Huiqin Guo

Fabrication of carbon nitride nanotubes by a simple water-induced morphological transformation process and their efficient visible-light photocatalytic activity

Carbon nitride nanotubes (C3N4 NTs) were synthesized based on the nanosheets roll-up mechanism by a simple water-induced morphological transformation process using graphitic carbon nitride (g-C3N4) as a precursor. Water was used as the phase-transfer reagent, making the preparation process environmentally friendly. The visible-light photocatalytic activity of the as-prepared C3N4 NTs significantly increased compared to bulk g-C3N4 and g-C3N4 nanosheets toward rhodamine B degradation and hydrogen evolution from water-splitting. This result can be attributed to the high photogenerated carrier transfer efficiency, excellent mass transfer capability, sufficient active sites, and enhanced light utilization efficiency of C3N4 NTs.

Urine Metabolite Profiling of Human Colorectal Cancer by Capillary Electrophoresis Mass Spectrometry Based on MRB.

Aim. The study was to investigate the metabolic profile of urine metabolites and to elucidate their clinical significance in patients with colorectal cancer. Methods. Colorectal cancers from early stage and advanced stage were used in this study. Urine samples of colorectal cancer patients and healthy adults were collected and subjected to capillary electrophoresis mass spectrometry based on moving reaction boundary analysis. The metabolic data were analyzed by SPSS 17.0 to find urinary biomarkers for colorectal cancer. Results. The results indicated that the urine metabolic profiling of colorectal cancer patients had significant changes compared with the normal controls, and there were also differences between early stage and advanced colorectal cancer patients. Compared with the control group, the levels of isoleucine, valine, arginine, lactate acid and leucine increased (P < 0.05), but those of histidine, methionine, serine, aspartic acid, citric acid, succinate, and malic acid decreased in urine samples from colorectal cancer (P < 0.05). Furthermore, the levels of isoleucine and valine were lower in urine of patients with advanced colorectal cancer than those in early stage colorectal cancer (P < 0.05). Conclusion. The technique of capillary electrophoresis mass spectrometry based on MRB could reveal the significant metabolic alterations during progression of colorectal cancer, and the method is feasible and may be useful for the early diagnosis of colorectal cancer.

Fabrication of porous g-C 3 N 4 and supported porous g-C 3 N 4 by a simple precursor pretreatment strategy and their efficient visible-light photocatalytic activity

Porous g-C 3 N 4 and supported porous g-C 3 N 4 were fabricated for the first time by a simple strategy using pretreated melamine as a raw material and pretreated quartz rod as a substrate. The formation of a richly porous microstructure can be attributed to the co-existence of different pore-fabricating units in the preparation system for porous g-C 3 N 4 . The richly porous microstructure endowed the as-prepared porous g-C 3 N 4 with an excellent photocatalytic activity. The as-prepared supported porous g-C 3 N 4 exhibited considerable stability because of the existence of chemical interaction between porous g-C 3 N 4 and the quartz rod substrate. The photocatalytic activity of the supported porous g-C 3 N 4 was competitive with that of porous g-C 3 N 4 in powder form because neither the surface migration of photogenerated electrons nor the diffusion of the target organic pollutant were affected by the construction of the quartz rod reactor. The photocatalytic activity of the as-prepared porous g-C 3 N 4 and supported porous g-C 3 N 4 was preliminarily evaluated by the treatment of single-component organic wastewater under visible-light irradiation. Subsequently, the as-prepared porous g-C 3 N 4 was further applied in conventional hydrogen evolution and a new system for simultaneous hydrogen evolution with organic-pollutant degradation. The hydrogen yield and degradation efficiency both increased with increasing photocatalytic activity of the as-prepared materials in the system for simultaneous hydrogen evolution with organic-pollutant degradation.

Fabrication of highly dispersed platinum-deposited porous g-C3N4 by a simple in situ photoreduction strategy and their excellent visible light photocatalytic activity toward aqueous 4-fluorophenol degradation

A series of highly dispersed platinum-deposited porous g-C 3 N 4 (Pt/pg-C 3 N 4 ) were successfully fab-ricated by a simple in situ photoreduction strategy using chloroplatinic acid and porous g-C 3 N 4 as precursors. Porous g-C 3 N 4 was fabricated by a pretreatment strategy using melamine as a raw ma-terial. The morphology, porosity, phase, chemical structure, and optical and electronic properties of as-prepared Pt/pg-C 3 N 4 were characterized. The photocatalytic activity of as-prepared Pt/pg-C 3 N 4 was preliminarily evaluated by the degradation of aqueous azo dyes methyl orange under visible light irradiation. The as-prepared Pt/pg-C 3 N 4 were further applied to the degradation and mineral-ization of aqueous 4-fluorophenol. The recyclability of Pt/pg-C 3 N 4 was evaluated under four con-secutive photocatalytic runs.

Surface molecular imprinting on carbon microspheres for fast and selective adsorption of perfluorooctane sulfonate

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant with high biological and chemical stability. It is important to develop fast and selective adsorption method for PFOS wastewater treatment. In this study, novel molecularly imprinted polymer (MIP) for PFOS adsorption was prepared. To obtain rapid adsorption kinetics, the MIP has been designed as the surface polymer using the carbon microsphere as carrier (MIP-CMSs). To ensure high adsorption selectivity to the template, two monomers with different functional structures, namely methacryloyloxyethyl trimethyl ammonium chloride (DMC) and 2-(trifluoromethyl)acrylic acid (TFMA), were employed as bi-functional monomers. The structure and morphology of MIP-CMSs were characterized using field emission scanning electron microscopy with the energy dispersive spectrometer, transmission electron microscopy, and Fourier transformation infrared spectroscopy. Based on the adsorption experiments, it was concluded that MIP-CMSs had specific binding property for PFOS on acidic condition. The adsorption equilibrium time was 1h, while the adsorption capacity was 75.99 mg g-1 at pH 3. Coexistence with contaminants with different structures had little influence on the selectivity for PFOS. The spent MIP-CMSs could be regenerated by the methanol and acetic acid mixed solution. The electrostatic interaction and molecular size played important roles in recognizing the target compound in the adsorption process.