Carbon Membranes Derived From Polymer Blend Of Polyetherimide And Polyethylene Glycol For Gas Separation

Teknologi membran menawarkan banyak kelebihan berbanding kaedah pemisahan gas konvensional seperti kesederhanaan dan kemudahan operasi. Membran karbon mempunyai rintangan haba yang tinggi dan kestabilan kimia yang baik dalam persekitaran mengakis. Dalam kajian ini, dalam usaha untuk meningkatkan kebolehtelapan gas, membran karbon telah disintesis daripada gaulan polimer polieterimida (PEI) dan polietilena glikol (PEG). Membran karbon PEG/PEI telah disintesis di atas sokongan alumina disalut dengan lapisan pertengahan Al2O3. Kesan parameter penyediaan yang berbeza kepada morfologi, sifat struktur dan prestasi pemisahan membran karbon telah dikaji dengan mengubah nisbah gaulan (0, 0.1, 0.2, 0.3 dan 0.4 PEG:PEI), suhu karbonisasi (550, 600, 650 dan 700 °C), kadar pemanasan (1, 3, 5 dan 7 °C/minit) dan masa rendaman (1, 2 dan 3 jam). Membran karbon PEG/PEI dengan prestasi pemisahan yang terbaik terus diuji pada suhu penyerapan (25, 50, 75 dan 100 °C) dan tekanan suapan (2, 2.5, 3 dan 3.5 bar) yang berbeza. Prestasi pemisahan membran karbon PEG/PEI terus disiasat dengan campuran gas binari CO2/CH4, CO2/N2 dan O2/N2. Daripada keputusan pencirian, membran karbon PEG/PEI terdiri daripada tiga lapisan berbeza; lapisan karbon, lapisan pertengahan Al2O3 dan sokongan alumina. Keputusan XRD menunjukkan bahawa membran karbon PEG/PEI mempunyai struktur amorfus. Luas permukaan BET membran karbon terhasil daripada nisbah gaulan 0.1 PEG:PEI (ditandakan sebagai membran karbon PEG1/PEI) meningkat kepada 544.07 m2/g berbanding 248.75 m2/g oleh membran karbon tulen PEI. Ketelapan CO2 dan O2 membran karbon PEG1/PEI meningkat kepada masingmasing 1685 dan 927 barrer berbanding 421 dan 262 barrer dipamerkan oleh membran karbon PEI. Membran karbon yang diperoleh daripada nisbah gaulan 0.1 PEG:PEI dan dikarbonisasi pada suhu 650 °C dengan kadar pemanasan 1 °C/minit dan masa rendaman 2 jam menunjukkan prestasi pemisahan yang terbaik dengan pemilihan unggul CO2/CH4, CO2/N2 dan O2/N2 yang tertinggi iaitu masing-masing 64.72, 38.02 dan 5.05. Bagi campuran gas binari, sampel ini mempamerkan pemilihan CO2/CH4, CO2/N2 dan O2/N2 masing-masing sebanyak 38.10, 34.74 dan 3.98. Prestasi membran karbon terjejas akibat kesan penuaan membran. Selepas proses pembangunan semula pada suhu 300 °C, ketelapan CO2 dan O2 membran karbon PEG1/PEI pulih sebanyak 80 % daripada ketelapan asal dengan pemilihan unggul CO2/CH4, CO2/N2 dan O2/N2 masing-masing 75.23, 45.54 dan 6.09. Secara keseluruhan, membran karbon PEG1/PEI menunjukkan prestasi pemisahan yang lebih baik dengan peningkatan ketelapan gas dan pemilihan unggul berbanding membran karbon PEI. ________________________________________________________________________________________________________________________ Membrane technology offers many advantages over conventional gas separation methods such as simplicity and ease operation. Carbon membrane has a high thermal resistance and good chemical stability in corrosive environments. In the present study, in order to enhance the gas permeability, carbon membrane was synthesized from polymer blend of polyetherimide (PEI) and polyethylene glycol (PEG). The PEG/PEI carbon membrane was synthesized on the alumina support coated with an Al2O3 intermediate layer. The effect of different preparation parameters on the carbon membranes properties and separation performance were studied by varying the blend ratios (0, 0.1, 0.2, 0.3 and 0.4 PEG:PEI), carbonization temperatures (550, 600, 650 and 700 °C), heating rates (1, 3, 5 and 7 °C/min) and soaking times (1, 2 and 3 h). The PEG/PEI carbon membrane with the best separation performance was further tested at the different permeation temperatures (25, 50, 75 and 100 °C) and feed pressures (2.0, 2.5, 3.0 and 3.5 bar). The PEG/PEI carbon membrane separation performance was further investigated with the binary gas mixtures of the CO2/CH4, CO2/N2 and O2/N2. From the characterization results, the PEG/PEI carbon membranes consist of three distinguish layers; a carbon layer, Al2O3 intermediate layer and alumina support. The XRD results revealed that the PEG/PEI carbon membrane has an amorphous structure. The BET surface area of the carbon membrane derived from 0.1 PEG:PEI blend ratio (denoted as PEG1/PEI carbon membrane) increased to 544.07 m2/g ratio rather than 248.75 m2/g by pure PEI carbon membrane. The CO2 and O2 permeability of the PEG1/PEI carbon membrane increased to 1685 and 927 barrer, respectively rather than 421 and 262 barrer exhibited by PEI carbon membrane, respectively. The carbon membrane derived from 0.1 PEG:PEI blend ratio and carbonized at temperature of 650 °C with heating rate of 1 °C/min and 2 h of soaking time showed the best separation performance with the highest of the CO2/CH4, CO2/N2 and O2/N2 ideal selectivities of 64.72, 38.02 and 5.05, respectively. For binary gas mixtures, this sample exhibited the CO2/CH4, CO2/N2 and O2/N2 selectivities of 38.10, 34.74 and 3.98, respectively. The carbon membrane performance was affected by the effect of membrane aging. After regeneration at temperature of 300 °C, the PEG1/PEI carbon membrane restored about 80 % of the original CO2 and O2 permeability with CO2/CH4, CO2/N2 and O2/N2 ideal selectivity of 75.23, 45.54 and 6.09, respectively. Overall, the PEG1/PEI carbon membranes exhibited better separation performance with enhanced gas permeability and ideal selectivity compared to pure PEI carbon membrane

