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Clarifying the reaction pathways at the solid–water interface and in bulk water solution is of great significance for the design of heterogeneous catalysts for selective oxidation of organic pollutants. However, achieving this goal is daunting because of the intricate interfacial reactions at the catalyst surface. Herein, we unravel the origin of the organic oxidation reactions with metal oxide catalysts, revealing that the radical-based advanced oxidation processes (AOPs) prevail in bulk water but not on the solid catalyst surfaces. We show that such differing reaction pathways widely exist in various chemical oxidation (e.g., high-valent Mn 3+ and MnO X ) and Fenton and Fenton-like catalytic oxidation (e.g., Fe 2+ and FeOCl catalyzing H 2 O 2 , Co 2+ and Co 3 O 4 catalyzing persulfate) systems. Compared with the radical-based degradation and polymerization pathways of one-electron indirect AOP in homogeneous reactions, the heterogeneous catalysts provide unique surface properties to trigger surface-dependent coupling and polymerization pathways of a two-electron direct oxidative transfer process. These findings provide a fundamental understanding of catalytic organic oxidation processes at the solid–water interface, which could guide the design of heterogeneous nanocatalysts.

S-RNase plays vital roles in the process of self-incompatibility (SI) in

As one of the extensively used feed additives in livestock and poultry breeding, p-arsanilic acid (p-ASA) has become an organoarsenic pollutant with great concern. For the efficient removal of p-ASA from water, the combination of chemical oxidation and adsorption is recognized as a promising process. Herein, hollow/porous Mn-Fe-mixed oxide (MnFeO) nanocubes were synthesized and used in coupling with peroxymonosulfate (PMS) to oxidize p-ASA and remove the total arsenic (As). Under acidic conditions, both p-ASA and total As could be completely removed in the PMS/MnFeO process and the overall performance was substantially better than that of the Mn/Fe monometallic system. More importantly, an interface-promoted direct oxidation mechanism was found in the p-ASA-involved PMS/MnFeO system. Rather than activate PMS to generate reactive oxygen species (i.e., SO4·-, ·OH, and 1O2), the MnFeO nanocubes first adsorbed p-ASA to form a ligand-oxide interface, which improved the oxidation of the adsorbed p-ASA by PMS and ultimately enhanced the removal of the total As. Such a direct oxidation process achieved selective oxidation of p-ASA and avoidance of severe interference from the commonly present constituents in real water samples. After facile elution with dilute alkali solution, the used MnFeO nanocubes exhibited superior recyclability in the repeated p-ASA removal experiments. Therefore, this work provides a promising approach for efficient abatement of phenylarsenical-caused water pollution based on the PMS/MnFeO oxidation process.

The conversion of lignocellulosic biomass waste into fuels and chemicals can be regarded as a carbon-neutral circular framework, which is particularly appealing for our sustainable society. In this...

Significance The Fenton-like process based on peroxymonosulfate (PMS) has been widely investigated and recognized as a promising alternative in recent years for the degradation of persistent organic pollutants. However, the sluggish kinetics of PMS activation results in prohibitive costs and substantial chemical inputs, impeding its practical applications in water purification. This work demonstrates that tuning the electronic structure of single-atom sites at the atomic level is a powerful approach to achieve superior PMS activation kinetics. The Cu-based catalyst with the optimized electronic structure exhibits superior performance over most of the state-of-the-art heterogeneous Fenton-like catalysts, while homogeneous Cu(II) shows very poor activity. This work provides insights into the electronic structure regulation of metal centers and structure–activity relationship at the atomic level.

Precise synthesis of porous materials is essential for their applications. Self-assembly is a widely used strategy for synthesizing porous materials, but quantitative control of the assembly process still remains a great challenge. Here, a quantitative coassembly approach is developed for synthesizing resin/silica composite and its derived porous spheres. The assembly behaviors of the carbon and silica precursors are regulated without surfactants and the growth kinetics of the composite spheres are quantitatively controlled. This assembly approach enables the precise control of the size and pore structures of the derived carbon spheres. These carbon spheres provide a good platform to explore the structure-performance relationships of porous materials, and demonstrate their pore structure-dependent performance in catalytic water decontamination. This work provides a simple and robust approach for precise synthesis of porous spheres and brings insights into function-oriented design of porous materials.

