In this paper, the ability of coconut bunch waste (CBW), an agricultural waste available in large quantity in Malaysia, to remove basic dye (methylene blue) from aqueous solution by adsorption was studied. Batch mode experiments were conducted at 30 degrees C to study the effects of pH and initial concentration of methylene blue (MB). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 70.92 mg/g at 30 degrees C. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model.
Bamboo, an abundant and inexpensive natural resource in Malaysia was used to prepare activated carbon by physiochemical activation with potassium hydroxide (KOH) and carbon dioxide (CO(2)) as the activating agents at 850 degrees C for 2h. The adsorption equilibrium and kinetics of methylene blue dye on such carbon were then examined at 30 degrees C. Adsorption isotherm of the methylene blue (MB) on the activated carbon was determined and correlated with common isotherm equations. The equilibrium data for methylene blue adsorption well fitted to the Langmuir equation, with maximum monolayer adsorption capacity of 454.2mg/g. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. The adsorption of methylene blue could be best described by the pseudo-second-order equation. The kinetic parameters of this best-fit model were calculated and discussed.
Mixed matrix membranes (MMMs) separation is a promising technology for gas permeation and separation involving carbon dioxide (CO2). However, finding a suitable type of filler for the formation of defect-free MMMs with enhancement in gas permeability remains a challenge. Current study focuses on synthesis of KIT-6 silica and followed by the incorporation of KIT-6 silica as filler into polysulfone (PSF) polymer matrix to fabricate MMMs, with filler loadings of 0-8 wt %. The effect of KIT-6 incorporation on the properties of the fabricated MMMs was evaluated via different characterization techniques. The MMMs were investigated for gas permeability and selectivity with pressure difference of 5 bar at 25 °C. KIT-6 with typical rock-like morphology was synthesized. Incorporation of 2 wt % of KIT-6 into PSF matrix produced MMMs with no void. When KIT-6 loadings in the MMMs were increased from 0 to 2 wt %, the CO2 permeability increased by ~48%, whereas the ideal CO2/CH4 selectivity remained almost constant. However, when the KIT-6 loading in PSF polymer matrix was more than 2 wt %, the formation of voids in the MMMs increased the CO2 permeability but sacrificed the ideal CO2/CH4 selectivity. In current study, KIT-6 was found to be potential filler for PSF matrix under controlled KIT-6 loading for gas permeation.
Membrane distillation (MD) is an advantageous separation process compared with pressure-driven technologies and was subsequently introduced to treat aquaculture wastewater. Harnessing a superhydrophobic membrane in an MD process is of extreme importance to prevent membrane wetting. In this work, the electrospun polypropylene (PP) membrane was surface modified by depositing an additional coating of PP via the solvent-exchange method, thereby improving the membrane's superhydrophobicity. Layer-by-layer deposition of PP caused the formation of uniform polymer spherulites on the membrane surface, which levelled up the membrane's surface roughness. A superhydrophobic surface was achieved by applying a single-layered PP coating, with static water contact angle of 152.2° and sliding angle of 12.5°. While all membranes achieved almost perfect salt rejection (up to 99.99%), the MD permeate flux improved by 30%, average of 13.0 kg/m2h, when the single-layered PP-coated membrane was used to treat the high salinity water in both 2 and 60 hr MD processes. Further layers of coating resulted in larger size of PP spherulites with higher sliding angle, followed by lowered flux in MD. The evenness of the surface coating and the size of the aggregate PP spherulites (nano-scaled) are two predominant factors contributing to the superhydrophobicity character of a membrane.
