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Recently, metal–organic framework (MOF)/peroxymonosulfate (PMS) systems have shown great potential in the treatment of antibiotic-containing wastewater. Herein, a Co–Ti-400 Fenton-like catalyst was synthesized by calcining Co-doped MIL-125(Ti) (Co–Ti) at 400 °C. Co–Ti-400 revealed an excellent catalytic performance for tetracycline hydrochloride (TCH) removal by activating PMS in a wide pH range (pH = 2–11). Significantly, 96.2% of TCH was removed in 1 hour over the catalyst (70 mg L−1 of TCH, 0.2 g L−1 of catalyst, 1 mM PMS, and pH = 4). Furthermore, Co–Ti-400 exhibited enhanced catalytic activity and stability in four cycles compared to the uncalcined sample (Co–Ti). Radicals (·OH, O2˙−, and SO4˙−) and 1O2 were proved to be the main active species during TCH degradation. Notably, Co–Ti-400/PMS showed good anti-interference towards inorganic salts in water. A reasonable degradation mechanism was proposed based on LC-MS analysis. With its exceptional catalytic performance and broad pH adaptability, Co–Ti-400 can be considered a potential catalyst for antibiotic removal. [ABSTRACT FROM AUTHOR]

The removal of harmful formaldehyde (HCHO) pollutants in indoor air is of great importance to protect human health. Herein, a flexible Pt/γ-Al2O3 (PAO) nanofiber membrane with a hierarchically porous structure was prepared by a one-step electrospinning method. The effects of Pt contents and calcination temperatures on the catalytic performance for HCHO oxidation at room temperature were investigated. The results indicate that Pt nanoparticles (NPs) are firmly decorated on the surface of γ-Al2O3 nanofibers since the loading of Pt NPs and the preparation of γ-Al2O3 nanofibers are conducted at the same time. PAO can oxidize HCHO to CO2 and H2O completely at room temperature. The catalytic activity of PAO first increases and then decreases with increasing Pt content or calcination temperature. The Pt content of 2 wt% and the calcination temperature of 700 °C are the optimal preparation parameters. The catalytic activity of PAO maintains good stability in 6 cycling tests after a simple regeneration heat treatment at 180 °C. The dioxymethylene, CO, carbonate and formate species are the main intermediates. The mechanism for HCHO oxidation was proposed as follows: HCHO + O2 → DOM and formate → carbonate species and CO → CO2. PAO also exhibits good flexibility and mechanical properties, good filtration performance for particulate matter and good fluid permeability. This work will shed a light on the design and fabrication of bifunctional catalytic materials for both HCHO and particulate matter removal in air purification. [ABSTRACT FROM AUTHOR]

Singlet oxygen (1O2) species have been widely studied in catalytic oxidation and photodynamic therapy (PDT) and so on due to their unique properties, such as their long lifetime, wide pH tolerance, relative long migration distance, and high selectivity. In this work, 1O2 could be generated over CeO2/K,Na-codoped g-C3N4 heterojunction (CeO2/CN) fabricated using a molten salt method in the presence of H2O2 in dark for the first time, which was used as a Fenton-like catalyst to degrade the emerging tetracycline hydrochloride (TCH) pollutant through a Fenton-like reaction. A significantly-enhanced catalytic activity was observed over CeO2/CN compared with g-C3N4 and commercial CeO2. The Ce4+/Ce3+ redox system was found to play a vital role in the formation of 1O2 from the disproportionation of superoxide radical (˙O2−). The 1O2 and ˙O2− radicals were observed as the main active species in the highly-efficient degradation of TCH over a wide pH range (1.20–11.20). The strong interfacial interaction of CeO2/CN promoted the Ce4+/Ce3+ redox and the generation of active species. The catalytic mechanism of TCH decomposition was also proposed. This finding introduces an efficient and promising approach for the preparation of the highly-effective Fenton-like catalysts for water purification. [ABSTRACT FROM AUTHOR]

