Biodiesels and biolubricants are synthetic esters produced mainly via a transesterification of other esters from bio-based resources, such as plant-based oils or animal fats. Microwave heating has been used to enhance transesterification reaction by converting an electrical energy into a radiation, becoming part of the internal energy acquired by reactant molecules. This method leads to major energy savings and reduces the reaction time by at least 60% compared to a conventional heating via conduction and convection. However, the application of microwave heating technology alone still suffers from non-homogeneous electromagnetic field distribution, thermally unstable rising temperatures, and insufficient depth of microwave penetration, which reduces the mass transfer efficiency. The strategy of integrating multiple technologies for biodiesel and biolubricant production has gained a great deal of interest in applied chemistry. This review presents an advanced transesterification process that combines microwave heating with other technologies, namely an acoustic cavitation, a vacuum, ionic solvent, and a supercritical/subcritical approach to solve the limitations of the stand-alone microwave-assisted transesterification. The combined technologies allow for the improvement in the overall product yield and energy efficiency. This review provides insights into the broader prospects of microwave heating in the production of bio-based products.
Abundant lignocellulosic biomass from various industries provides a great potential feedstock for the production of value-added products such as biofuel, animal feed, and paper pulping. However, low yield of sugar obtained from lignocellulosic hydrolysate is usually due to the presence of lignin that acts as a protective barrier for cellulose and thus restricts the accessibility of the enzyme to work on the cellulosic component. This review focuses on the significance of biological pretreatment specifically using ligninolytic enzymes as an alternative method apart from the conventional physical and chemical pretreatment. Different modes of biological pretreatment are discussed in this paper which is based on (i) fungal pretreatment where fungi mycelia colonise and directly attack the substrate by releasing ligninolytic enzymes and (ii) enzymatic pretreatment using ligninolytic enzymes to counter the drawbacks of fungal pretreatment. This review also discusses the important factors of biological pretreatment using ligninolytic enzymes such as nature of the lignocellulosic biomass, pH, temperature, presence of mediator, oxygen, and surfactant during the biodelignification process.
Cattle slaughterhouses generate wastewater that is rich in organic contaminant and nutrients, which is considered as high strength wastewater with a high potential for energy recovery. Work was undertaken to evaluate the efficiency of the 12 L laboratory scale conventional and a modified upflow anaerobic sludge blanket (UASB) reactors (conventional, R1 and modified, R2), for treatment of cattle slaughterhouse wastewater (CSWW) under mesophilic condition (35 ± 1 °C). Both reactors were acclimated with synthetic wastewater for 30 days, then continuous study with real CSWW proceeds. The reactors were subjected to the same loading condition of OLR, starting from 1.75, 3, 5 10, 14, and 16 g L-1d-1, corresponding to 3.5, 6, 10, 20, 28, and 32 g COD/L at constant hydraulic retention time (HRT) of 24 h. The performance of the R1 reactor drastically dropped at OLR 10 g L-1d-1, and this significantly affected the subsequent stages. The steady-state performance of the R2 reactor under the same loading condition as the R1 reactor revealed a high COD removal efficiency of 94% and biogas and methane productions were 27 L/d and 89%. The SMP was 0.21 LCH4/gCOD added, whereas the NH3-N alkalinity ratio stood at 651 mg/L and 0.2. SEM showed that the R2 reactor was dominated by Methanosarcina bacterial species, while the R1 reactor revealed a disturb sludge with insufficient microbial biomass.
The objective of this research is to examine the impact of bioenergy usage on health outcomes, especially adult mortality in both developed and underdeveloped countries in the European Union, where the use of solid biomass is growing to generate bioheat, biocool, and biopower. Over the period studied, findings indicate that increased consumption of bioenergy has increased mortality rates in developed and underdeveloped EU28 countries during the period 1990-2018. This feedback proposes, using generalized least squares (GLS), that the resulting death rate from burning biomass-related cases is higher in the EU15 developed countries compared to EU13 underdeveloped countries. There is a need to lower burning biomass in the entire EU15 countries, more importantly its developed region, by critically evaluating the bioenergy production life cycle before it is available for final consumption. However, there is a continuous need to intensify stringent production procedures in the bioenergy industry in EU15 countries, more importantly the imported biomass crops for energy use. There is also a need to be consistent with the campaign on the usage of bioenergy products, i.e., bioheat, bioelectricity, and biofuels, particularly in the rural areas where the use of wood fuels for cooking, heating, and cooling are significant in EU15 developed countries in comparison to EU13 developing countries.
