In this work, the capture of carbon dioxide using a dense hollow fiber membrane was studied experimentally and theoretically. The factors affecting the flux and recovery of carbon dioxide were studied using a lab-scale system. Experiments were conducted using a mixture of methane and carbon dioxide to simulate natural gas. The effect of changing the CO₂ concentration from 2 to 10 mol%, the feed pressure from 2.5 to 7.5 bar, and the feed temperature from 20 to 40 °C, was investigated. Depending on the solution diffusion mechanism, coupled with the Dual sorption model, a comprehensive model was implemented to predict the CO₂ flux through the membrane, based on resistance in the series model. Subsequently, a 2D axisymmetric model of a multilayer HFM was proposed to simulate the axial and radial diffusion of carbon dioxide in a membrane. In the three domains of fiber, the CFD technique was used to solve the equations for the transfer of momentum and mass transfer by using the COMSOL 5.6. Modeling results were validated with 27 experiments, and there was a good agreement between the simulation results and the experimental data. The experimental results show the effect of operational factors, such as the fact that temperature was directly on both gas diffusivity and mass transfer coefficient. Meanwhile, the effect of pressure was exactly the opposite, and the concentration of CO₂ had almost no effect on both the diffusivity and the mass transfer coefficient. In addition, the CO₂ recovery changed from 9% at a pressure equal to 2.5 bar, temperature equal to 20 °C, and a concentration of CO₂ equal to 2 mol%, to 30.3% at a pressure equal to 7.5 bar, temperature equal to 30 °C, and concentration of CO₂ equal 10 mol%; these conditions are the optimal operating point. The results also manifested that the operational factors that directly affect the flux are pressure and CO₂ concentration, while there was no clear effect of temperature. This modeling offers valuable data about the feasibility studies and economic evaluation of a gas separation unit operation as a helpful unit in the industry.

The disposal of wastewater resulting from petroleum industries presents a major environmental challenge due to the presence of hard-to-degrade organic pollutants, such as oils and hydrocarbons, and high chemical oxygen demand (COD). In this study, an efficient and eco-friendly method was developed to treat such wastewater using a photocatalyst composed of biochar derived from pistachio shells and loaded with zinc oxide (ZnO) nanoparticles. The biochar-ZnO composite was prepared via a co-precipitation-assisted pyrolysis method to evaluate its efficiency in the photocatalytic degradation of petroleum wastewater (PW). The synthesized material was characterized using various techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy, to determine surface morphology, crystal structure, and functional groups present on the catalyst surface. Photocatalytic degradation experiments were conducted under UV and sunlight for 90 h of irradiation to evaluate the performance of the proposed system in removing oil and reducing COD levels. Key operational parameters, such as pH (2–10), catalyst dosage (0–0.1) g/50 mL, and oil and COD concentrations (50–500) ppm and (125–1252) ppm, were optimized by response surface methodology (RSM) to obtain the maximum oil and COD removal efficiency. The oil and COD were removed from PW (90.20% and 88.80%) at 0.1 g/50 mL of PS/ZnO, a pH of 2, and 50 ppm oil concentration (125 ppm of COD concentration) under UV light. The results show that pollutant removal is slightly better when using sunlight (80.00% oil removal, 78.28% COD removal) than when using four lamps of UV light (77.50% oil removal, 75.52% COD removal) at 0.055 g/50 mL of PS/ZnO, a pH of 6.8, and 100 ppm of oil concentration (290 ppm of COD concentration). The degradation rates of the PS/ZnO supported a pseudo-first-order kinetic model with R² values of 0.9960 and 0.9922 for oil and COD. This work indicates the potential use of agricultural waste, such as pistachio shells, as a sustainable source for producing effective catalysts for industrial wastewater treatment, opening broad prospects in the field of green and nanotechnology-based environmental solutions in the development of eco-friendly and effective wastewater treatment technologies under solar light.

