Selective Catalytic Oxidation of Lean-H2S Gas Stream to Elemental Sulfur at Lower Temperature

Ceria-supported vanadium catalysts were studied for H2S removal via partial and selective oxidation reactions at low temperature. The catalysts were characterized by N2 adsorption at 77 K, Raman spectroscopy, X-ray diffraction techniques, and X-ray fluorescence analysis. X-ray diffraction and Raman analysis showed a good dispersion of the V-species on the support. A preliminary screening of these samples was performed at fixed temperature (T = 327 °C) and H2S inlet concentration (10 vol%) in order to study the catalytic performance in terms of H2S conversion and SO2 selectivity. For the catalyst that exhibited the higher removal efficiency of H2S (92%) together with a lower SO2 selectivity (4%), the influence of temperature (307–370 °C), contact time (0.6–1 s), and H2S inlet concentration (6–15 vol%) was investigated.

Design and cost estimation of solar powered reverse osmosis desalination system

Photovoltaic assisted reverse osmosis (PV-RO) has been proven an efficient renewable energy-based desalination technique to provide drinkable water, especially in remote areas. In this manuscript, a simulation based RO design system was adopted to evaluate the desalination performance for three cities of Pakistan, that is, Lahore, Hasil Pur, and Faisalabad. The inlet concentration of Lahore, Hasil Pur, and Faisalabad was reduced from 1495, 2190, and 7683 TDS to 295.44, 237.69, and 241.98 TDS respectively, according to the WHO drinking water recommendations. The RO desalination system was integrated with the photovoltaic system to fulfill the energy requirement for desalination. The energy requirement for the RO system for the working of 10 h/day with the freshwater production rate of 0.80 m3/h for Lahore, Hasil Pur, and Faisalabad is 60, 95, and 311 kWh/month, respectively. According to PVsyst software, the energy demand can be accomplished by installing 9 PV panels in Lahore, 15 PV panels in Hasil Pur, and 40 PV panels in Faisalabad. The simulation results in PVsyst showing that the battery losses will be 52.2% in Lahore, 51.1% in Hasil Pur, and 49% in Faisalabad.

Thermodynamic, Kinetic and Isotherm Study of 4-chloro-2-methyl Phenoxy Acetic Acid (MCPA) by (PV/S-g-3D-GO/N) from Aquatic Solutions

BackgroundIn this study removal efficiency of 4-chloro-2-methyl-phenoxy acetic acid (MCPA) by 3D polymer nano-magnetic (PV/S-g-3D-GO/N) was investigated.MethodsThe effects of operation parameters including adsorbent mass, influent flow rate and inlet concentration on the adsorption performance are investigated.ResultsMaximum adsorption capacity (4.36 mg/g) was achieved at optimum conditions (pH: 3, contact time: 300 min, adsorbent dosage: 5 g/l and temperature: 50 °C). Moreover, adsorption isotherm and kinetics were agreed with the Langmuir model (R2 = 0.997) and pseudo-second-order model (R2 = 0.999), respectively. Thermodynamic studies also show that adsorption process was spontaneous (ΔG < 0) and endothermic (ΔH > 0).ConclusionAccording to removal efficiency (100%), this adsorbent is an excellent alternative for removal herbicide in high temperature industry.

Adsorção de cromo hexavalente usando rejeito de beneficiamento de carvão em modelo de batelada e coluna de leito fixo

The objective of this work is to utilize a coal beneficiation tailing from Moatize (Mozambique) for the adsorption of hexavalent chromium from water in batch model and fixed bed column. Coal waste was used in particle size between 0.7 and 1.5 mm. The effects of pH, contact time and solid adsorbent concentration were analyzed by batch experiments. The results indicated that it was possible to obtain 98.6% of removal under the experimental conditions of pH 2, 10 h of process and 8 g.L-1 of solid adsorbent. From these experimental results, equilibrium isotherms were build and Langmuir and Sips models presented a better fit to the experimental data. The adsorption of chromium hexavalent from aqueous solution onto coal waste was investigated in a fixed bed column at 298 K. The effects of the inlet concentration, feed flow rate, bed depth on adsorption were investigated. In general, the evaluated parameters improved as a results increase in a Z (bed deep) and decreases in Q (feed flow rate). These performance metrics also improved as C0 (inlet concentration) was increased.

Geometry optimization, factors screening, and introduce a predicting mathematical model of inhalation exposure chamber’s performance.

Background Optimizing the geometry of an inhalation exposure chamber (IEC) results in a uniform and stable distribution of the test atmosphere and enables the modeling of its performance. This study was conducted for the first time to optimize and model the performance of an IEC.Methods The current study was performed on the initial design of the ASRA chamber and to optimize and model it. The matrix of experiments was determined by the design expert software (DE7). The mean of particle concentration (MPC) in the respiratory zone of animals as the response variable, and height of the cylindrical section of the chamber, carrier gas density, inlet concentration, and particle aerodynamic diameter ( da ) as independent variables were considered. Experiments were performed by numerical simulation using ANSYS Workbench package. Particle concentration sampling was measured in 40 points at the opening of each holder in CFD-Post software. To determine the optimal range of the chamber's height, the different of MPC among the holders’ opening was investigated by the ANOVA test. The final mathematical model was achieved by analyzing the response variables in DE7.Results Thirty designs in five geometries with different heights were introduced as the matrix of experiments by DE7. The optimal height was obtained 2-2.5 times the radial of the cylindrical section. Analysis of the results suggested a linear model (2FI) with coefficients of recognition higher than 99%. The final model was significant with the presence of the inlet concentration and da . Gas density and height had no significant effect and were removed ( P >0.05).Conclusion The optimization of the geometry of the ASRA chamber resulted in a uniform and stable distribution of the particles and provided an accurate mathematical model to predict the particle concentration in the target zone.

Computational fluid dynamics analysis of flow through immobilized catalyzed packed bed reactor for removal of 4-chlorophenol from wastewater

The computational fluid dynamics (CFD) simulation of the packed bed reactor (PBR) was carried out using ANSYS Fluent software. The various process parameters, such as inlet concentration of 4-chlorophenol (4-CP), flow rate, bed height, and porosity, were optimized to predict maximum biodegradation of 4-CP in immobilized catalyzed PBR. The geometrical mesh of the PBR was constructed using Gambit software, and a mesh size of 236995 was selected from the grid-independent study. A laminar flow model was used to understand the hydrodynamics as well as concentration profile of 4-CP inside the PBR using Fluent software. Through CFD, the effect of the flow rate, inlet concentration, and the bed height and porosity of the immobilized catalyst bed on the static pressure, mass imbalance, velocity, and stress-strain field inside the PBR was visualized. CFD simulation study predicted that maximum biodegradation of 4-CP was found in the presence of 500 mg/L of inlet concentration of 4-CP, 4 mL/min of flow rate, 18 cm of bed height and 0.375 of porosity. An experimental study was conducted for wastewater flow through the <i>B. subtilis MF447840.1</i> immobilized catalyzed PBR to remove the 4-CP in the laminar flow region. It was evident that CFD simulated results agreed well with experimental values.