Surging growth of aquaculture industry has alarmed the public when the wastewater discharged had an adverse effect on the environment. This current study is a pioneer in the use of membrane distillation (MD) to treat real aquaculture wastewater. In addition to excellent hydrophobicity, the slippery surface of membrane used for MD is another key factor that enhances the performance of MD. The slippery surface of the membrane was tuned by layering high-viscosity and low-viscosity polypropylene (PP) polymers on the electrospun membrane by solvent-exchanged method. While the high-viscosity PP coating (PP/HV) rendered the membrane surface slippery, the low-viscosity PP coating (PP/LV) caused the fish farm wastewater to have stick-slip movement on the membrane surface. In the long-term 70-hour direct contact membrane distillation (DCMD) separation, PP/HV and PP/LV membranes can perfectly eliminate the undesirable components in the fish farm wastewater. The PP/HV membrane has registered a flux of 19.1 kg/m2·h, while the flux of PP/LV membrane was only 7.3 kg/m2·h. The PP/HV membrane also showed excellent anti-scaling properties in relative to the PP/LV membrane. This is because the PP/HV membrane promotes effortless gliding of the feed water along the surface of the membrane, while the surface of the PP/LV membrane has a static water boundary. Therefore, it can be concluded that the application of MD using the membrane coated with high-viscosity PP polymer is a feasible technology for the treatment of aquaculture wastewater.
The surge in the use of antibiotics, especially in aquaculture, has led to development of antibiotic resistance genes, which will harm environmental and public health. One of the most commonly used antibiotics in aquaculture is oxytetracycline (OTC). Employing photocatalysis, this study compared OTC degradation efficiency of two different types of common photocatalysts, TiO2 and graphitic carbon nitride (GCN) in terms of their photochemical properties and underlying photocatalytic mechanism. For reference purpose, self-synthesized GCN from urea precursor (GCN-Urea) and commercial GCN (GCN-Commercial) were both examined. OTC adsorption-photocatalysis removal rates in pure OTC solution by TiO2, GCN-Urea and GCN-Commercial were attained at 95%, 60% and 40% respectively. Photochemical properties evaluated included light absorption, band gap, valence and conduction band positions, photoluminescence, cyclic voltammetry, BET surface area and adsorption capability of the photocatalysts. Through the evaluations, this study provides novel insights towards current state-of-the-art heterogeneous photocatalytic processes. The electron-hole recombination examined by photoluminescence is not the key factor influencing the photocatalytic efficacies as commonly discussed. On the contrary, the dominating factors governing the higher OTC degradation efficiency of TiO2 compared to GCN are the high mobility of electrons that leads to high redox capability and the high pollutant-photocatalyst affinity. These claims are proven by 86% and 40% more intense anodic and cathodic cyclic voltammetry curve peaks of TiO2 as compared to both GCNs. OTC also demonstrated 1.7 and 2.3 times higher affinity towards TiO2 than GCN-Urea and GCN-Commercial. OTC removal by TiO2 in real aquaculture wastewater only achieved 50%, due to significant inhibition effect by dissolved solids, dissolved organic matters and high ionic contents in the wastewater.
Separation of carbon dioxide (CO(2)) from gaseous mixture is an important issue for the removal of CO(2) in natural gas processing and power plants. The ordered mesoporous silicas (OMS) with uniform pore structure and high density of silanol groups, have attracted the interest of researchers for separation of carbon dioxide (CO(2)) using adsorption process. These mesoporous silicas after functionalization with amino groups have been studied for the removal of CO(2). The potential of functionalized ordered mesoporous silica membrane for separation of CO(2) is also recognized. The present paper reviews the synthesis of mesoporous silicas and important issues related to the development of mesoporous silicas. Recent studies on the CO(2) separation using ordered mesoporous silicas (OMS) as adsorbent and membrane are highlighted. The future prospectives of mesoporous silica membrane for CO(2) adsorption and separation are also presented and discussed.
The development of mixed matrix membranes (MMMs) for effective gas separation has been gaining popularity in recent years. The current study aimed at the fabrication of MMMs incorporated with various loadings (0-4 wt%) of functionalized KIT-6 (NH2KIT-6) [KIT: Korea Advanced Institute of Science and Technology] for enhanced gas permeation and separation performance. NH2KIT-6 was characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and N2 adsorption-desorption analysis. The fabricated membranes were subjected to FESEM and FTIR analyses. The effect of NH2KIT-6 loading on the CO2 permeability and ideal CO2/CH4 selectivity of the fabricated membranes were investigated in gas permeation and separation studies. The successfulness of (3-Aminopropyl) triethoxysilane (APTES) functionalization on KIT-6 was confirmed by FTIR analysis. As observed from FESEM images, MMMs with no voids in the matrix were successfully fabricated at a low NH2KIT-6 loading of 0 to 2 wt%. The CO2 permeability and ideal CO2/CH4 selectivity increased when NH2KIT-6 loading was increased from 0 to 2 wt%. However, a further increase in NH2KIT-6 loading beyond 2 wt% led to a drop in ideal CO2/CH4 selectivity. In the current study, a significant increase of about 47% in ideal CO2/CH4 selectivity was achieved by incorporating optimum 2 wt% NH2KIT-6 into the MMMs.