Carbon-based materials are recognized as promising candidates for pollutant degradation because of their environmental benignity. Massive and cost-effective production and efficient recovery of carbon-based catalysts are crucial to apply this technology. However, various nanostructured carbons with different dimensions are usually utilized as precursors while not considering their complex preparation procedures and the high costs of ingredients. Moreover, catalyst separation and recovery are not given sufficient attention. In this work, a calcium salt-assisted pyrolysis strategy is proposed to tune the catalytic site formation of carbon-based catalysts. Results show that blending equal amounts of Ca

As one of the extensively used feed additives in livestock and poultry breeding

Various photocatalysts have been fabricated and tested for the treatment of water and wastewater. As visible-light-driven photocatalysts, bismuth oxybromide nanomaterials have weak responses to visible light and low activities of using photogenerated h+ to produce hydroxyl radicals ( OH), both of which are limited by their band structures. Thus, modification of bismuth oxybromide to form an optimized band structure is essential to enhance its photocatalytic activity for environmental applications. In this work, an oxygen-rich bismuth oxybromide nanomaterial, Bi24O31Br10 nanobelt, was fabricated using a solvothermal method, which possessed a narrower band gap and a more positive position of valance band top. As a result, this catalyst exhibited a strong response to visible light and produced large quantities of OH directly via its photogenerated h+, which contributed to the outstanding performance of photocatalysis, as evidenced by the experimental results and density functional theoretical (DFT) calculations. Under visible light irradiation, the Bi24O31Br10 nanobelt exhibited a substantially enhanced photocatalytic efficiency for the degradation of bisphenol A compared to those of Bi24O31Br10 and BiOBr nanosheets. Moreover, this catalyst could resist most interfering ions and was able to treat two types of actual industrial wastewaters efficiently. This work elucidates a new approach to modify photocatalysts and is helpful to expand practical applications of photocatalytic technologies for water and wastewater treatment.

The catalytic properties of ultrafine metal nanoparticles (NPs) are usually limited by their dispersion of NPs; support is thus needed for ultrafine metal NPs. However, single-dimensional supports ...

Recently, peroxymonosulfate (PMS)-based advanced oxidation processes have exhibited broad application prospects in the environment field. Accordingly, a simple, rapid, and ultrasensitive method is highly desired for the specific recognition and accurate quantification of PMS in various aqueous solutions. In this work, SO4•–-induced aromatic hydroxylation was explored, and based on that, for the first time, a novel fluorescence method was developed for the PMS determination using Co2+ as a PMS activator and benzoic acid (BA) as a chemical probe. Through a suite of spectral, chromatographic, and mass spectrometric analyses, SO4•– was proven to be the dominant radical species, and salicylic acid was identified as the fluorescent molecule. As a result, a whole radical chain reaction mechanism for the generation of salicylic acid in the BA/PMS/Co2+ system was proposed. This fluorescence method possessed a rapid reaction equilibrium (

In this paper, we consider an integrated error concealment system for lost color frames and lost depth frames in multiview videos with depths. We first proposed a pixel-based color error-concealment method with the use of depth information. Instead of assuming that the same moving object in consecutive frames has minimal depth difference, as is done in a state-of-the-art method, a more realistic situation in which the same moving object in consecutive frames can be in different depths is considered. In the derived motion vector candidate set, we consider all the candidate motion vectors in the set, and weight the reference pixels by the depth differences to obtain the final recovered pixel. Compared with the two state-of-the-art methods, the proposed method has average peak signal-to-noise ratio gains of up to 8.73 and 3.98 dB, respectively. Second, we proposed an iterative depth frame error-concealment method. The initial recovered depth frame is obtained by depth-image-based rendering from another available view. The holes in the recovered depth frame are then filled in the proposed priority order. Preprocessing methods (depth difference compensation and inconsistent pixel removal) are performed to improve the performance. Compared with a method that uses the available motion vector in a color frame to recover the lost depth pixels, the hybrid motion vector extrapolation method, the inpainting method and the proposed method have gains of up to 4.31, 10.29, and 6.04 dB, respectively. Finally, for the situation in which the color and the depth frames are lost at the same time, our two methods jointly perform better with a gain of up to 7.79 dB.

