over Co3O4/ZSM-5 catalyst, using chlorobenzene as lowboiling point solvent. Different metal oxide supported catalysts were prepared by incipientwetness impregnation (IWI), PEG-additive (PEG) and deposition precipitation with ammonia evaporation (DP) methods. Their catalytic performances for the thermal decomposition of HDC were tested. The catalyst screening results showed that Co3O4/ZSM-525 catalysts prepared by different methods showed different performances in the order of Co3O4/ZSM-525(PEG) N Co3O4/ZSM-525(IWI) N Co3O4/ZSM-525(DP). The physicochemical properties of Co3O4/ZSM- 525 catalyst were characterized by XRD, FTIR, N2 adsorption-desorption measurements, NH3-TPD and XPS. The superior catalytic performance of Co3O4/ZSM-525(PEG) catalyst was attributed to its relative surface content of Co3+, surface lattice oxygen content and total acidity. Under the optimized reaction conditions: 6.5% HDC concentration in chlorobenzene, 1 wt% Co3O4/ZSM-525(PEG) catalyst, 250 °C temperature, 2.5 h time, 800 ml·min?1 nitrogen flow rate and 1.0 MPa pressure, the HDC conversion and HDI yield could reach 100% and 92.8% respectively. The Co3O4/ZSM-525(PEG) catalyst could be facilely separated from the reaction mixture, and reused without degradation in catalytic performance. Furthermore, a possible reaction mechanism was proposed based on the physicochemical properties of the Co3O4/ZSM-525 catalysts.     

Polymer-based chelating adsorbents for the selective removal of boron from water and wastewater: A review

Boron removal from water is a highly interesting research area that has been addressed in various investigations in the recent years. This is due to the expansion of harmful effects of boron traces in water streams on the environment and human health with the rise in boron global demand in various industries that coincided with the implantation of more stringent water quality standards. Various technologies have been applied for the removal of boron from water solutions, including ion exchange technology, which has a great potential in treating varieties of boron-containing streams up to levels in parts per million using boron-selective adsorbents. This article comprehensively reviews the latest progress in the development of polymer-based boron-selective (chelating) materials and their applications for the removal of boron from water solutions, including commercial boron-selective resins (BSRs) and their researched counterparts. The emerging trends in the development of alternative adsorbents with different substrates, morphologies, and functional groups are also elucidated. The future directions to overcome the limitations of the present generation of resins are also discussed.     

On the enhanced antibacterial activity of plasma electrolytic oxidation (PEO) coatings that incorporate particles: A review

Biomaterials are substances of artificial or natural origin that are used to improve, treat, heal or replace the tissue or bone of a human or animal body. Due to the ever-increasing progress and the widespread use of biomaterials for various biomedical purposes, different methods are used to modify their surface characteristics. One of the problems facing biomaterials such as implants, prostheses, and stents is the presence of various bacteria that can cause adverse side effects such as infection, swelling, and tenderness. This raises the issue of their resistance to bacterial infection, a subject that needs to be thoroughly investigated. So far, a variety of methods have been developed to treat or coat biomaterials and make them resistant to bacterial infections. One of the most promising approaches is the plasma electrolytic oxidation (PEO) process. This process is not only successful in the formation of porous, hard, corrosion-resistant, wear-resistant, and biocompatible coatings but also can be easily manipulated to introduce antibacterial agents to the coatings structure. The addition of nano- or micro-sized particles in the electrolytes has been proven to not only modify the composition and structure of the PEO coatings, but also bring about a strong antibacterial activity. In light of recent advances in this field, the following review aims at discussing different aspects of particles addition in PEO electrolytes when the antibacterial activity is the main concern.     

