Different effects of selenium speciation on selenium absorption, selenium transformation and cadmium antagonism in garlic.

Currently, planting selenium-rich crops using inorganic selenium such as selenate and selenite is used to address human selenium deficiency problems. In this paper, besides the above two traditional inorganic selenium speciation, we chose a new organic selenium speciation of potassium selenocyanoacetate to investigate the different effects of selenium speciation on selenium absorption, selenium transformation and cadmium antagonism via foliar application. Plantingexperiments showed that the selenium content of garlic bulbs treated with organic selenium was 1.8-3.9 times higher than that of inorganic selenium. Additionally, the absorption and transformation efficiency of organic selenium in garlic was also the highest, reaching over 95 %. Importantly, it was noteworthy that the cadmium content in bulbs treated with organic selenium was significantly lower than the Chinese food safety standard (0.2 mg/kg). Hence, this study provides an efficient organic selenium speciation which is beneficial to meet human selenium requirements and ensure safe utilization of cadmium-contaminated soils.

Natural alumina/silica suspended particles in water to enhance ofloxacin degradation with UVA-H2O2 driven by surface chemistry.

UV-H2O2 is the most widely used oxidizing system with established effectiveness and a high level of technical development for practical application. However, little attention was paid on the effect of suspended particles in natural water on organic contaminants removal via UV-H2O2 technique. In this study, this effect of suspended particles to enhance the contaminant degradation was explored using silica/alumina-based oxides (MCM-41 and Al@MCM-41) as the representative. The results showed that MCM-41 had no effect on OFX degradation compared with UV-H2O2. While the degradation efficiency and reaction rate were greatly enhanced at a pH range of 3.0-9.0 especially at acidic pH values (3.0-5.0) in the presence of Al@MCM-41. The probe experiments proved that OFX adsorption followed by surface reaction process played an important role to enhance the performance of UV-H2O2. Based on the characterization results, the positive effect of suspended particles was not related to their surface area and pore size distribution, but dependent on the chemical composition and surface acid-base property. The suspended particles can provide an active surface composed of acid and base sites. The base site can create a local basic micro-environment by producing more •OH et al. While the dissociated acid sites in Al@MCM-41 with a negative charged surface favor OFX adsorption and then reaction with produced ROS. Our findings suggest that the enhanced performance of UVA-H2O2 induced by suspended particles should be concerned.

Submerged anaerobic membrane bioreactor (SAnMBR) performance on sewage treatment: removal efficiencies, biogas production and membrane fouling.

A submerged anaerobic membrane reactor (SAnMBR) was employed for comprehensive evaluation of sewage treatment at 25 °C and its performance in removal efficiency, biogas production and membrane fouling. Average 89% methanogenic degradation efficiency as well as 90%, 94% and 96% removal of total chemical oxygen demand (TCOD), biochemical oxygen demand (BOD) and nonionic surfactant were obtained, while nitrogen and phosphorus were only subjected to small removals. Results suggest that SAnMBRs can effectively decouple organic degradation and nutrients disposal, and reserve all the nitrogen and phosphorus in the effluent for further possible recovery. Small biomass yields of 0.11 g mixed liquor volatile suspended solids (MLVSS)/gCOD were achieved, coupled to excellent methane production efficiencies of 0.338 NLCH4/gCOD, making SAnMBR an attractive technology characterized by low excess sludge production and high bioenergy recovery. Batch tests revealed the SAnMBR appeared to have the potential to bear a high food-to-microorganism ratio (F/M) of 1.54 gCOD/gMLVSS without any inhibition effect, and maximum methane production rate occurred at F/M 0.7 gCOD/gMLVSS. Pore blocking dominated the membrane fouling behaviour at a relative long hydraulic retention time (HRT), i.e. >12 hours, while cake layer dominated significantly at shorter HRTs, i.e. <8 hours.

Enhanced Fenton Catalytic Efficiency of γ-Cu-Al2O3 by σ-Cu²âº-Ligand Complexes from Aromatic Pollutant Degradation.