Bismuth oxychloride (BiOCl) is a typical UV-light-sensitive photocatalyst with a unique layered structure, but exhibits no response towards visible light. This is a main limitation for its practical applications in photocatalytic degradation of pollutants. Among various methods to expand the light absorption region, doping modification is an efficient approach because it can tailor the band structure by forming a doping energy level without changing the layered structure substantially. In this case, the static electric field in the BiOCl crystal can be retained. Since cobalt (Co) exhibits good electrochemical properties, it is an ideal element for doping modification to expand the light absorption region and enhance the charge separation efficiency of BiOCl. In this work, Co-doped BiOCl nanosheets were prepared using a simple hydrothermal route. The doped Co expanded the light absorption region and enhanced the charge separation efficiency by forming a doping energy level in the band gap of BiOCl. As a result, the Co-BiOCl nanosheets exhibited an outstanding photocatalytic performance in degrading bisphenol A (BPA) under visible light irradiation with a degradation rate of 3.5 times higher than that of BiOCl. On the basis of the experimental results and density functional theory calculations, the mechanism of visible-light-driven catalytic BPA degradation by the Co-BiOCl nanosheets was elucidated. Therefore, the feasibility of Co-doping modification for BiOCl was confirmed, and a novel and efficient strategy was provided for the design and synthesis of high-performance photocatalysts.

The persulfate-based advanced oxidation process is a promising technology for water treatment, while its effectiveness depends mainly on the activation efficiency of catalysts and the oxidant yield derived from persulfate. Thus, exploration of efficient and cost-effective activators for persulfate decomposition is highly desired. In this work, biochar, which was synthesized via a facile one-pot pyrolysis of sewage sludge, was proven to be an efficient persulfate activator for pollutant degradation. For a representative endocrine disrupting pollutant, bisphenol A, an average removal rate of 3.21 mol BPA per mol oxidant per h could be achieved by peroxymonosulfate in a wide pH range of 4.0–10.0 at a biochar dosage of 0.2 g L−1. Also, a high mineralization efficiency of ∼80% (total organic carbon removal) was obtained within 30 min. A further catalytic mechanism study demonstrated that singlet oxygen, which was catalytically produced by the ketone structure inside the biochar, was the main reactive species responsible for bisphenol A degradation. More importantly, metals in the sludge precursor were found to play an important role in the active site formation during the pyrolysis of raw sludge. This work not only provides a novel value-added reuse approach for sewage sludge as an efficient persulfate activator but also would be beneficial for further designing and fabricating carbon-based persulfate catalysts.

Iron-nickel-based electrocatalysts are a group of noble-metal-free and high-performance candidate for oxygen evolution reaction (OER), and autoxidation always occurs in their OER process. Autoxidation is a double-edged sword: it could in-situ generate high-catalytic activity sites to accelerate OER, but it also results in the attenuation of conductivity and the dissolution of active components. In this work, we propose a new strategy to relieve the negative impacts of autoxidation on OER through designing three-dimensional (3D) iron-nickel sulfide nanosheets/reduced graphene oxide (FeNiS2 NS/rGO) nanohybrids via a one-pot colloidal method, which enabled the well dispersion and strong coupling of FeNiS2 NS on the rGO. Such an interconnected 3D architecture could facilitate excellent electron transport, provide large amounts of active sites and prevent the dissolution of active components. The FeNiS2 NS/rGO delivered extremely low overpotentials of 270 mV and 200 mV to reach a current density of 10 mA cm−2, and rapid kinetics with Tafe slope of 38 mV dec−1 and 40 mV dec−1 for OER in 0.1 and 1.0 M KOH, respectively. Moreover, they could retain a great stability without activity loss over long-term continuous electrolysis and long-ageing time under air conditions. This work provides an efficient approach to resolve the autoxidation problem of FeNiS2 NS in the OER process and develops a promising earth-abundant OER electrocatalyst towards practical applications.