Bacteria isolated from thermophilic environment that can produce cellulase as well as utilise agro-waste biomass have a high potential for developing thermostable cellulase required in the biofuel industry. The cost for cellulase represents a significant challenge in converting lignocellulose to fermentable sugars for biofuel production. Among three potential bacteria examined, Bacillus licheniformis 2D55 (accession no. KT799651) was found to produce the highest cellulolytic activity (CMCase 0.33 U/mL and FPase 0.09 U/mL) at 18-24 h fermentation when grown on microcrystalline cellulose (MCC) as a carbon source in shake flask at 50 °C. Cellulase production process was further conducted on the untreated and NaOH pretreated rice straw (RS), rice husk (RH), sugarcane bagasse (BAG) and empty fruit bunch (EFB). Untreated BAG produced the highest FPase (0.160 U/mL), while the highest CMCase (0.150 U/mL) was supported on the pretreated RH. The mixture of untreated BAG and pretreated RH as agro-waste cocktail has remarkably improved CMCase (3.7- and 1.4-fold) and FPase (2.5- and 11.5-fold) compared to the untreated BAG and pretreated RH, respectively. The mechanism of cellulase production explored through SEM analysis and the location of cellulase enzymes of the isolate was also presented. Agro-waste cocktail supplementation provides an alternative method for an efficient production of cellulase.
Cyanobacteria are widely distributed Gram-negative bacteria with a long evolutionary history and the only prokaryotes that perform plant-like oxygenic photosynthesis. Cyanobacteria possess several advantages as hosts for biotechnological applications, including simple growth requirements, ease of genetic manipulation, and attractive platforms for carbon neutral production process. The use of photosynthetic cyanobacteria to directly convert carbon dioxide to biofuels is an emerging area of interest. Equipped with the ability to degrade environmental pollutants and remove heavy metals, cyanobacteria are promising tools for bioremediation and wastewater treatment. Cyanobacteria are characterized by the ability to produce a spectrum of bioactive compounds with antibacterial, antifungal, antiviral, and antialgal properties that are of pharmaceutical and agricultural significance. Several strains of cyanobacteria are also sources of high-value chemicals, for example, pigments, vitamins, and enzymes. Recent advances in biotechnological approaches have facilitated researches directed towards maximizing the production of desired products in cyanobacteria and realizing the potential of these bacteria for various industrial applications. In this review, the potential of cyanobacteria as sources of energy, bioactive compounds, high-value chemicals, and tools for aquatic bioremediation and recent progress in engineering cyanobacteria for these bioindustrial applications are discussed.
The synthesis of oxygenated fuel additives via solvent freebase-catalyzed etherification of glycerol is reported. The products of glycerol etherification arediglycerol (DG) and triglycerol (TG) with DG being the favorable one. The catalytic activity of different homogeneous alkali catalysts (LiOH, NaOH, KOH and Na(2)CO(3)) was investigated during the glycerol etherification process. LiOH exhibited an excellent catalytic activity during this reaction, indicated by the complete glycerol conversion with a corresponding selectivity of 33% toward DG. The best reaction conditions were a reaction temperature of 240°C, a catalyst/glycerol mass ratio of 0.02 and a reaction time of 6h. The influences of various reaction variables such as nature of the catalyst, catalyst loading, reaction time and reaction temperature on glycerol etherification were elucidated. Industrially, the findings attained in this study might contribute towards promoting the biodiesel industry through utilization of its by-products.
This study reports the conversion of Jatrophacurcas L. oil to biodiesel catalyzed by sulfated zirconia loaded on alumina catalyst using response surface methodology (RSM), specifically to study the effect of interaction between process variables on the yield of biodiesel. The transesterification process variables studied were reaction temperature, reaction duration, molar ratio of methanol to oil and catalyst loading. Results from this study revealed that individual as well as interaction between variables significantly affect the yield of biodiesel. With this information, it was found that 4h of reaction at 150°C, methanol to oil molar ratio of 9.88 mol/mol and 7.61 wt.% for catalyst loading gave an optimum biodiesel yield of 90.32 wt.%. The fuel properties of Jatropha biodiesel were characterized and it indeed met the specification for biodiesel according to ASTM D6751.
Torrefaction process of biomass material is essential in converting them into biofuel with improved calorific value and physical strength. However, the production of torrefied biomass is loose, powdery, and nonuniform. One method of upgrading this material to improve their handling and combustion properties is by densification into briquettes of higher density than the original bulk density of the material. The effects of critical parameters of briquetting process that includes the type of biomass material used for torrefaction and briquetting, densification temperature, and composition of binder for torrefied biomass are studied and characterized. Starch is used as a binder in the study. The results showed that the briquette of torrefied rubber seed kernel (RSK) is better than torrefied palm oil shell (POS) in both calorific value and compressive strength. The best quality of briquettes is yielded from torrefied RSK at the ambient temperature of briquetting process with the composition of 60% water and 5% binder. The maximum compressive load for the briquettes of torrefied RSK is 141 N and the calorific value is 16 MJ/kg. Based on the economic evaluation analysis, the return of investment (ROI) for the mass production of both RSK and POS briquettes is estimated in 2-year period and the annual profit after payback was approximately 107,428.6 USD.