Controlled Carbonization Heating Rate for Enhancing CO2 Separation Based on Single Gas Studies

Concerns about the impact of greenhouse gas have driven the development of new separation technology to meet CO2 emission reduction targets. Membrane-based technologies using carbon membranes that are able to separate CO2 efficiently appears to be a competitive method. This research was focused on the development of carbon membranes derived from polymer blend of polyetherimide and polyethylene glycol to separate CO2 rendering it suitable to be used in many applications such as landfill gas purification, CO2 removal from natural gas or flue gas streams. Carbonization process was conducted at temperature of 923 K and 2 h of soaking time. To enhance membrane separation properties, pore structure was tailored by varying the carbonization heating rates to 1, 3, 5, and 7 K / min. The effect of carbonization heating rate on the separation performance was investigated by single gas permeabilities using CO2 , N2 , and CH4 at room temperature. Carbonization heating rate of 1 K / min produced carbon membrane with the most CO2 / N2 and CO2 / CH4 selectivity of 38 and 64, respectively, with the CO2 permeability of 211 barrer. Therefore, carbonization needs to be carried out at sufficiently slow heating rates to avoid significant loss of selectivity of the derived carbon membranes

Encapsulation of freeze-dried propolis powder: Study of in vitro disintegration and dissolution

Propolis is a resinous material collected by bees from various plant sources. Propolis has been used since ancient times for medicinal purposes. In this study, the propolis extracts were dried using a freeze-drying technique to preserve its medicinal properties. The effect of different freezing temperatures on the yield and propolis powder flow ability characteristics was evaluated. The potential of propolis powder to be encapsulated in hard gelatin capsules and hard hydroxypropyl methylcellulose (HPMC) capsules were investigated. The mass uniformity, in vitro disintegration and dissolution performance of the propolis powder in hard gelatine capsules and hard HPMC capsules were determined after encapsulation. The amount of propolis powder produced after freeze-drying decreased with decreasing of freezing temperature from -50°C to -80°C. Propolis powder obtained at -80°C of freezing temperature showed excellent flow ability characteristics. The average mass of propolis powder in hard gelatine capsules and the propolis powder in hard HPMC capsules was 0.5578 ± 0.019g and 0.5559 ± 0.020 g, respectively. In vitro disintegration test showed that the propolis powder that was loaded into the hard gelatine capsules disintegrated faster than the propolis powder loaded into the hard HPMC capsules, which were 1.7 to 7.8 min and 3.7 to 8.4 min in all four media solutions. Among the dissolution media tested, 1 % SLS in water showed the highest release of flavonoid. The studies of an encapsulated form of propolis powder are recommended prior to the release of a dietary supplement or clinical trial investigational product to ensure its efficacy