A high-efficient, low-cost, and eco-friendly catalyst is highly desired to activate peroxides for environmental remediation. Due to the potential synergistic effect between bimetallic oxides’ two different metal cations, these oxides exhibit superior performance in the catalytic activation of peroxymonosulfate (PMS). In this work, novel Mn1.8Fe1.2O4 nanospheres were synthesized and used to activate PMS for the degradation of bisphenol A (BPA), a typical refractory pollutant. The catalytic performance of the Mn1.8Fe1.2O4 nanospheres was substantially greater than that of the Mn/Fe monometallic oxides and remained efficient in a wide pH range from 4 to 10. More importantly, a synergistic effect between solid-state Mn and Fe was identified in control experiments with Mn3O4 and Fe3O4. Mn was inferred to be the primary active site in the surface of the Mn1.8Fe1.2O4 nanospheres, while Fe(III) was found to play a key role in the synergism with Mn by acting as the main adsorption site for the reaction substrates....

Visible light responsive photocatalysts can directly harvest energy from solar light, offering a desirable way to resolve environmental pollution problems through utilizing solar energy. Bismuth oxychloride (BiOCl) with a band gap of about 3.4 eV is widely recognized as an effective photocatalyst for the degradation of organic dye molecules under visible light irradiation, but such a photocatalytic degradation has to be assisted by dye-sensitization. Thus, preparation of BiOCl photocatalyst to achieve visible light response without dye-sensitization is greatly desired, as this would greatly expand their practical applications for the degradation of non-dye pollutants. In this work, oxygen-rich Bi 12 O 17 Cl 2 nanobelts with a band gap of 2.07 eV were synthesized by using a solvothermal route, and their photocatalytic performance was evaluated through photodegrading a colorless contaminant bisphenol A (BPA) in an aqueous solution. In comparison with BiOCl, which is not sensitive to visible light, the oxygen-rich Bi 12 O 17 Cl 2 nanobelts exhibited a drastically enhanced visible-light photoreactivity and were also superior to the well-known photocatalyst TiO 2 (P25). The greatly enhanced photocatalytic performance of the Bi 12 O 17 Cl 2 nanobelts was attributed to their efficient visible light absorption. Our findings might be helpful to explore visible light bismuth-based photocatalysts for pollutant degradation and water treatment.

It is still challenging to produce superoxide and hydroxyl radicals through activating molecular oxygen under broad-spectrum light in environmental photocatalysis. In this work, nitrogen-doped graphene quantum dots (N-GQDs) modified BiO2-x nanosheets were successfully fabricated and exhibited superior performance in light-harvesting, electron-hole pair separation, and full-spectrum driven molecular oxygen activation. The hybridized photocatalyst with a N-GQDs weight ratio of 0.4wt% (GBO-0.4) exhibited an excellent photocatalytic activity toward tetracycline degradation with a 4.0-fold, 2.9-fold and 5.5-fold higher reaction rate under full-spectrum, visible and near-infrared light irradiations than that of pure BiO2-x, respectively. The enhanced photocatalytic performance was ascribed to the electron collection effect and up-conversion photoluminescence properties of the N-GQDs as well as the synergistic effects of the developed nanojunction. Efficient molecular oxygen activation was achieved via the construction of a bulk-to-surface channel between BiO2-x and N-GQDs. DFT calculations were also used to explore the geometric and electronic structure variations of BiO2-x after the introduction of N-GQDs. The high photostability and mineralization ability toward tetracycline degradation confirm the promising application prospects of the N-GQDs/BiO2-x photocatalyst. This work provides a rational strategy for designing 0D/2D nanoscale heterostructure photocatalysts with improved full-spectrum photoactivity for environmental applications.