Due to its environment-friendly and replenishable characteristics, biodiesel has the potential to substitute fossil fuels as an alternative source of energy. Although biodiesel has many benefits to offer, manufacturing biodiesel on an industrial scale is uneconomical as a high cost of feedstock is required. A novel sulfonated and magnetic catalyst synthesised from a palm kernel shell (PMB-SO3H) was first introduced in this study for methyl ester or biodiesel production to reduce capital costs. The wasted palm kernel shell (PKS) biochar impregnated with ferrite Fe3O4 was synthesised with concentrated sulphuric acid through the sulfonation process. The SEM, EDX, FTIR, VSM and TGA characterization of the catalysts were presented. Then, the optimisation of biodiesel synthesis was catalysed by PMB-SO3H via the Response Surface Methodology (RSM). It was found that the maximum biodiesel yield of 90.2% was achieved under these optimum operating conditions: 65 °C, 102 min, methanol to oil ratio of 13:1 and the catalyst loading of 3.66 wt%. Overall, PMB-SO3H demonstrated acceptable catalysing capability on its first cycle, which subsequently showed a reduction of the reusability performance after 4 cycles. An important practical implication is that PMB-SO3H can be established as a promising heterogeneous catalyst by incorporating an iron layer which can substantially improve the catalyst separation performance in biodiesel production.
Anaerobic digestion for palm oil mill effluent (POME) is widely known for its potential in biogass production. In this study, the potential of using cattle manure for biogas production in complete mix anaerobic bioreactor was investigated using POME at unregulated pH and temperature. Two identical bioreactors were used in this study; namely R1 and R2 fed with cattle manure without and with POME as inoculum, respectively. Both bioreactors were allowed for five days to run in batch mode followed by semi continuous operations at HRT of 20 days. R2 produced 41% methane content compared to 18% produced in R1. A better COD percentage reduction of 45% was found in R2 which was operated with POME as inoculum compared to R1 with 35%. These results indicated that POME as inoculum has an influence on the start-up time and the rate of biogas produced.This findings will help in waste reduction.
Carbon from jatropha seed hull (JC) was prepared to study the adsorption of cadmium ions (Cd(2+)) from aqueous solutions under various experimental conditions. Batch equilibrium methods have been used to study the influences of the initial metal ion concentration (0.5-50 ppm), dosage (0.2-1 g), contact time (0-300 min), pH (2-7), and temperature (26-60 °C) on adsorption behavior. It has been found that the amount of cadmium adsorbed increases with the initial metal ion concentration, temperature, pH, contact time, and amount of adsorbent. A kinetic study proved that the mechanism of Cd(2+) adsorption on JC followed a three steps process, confirmed by an intraparticle diffusion model: rapid adsorption of metal ions, a transition phase, and nearly flat plateau section. The experimental results also showed that the Cd(2+) adsorption process followed pseudo-second-order kinetics. The Langmuir and Freundlich adsorption isotherm models were used to describe the experimental data, with the former exhibiting a better correlation coefficient than the latter (R² = 0.999). The monolayer adsorption capacity of JC has been compared with the capacities of the other reported agriculturally-based adsorbents. It has been clearly demonstrated that this agricultural waste generated by the biofuel industry can be considered a potential low-cost adsorbent for the removal of Cd(2+) from industrial effluents.
Water is an essential component of agriculture-food production. As the biomass and biofuel are known excellent sources of renewable and sustainable energy, cultivating process consumes significant quantities of water. Without sufficient, good-quality and easily accessible water, the European agriculture-food production could thus be under threat. This research analyses the impact of the water supply on the bioenergy production in the 28 European Union countries, for the 1990-2018 period within the pathway of the European Union 2030 agenda for sustainable development. The findings using the generalised least squares (GLS) technique show that bioenergy production and population density appear to decrease water supply. Precisely, the magnitude of the effects is - 0.224 and - 0.136 for developing countries and developed countries in the EU, respectively. This indicates that a serious reduction of water security is more likely to happen in developed countries than in developing countries as a result of the increase in bioenergy consumption. In the meantime, fossil fuel, income generation activities and institutional quality have already positively affected water supply. Thus, these findings implied that water scarcity is becoming one of the main obstacles for bioenergy expansion and growth. The results were also further verified by the random effect and pooled oriented least squares method. This study recommends that the Member of the European Union States should continue to increase bioenergy production in the energy mix efforts without any strenuous water security issues. Notwithstanding, there are several situations where a developing bioenergy industry is unlikely to be constrained by water shortage, and with the drive of bioenergy demand, the efforts might unlock new opportunities to adapt to water-related challenges and to improve water usage efficiencies. The authorities should illustrate organised water security and sustainable bioenergy policy by way of developing alternative strategies in reducing fossil fuel power and related CO2 emissions, accordingly to the unique characteristics of both developed and developing countries in the EU.
