CO2 selective carbon tubular membrane: the effect of stabilization temperature on BTDA-TDI/MDI P84 co-polyimide

Membranes offer remarkable attributes such as possessing small equipment footprints, having high efficiency and are environmentally friendly, with carbon membranes progressively investigated for gas separation applications. In this study, carbon tubular membranes for CO2 separation are prepared via dip-coating method with P84 co-polyimide as carbon precursor. The prepared membranes were characterized using Thermogravimetric Analysis (TGA), pore structure analysis Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and pure gas permeation system. The permeation properties of the carbon membranes are measured and analyzed using CO2, CH4 and N2 gases. The P84-based carbon tubular membrane stabilized at 300°C and featured excellent permeation properties with permeance range of 2.97±2.18, 3.12±4.32 and 206.09±3.24 GPU for CH4, N2 and CO2 gases, respectively. This membrane exhibited the highest CO2/CH4 and CO2/N2 selectivity of 69.48±1.83 and 65.97±2.87, respectively

Limitation in fabricating PSf/ZIF-8 hollow fiber membrane for CO2/CH4 separation

Hollow fiber membrane configuration is way forward in membrane development since it possesses higher packing density and effective surface area per unit module compared to other configuration. Since majority of mixed matrix membrane (MMM) for gas separation reported focuses on flat sheet membrane development, this report aims to address the challenges faced in fabricating hollow fiber MMM. In this study, hollow fiber formulation is fabricated and their MMM using different types of fillers (virgin and modified ZIF-8) are prepared and used as a dispersed phase. The neat hollow fiber membrane shows good results with CO2 permeance of 104.39 GPU and CO2/CH4 selectivity of 29.28, in comparison with reported literature. Upon filler incorporation, the resulted MMMs appear to be diminished in both CO2 permeance and CO2/CH4 selectivity. While using modified ZIF-8, lesser deterioration was shown compared to pure ZIF-8, this phenomenon is likely to occur due to the changes in solution stability which causes notable changes in membrane morphology and performances

Effect of Membrane Materials and Operational Parameters on Performance and Energy Consumption of Oil/Water Emulsion Filtration

Membrane technology is one of reliable options for treatment of oil/water emulsion. It is highly attractive because of its effectiveness in separating fine oil droplets of 3000 ppm to a point of no flux

Controlled dip-coating times for improving Co2 selective of PI/NCC based supported carbon membrane

Carbon membrane can be regarded as the future separation media in gas separation process due to its high gas separation performance, easy processability, and moderate energy requirement compared to conventional separation process. In this study, the fabrication of tubular carbon membrane prepared from PI blends with nanocrystalline cellulose (NCC) was investigated. The influence of dip-coating duration (15, 30, 45, and 60 min) towards the physicochemical properties and CO2/CH4 and O2/N2 separation was explored. The process of carbonization was conducted at 800°C with rate of heating at 3°C/min under argon gas flow (200 mL/min). Pure gas permeation tests were performed to investigate the prepared carbon membrane’s mechanism of transport at ambient temperature and a feed pressure of 8 bar. The carbon membrane with CO2/CH4 and O2/N2 selectivity of 68.23 ± 3.27 and 9.29 ± 2.54 and CO2 and O2 permeance of 213.56 ± 2.17 and 29.92 ± 1.44 GPU, respectively, were obtained when applying 45 min dip-coating

Isotherms, kinetics, and thermodynamics of boron adsorption on fibrous polymeric chelator containing glycidol moiety optimized with response surface method

A fibrous boron chelator containing glycidol moiety (PE/PP-g-PVAm-G) was prepared by radiation induced grafting of N-vinylformamide (NVF) onto polyethylene/polypropylene (PE/PP) non-woven sheet followed by hydrolysis and immobilization of glycidol moiety. The glycidol density was controlled by optimization of the reaction parameters using the Box-Behnken design of response surface methodology (RSM). The properties of the PE/PP-g-PVAm-G were evaluated using Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and energy dispersive x-ray (EDX) analysis, X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). A maximum glycidol density yield of 5.0 mmol·g−1 was obtained with 11.8 vol%, 78.9 °C and 109.4 min for glycidol concentration, reaction temperature and time, respectively. The isotherms, kinetics, and thermodynamic behavior of boron adsorption on the optimized chelator were investigated. The boron adsorption was pH-dependent and attained a maximum adsorption capacity of 25.7 mg·g−1. The equilibrium isotherm proceeded by Redlich–Peterson model whereas the kinetics was best expressed by the pseudo-second-order equation. The thermodynamic analysis revealed that boron adsorption is endothermic and spontaneous. The fibrous chelator demonstrated high boron selectivity and strong resistance to foreign ions with uncompromised regeneration efficiency after five adsorption/desorption cycles. The PE/PP-g-PVAm-G chelator seems to be very promising for boron removal from aqueous media

Fabrication of magnesium bentonite hollow fibre ceramic membrane for oil-water separation