二氧化氯催化氧化处理活性艳红染料废水催化剂的制备与应用

研究了二氧化氯催化氧化用催化剂的制备条件与催化剂性能。实验结果表明，在工业催化剂载体上负载Cu^2+活性组分的催化剂制备优化条件为：w(Cu²⁺)=6%，焙烧温度500 ℃，焙烧时间4 h。用此催化剂进行二氧化氯催化氧化处理COD为2 700 mg·L^-1的活性艳红染料配制废水时，COD去除率达75%；催化剂寿命与再生实验表明，该方法在技术与经济上都具有较强实用性。     

A structured catalyst: Noble metal supported on a plate-type zirconia substrate prepared by anodic oxidation for steam reforming of hydrocarbon

A structured catalyst: noble metal supported on a plate-type zirconia substrate was prepared by subjecting a zirconium plate to a process consisting of anodic oxidation in an oxalic acid bath and calcination in the air, followed by rhodium or ruthenium component deposition by the dipping treatment. The catalytic performances of the prepared catalysts were evaluated for steam reforming of n-butane and propane. The substrate surface was significantly corroded by the anodic oxidation and calcination, and a rugged zirconia layer about 100 μm thick was formed. The crystalline state of zirconia was mainly monoclinic and tetragonal. In steam reforming of n-butane, the structured ruthenium catalyst had some activity, while the activity of the rhodium catalyst exceeded that of the commercial catalyst. For the rhodium catalyst, its reforming activity was improved by changing the temperature of dipping bath and the number of dips for adjustment of the rhodium deposition state. The rhodium catalyst prepared by dipping twice at a bath temperature of 25 °C has the largest metal surface area and a higher metal dispersion, which were thought to be the causes for the high performance. In steam reforming of propane, the rhodium catalyst showed a significantly higher activity than the commercial catalyst. The rhodium catalyst was less prone to deterioration of activity due to n-butane and propane reforming.     

CuCe氧化物催化剂的制备及CWPO降解双酚A废水研究

为解决Fenton法存在活性组分流失及通常在pH 2～3条件下运行的局限性,采用柠檬酸络合法制备了CuCe氧化物催化剂,建立了双酚A非均相催化湿式过氧化氢氧化（CWPO）反应体系。考察了焙烧温度、Cu/Ce摩尔比、H₂O₂用量、双酚A初始浓度和pH对催化剂物化结构和CWPO性能的影响。并分析了可能的降解路径。结果表明：催化剂具有良好的高温稳定性和pH适应性,在pH 1.6～7.9范围内对双酚A都具有较高的降解性能,不需要调节pH。在焙烧温度450℃、Cu/Ce摩尔比1.0、催化剂用量1 g·L^-1、H₂O₂用量196 mmol·L^-1、BPA浓度152 mg·L^-1、pH 6.6、反应温度75℃、反应95 min后,BPA和TOC去除率分别为91.8%和84.5%,Cu²⁺析出浓度为19.3 mg·L^-1。推测了双酚A可能的降解路径。     

Glass-ceramic phosphors for solid state lighting: A review

Solid state lighting, including phosphor converted light-emitting diodes (LEDs) and laser diodes (LDs), have released high demand to develop thermally stable phosphors. For this purpose, inorganic glass-ceramics (GCs) embedded with phosphor particles can act as competitive candidates. They are superior to traditional phosphors or resin/silica composites through successfully overcoming thermal aging and color temperature drifting problems and simultaneously maintaining high luminescent efficiencies. Inorganic GC phosphors can be classified into devitrified glass-ceramics, PiG (Phosphor-in-Glass) and sintered glass-ceramics. This review summarized the recent progress on LED/LD GC phosphors from the aspects of design principles, synthesis methods, microstructure-property relationships and their application studies. In addition, some challenging issues (e.g., crystallization behavior of luminous phase in glass, corrosion behavior of phosphor by glass matrix) are also discussed in detail. Significant issues of glass-ceramics packed LED/LD, such as luminescence efficiency, chromaticity, correlated color temperature and color gamut, are sorted out as well. Potential research directions are further suggested for not only developing new glass-ceramic phosphors but feeding upon various practical application.