Miscanthus is regarded as a desired bioenergy crop with enormous lignocellulose residues for biofuels and other chemical products. In this study, the effect of different pretreatments (including microwave, NaOH, CaO, and microwave + NaOH/CaO) on sugar yields was investigated, leading to largely varied hexose yields at 4.0–73.4% (% cellulose) released from enzymatic hydrolysis of pretreated Miscanthus residues. Among them, the highest yield of 73.4% for hexoses was obtained from 12% NaOH (w/v) solution pretreatment, whereas 1% CaO (w/w) and microwave pretreatment resulted in a lower hexose yield than the control (without pretreatment). The sugar yield from microwave followed with 1% NaOH pretreatment was 4.3 times higher than that of microwave followed with 1% CaO. However, the enzymatic hydrolysis efficiencies of the sample were 15.2% and 58.5% under microwave pretreatment followed by 12% NaOH or 12.5% CaO, respectively, which were lower than those of the same concentration of alkali (NaOH and CaO) pretreatments. To investigate the mechanism of varied enzymatic saccharification under different pretreatments, the changes in the surface structure and porosity of the Miscanthus‐pretreated lignocelluses were studied by means of Fourier transform infrared, Congo red staining, and scanning electron microscopy analysis. The results show that the different pretreatments destroy the cell wall cladding structure and reduce the bonding force between cellulose, hemicellulose, and lignin to different degrees, therefore increasing the accessibility of cellulose and enhancing cellulose digestion. [ABSTRACT FROM AUTHOR]

Highlights: [•] Oxidative decomposition of formaldehyde on Pt/TiO2 occurs at room temperature. [•] Fluoride poisoning phenomenon of Pt/TiO2 nanosheets is explained. [•] This poisoning is due to F-blocking of Pt catalytic active sites. [•] Pt/TiO2 nanosheet-type catalysts can be easily regenerated by washing with NaOH solution. [Copyright &y& Elsevier]

To overcome the drawbacks of high air resistance and the need to be pressed into tablets or attached to other big-block supports for powder catalysts in the application of air purification, a mat-like hierarchically porous TiO2 nanofibers (TF) decorated with Pt nanoparticles (NPs) catalyst (Pt/TF) was synthesized by dipping the hierarchically porous TF mat fabricated by electrospinning into an H2PtCl6 solution followed by NaBH4 reduction. Such a mat-like catalyst has a smaller air resistance than a powder catalyst because of its hierarchical macro-/mesoporous structure and can be used directly in air-purification systems because of its larger size. In addition, the as-prepared Pt/TF catalyst showed enhanced catalytic activity compared to a Pt-NP-decorated commercial TiO2 (P25) catalyst in the decomposition of formaldehyde at room temperature because of its accessible Pt NPs and hierarchical porous structure that facilitates the diffusion of reactants and products. This work will provide some new insights into the design and fabrication of advanced catalysts for indoor air purification. [ABSTRACT FROM AUTHOR]

Herein, we for the first time report the production of H2 using Degussa P25 TiO2 powder (P25) from a mixed aqueous solution of methanol and Ni(NO3)2. The effect of the amount of Ni(NO3)2 on the photocatalytic H2-production activity of TiO2 was investigated and discussed. The results indicate that the photocatalytic H2-production activity of TiO2 is significantly enhanced in the presence of Ni(NO3)2. The optimal Ni(NO3)2 amount (the molar ratio of Ni(NO3)2 to TiO2 and Ni(NO3)2) was found to be 0.32 mol%, giving a H2-production rate of 2547 μmol h−1 g−1 with a quantum efficiency (QE) of 8.1% at 365 nm, exceeding that of pure TiO2 by 135 times. This high photocatalytic H2-production activity is due to the adsorption of Ni2+ on the surface of TiO2. The potential of Ni2+/Ni (Ni2+ + 2e− = Ni, Eo = −0.23 V) is slightly lower than the conduction band (CB) of anatase TiO2 (−0.26 V), but higher than the reduction potential of H+/H2 (2H+ + 2e− = H2, Eo = −0.00 V), which favors electron transfer from TiO2 to Ni2+ and reduction of Ni2+ to Ni0. The role of metallic Ni is to help charge separation and to act as a co-catalyst for H2 production, thus enhancing the photocatalytic H2-production activity of TiO2. [ABSTRACT FROM AUTHOR]

