Synthetic polyelectrolytes of varying charge densities but similar molar mass based on acrylamide and their applications on palm oil mill effluent treatment

Cationic polyacrylamides of varying charge densities but similar molar mass were synthesized using free radical polymerization and Mannich reaction, characterized by different methods and applied as flocculants for palm oil mill effluents (POME). Flocculant performance was assessed by determining the polymer dosage, pH of POME and the removal efficiency of the resulting supernatants using turbidity, suspended solids and chemical oxygen demand as indicators. The pH of POME was adjusted to 3 prior to flocculation. It was found that varying the charge density of the polymer from 48.2-485 C/g affects flocculant performance significantly. Polymer adsorption increased as the charge density of the polymers increased. High charge density cationic polyacrylamide (485 C/g) is the most effective polymer as it obtains 98% turbidity removal, 98.7% suspended solids removal and 54% chemical oxygen demand removal with a dosage as low as 32 mg/l at pH 3 of POME.     

Effects of silicone and ascorbyl palmitate on the quality of palm olein used for frying of prawn crackers

The effects of ascorbyl palmitate (AP) and silicone on the quality changes of refined, bleached and deodorised palm olein (RBD olein) during intermittent frying of prawn crackers for 4.5 h per day were evaluated. The percentage polar components, the C18:2/C16:0 fatty acid ratio, and the acid value of used frying oil without additives were comparable to those for oil containing 200 mg kg^?1 AP. Oil with 2 mg kg^?1 silicone as well as oil containing 200 mg kg^?1 AP plus 2 mg kg^?1 silicone that had been used for frying had lower percentage polar components, higher C18:2/C16:0 ratios and lower acid values than RBD olein without additive. The results showed that silicone had a protective effect on the oil but that the rate of deterioration of the oil in the presence of AP was comparable to that of oil without additive during frying of prawn crackers. The results also showed that the extent of oil oxidation in RBD olein subject to static heating at 180°C for 4.5 h per day for four consecutive days was comparable to that of RBD olein without additive that had been used for frying of prawn crackers.     

Biohydrogen production by Clostridium butyricum EB6 from palm oil mill effluent

A hydrogen producer was successfully isolated from anaerobic digested palm oil mill effluent (POME) sludge. The strain, designated as Clostridium butyricum EB6, efficiently produced hydrogen concurrently with cell growth. A controlled study was done on a synthetic medium at an initial pH value of 6.0 with 10 g/L glucose with the maximum hydrogen production at 948 mL H₂/L-medium and the volumetric hydrogen production rate at 172 mL H₂/L-medium/h. The supplementation of yeast extract was shown to have a significant effect with a maximum hydrogen production of 992 mL H₂/L-medium at 4 g/L of yeast extract added. The effect of pH on hydrogen production from POME was investigated. Experimental results showed that the optimum hydrogen production ability occurred at pH 5.5. The maximum hydrogen production and maximum volumetric hydrogen production rate were at 3195 mL H₂/L-medium and 1034 mL H₂/L-medium/h, respectively. The hydrogen content in the biogas produced was in the range of 60–70%.     

基于二维EMD和小波阈值的掌纹图像去噪

为有效抑制掌纹图像中含有的噪声、提高特征提取的精度,提出一种基于二维经验模式分解和小波阈值去噪相结合的掌纹图像去噪新方法。首先,对含有噪声的掌纹图像进行二维EMD分解,得到不同特征尺度的本征模函数子图像;然后对中高频成分的IMF进行小波多阈值去噪;最后将去噪处理后的各IMF与残差图像通过加和进行重构。实验结果表明,该方法与单独的二维EMD滤波及小波阈值去噪相比,去噪效果更明显,提取的主线和细节特征更清晰,因而均方误差最小、峰值信噪比最高。     

Influence of SFC, microstructure and polymorphism on texture (hardness) of binary blends of fats involved in the preparation of industrial shortenings

Several binary blends of vegetable oils commonly used in industrial shortenings (i.e., palm oil (PO), hydrogenated palm oil (HPO), soybean oil (SO), hydrogenated soybean oil (HSO), low-erucic acid rapeseed oil (LERO), hydrogenated low-erucic acid rapeseed oil (HLERO)) were studied for their physical properties such as solid fat content (SFC) by nuclear magnetic resonance (NMR) and textural properties (hardness). Microstructure was also observed by microscopy in order to explain the variability in hardness for samples having the same SFC values. The blends studied by microscopy were the following: HSO, HPO and HLERO diluted in LERO. For these three blends which had the same SFC, the level of network structure was different. HSO diluted in LERO had more crystals, closer to each other and overlapped. This can explain that HSO has a higher hardness than HPO or HLERO, for a same SFC value, when diluted in LERO. Polymorphism was also observed by powder X-ray diffraction. The variability in hardness for samples having the same SFC is due to various crystal types and/or network structures that are formed upon crystallization of hard fats. This work demonstrates that for binary blends of studied oils, changes in the hardness are controlled mostly by the SFC, polymorphism and also by the material’s microstructure.     

Optimization and corrosion inhibition of Palm kernel leaves on mild steel in oil and gas applications

This study investigated the effectiveness of palm kernel leaves extract (PKLE) as green inhibitor using Central Composite Design (CCD). Phytochemical analysis was performed on the extract. Process variables used for the optimization in this study were: concentration of extract (0.5–1.5 g per litre), time (3–5 days), and temperature (30–50 °C) respectively. Surface characterization was done with Scanning Electron Microscope (SEM). Bioactive constituents were observed from the result of the phytochemical analysis. The best process levels were: inhibitor concentration (1.500 g/l), temperature (30 °C) and time (3 days) with inhibition efficiency of 96.74 %; while the optimal process level validated gave 97.20 %. The SEM results revealed that more film was observed on the validated optimal process level. The PKLE extract was an effective inhibitor.     