This study aims to identify current and future research trends in sustainable bioenergy production. The systematic review is conducted using a social network analysis method. The data were collected from the Web of Science and Scopus database (2010-2021). Out of the 1747 articles reviewed, 100 were found to be relevant for thematic analysis. The results uncovered four domains of palm oil biodiesel production for sustainable energy management: (1) renewable energy, (2) biodiesel, (3) bioenergy, and (4) life cycle assessment. This study has proposed a sustainable bioenergy production framework based on the four main domains. The framework sheds light on the future of sustainable bioenergy production. The findings indicate the potential growth of the research topic, including sustainable bioenergy, palm oil biodiesel, energy management, and carbon emissions reduction. Future research must incorporate the energy management framework to design a sustainable energy management ecosystem strategy. In addition, the industry must comply with the international sustainability standard and sustainable development goals to manage the energy supply chain and consistency of palm oil biodiesel production.
Malaysian authorities has planned to minimize and stop when applicable unsanitary dumping of waste as it puts human health and the environment at elevated risk. Cost, energy and revenue are mostly adopted to draw the blueprint of upgrading municipal solid waste management system, while the carbon footprint emissions criterion rarely acts asa crucial factor. This study aims to alert Malaysian stakeholders on the uneven danger of carbon footprint emissions of waste technologies. Hence, three scenarios have been proposed and assessed mainly on the carbon footprint emissions using the 2006 IPCC methodology. The first scenario is waste dumping in sanitary landfills equipped with gas recovery system, while the second scenario includes anaerobic digestion of organics and recycling of recyclable wastes such as plastic, glass and textile wastes. The third scenario is waste incineration. Besides the carbon footprint emissions criterion, other environmental concerns were also examined. The results showed that the second scenario recorded the lowest carbon footprint emissions of 0.251t CO2 eq./t MSW while the third scenario had the highest emissions of 0.646t CO2 eq./t MSW. Additionally, the integration between anaerobic digestion and recycling techniques caused the highest avoided CO2 eq. emissions of 0.74t CO2 eq./t MSW. The net CO2 eq. emissions of the second scenario equaled -0.489t CO2 eq./t MSW due to energy recovery from the biogas and because of recycled plastic, glass and textile wastes that could replace usage of raw material. The outcomes also showed that the first scenario generates huge amount of leachate and hazardous air constituents. The study estimated that a ton of dumped waste inside the landfills generates approximately 0.88m3 of trace risky compounds and 0.188m3 of leachate. As for energy production, the results showed that the third scenario is capable of generating 639kWh/t MSW followed by the second scenario with 387.59kWh/t MSW. The first scenario produced 296.79kWh/t MSW. In conclusion, the outcomes of this study recommend an integrated scenario of anaerobic digestion and recycling techniques to be employed in Malaysia.
The dataset presented here are part of the data planned to produce biodiesel from flaxseed. Biodiesel production from flaxseed oil through transesterification process using KOH as catalyst, and the operating parameters were optimized with the help of face-centered central composite design (FCCD) of response surface methodology (RSM). The operating independent variables selected such as, methanol oil ratio (4:1 to 6:1), catalyst (KOH) weight (0.40-1.0%), temperature (35 °C-65 °C), and reaction time (30 min-60 min) were optimized against biodiesel yield as response. The maximum yield (98.6%) of biodiesel from flaxseed can achieved at optimum methanol oil ratio (5.9:1), catalyst (KOH) weight (0.51%), reaction temperature (59.2 °C), and reaction time (33 min). The statistical significance of the data set was tested through the analysis of variance (ANOVA). These data were the part of the results reported in "Optimization of process variables for biodiesel production by transesterification of flaxseed oil and produced biodiesel characterizations" Renewable Energy [1].