In the present work, a novel eco-friendly nanocatalyst (NC) calcium oxide (CaO) is synthesized from the waste of tomato plants by physical method for the degradation of oil in oily wastewater by photocatalytic technology as a sophisticated oxidation process. The characterization of NC prepared is described by dynamic light scattering (DLS), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray (EDX) spectroscopy, which illustrated that the NC prepared possessed a nanoscale size and a cubic crystal structure. The activity of NC in the photodegradation process is evaluated using oil concentration (100–500 ppm), amount of NC (0.1–1) g/L, and pH (4–12) at a specific aeration rate of 1 L/min and time irradiation of 30–180 min and under UV light. The findings showed that the degradation efficiency of oil increased with an increased amount of NC, time, and pH while decreasing with increased oil concentration. The maximum degradation of oil reached 83.0% at optimum conditions (oil concentration = 100 ppm, amount of NC = 0.6 g/L, pH = 7, time of irradiation = 120 min, and temperature = 23 ◦C). This work illustrates that the novel NC can be employed as an environmentally friendly and economical photocatalyst and might be improved in its characteristics and performance by thermal technique (calcination) to enhance the reduction of oil from oily wastewater.

The growing concern about global warming and climate has raised the research field dedicated to finding solutions. One area that has received considerable attention is the exponential increase of carbon dioxide emissions from the atmosphere from the petroleum and gas industries. So, to solve this problem, researchers investigated new ways to collect CO2 from the air depending on the fact that CO2 is soluble in water because using aqueous amine absorbents to collect CO2 has a lot of drawbacks, such as the need for tremendous energy to recycle the solvent and high operational costs. In this study, a specific type of deep eutectic solvent (DES), namely Choline chloride + monoethanolamine (ChCl-MEA), was used as a promising solvent in the CO2 capture process. Solubility measurements were conducted at 1:6 molar ratios. The amines chosen are typical of basic amines. Experiment absorption data were investigated at various parameters, including a concentration range of 0–3 mol/L, temperatures ranging from 25 to 45 °C, and absorption durations ranging from 60 to 120 minutes, to get the best conditions for high-loading CO2 uptake. The study found that amine-based DESs had a significantly greater absorption capacity than monoethanolamine-based and conventional DESs. The study examined what happened when water was added to a deep eutectic solvent made of choline chloride and monoethanolamine (ChCl-MEA DES). The most effective way to absorb CO2 was physical absorption, which can hold 276.13 mol CO2 per gram of DES at 1 bar and 29.025 °C when mixed with water. The deep eutectic was mixed with water to increase the absorption efficiency. 10 ml of aqueous solution (DESs + water) was taken. The combination of DES and water significantly increased CO2's low solubility. The modified Design-Expert model satisfactorily represents the experimental solubility of CO2 in the solvent. The average percent differences between experimental and projected values were 10.7% and 6.8% for binary and ternary systems, respectively. The optimal conditions for maximum absorption rate were 29.025°C, 2.233 mol/L, and 101 minutes, with an absorption ratio of 0.0734 mol/kg.min and efficiency of absorption of 85.3% for solution DESs and water.

The separation of CO₂ from flue gases presents a crucial challenge that needs to be addressed. However, membrane processes offer a promising alternative solution. Polysulfone (PSF)membranes were prepared using N-methyl-2-pyrrolidone (NMP) and tetrahydrofuran (THF) using a dry–wet phase inversion technique. The membranes were fabricated with the selection of casting parameters, PSF concentration (20–30 wt%), solvent ratio of THF/NMP (0/100–35/65), and evaporation time (0–4 min). In this work, the interaction between these influencing factors during preparation and membrane performance was studied. Scanning electron microscopy (SEM) was used to characterize the membranes for morphological investigation. Taguchi statistical analysis was employed in the Minitab-19 software used for the design of the experiments in this study, and the responses of the CO₂ permeance and CO₂/N₂ separation factor were analyzed and optimized based on the casting parameters. The results showed the CO₂ permeance of the membranes was determined between 1.25 ± 0.04 and 8.47 ± 0.51GPU and selectivity was between 2.95 and 8.92.