Mesoporous Cu-doped γ-Al2O3 (γ-Cu-Al2O3) was prepared via an evaporation-induced self-assembly process, in which Cu(+/2+) was co-incorporated into mesoporous γ-Al2O3 by chemical bonding of Al-O-Cu. The catalyst was found to be highly effective and stable for the degradation and mineralization of aromatic pollutants, as demonstrated with bisphenol A, 2,4-dichlorophenoxyacetic acid, ibuprofen, diphenhydramine, and phenytoin in the presence of H2O2 under neutral pH conditions. In addition, the high utilization efficiency of H2O2 was maintained at approximately 90% prior to the disappearance of the initial aromatic pollutants. On the basis of all of the characterization results, the pollutant degradation processes predominantly occurred on the surface of the catalyst due to the formation of σ-Cu-ligand complexes between the phenolic OH group and the surface Cu. In the reaction system, in addition to the unselective oxidation by (•)OH, H2O2 directly attacked the σ-Cu(2+)-complexes aromatic ring with the phenolic OH group, which resulted in the formation of (•)OH and HO-adduct radicals that were oxidized to hydroxylation products by reduction of Cu(2+) in the σ-Cu(2+)-complexes to Cu(+). The process prevented Cu(2+) from oxidizing H2O2 to form HO2(•)/O2(•-) or O2, and enhanced the Cu(+)/Cu(2+) cycle, the formation of (•)OH, and the utilization efficiency of H2O2. Therefore, an extraordinarily high degradation and mineralization of the aromatic pollutants was observed.

Mechanism of catalytic ozonation in Fe 2O3/Al 2O3@SBA-15 aqueous suspension for destruction of ibuprofen.

Fe2O3 and/or Al2O3 were supported on mesoporous SBA-15 by wet impregnation and calcinations with AlCl3 and FeCl3 as the metal precursor and were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectra (FTIR) of adsorbed pyridine. Fe2O3/Al2O3@SBA-15 was found to be highly effective for the mineralization of ibuprofen aqueous solution with ozone. The characterization studies showed that Al-O-Si was formed by the substitution of Al(3+) for the hydrogen of surface Si-OH groups, not only resulting in high dispersion of Al2O3 and Fe2O3 on SBA-15, but also inducing the greatest amount of surface Lewis acid sites. By studies of in situ attenuated total reflection FTIR (ATR-FTIR), in situ Raman, and electron spin resonance (ESR) spectra, the chemisorbed ozone was decomposed into surface atomic oxygen species at the Lewis acid sites of Al(3+) while it was converted into surface adsorbed (•)OHads and O2(•-) radicals at the Lewis acid sites of Fe(3+). The combination of both Lewis acid sites of iron and aluminum onto Fe2O3/Al2O3@SBA-15 enhanced the formation of (•)OHads and O2(•-) radicals, leading to highest reactivity. Mechanisms of catalytic ozonation were proposed for the tested catalysts on the basis of all the experimental information.

Catalytic ozonation of selected pharmaceuticals over mesoporous alumina-supported manganese oxide.

Catalytic ozonation of five pharmaceutical compounds (PhACs)-phenazone, ibuprofen, diphenhydramine, phenytoin, and diclofenac sodium in alumina-supported manganese oxide (MnOx) suspension was carried out with a semicontinuous laboratory reactor. MnOx supported by mesoporous alumina (MnOx/MA) was highly effective in mineralizing the PhACs in aqueous solution. Fourier transform infrared (FTIR) spectroscopy and in situ attenuated total reflection FTIR (ATR-FTIR) spectroscopy were used to examine the interaction of ozone with different catalysts undervarious conditions. The crucial active sites, surface oxide species at 1380 cm(-1), were formed by the interaction of ozone with Lewis acid sites on the alumina surface. New surface hydroxyl groups at 2915 and 2845 cm(-1) were produced by the interaction of the catalyst and ozone in aqueous suspension and became active sites in the presence of MnOx. The introduction of MnOx enhanced the formation and activation of surface hydroxyl groups, causing higher catalytic reactivity. On the basis of these findings, a reaction mechanism is proposed for the catalytic ozonation of PhACs in MnOx/MA suspension.