Life cycle assessment was used to evaluate the environmental impacts of phytoplanktonic biofuels as possible sustainable alternatives to fossil fuels. Three scenarios were examined for converting planktonic biomass into higher-value commodities and energy streams using the alga Scenedesmus sp. and the cyanobacterium Arthrospira sp. as the species of interest. The first scenario (Sc-1) involved the production of biodiesel and glycerol from the planktonic biomass. In the second scenario (Sc-2), biodiesel and glycerol were generated from the planktonic biomass, and biogas was produced from the residual biomass. The process also involved using a catalyst derived from snail shells for biodiesel production. The third scenario (Sc-3) was similar to Sc-2 but converted CO2 from the biogas upgrading to methanol, which was then used in synthesizing biodiesel. The results indicated that Sc-2 and Sc-3 had a reduced potential (up to 60 % less) for damaging human health compared to Sc-1. Sc-2 and Sc-3 had up to 61 % less environmental impact than Sc-1. Sc-2 and Sc-3 reduced the total cumulative exergy demand by up to 44 % compared to Sc-1. In conclusion, producing chemicals and utilities within the biorefinery could significantly improve environmental sustainability, reduce waste, and diversify revenue streams.
Waste-to-energy conversion presents a pivotal strategy for mitigating the energy crisis and curbing environmental pollution. Pyrolysis is a widely embraced thermochemical approach for transforming waste into valuable energy resources. This study delves into the co-pyrolysis of terrestrial biomass (potato peel) and marine biomass (Sargassum angastifolium) to optimize the quantity and quality of the resultant bio-oil and biochar. Initially, thermogravimetric analysis was conducted at varying heating rates (5, 20, and 50 °C/min) to elucidate the thermal degradation behavior of individual samples. Subsequently, comprehensive analyses employing FTIR, XRD, XRF, BET, FE-SEM, and GC-MS were employed to assess the composition and morphology of pyrolysis products. Results demonstrated an augmented bio-oil yield in mixed samples, with the highest yield of 27.1 wt% attained in a composition comprising 75% potato peel and 25% Sargassum angastifolium. As confirmed by GC-MS analysis, mixed samples exhibited reduced acidity, particularly evident in the bio-oil produced from a 75% Sargassum angastifolium blend, which exhibited approximately half the original acidity. FTIR analysis revealed key functional groups on the biochar surface, including O-H, CO, and C-O moieties. XRD and XRF analyses indicated the presence of alkali and alkaline earth metals in the biochar, while BET analysis showed a surface area ranging from 0.64 to 1.60 m2/g. The favorable characteristics of the products highlight the efficacy and cost-effectiveness of co-pyrolyzing terrestrial and marine biomass for the generation of biofuels and value-added commodities.
Magnetic collection of the microalgae Chlorella sp. from culture media facilitated by low-gradient magnetophoretic separation is achieved in real time. A removal efficiency as high as 99% is accomplished by binding of iron oxide nanoparticles (NPs) to microalgal cells in the presence of the cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA) as a binder and subsequently subjecting the mixture to a NdFeB permanent magnet with surface magnetic field ≈6000 G and magnetic field gradient <80 T m(-1) . Surface functionalization of magnetic NPs with PDDA before exposure to Chlorella sp. is proven to be more effective in promoting higher magnetophoretic removal efficiency than the conventional procedure, in which premixing of microalgal cells with binder is carried out before the addition of NPs. Rodlike NPs are a superior candidate for enhancing the magnetophoretic separation compared to spherical NPs due to their stable magnetic moment that originates from shape anisotropy and the tendency to form large NP aggregates. Cell chaining is observed for nanorod-tagged Chlorella sp. which eventually fosters the formation of elongated cell clusters.
The immobilisation of Chlorella vulgaris 211/11B entrapped in combinations of natural matrices to simplify the harvesting process was demonstrated in this study. Three combinations of matrices composed of calcium alginate (CA) and sodium alginate (SA), sodium carboxymethyl cellulose (CMC) and SA, and mixed matrices (SA, CA, and CMC) were investigated. The number of cells grown for each immobilised matrix to microalgae volume ratios (0.2:1-1:1) were explored and compared with using SA solely as a control. The optimum volume ratios obtained were 1:1 for SA, 0.3:1 for CA and SA, 1:1 for CMC and SA, and 0.3:1 for mixed matrices. The immobilised microalgae of mixed matrices exhibited the highest number of cells with 1.72 × 109 cells/mL at day 10 and 30.43% of oil extraction yield followed by CA and SA (24.29%), CMC and SA (13.00%), and SA (6.71%). Combining SA, CA, and CMC had formed a suitable structure which improved the growth of C. vulgaris and increased the lipid production compared to the immobilisation using single matrix. Besides, the fatty acids profile of the oil extracted indicates a high potential for biodiesel production.