Photocatalytic decomposition of CCl4 on Zr-MCM-41

Poly(ionic liquid)s for Photo-Driven CO2 Cycloaddition: Electron Donor-Acceptor Segments Matter

CO₂ cycloaddition with epoxides is a key catalytic procedure for CO₂ utilization. Several metal-based catalysts with cocatalysts are developed for photo-driven CO₂ cycloaddition, while facing difficulties in product purification and continuous reaction. Here, poly(ionic liquid)s are proposed as metal-free catalysts for photo-driven CO₂ cycloaddition without cocatalysts. A series of poly(ionic liquid)s with donor-acceptor segments are fabricated and their photo-driven catalytic performance (conversion rate of 83.5% for glycidyl phenyl ether) outstrips (≈4.9 times) their thermal-driven catalytic performance (17.2%) at the same temperature. Mechanism studies confirm that photo-induced charge separation is promoted by the donor-acceptor segments and can accelerate the CO₂ cycloaddition reaction. This work paves the way for the further use of poly(ionic liquid)s as catalysts in photo-driven CO₂ cycloaddition.

Photodegradation of Fipronil by Zn-AlPO4 Materials Synthesized by Non-Hydrolytic Sol–Gel Method

In recent decades, the increasing use of pesticides to improve food productivity has led to the release of effluents that contaminate the environment. To prepare a material that may help to treat effluents generated during agricultural practice, we used a new method based on the non-hydrolytic sol-gel route to obtain zinc photocatalysts in aluminophosphate matrixes. IR spectroscopy, X-ray diffraction, thermal analysis, differential scanning electron microscopy, energy dispersion spectroscopy, and specific surface area and pore volume determined from the nitrogen adsorbed were used to characterize materials treated at different temperatures. X-ray analysis showed how heat-treatment affected the structure of the material: Zn-AlPO4 in the trigonal and orthorhombic phase was obtained at 750 and 1000 °C, respectively. These phases directly influenced the ability of the material to generate OH radicals. The capacity of the materials to treat effluents was tested in the photodegradation of the pesticide Fipronil. The photocatalytic reactions were monitored by ultraviolet-visible spectroscopy and gas chromatography-mass spectrometry analyses. Zn-AlPO4 treated at 750 °C showed better photodegradation results--it removed 80% of the pesticide in 2 h when higher mass (150 mg) was tested. Long-time treatment of the effluent with Zn-AlPO4 treated at 750 °C completely photodegraded Fipronil. GC-MS analysis confirmed the photodegration profile, and only traces of Fipronil were observed after photocatalytic reaction for 120 min in the presence of Zn-AlPO4 treated at 750 °C under UV radiation.

Hepatotoxicity and nephrotoxicity in rats induced by carbon tetrachloride and the protective effects of Teucrium polium and vitamin C

This work investigated the protective effects of Teucrium polium (T. polium) and vitamin C (Vit C) against carbon tetrachloride (CCl₄) induced hepatotoxicity and nephrotoxicity in rats. T. polium reduced the Fer reduced antioxidant power (FRAP) (IC₅₀ = 0.89 mg/ml) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) (IC₅₀ = 0.049 µg/ml) than Vit C, FRAP (IC₅₀ = 0.71 mg/ml) and DPPH (IC₅₀ = 0.029 µg/ml). Male albino Wistar rats were divided into six groups: Group I was used as controls, Group II received CCl₄ in olive oil (0.5 ml/kg) by gavage, Group III received CCl₄ in olive oil (0.5 ml/kg) by gavage after 3 d of receiving T. polium (5 g/l), orally, Group IV received T. polium (5 g/l) alone, by gavage, for 7 d, Group V received CCl₄ in olive oil (0.5 ml/kg) by gavage after 3 d of receiving Vit C (250 mg/kg) by gavage and Group VI received Vit C (250 mg/kg) alone by gavage. CCl₄ showed an increase of serum hepatic and renal markers aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine. Moreover, we noted an increase of lipid peroxidations and a decrease in antioxidants enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) of CCl₄ rats compared to controls. The pretreatment with (200 mg/kg) of T. polium and with Vit C (250 mg/kg) by gavage, for 7 d, displayed their ability to protect against oxidative damage and biochemical changes induced by CCl₄. Our results were in accordance with histopathological observations.

Triethylenetetramine-Modified P123-Occluded Zr-SBA-15 Molecular Sieve for CO2 Adsorption

A pluronic 123 (P123)-occluded mesoporous molecular sieve Zr-SBA-15, Zr-SBA(P) was modified with triethylenetetramine (TETA) and tested for CO2 adsorption. The synthesized materials were characterized by powder X-ray diffraction, N2 adsorption–desorption, dispersive spectroscopy, thermogravimetric analysis, temperature-programmer desorption of CO2, and Fourier transform infrared spectroscopy. The results of CO2 adsorption show that the TETA and P123 species have positive effects on the CO2 adsorption capacity of the adsorbent, and the performance of the as-prepared adsorbent in a stream of low CO2 concentration is excellent. At 50 wt-% TETA loading, Zr-SBA(P) has a maximum capacity of 4.27 mmol g–1 in a stream of 5 % CO2 at 50°C, ~33.5 % higher than the adsorbent prepared in the absence of P123. In addition, the adsorbent is superior in reusability. It is envisaged that the adsorbent will find wide application in CO2 capture.

Photodecomposition of chloroform catalyzed by unmodified MCM-41 mesoporous silica

Unactivated MCM-41 mesoporous silica catalyzes the photodecomposition of chloroform to phosgene and hydrogen chloride under near-UV (λ > 360 nm) irradiation. The rate of photodecomposition increases toward an asymptotic limit as the O(2) partial pressure is increased. Deuterochloroform does not decompose under the same experimental conditions. Low concentrations of both cyclohexane and ethanol quench the photodecomposition, whereas water, up to its solubility limit, does not. Dissolved tetraalkylammonium salts suppress photodecomposition. The data are consistent with a mechanism in which light absorption by an SiO(2) defect yields an electron-deficient oxygen atom, which then abstracts hydrogen from chloroform. The resulting CCl(3) radicals react with oxygen to form a peroxy radical that decomposes, eventually yielding phosgene and hydrogen chloride.