Qualitative risk assessment in V-Blender using Bayesian Network

The development of solid dosage is very important in the production process, especially in powder blending. Moreover, the homogeneity of products can be influenced by the performance of powder blending operations that do not conform to the desired specifications and therapeutic effect as regulation by the Food and Drug Administration (FDA) may be detrimental to consumers. In addition, the International Conference on Harmonization (ICH) has also taken initiatives to improve production standards by establishing ICH 9 for Quality Risk Management (QRM). This is why drugs must be manufactured with high quality, safety, and effectiveness to ensure the safety of drug manufacturers as well as consumers. The objective of this research work is to study and investigated the probabilistic relationship between process parameters that can affect the blender performance that led to blending inhomogeneity by using the Qualitative Risk Assessment (QRA) method. QRA method is performed in order to categorize the identification risk level exposed in powder blending with low, medium, and high levels. The method of QRA that has been applied in this study is the Bayesian Network (BN) model. Furthermore, the BN is one of the risk assessment tools that present the parameters and their conditional independence using a directed aversion plot (DAG). The BN was used to verify the process parameters that could cause the failure of blending unit operation are fill level, loading order, blending time, and blending speed. However, from the outcome, the critical process parameters (CPPs) that have a greater risk of affecting homogeneity are a combination of fill level, loading order, and blending speed with 0.62 while the highest probabilities value of failure was a combination of fill volume, loading order and blending time with 0.92. The medium probabilities value of failure was a combination of fill level, blending time, blending speed, and combination of loading order, blending time and blending speed, which was 0.77 and 0.69, respectively. Moreover, it can be concluded that the failure that caused by the related process parameter is 0.75 for a true statement while the false statement is 0.25. This can be concluded that not all of the process parameters can impact the blender operation on the degree of product homogeneity. For further studies, it is possible to address the limitation of the BN in combination with a quantitative risk assessment to confirm the results and minimize the risk of failure by practicing the preventive method

Effects of extraction method, solvent and time on the bioactive compounds and antioxidant activity of Tetrigona apicalis Malaysian propolis

Propolis, a type of resin produced by honey bees, has many medicinal properties. Various extraction methods and conditions had been studied to extract the bioactive compounds from raw propolis. However, different extraction methods and extraction conditions were reported to exhibit different extraction efficiencies. Hence, in this study, different extraction methods, namely maceration, ultrasound-assisted extraction and combination of maceration and ultrasound-assisted extraction, as well as extraction solvents and extraction times, were examined to investigate the effects on the amount of total phenolic content, total flavonoid content and antioxidant activity of Tetrigona apicalis Malaysian propolis extract. Experimental results showed that combination method of maceration and ultrasound-assisted extraction is the best method for extracting the highest amount of total phenolic content with 70% aqueous ethanol as solvent and obtained at the longest extraction time (24 h of maceration and 60 min of ultrasound-assisted extraction). While for total flavonoid content, maceration exhibited the best extraction method and the highest amount of flavonoid was obtained from 80% aqueous ethanol at the lowest extraction time (8 h). Meanwhile, antioxidant activity was found to have strong correlations with phenolic and flavonoid contents. In conclusion, it is crucial to develop effective extraction method and conditions depending on the targeted compounds and desired properties to enhance the extraction efficiency. © 2021 International Bee Research Association

Highly sensitive SPR response of Au/chitosan/graphene oxide nanostructured thin films toward Pb (II) ions

Optical sensors based on surface plasmon resonance (SPR) are utilized for detecting toxic heavy metals in solutions. To improve the sensitivity of SPR sensors, nanostructured thin films with active layers can be synthesized. In this study, the response to Pb (II) was measured and compared for SPR sensors incorporating gold–chitosan–graphene oxide (Au/CS/GO) nanostructured thin films and Au/CS films. The characterization of Au/CS/GO using FESEM analysis revealed a film composed of nanosheets with wrinkled, rough surfaces. The results from XRD analysis confirmed the successful incorporation of GO in the prepared films. Additionally, AFM analysis determined that the Au/CS/GO films had a root mean square (rms) roughness of 28.38 nm and were considerably rougher than the Au/CS films. Upon exposure to a 5 ppm Pb (II) ion solution, the Au/CS/GO films exhibited higher SPR sensitivity, as much as 1.11200 ppm−1, than Au/CS films, 0.77600 ppm−1. This enhancement of the SPR response was attributed to strong covalent bonding between CS and GO in these films. These results indicated that the Au/CS/GO films show potential for the detection of heavy metal pollution in environmental applications

