•Porous stannosilicate beads have been prepared using porous anion-exchange resin as hard template.•Sn species in the beads can be highly accessible via the continuous large-mesopore system.•Thanks to their bead format, the catalysts could be extremely straightforward separated from the reaction media.Porous anion-exchange resin was introduced as hard template to hydrothermally synthesize tin-containing mesoporous silica beads (Sn-MesoSB) with the diameter in the range of 0.3–0.9 mm. The characterization results showed the existence of continuous large-mesopore channels and tetrahedral tin species in the bead samples. Sn-MesoSB proved to exhibit high catalytic performances in the Baeyer-Villiger oxidation of adamantanone by using H2O2 as green oxidant, mainly attributed to the enhancement of the access to the catalytic tin sites through the continuous large-mesopore channels. Under the optimized experimental conditions, the conversion of adamantanone approached ca.100% in dioxane for 3 h at 90 °C. Notably, the bead format of such material could be remained during the catalysis procedure, which favors to the straightforward separation from the reaction system without any means of filtration or centrifugation. Working as a liquid-phase heterogeneous catalyst, this is pretty appealing to potential industrial applications. The catalyst was robust and can be reused up to 5 times without significant loss of activity and selectivity, pointing out that the tin species incorporated in the framework possessed high stability. Moreover, the bead material exhibits activity and selectivity in the Baeyer-Villiger oxidations with a broad range of substrates.Mesoporous stannosilicate beads are highly active for Baeyer-Villiger oxidations with H2O2 and can be easily separated from the reaction solution.Download high-res image (150KB)Download full-size image

Mesoporous silica spheres with hierarchical hollow/nano structure (MSSH-H/N) have been successfully prepared by a template-guided approach, in which cetyltrimethyl ammonium bromide (CTAB) and polystyrene (PS) emulsion was used as the template of mesopores and hollow core, respectively. A consecutive template mechanism and the formation of the hierarchical hollow/nano structure were proposed on basis of the combined characterizations including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction patterns (XRD) and nitrogen sorption analysis, which showed that the hierarchical structure is composed of mesoporous hollow SiO2 spheres and discrete mesoporous SiO2 nanoparticles coating on the shell. Ibuprofen (IBU) was chosen as a drug model in delivery and release experiments, and these MSSH-H/N samples exhibited higher drug loading capacity, desired low initial IBU release rate and typical two-phase drug release behavior compared with conventional single-structure (single-shelled) hollow mesoporous silica spheres due to their unique hierarchical hollow/nano structure.

•Developed an Aerosol Type Analysis method (ATAM) for typical aerosol concentrations.•Applied ATAM on the surface-level PM2.5 prediction.•Discussed the estimating results on a seasonal and overall basis.Surface-level particulate matter is closely related to column aerosol optical thickness (AOT). Previous researches have successfully used column AOT and different meteorological parameters to estimate surface-level PM concentration. In this study, the performance of a selected linear model that estimates surface-level PM2.5 concentration was evaluated following the aerosol type analysis method (ATAM) for the first time. We utilized 443 daily average data for Xuzhou, Jiangsu province, collected using Aerosol Robotic Network (AERONET) during the period October 2013 to April 2016. Several parameters including atmospheric boundary layer height (BLH), relative humidity (RH), and effective radius of the aerosol size distribution (Ref) were used to assess the relationship between the column AOT and PM2.5 concentration. By including the BLH, ambient RH, and effective radius, the correlation (R2) increased from 0.084 to 0.250 at Xuzhou, and with the use of ATAM, the correlation increased further to 0.335. To compare the results, 450 daily average data for Beijing, pertaining to the same period, were utilized. The study found that model correlations improved by varying degrees in different seasons and at different sites following ATAM. The average urban industry (UI) aerosol ratios at Xuzhou and Beijing were 0.792 and 0.451, respectively, demonstrating poorer air conditions at Xuzhou. PM2.5 estimation at Xuzhou showed lower correlation (R2 = 0.335) compared to Beijing (R2 = 0.407), and the increase of R2 at Xuzhou and Beijing site following use of ATAM were 33.8% and 12.4%, respectively.

•The optical characteristic of the TiO2/C is studied.•The energy-absorption characteristic of TiO2/C is studied.•A new photocatalytic enhancement mechanisms of TiO2/C is proposed.The reason for the significant photocatalytic activity improvement exhibited by TiO2/C is currently a topic of great research interest, and many different explanations of this phenomenon have been proposed. In this paper, we provide a new explanation of this enhancement mechanism that takes into consideration the energy absorption characteristics of TiO2/C. First, we determined the relationship among the wavelength of the incident light, the TiO2 particle radius, and the energy of the scattered light based on the results of Mie analysis. Then the energy absorption characteristics inside TiO2/C were observed using the finite-difference time-domain method. The calculated results revealed that light can be scattered by TiO2 particles during the light transfer process, causing the amorphous C near the TiO2 particles to absorb more energy than the C in other regions. This phenomenon can enable the amorphous C near the TiO2 particles to produce photoelectrons, which can subsequently migrate to the conduction band of TiO2, resulting in enhanced photocatalytic activity.Download high-res image (81KB)Download full-size image