The synthesis of nanocomposite with controlled surface morphology plays a key role for pollutant removal from aqueous environments. The influence of the molecular size of the polyelectrolyte in synthesizing silica-iron oxide core-shell nanocomposite with open shell structure was investigated by using dynamic light scattering, atomic force microscopy, and quartz crystal microbalance with dissipation (QCM-D). Here, poly(diallydimethylammonium chloride) (PDDA) was used to promote the attachment of iron oxide nanoparticles (IONPs) onto the silica surface to assemble a nanocomposite with magnetic and catalytic bifunctionality. High molecular weight PDDA tended to adsorb on silica colloid, forming a more extended conformation layer than low molecular weight PDDA. Subsequent attachment of IONPs onto this extended PDDA layer was more randomly distributed, forming isolated islands with open space between them. By taking amoxicillin, an antibiotic commonly found in pharmaceutical waste, as the model system, better removal was observed for silica-iron oxide nanocomposite with a more extended open shell structure.
Moringa oleifera seeds, an environmental friendly and natural coagulant are reported for the pretreatment of palm oil mill effluent (POME). In coagulation-flocculation process, the M. oleifera seeds after oil extraction (MOAE) are an effective coagulant with the removal of 95% suspended solids and 52.2% reduction in the chemical oxygen demand (COD). The combination of MOAE with flocculant (NALCO 7751), the suspended solids removal increased to 99.3% and COD reduction was 52.5%. The coagulation-flocculation process at the temperature of 30 degrees C resulted in better suspended solids removal and COD reduction compared to the temperature of 40, 55 and 70 degrees C. The MOAE combined with flocculant (NALCO 7751) reduced the sludge volume index (SVI) to 210mL/g with higher recovery of dry mass of sludge (87.25%) and water (50.3%).
Health literacy is progressively seen as an indicator to describe a nation's health status. To improve health literacy, countries need to address health inequalities by examining different social demographic factors across the population. This assessment is crucial to identify and evaluate the strengths and limitations of a country in addressing health issues. By addressing these health inequalities, a country would be better informed to take necessary steps to improve the nation's health literacy. This study examines health literacy levels in Malaysia and analyses socio-demographic factors that are associated with health literacy. A cross-sectional survey was carried out using the HLS-M-Q18 instrument, which was validated for the Malaysian population. Multi-stage random sampling strategy was used in this study, utilising several sampling techniques including quota sampling, cluster sampling, and simple random sampling to allow random data collection. A total of 855 respondents were sampled. Our results showed that there were significant associations between health literacy and age, health status, and health problems. Our findings also suggest that lower health literacy levels were associated with the younger generation. This study's findings have provided baseline data on Malaysians' health literacy and provide evidence showing potential areas of intervention.
Hemorrhoidectomy is one of the most common surgical interventions to remove the third and fourth degrees of prolapse hemorrhoid. We carried out this systematic review and meta-analysis of the randomized controlled trials (RCTs) to comprehensively evaluate the efficacy of harmonic scalpel (HS) versus bipolar diathermy (BD) methods in terms of decreasing intraoperative and postoperative morbidities among patients undergoing hemorrhoidectomy. Suitable citations were found utilizing digital medical sources, including the CENTRAL, Web of Science, PubMed, Scopus, and Google Scholar, from inception until December 2022. Only RCTs that matched the inclusion requirements were selected. We used the updated Cochrane risk of bias (ROB) tool (version 2) to assess the quality of the involved citations. The Review Manager (version 5.4 for Windows) was used to perform the pooled analysis. Data were pooled and reported as mean difference (MD) or risk ratio (RR) with a 95% confidence interval (CI) in random-effects models. Overall, there was no significant difference between HS and BD in terms of decreasing intraoperative morbidities like operative time, intraoperative blood loss, mean duration of hospital stay, and mean duration of first bowel movement (P>0.05). Similarly, the rate of postoperative complications like pain, bleeding, urinary retention, anal stenosis, flatus incontinence, and wound edema; was similar in both groups with no significant difference (P>0.05). In conclusion, our pooled analysis revealed there was no substantial difference between HS and BD in terms of intraoperative and postoperative endpoints. Additional RCTs with larger sample sizes are needed to consolidate the power and quality of the presented evidence.