Comparison of Total Phenolic Contents and Antioxidant Activities of Centella asiatica Extracts Obtained by Three Extraction Techniques

Through different extraction techniques, the potential of Centella asiatica as a natural source of antioxidant was investigated. The C. asiatica aqueous extracts were obtained via infusion, decoction and ultrasound-assisted extraction techniques. The effects of different extraction techniques were studied on the extraction yield, total phenolic contents and antioxidant activity. The total phenolic contents of the extracts and antioxidant activity were examined using the Folin-Ciocalteu’s reagent and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assay, respectively. Results indicated that the UAE exhibited the highest extraction yield, highest total phenolic contents, as well as highest antioxidant activity. The yield of the extracts increased in the order of infusion < decoction < UAE which were 18.2 %, 23.6% and 25.4 %, respectively. All extraction techniques had a significant effect (p <0.05) on the total phenolic contents and antioxidant activity of C. asiatica extracts. The total phenolic contents ranged from 3.42 0.030 to 8.32 0.105 mg GAE/g dry extract while the antioxidant activity was in the range of 75 to 86 %. This study confirms that C. asiatica has the potential to be a good resource for the future development of natural antioxidant. In addition, extraction via UAE can be an ideal technique to obtain phytochemical-rich extracts from medicinal plants

Controlled Carbonization Heating Rate for Enhancing CO2 Separation Based on Single Gas Studies

Concerns about the impact of greenhouse gas have driven the development of new separation technology to meet CO2 emission reduction targets. Membrane-based technologies using carbon membranes that are able to separate CO2 efficiently appears to be a competitive method. This research was focused on the development of carbon membranes derived from polymer blend of polyetherimide and polyethylene glycol to separate CO2 rendering it suitable to be used in many applications such as landfill gas purification, CO2 removal from natural gas or flue gas streams. Carbonization process was conducted at temperature of 923 K and 2 h of soaking time. To enhance membrane separation properties, pore structure was tailored by varying the carbonization heating rates to 1, 3, 5, and 7 K / min. The effect of carbonization heating rate on the separation performance was investigated by single gas permeabilities using CO2 , N2 , and CH4 at room temperature. Carbonization heating rate of 1 K / min produced carbon membrane with the most CO2 / N2 and CO2 / CH4 selectivity of 38 and 64, respectively, with the CO2 permeability of 211 barrer. Therefore, carbonization needs to be carried out at sufficiently slow heating rates to avoid significant loss of selectivity of the derived carbon membranes

Comparative study on surgical outcomes between laparoscopic and open cornuotomy in urban tertiary center of Malaysia

Study Objective: The objective of the study was to evaluate the prevalence of interstitial ectopic pregnancy and to compare the surgical outcomes of laparoscopic cornuotomy (LC) and laparotomy (open) cornuotomy (OC) of cornual ectopic pregnancy and to analyze its associated factors. Materials and Methods: A cross-sectional study was conducted involving cases of interstitial ectopic in Hospital Putrajaya, Putrajaya, Malaysia, over a 10-year period (2005–2014). Data on sociodemographic, clinical profile, perioperative, and postoperative were obtained from the electronic medical records. Measurement and Main Results: The prevalence of cornual pregnancy was 4.0% (n = 14) out of total 347 cases of all ectopic pregnancies in Putrajaya Hospital. The mean ± standard deviation age of patient in the LC group and OC group was 29.3 ± 5.9 years and 31.4 ± 7.3 years, respectively. The duration of hospitalization and mean operating time were both significantly shorter in the LC group than in the OC group (1.43 ± 0.54 versus 2.57 ± 0.79 and 61.4 ± 15.7 min versus 97.1 ± 38.2 min, respectively, P < 0.05).There were no statistically significant differences between both groups for the estimated blood loss, requirement of blood transfusion, complications, and future fertility. Conclusion: Laparoscopic cornual resection (cornuotomy) is a safe and less invasive procedure with a comparable complication rate. It has shown that it is feasibility and should be considered as initial treatment in managing those cases in trained hand surgeons