Hydrogen-enriched palm biodiesel as a potential alternative fuel for diesel engines: Investigating performance and emission characteristics and mitigation strategies for air pollutants

Palm biodiesel is one of the most suitable alternative fuels due to its capability to replace traditional fossil fuel usage in IC engines. Even as palm biodiesel (POBD) reduces harmful pollutant gases, the engine performance is not on an equal scale with neat diesel. To address this shortcoming, an investigation was carried out to examine the application of palm biodiesel (PBD) and hydrogen induction through the intake air at the flow rates of 6 and 8LPM (Litre Per Minute) in the compression ignition (CI) engine. The experimental study shows that POBD has poor engine performance and moderate pollution reduction compared with neat diesel. When compared to POBD and neat diesel, the higher calorific value and other H₂ characteristics improve combustion properties, resulting in higher engine performance and lower pollutant gases (except NOx). When compared to the palm biodiesel blend (BD 30), the results of BD30+8LPM reduced the Specific fuel consumption (SFC) by 0.0885kg/kWh and improved the brake thermal efficiency (BTE) by 6.67%. The Carbon monoxide (CO), hydro carbon (HC), and smoke opacity were reduced by 0.047% volume, 29.2 ppm, and 6.52% respectively. A marginal increase in NOx was seen as 297.6 ppm.     

Gasification process of palm kernel shell to fuel gas: Pilot-scale experiment and life cycle analysis

This research demonstrates a palm kernel shell gasification system for producing fuel gas, also known as producer gas. Using air as an oxidant, the gasification process converts palm kernel shells into fuel gas which contains combustible gases, such as hydrogen, carbon monoxide, and methane with nitrogen dominating the composition of the gas. This fuel gas can supply heat via direct combustion or generate electricity for fossil fuel substitution of an internal combustion engine. As a biomass-derived gas, the fuel gas is characterized as carbon-neutral inherently. During the conversion process, the system needs electricity to power the screw feeder, air blowers, and cooling-water pumps, and to rotate the gasifier's bottom plate to take the char out. Based on the experiments, mass balance, and energy balance calculations, this study examines the global warming, acidification, and eutrophication potential using the openLCA v1.10.3 software and Environmental Footprint (MID-Point indicator) database for impacts assessment when the system is operated in Indonesia and Malaysia with various electricity sources. It is found that the feedstock contributed most of the global warming potential and eutrophication potential, while the electricity dominated the acidification potential. This study recommends operation at a lower equivalent ratio to reduce environmental impacts.     

A novel pico-hydro power (PHP)-Microbial electrolysis cell (MEC) coupled system for sustainable hydrogen production during palm oil mill effluent (POME) wastewater treatment

Due to accelerating global efforts toward decarbonization, a clean hydrogen (H₂) producing technology, Microbial Electrolysis Cell (MEC), has garnered considerable attention. However, MEC's external energy requirement has raised concerns about its sustainability, scalability and application costs. The objective of this research was to build a renewable energy generating system for MECs' performance enhancement during the treatment of Palm oil mill effluent (POME). A novel integration of a pico-hydro-power generator (PHP) with single-chambered MECs exceptionally improved its performance. The performance boost was observed as 1.16 m³-H₂/m³d H₂ and 113 A/m³current production in concomitant with 73% organics removal from Palm Oil Mill Effluent (POME) wastewater, which is higher than the previous single-chambered MECs studies. 78% H₂ recovery r_cat (H₂) along with 57% coulombic efficiency (CE) corroborated the removal of a high percentage of electrons from POME organic materials to generate >96% pure H₂. The MEC nourished POME wastewater degrading communities while stimulating growth of electroactive Geobacter in the anodic biofilm which produced H₂. The overall H₂ recovery, COD removal rate and energy efficiency of PHP-MEC are superior than other MECs powered by other external renewable energy sources reported to date. The PHP-MEC prototype paves the path of scale up studies to build a renewable energy dependent future.     

Current challenges and future technology in photofermentation-driven biohydrogen production by utilizing algae and bacteria

Biohydrogen is perceived as the versatile fuel of the future, having the ability to replace fossil fuels in many industrial and commercial sectors and offering the promise of fulfilling future renewable energy demands. Among various options available for the generation of biohydrogen, photofermentation with the help of microbes and algae is one of the most eye-catching approaches due to its relative efficiency, cost economics, and reduced environmental impacts. Generation of biohydrogen by dark fermentation, microbial electrolysis cell as well as photofermentation, along with their bioprocesses, already have been discussed in earlier literature. Photofermentation offers advantages of both biophotolysis (utilization of light energy) and dark fermentation (utilization of organic waste materials as substrate). Many researchers have been reported successful biohydrogen production from photofermentation-based techniques, however not much information is available regarding the considerable gap in industrial and economic challenges in the production of biohydrogen at the commercial level through photofermentation. Efforts have been made in this review to provide updated information on various new technologies being used in this sector, such as the integration of photofermentation with dark fermentation, the use of recombinant DNA technology, and the use of bionanotechnology to improve biohydrogen production through the utilization of various waste. Various challenges in this sector, as well as future perspectives, have been meticulously addressed in order to explore the future of green biohydrogen production for a sustainable future.