In this study, the overall performance of a biofilter was evaluated in terms of its elimination capacity by using 3-D mesh techniques. The overall results indicate that the agreement between experimental data and model predictions is excellent for benzene, toluene, ethylbenzene and o-xylene (BTEX). In this study, the maximum removal rate (rmax) values for BTEX were 0.0117, 0.0126, 0.0081 and 0.0146 g m–3 h–1, and the half-saturation constant (KS) values were calculated to be 0.269, 0.297, 0.156 and 0.394 g m–3, respectively. For this system, the coefficients of determination (r2) of BTEX compounds were greater than 0.97. The BTEX concentration profiles along the depth were also determined using a convection–diffusion reactor (CDR) model. The sums of squares of the errors (SSEs) of BTEX were 0.0078, 0.0059, 0.0129 and 0.0269, respectively, with r2 values greater than 0.99 for all four compounds at low concentrations. 相似文献
Curcumin‐sensitized perovskite Bi0.5Na0.5TiO3 (BNT) was synthesized for visible light photocatalytic decolorization of rhodamine 6G (Rh6G). Cube‐shaped perovskite BNT was synthesized by solid‐state route, and curcumin sensitization was performed using hydrothermal method. The surface sensitization of curcumin was analyzed by UV–Vis absorption spectra and FTIR. The degradation kinetics of Rh6G over Cur‐BNT were investigated and discussed through first‐order Langmuir–Hinshelwood kinetic model. The effect of catalyst dose on photocatalytic decolorization process was investigated. Photocatalysis was performed with different scavengers to investigate the role of active hole and radical species and photocatalytic degradation mechanism of Rh6G. 相似文献
A 0.5(Ba0.7Ca0.3)TiO3–0.5Ba(Zr0.1Ti0.9)O3 (BCT-BZT) ceramic was studied for photocatalysis and piezocatalysis effects using dye degradation (methylene blue, rhodamine B, and methyl orange) and bacterial (Escherichia coli) disinfection from aqueous solution. To examine the effect of ferroelectric polarization, BCT-BZT powder was poled using the corona poling technique. Same time, BCT-BZT was converted into Ag/BCT-BZT composites as Ag induced surface plasmon resonance effect during photocatalysis. Piezocatalysis performance was assessed for dyes mineralization under ultrasonication. There was a significant impact of silver nanoparticles on the photo/piezocatalysis performance of BCT-BZT. Similarly, electric poling has also played a positive role in improving the photo/piezocatalysis in view of various dye degradation. These samples also showed effective antibacterial performance. 相似文献
BaTi1−xFexO3 compositions (for x = 0, 0.1, and 0.2) were prepared via a solid-state reaction route. The presence of iron (Fe) in barium titanate (BaTiO3) eventually decreased the energy bandgap; thus, its utilization for water cleaning application through photocatalysis process was explored (using methylene blue [MB] dye as an indicative pollutant in water). Characterization of the synthesized powder was performed through scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. The bandgap of the synthesized powder was calculated as 3.2, 2.12, and 1.67 eV for BaTi1−xFexO3 compositions (for x = 0, 0.1, and 0.2), respectively. BaTi0.8Fe0.2O3 powder showed excellent results, and ∼71% of the MB dye (∼5 mg/L concentrated) was degraded using the photocatalysis process under visible light. To check the potentiality of BaTi1−xFexO3 compositions (for x = 0, 0.1, and 0.2), the photocatalysis process was carried out by changing the concentration of MB dye (2.5–10 mg/L with a step of 2.5 mg/L) and the amount of BaTi0.8Fe0.2O3 powder (0.05–0.2 g with a step of 0.05 g) for ∼5-mg/L concentrated MB dye. The treated water was further used as a growth parameter and phytotoxicity analysis through germination index on the wheat seeds. Lastly, the BaTi1−xFexO3 compositions (for x = 0, 0.1, and 0.2) were explored for water cleaning applications under real-time solar irradiation. 相似文献
Eutectic high entropy alloy with seven components is designed based on the integrated computational materials engineering (ICME) framework. The framework includes thermodynamic prediction using calculation of phase diagrams (CALPHAD), microstructure simulation using phase-field method, and experimental validation. The designed alloy shows the eutectic structure consisting of FCC and laves phase in the composition range from 8.25 to 10 at. pct Ta. The simulation and experimental results are co-related and a framework is proposed that can be used for high entropy alloy design subjected to various manufacturing processes.