Fenton reaction is widely used for hazardous pollutant degradation. Reducing agents (RAs) have been proven to be efficient in promoting the generation of HO• in Fenton reaction by accelerating the redox cycle of Fe3+/Fe2+. However, the roles of different RAs in Fenton reaction remain unrevealed. In this work, the catalytic activity of three RAs, i.e., hydroxylamine (NH2OH), ascorbic acid (AA) and cysteine (Cys), on the degradation of benzoic acid (BA) and the hydroxyl radical formation in the Fenton-RAs system were investigated. Results show the catalytic performance of RAs in BA degradation by Fenton reaction followed an order of NH2OH > AA > Cys. Compared with the conventional Fenton system, the effective pH range in the Fenton-NH2OH system extended from 3.0 to 5.0, while the optimal pH in the Fenton-AA and Fenton-Cys systems ranged from 3.0 to 4.0. The Fenton-AA system exhibited a two-stage reaction toward BA degradation, which was different from the Fenton-NH2OH and Fenton-Cys systems. Furthermore, the dosing manner of AA was found to be a key factor governing its role in the Fenton-AA system. This observation suggests the different mechanisms behind the enhancement of the three RAs in Fenton system. Different from NH2OH and Cys, AA would inhibit the generation of HO•, especially at the fast stage of degradation process, where Fe3+ has not accumulated yet. In addition, the economic analysis using the electrical energy per order indicates Fenton-NH2OH system was economically feasible with the lowest energy input, compared to Fenton-AA and Fenton-Cys systems. These results are useful to better understand the roles of RAs in Fenton system, and also provide guidance about the selection and dosing manner of suitable RAs in the advanced oxidation processes.

A high-efficient, low-cost, and eco-friendly catalyst is highly desired to activate peroxides for environmental remediation. Due to the potential synergistic effect between bimetallic oxides' two different metal cations, these oxides exhibit superior performance in the catalytic activation of peroxymonosulfate (PMS). In this work, novel Mn

A series of BiOBrxI1−x solid solutions were explored as novel visible light-sensitive photocatalysts. These BiOBrxI1−x solid-solution photocatalysts grew into two-dimensional nanoplates with exposed (001) facets and possessed continuously modulated band gaps from 2.87 to 1.89 eV by decreasing the Br/I ratio. The photocatalytic activities of these samples were measured and the samples exhibited visible light-driven activities for the degradation of Rhodamine B (RhB). In particular, BiOBr0.8I0.2 exhibited the highest activity for the degradation of RhB. This result could be attributed to the balance between the effective light absorption and adequate redox potential. Additionally, investigations into the photocatalytic mechanism showed that the photodegradation of RhB over BiOBr0.8I0.2 solid-solution photocatalysts involved direct holes oxidation, in which the reaction that dominated during photocatalysis was determined by the potential of the valence band. Furthermore, a high stability in the photocatalytic activity of BiOBr0.8I0.2 was demonstrated by the cycling photocatalytic experiment and long-term irradiation, which might offer opportunities for its practical application as a catalyst.

The horticultural industry is getting more prospective with upgrading of the living standard in Guangxi Province, China. Compared to other crops, horticultural products not only are used as foods for human health but also contribute to healing of the people's spirit. The present status and constraints of the horti- cultural industry in Guangxi Province were reviewed in each of the fruit, vegetable and flower industries, in connection with favorable weather conditions and resources of the province. Strategies for developing the horticultural industry in Guangxi Province were given as follows: (1) to work out a comprehensive plan with addressing the regional specificities; (2) to strengthen the abilities of technical supporters; and (3) to enhance the investment fund to establish a production base and to set up the information exchange service system for marketing.

We consider an application of sparse optimization in the error concealment area. State-of-the-art spatial and temporal error concealment method is improved and compared. By solving for limited numbers of significant predictors using the sparse optimization, our algorithm performs subjectively and objective better for the concealed result.