As research continues, the control on the polymorph and morphology of calcium carbonate ( CaCO3) becomes a hot topic because its application is limited by these parameters. The polymorph and morphology control of CaCO3 was successfully achieved via temperature and PEG ( Mw = 6000) during the decomposition of Ca( HCO3)2, which has rarely been employed to prepare precipitated CaCO3. As-prepared CaCO3 was characterized using XRD and SEM. In the case of no PEG, rhombohedra calcite, lamellar vaterite, rod- and needlelike aragonite are observed, and calcite is the major phase at all samples and it increases with temperature, whereas vaterite and aragonite decrease with temperature. The addition of PEG restrains the formation of vaterite and promotes the emergence of needlelike aragonite particles at 70°C, and prevents the generation of calcite and encourages the production of rodlike aragonite particles at 80°C and 90°C. This work not only provides a new way on the preparation of CaCO3 powder but also presents the feasible control method in this route. [ABSTRACT FROM AUTHOR]

As research continues, the control on the polymorph and morphology of calcium carbonate ( CaCO3) becomes a hot topic because its application is limited by these parameters. The polymorph and morphology control of CaCO3 was successfully achieved via temperature and PEG ( Mw = 6000) during the decomposition of Ca( HCO3)2, which has rarely been employed to prepare precipitated CaCO3. As-prepared CaCO3 was characterized using XRD and SEM. In the case of no PEG, rhombohedra calcite, lamellar vaterite, rod- and needlelike aragonite are observed, and calcite is the major phase at all samples and it increases with temperature, whereas vaterite and aragonite decrease with temperature. The addition of PEG restrains the formation of vaterite and promotes the emergence of needlelike aragonite particles at 70°C, and prevents the generation of calcite and encourages the production of rodlike aragonite particles at 80°C and 90°C. This work not only provides a new way on the preparation of CaCO3 powder but also presents the feasible control method in this route. [ABSTRACT FROM AUTHOR]

Photocatalytic for hydrogen peroxide (H 2 O 2 ) production is thought as a promising technology owing to its clean and green properties with the cheap and easily available raw materials of H 2 O and O 2 . Herein, Pt/g-C 3 N 4 Schottky junction photocatalysts with ultralow Pt contents (0.025-0.1 wt %) were successfully fabricated by an impregnation-reduction method. It can efficiently reduce O 2 to generate H 2 O 2 without a sacrificial agent under visible-light irradiation. The yield of H 2 O 2 produced over Pt0.05/g-C 3 N 4 with the optimal 0.05 wt % Pt reached 31.82 μM, which was 2.46 times that of g-C 3 N 4 and higher than most of those in the literature. It also showed good stability in three repeated tests. The deposition of highly dispersed metal Pt nanoparticles with low and limited content can expose enough active Pt atoms, significantly enhance the separation efficiency of photogenerated carriers, and reduce its negative effect on H 2 O 2 decomposition, resulting in improved and outstanding efficiency of H 2 O 2 production. The ·O 2 - radicals were found to be the main active species. The mechanism of photocatalytic H 2 O 2 production was confirmed to be a two-step single electron route (O 2 + e - → ·O 2 - → H 2 O 2 ).

Singlet oxygen ( 1 O 2 ) species have been widely studied in catalytic oxidation and photodynamic therapy (PDT) and so on due to their unique properties, such as their long lifetime, wide pH tolerance, relative long migration distance, and high selectivity. In this work, 1 O 2 could be generated over CeO 2 /K,Na-codoped g-C 3 N 4 heterojunction (CeO 2 /CN) fabricated using a molten salt method in the presence of H 2 O 2 in dark for the first time, which was used as a Fenton-like catalyst to degrade the emerging tetracycline hydrochloride (TCH) pollutant through a Fenton-like reaction. A significantly-enhanced catalytic activity was observed over CeO 2 /CN compared with g-C 3 N 4 and commercial CeO 2 . The Ce 4+ /Ce 3+ redox system was found to play a vital role in the formation of 1 O 2 from the disproportionation of superoxide radical (˙O 2 - ). The 1 O 2 and ˙O 2 - radicals were observed as the main active species in the highly-efficient degradation of TCH over a wide pH range (1.20-11.20). The strong interfacial interaction of CeO 2 /CN promoted the Ce 4+ /Ce 3+ redox and the generation of active species. The catalytic mechanism of TCH decomposition was also proposed. This finding introduces an efficient and promising approach for the preparation of the highly-effective Fenton-like catalysts for water purification.