This study is to estimate in-hospital mortality in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patients stratified by hemoglobin (Hb) level. Patients were stratified according to hemoglobin level into two groups, that is, Hb <100 g/L and Hb >100 g/L. A total of 6931 patients were included. Of these, 6377 (92%) patients had hemoglobin levels >100 g/L. The mean age was 44 ± 17 years, and 66% of the patients were males. The median length of overall hospital stay was 13 days [2; 31]. The remaining 554 (8%) patients had a hemoglobin level <100 g/L. Overall mortality was 176 patients (2.54%) but was significantly higher in the group with hemoglobin levels <100 g/L (124, 22.4%) than in the group with hemoglobin levels >100 g/L (52, 0.82%). Risk factors associated with increased mortality were determined by multivariate analysis. The Kaplan-Meier survival analysis showed hemoglobin as a predictor of mortality. Cox proportional hazards regression coefficients for hemoglobin for the HB ≤ 100 category of hemoglobin were significant, B = 2.79, SE = 0.17, and HR = 16.34, p
This study was aimed at gaining a quantitative understanding of the effect of protein quantity and membrane pore structure on protein immobilization. The concentration of immobilized protein was measured by staining with Ponceau S and measuring its color intensity. In this study, both membrane morphology and the quantity of deposited protein significantly influenced the quantity of protein immobilization on the membrane surface. The sharpness and intensity of the red protein spots varied depending on the membrane pore structure, indicating a dependence of protein immobilization on this factor. Membranes with smaller pores resulted in a higher color density, corresponding to enhanced protein immobilization and an increased assay sensitivity level. An increased of immobilized volume has a significant jagged outline on the protein spot but, conversely, no difference in binding capacity.
Over the past decade, L-homophenylalanine is extensively used in the pharmaceutical industry as a precursor for production of angiotensin-converting enzyme (ACE) inhibitor, which possesses significant clinical application in the management of hypertension and congestive heart failure (CHF). A number of chemical methods have been reported thus far for the synthesis of L-homophenylalanine. However, chemical methods generally suffer from process complexity, high cost, and environmental pollution. On the other hand, enantiomerically pure L-homophenylalanine can be obtained elegantly and efficiently by employing biocatalytic methods, where it appears to be the most attractive process in terms of potential industrial applications, green chemistry and sustainability. Herein we review the biocatalytic synthesis of vital L-homophenylalanine as potentially useful intermediate in the production of pharmaceutical drugs in environmentally friendly conditions, using membrane bioreactor for sustainable biotransformation process. One envisages the future prospects of developing an integrated membrane bioreactor system with improved performance for L-homophenylalanine production.
The discharge of palm oil mill effluent (POME) causes serious pollution problems and the membrane based POME treatment is suggested as a solution. Three different designs, namely Design A, B and C distinguished by their different types and orientations of membrane system are proposed. The results at optimum condition proved that the quality of the recovered water for all the designs met the effluent discharge standards imposed by the Department of Environment (DOE). The economic analysis at the optimum condition shows that the total treatment cost for Design A was the highest (RM 115.11/m(3)), followed by Design B (RM 23.64/m(3)) and Design C (RM 7.03/m(3)). In this study, the membrane system operated at high operating pressure with low membrane unit cost is preferable. Design C is chosen as the optimal design for the membrane based POME treatment system based on the lowest total treatment cost.
