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In this paper, Cr/MnO2 catalysts were prepared by hydrothermal–calcination method and applied to the catalytic oxidation of formaldehyde (HCHO) at room temperature. The effects of calcination temperature on the physicochemical properties of Cr/MnO2 catalysts were investigated by means of N2 adsorption–desorption, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Based on this, the formaldehyde removal mechanism of Cr/MnO2 catalysts was proposed. The results showed that the specific surface area, OII/OI, Mn4+/Mn3+ and Cr6+/Cr3+ ratios of the Cr/MnO2 catalysts varied with the calcination temperature. The Cr/MnO2 catalyst calcined at 400 °C (CM400) has higher specific surface area (64.6 m2/g) and oxygen vacancy content, so it exhibits better formaldehyde removal performance, which could reach 92.1% within 22 h. It is concluded that the high specific surface area, abundant oxygen vacancy content, rich Mn4+ and Cr6+ species are primary reasons for the excellent formaldehyde removal performance of CM400 sample. The Cr/MnO2 catalysts reveal great application potential in indoor formaldehyde degradation, and will be promising industrial formaldehyde degradation catalyst. [ABSTRACT FROM AUTHOR]

CuxO/Bi2O3 oxides grown on nickel foam were synthesized via an electrodeposition method to degrade indoor HCHO under visible light irradiation and fully characterized by XRD, SEM, FT-IR, and UV-Vis technologies. The characterization results showed that the CuxO/Bi2O3 oxides were successfully loaded on nickel foam and the visible light response spectrum was expanded to 740 nm. Plackett–Burman design combined with central composite design has been used to optimize factors that affect HCHO removal performance. The results demonstrated that bismuth nitrate content, polyethylene glycol 600 content, sintering time, and lactic acid concentration were the four most important factors affecting the HCHO removal performance over CuxO/Bi2O3 sample. The optimum CuxO/Bi2O3 sample could degrade 88.796% of HCHO in 300 min at the conditions of 4.28 mol/L lactic acid, 4.86% polyethylene glycol 600, 194.03 min sintering time, and 45.83 g bismuth nitrate, and the HCHO removal rate remained 82.3% after five cycles. A plausible mechanism for the degradation of HCHO under visible light irradiation was proposed. This work provides a feasible solution for removing indoor formaldehyde in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

In this work, the Mn-doped Fe2O3 catalyst (Mn/Fe2O3) was prepared by hydrothermal and calcination methods to remove formaldehyde. The effect of calcination temperature on the structure and performance of Mn/Fe2O3 catalyst was elucidated by X-ray diffraction, Raman spectroscopy, scanning electron microscope, transmission electron microscopy, energy dispersive spectroscopy, selected area electron diffraction, N2 adsorption–desorption, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The result showed that the Mn/Fe2O3 catalyst calcined at 200 ℃ (MFC200) possessed the best specific surface area (176.04 m2/g, 4.96 times that of pure Fe2O3). The active oxygen content on the catalyst surface varies with the calcination temperature, and that of MFC200 sample is the highest compared with the samples calcined at other calcination temperatures. In addition, the content of Mn4+ species also varies with the calcination temperature, which plays a key role in Mn/Fe2O3 catalysts for HCHO removal. It is concluded that the high specific surface area, the abundant active oxygen species and rich Mn4+ were contributed to the excellent formaldehyde removal performance of MFC200 sample. The Mn/Fe2O3 catalyst will be a promising catalyst to degrade formaldehyde in industrial applications. [ABSTRACT FROM AUTHOR]

The Ce‐CdS‐TiO2 photocatalysts were successfully synthesized by a simple sol‐gel way and loaded on the nickel foam. The specific surface area, crystalline phase, microstructure and surface functional groups of prepared photocatalysts were characterized by Brunauer‐Emmett‐Teller (BET) surface area, X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT‐IR). The photocatalytic tests of Ce‐CdS‐TiO2 samples demonstrated that Ce as the active component plays an irreplaceable role in degradation of gaseous formaldehyde. The results showed that high Ce doping levels restrained the photocatalytic activity due to lower specific surface area, whereas moderate doping levels showed the highest photocatalytic performance due to higher specific surface area and evenly dispersion of the active component. The rate of formaldehyde degradation on 0.9 wt % Ce‐CdS‐TiO2, 1.5 wt % Ce‐CdS‐TiO2, and 2.1 wt % Ce‐CdS‐TiO2 photocatalysts can reach to 59, 84, and 49 %, respectively, which are higher than pure TiO2 (20 %). Ce‐doping into CdS‐TiO2 photocatalyst produce the Ce‐O‐Ti bonds, which enhanced the interaction between Ce and TiO2. The introduction of Ce increased the UV/Vis absorption of Ce‐CdS‐TiO2 photocatalyst. Furthermore, Ce‐CdS‐TiO2 possesses high photocatalytic performance, since Ce may reduce the recombination of photoexcited electrons and holes. [ABSTRACT FROM AUTHOR]

In the present work, both field investigation and laboratory experiment were carried out to testify whetherPolygonum lapathifoliumL. is a potential manganese (Mn) hyperaccumulator. Results from field investigation showed thatP. lapathifoliumhad great tolerance and accumulation to Mn. Mn concentrations in leaves were the highest, varied from 6889.2 mg kg-1 dry weight (DW) to18841.7 mg kg−1DW with the average of 12180.6 mg kg−1. The values of translocation factor (the concentrations of Mn in leaf to that in root) ranged from 5.72 to 9.53. Results from laboratory experiment illuminated thatP. lapathifoliumcould grow well and show no toxic symptoms even under high Mn stress (16 mmol L−1). Although the changes of antioxidant enzymes activities were triggered under Mn stress, the alterations of pigments were not significant (P > 0.05) as compared with control. Total plant biomass and plant height increased with increasing Mn supply. Mn concentrations in leaves and stems were constantly greater than those in roots, the ratio of concentrations in leaves to that in roots were 2.58–6.72 and the corresponding values in stems to that in roots were 1.45–3.18. The results showed thatP. lapathifoliumis a Mn-hyperaccumulator. [ABSTRACT FROM PUBLISHER]