Room temperature fracture toughness along with compressive deformation behavior at both room and high temperatures (900 °C, 1000 °C and 1100 °C) has been evaluated for ternary or quaternary hypoeutectic (Nb–12Si–5Mo and Nb–12Si–5Mo–20Ti) and hypereutectic (Nb–19Si–5Mo and Nb–19Si–5Mo–20Ti) Nb-silicide based intermetallic alloys to examine the effects of composition, microstructure, and annealing (100 hours at 1500 °C). On Ti-addition and annealing, the fracture toughness has increased by up to ~ 75 and ~ 63 pct, respectively with ~ 14 MPa√m being recorded for the annealed Nb–12Si–5Mo–20Ti alloy. Toughening is ascribed to formation of non-lamellar eutectic with coarse Nbss, which contributes to crack path tortuosity by bridging, arrest, branching and deflection of cracks. The room temperature compressive strengths are found as ~ 2200 to 2400 MPa for as-cast alloys, and ~ 1700 to 2000 MPa after annealing with the strength reduction being higher for the hypoeutectic compositions due to larger Nbss content. Further, the compressive ductility has varied from 5.7 to 6.5 pct. The fracture surfaces obtained from room temperature compression tests have revealed evidence of brittle failure with cleavage facets and river patterns in Nbss along with its decohesion at non-lamellar eutectic. The compressive yield stress decreases with increase in test temperature, with the hypoeutectic alloys exhibiting higher strength retention indicating the predominant role of solid solution strengthening of Nbss. The flow curves obtained from high temperature compression tests show initial work hardening, followed by a steady state regime indicating dynamic recovery involving the formation of low angle grain boundaries in the Nbss, as confirmed by electron backscattered diffraction of the annealed Nb–12Si–5Mo alloy compression tested at 1100 °C.
Computational fluid dynamics (CFD) simulations of the hydrodynamic behavior of rotating fluidized beds in static geometry (RFB-SG) are carried out for gas–solid flows. The rotating motion of the reactor bed is induced by the tangential injection of the gas along the circumference of the fluidization chamber. Steep gradients in the gas velocity fields both in radial and tangential direction generate turbulence. The radial and tangential drag forces fluidize the particle bed in both radial and tangential direction.An Eulerian two-fluid model is used. Gas phase turbulence is accounted for by a k–ε model adapted for rotational flows. The RFB-SG simulations provide guidelines for a design and operation with a high efficiency in gas–solid momentum transfer, excellent gas–solid separation and limited solids losses. Hydrodynamic variables like the centrifugal force, the injection pressure, the radial and tangential slip velocities, solids hold-up are calculated for both polymer particles (300 μm, 950 kg/m3, Geldart Group B) and glass beads (70 μm, 2500 kg/m3, Geldart Group A) to allow for a comparison among different fluidization chamber designs. Unstable bed behavior, like slugging and channeling, is also numerically predicted. 相似文献
Biohydrogen (bioH2) production from starch-containing wastewater is an energy intensive process as it involves thermophilic temperatures for hydrolysis prior to dark fermentation. Here we report a low energy consumption bioH2 production process with sago starch powder and wastewater at 30 °C using enriched anaerobic mixed cultures. The effect of various inoculum pretreatment methods like heat (80 °C, 2 h), acid (pH 4, 2.5 N HCl, 24 h) and chemical (0.2 g L−1 bromoethanesulphonic acid, 24 h) on bioH2 production from starch powder (1% w/v) showed highest yield (323.4 mL g−1 starch) in heat-treatment and peak production rate (144.5 mL L−1 h−1) in acid-treatment. Acetate (1.07 g L−1) and butyrate (1.21 g L−1) were major soluble metabolites of heat-treatment. Heat-treated inoculum was used to develop mixed cultures on sago starch (1% w/v) in minimal medium with 0.1% peptone-yeast extract (PY) at initial pH 7 and 30 °C. The effect of sago starch concentration, pH, inoculum size and nutrients (PY and Fe ions) on batch bioH2 production showed 0.5% substrate, pH 7, 10% inoculum size and 0.1% PY as the best H2 yielding conditions. Peak H2 yield and production rate were 412.6 mL g−1 starch and 78.6 mL L−1 h−1, respectively at the optimal conditions. Batch experiment results using sago-processing wastewater under similar conditions showed bioH2 yield of 126.5 mL g−1 COD and 456 mL g−1 starch. The net energy was calculated to be +2.97 kJ g−1 COD and +0.57 kJ g−1 COD for sago starch powder and wastewater, respectively. Finally, the estimated net energy value of +2.85 × 1013 kJ from worldwide sago-processing wastewater production indicates that this wastewater can serve as a promising feedstock for bioH2 production with low energy input. 相似文献