This study examined the performance of nanofiltration membranes to retain atrazine and dimethoate in aqueous solution under different pH conditions. Four nanofiltration membranes, NF90, NF200, NF270 and DK are selected to be examined. The operating pressure, feed pesticide and stirring rate were kept constant at 6x10(5) Pa, 10 mg/L and 1000 rpm. It was found that increasing the solution's pH increased atrazine and dimethoate rejection but reduced the permeate flux performance for NF200, NF270 and DK. However, NF90 showed somewhat consistent performance in both rejection and permeate flux regardless of the solution's pH. NF90 maintained above 90% of atrazine rejection and approximately 80% of dimethoate rejection regardless of the changes in solution's pH. Thus, NF90 is deemed the more suitable nanofiltration membrane for atrazine and dimethoate retention from aqueous solution compared to NF200, NF270 and DK.
In order to produce sufficient food supply for the ever-increasing human population, pesticides usage is indispensable in the agriculture sector to control crop losses. However, the effect of pesticides on the environment is very complex as undesirable transfers occur continually among different environmental sections. This eventually leads to contamination of drinking water source especially for rivers located near active agriculture practices. This paper studied the application of nanofiltration membrane in the removal of dimethoate and atrazine in aqueous solution. Dimethoate was selected as the subject of study since it is being listed as one of the pesticides in guidelines for drinking water by World Health Organization. Nevertheless, data on effectiveness of dimethoate rejection using membranes has not been found so far. Meanwhile, atrazine is classified as one of the most commonly used pesticides in Malaysia. Separation was done using a small batch-type membrane separation cell with integrated magnetic stirrer while concentration of dimethoate and atrazine in aqueous solution was analyzed using high performance liquid chromatography (HPLC). Four nanofiltration membranes NF90, NF200, NF270 and DK were tested for their respective performance to separate dimethoate and atrazine. Of all four membranes, NF90 showed the best performance in retention of dimethoate and atrazine in water.
Coagulation-flocculation is a proven technique for the treatment of high suspended solids wastewater. In this study, the central composite face-centered design (CCFD) and response surface methodology (RSM) have been applied to optimize two most important operating variables: coagulant dosage and pH, in the coagulation-flocculation process of pulp and paper mill wastewater treatment. The treated wastewater with high total suspended solids (TSS) removal, low SVI (sludge volume index) and high water recovery are the main objectives to be achieved through the coagulation-flocculation process. The effect of interactions between coagulant dosage and pH on the TSS removal and SVI are significant, whereas there is no interaction between coagulant dosage and water recovery. Quadratic models have been developed for the response variables, i.e. TSS removal, SVI and water recovery based on the high coefficient of determination (R(2)) value of >0.99 obtained from the analysis of variances (ANOVA). The optimum conditions for coagulant dosage and pH are 1045mgL(-1) and 6.75, respectively, where 99% of TSS removal, SVI of 37mLg(-1) and 82% of water recovery can be obtained.
The alumina ceramic membrane has been modified by the addition of palladium in order to improve the H(2) permeability and selectivity. Palladium-alumina ceramic membrane was prepared via a sol-gel method and subjected to thermal treatment in the temperature range 500-1100 degrees C. Fractal analysis from nitrogen adsorption isotherm is used to study the pore surface roughness of palladium-alumina ceramic membrane with different chemical composition (nitric acid, PVA and palladium) and calcinations process in terms of surface fractal dimension, D. Frenkel-Halsey-Hill (FHH) model was used to determine the D value of palladium-alumina membrane. Following FHH model, the D value of palladium-alumina membrane increased as the calcinations temperature increased from 500 to 700 degrees C but decreased after calcined at 900 and 1100 degrees C. With increasing palladium concentration from 0.5 g Pd/100 ml H(2)O to 2 g Pd/100 ml H(2)O, D value of membrane decreased, indicating to the smoother surface. Addition of higher amount of PVA and palladium reduced the surface fractal of the membrane due to the heterogeneous distribution of pores. However, the D value increased when nitric acid concentration was increased from 1 to 15 M. The effect of calcinations temperature, PVA ratio, palladium and acid concentration on membrane surface area, pore size and pore distribution also studied.