In this study, low-cost magnesium bentonite (MB) was used for the fabrication of bentonite hollow fibre (BHF) membrane with high pure water flux. MB powder was initially characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size distribution (PSD) analyser, Brunnauer -Emmett- Teller (BET) method, and field emission scanning electron microscope (FESEM). The BHF membrane obtained was then fabricated through dope suspension mixing, phase inversion and sintering process. The dope suspension was prepared by mixing MB, dispersant, polymer binder, and solvent using a planetary ball mill. While the spinning process was carried out at the extrusion rate of 8 mL/min, a fluid bore rate of 10 mL/min and air gap of 5 cm, and this was followed by sintering operation at 950 °C, 1000 °C, 1050 °C, and 1100 °C. The resulting BHF membrane was characterized by scanning electron microscopy (SEM) and XRD; the porosity test, water flux and oil rejection were also examined. The SEM surface morphology of BHF at sintering temperature of 950 °C showed spongy-like and nested macrovoids structure; the porosity was 49.09% with a mean pore size of 3.9 µm. The performance test on the bentonite-based hollow fibre membrane showed that the membrane prepared at 20 wt% and sintering temperature of 1000 °C, which induced high and stable permeate water flux and oil rejection of BHFC membrane were 544 L/m2 h and 97%, respectively. The results have shown that the presence of magnesium in bentonite can enhance and promote the needed support material for the fabrication of hollow fibre ceramic membrane

Development of asymmetric polysulfone and zeolitic imidazole framework 8 mixed matrix membrane for carbon dioxide and methane separation

Metal-Organic Framework (MOF) materials such as Zeolitic Imidazole Framework 8 (ZIF-8) have been considered among ideal filler in mixed matrix membrane (MMM) due to their good compatibility with various polymer matrices. However, limitations suffered by ZIF-8 such as commercially expensive and hardly available in small particle size and poor intrinsic separation properties have hindered its great potential. To address these issues, this study aims to synthesize and characterize ZIF-8, followed by fabricating and evaluating the performances of ZIF-8 loaded asymmetric flat sheet polysulfone (PSf) MMM for CO2/CH4 separation. ZIF- 8 was prepared via the method of aqueous room temperature media with base-type additive, triethylamine (TEA), with ratio ranging 0-0.007 to assist ZIF-8 formation. The synthesized ZIF-8s were characterized with respect to their phase crystallinity, particle size and thermal stability. The synthesis approach is considerably attractive due to relatively lower metal/ligands/solvent ratio requirement, rapid process, and high yield while retaining its intrinsic properties. The PSf/ZIF-8 MMMs incorporated with as-synthesized and heat-treated (100°C for 12 hours) ZIF-8 with different particle sizes (~100 nm, ~300 nm, and ~500 nm) were prepared via dry/wet phase inversion. The prepared membranes were evaluated with respect to their morphology, mechanical and thermal properties, and gas separation performance. Pure phase ZIF-8s were obtained with TEA/total mole ratios of 0.004-0.007 and its particle size decreased with increasing TEA ratios. The membrane characterizations as well as gas permeation test results showed that the heat-treated ZIF-8 with ~100nm particle size provided good interaction with PSf matrix. MMM loaded with 0.5wt% of heat-treated ZIF-8 produced the optimum CO2 permeance (29.22 GPU) and CO2/CH4 selectivity (23.16), while higher loading deteriorated the separation performances. Modification of ZIF-8 particle with 25mL and 50mL ammonium hydroxide solution at ice bath temperature, room temperature and 60°C was found to significantly improve its properties, i.e. phase crystallinity, pore properties and BET surface area, while preserving its overall structure. PSf/ZIF-8 MMM loaded with 0.5wt% ZIF-8 modified under 25mL ammonium hydroxide solution at 60°C increased CO2/CH4 selectivity 72% higher than neat PSf membrane, without diminishing CO2 permeance. Hence, the promising results obtained in this study demonstrates the potential of MOF, especially ZIF-8 based MMM for gas separation, specifically CO2 separation and thus warrants further investigation

VLE of Carbon Dioxide-Loaded Aqueous Potassium Salt of L-Histidine Solutions as a Green Solvent for Carbon Dioxide Capture: Experimental Data and Modelling

In this study, vapour-liquid equilibrium of CO2-loaded aqueous potassium salt of L-histidine was studied for a wide range of temperature (313.15–353.15 K), pressure (150–4000 kPa), and solvent concentrations (1–2.5 molar). The experimental results show that L-histidine has an excellent absorptive capacity for carbon dioxide. When compared to conventional solvent (monoethanolamine) and amino acid salt (potassium L-lysinate) at similar process conditions, L-histidine has superior absorption capacity. Moreover, modified Kent–Eisenberg model was used to correlate the VLE of the studied system with excellent agreement between the model and experimental values. The model exhibited an AARE% of 7.87%, which shows that it can satisfactorily predict carbon dioxide solubilities in aqueous potassium salt of L-histidine at other process conditions. Being a biological component in origin, almost negligibly volatile, and highly resistant to oxidative degradation, L-histidine offers certain operational advantages over other solvents used and has a promising potential for carbon dioxide capture