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This study highlights the microwave-assisted optimization on the production of pyrolysis liquid oil (PLO) from oil palm fiber (OPF)focusing on the liquid oil yield and the concentration of total phenolic content (TPC). Final temperature (400–600 °C) and AC loading (50–100 g) showed significant effects on the PLO yield andTPC concentration, compared to the holding time (15–30 min), as verified by using response surface methodology (RSM) via central composite design (CCD) approach. The TPC concentration is highly important for biomedical applications such as antioxidant and antimicrobial agent that will be presented in the future work. At optimum condition, highest PLO yield determined was 40.66 wt % together with 26.61 ± 0.96 mg gallic acid/g of TPC concentration. The major composition (73.4%) of concentrated pyrolysis liquid oil (CPLO)consisting of phenolic compound and its derivatives has been observed via GCMS analysis. Thus, this study successfully demonstrated the potential utilization of OPF as one of the sustainable feedstocks for the production of PLO. [ABSTRACT FROM AUTHOR]

Advancement in the design and development of microwave (MW) processing technology greatly depends on the knowledge of dielectric properties. This study is dedicated to provide new and useful data on the dielectric properties of five different types of biomass generated from Malaysian agricultural (oil palm shell, empty fruit bunch, rice husk, and coconut shell) and wood (sawdust) based industries. The dielectric properties were measured from room temperature to ~ 700 °C and at six different frequencies (397 MHz, 912 MHz, 1429 MHz, 1948 MHz, 2466 MHz, and 2986 MHz) using a cavity perturbation method. The dielectric properties (dielectric constant and loss factor) dropped slightly in the drying region (24 °C to 200 °C) due to removal of moisture and further it decreased in the pyrolysis region (200 °C to 450 °C) due to decomposition or removal of volatile matter. However, dielectric properties increased drastically beyond temperature 450 °C. Minimum MW absorption (maximum penetration depth) was observed in temperature range of 300 to 400 °C. Biochar which was formed after the pyrolysis process, showed high loss tangent as compared to the original biomass, suggesting it as a suitable material for MW absorber and catalyst applications. Thus, the data can be used to design and simulate MW biomass processing system for large scale application, assisting with selection of frequency and optimization of process parameters and system dimensions. [ABSTRACT FROM AUTHOR]

The use of solar–assisted absorption chiller for space cooling is limited to availability of solar radiation; hence, energy storage is very crucial in order to achieve extended hours of cooling operation. In this study, operational and performance characteristics of a solar driven lithium bromide-water absorption chiller integrated with absorption energy storage of the same working fluid are investigated. The integrated system simultaneously provides cooling and charging of the absorption energy storage during the hours of solar radiation. Simulation of the integrated system is carried out based on first law of thermodynamics. Effects of weather variables such as solar radiation and the influence of coupling absorption energy storage with an absorption chiller are investigated. The results indicate that cooling effect of the chiller varies with the variation of solar radiation, with maximum value of 20 kW for a collector area ( A c ) of 96 m 2 on a typical day in July, Dhahran, Saudi Arabia. The cooling COP of the integrated system during cooling/charging and discharging is found to be 0.69 and the energy storage density of the absorption energy storage is 119.6 kWh/m 3 . Furthermore, the operational characteristics of the proposed system showed that the internal operating parameters of the integrated chiller-absorption energy system such as solution temperatures and pressures are within reasonable levels. Hence, this indicates the possibility of integrating the absorption energy storage with absorption chiller. [ABSTRACT FROM AUTHOR]

An overview of the recent development in the production of activated carbon electrodes from agricultural waste biomass for application in supercapacitors is presented. The use of agricultural waste biomass as precursor for the production of activated carbons has been on the increase lately because it is cheap, readily available and also viewed as a veritable way of combating waste disposal problem in the agricultural industries. The effects of activating methods (physical, chemical and microwave-induced) and conditions on the properties of activated carbons are reviewed. The survey of articles published in the last decade indicates the viability of biomass active carbons being used as electrodes in supercapacitors. Under optimum process conditions, active carbons with specific capacitance as high as 374 F g −1 and high-rate long-cycle stability at 4 A g −1 have been produced. In this review, the influence of surface modification on activated carbon properties is also discussed. From the survey literature, it can be seen that the changes in surface chemistry and the introduction of specific surface functionalities on the surface of activated carbons impacted more on the electrochemical properties than the physiochemical properties of the activated carbons. [ABSTRACT FROM AUTHOR]

The electrochemical capacitor (EC), also called as supercapacitor, is an energy storage device possessing a unlimited life-cycle and high power density known to store energy in the double-layer or through supercapacitance as a result of an applied potential. Fundamental values in relation to the major chemical and physical qualities of electrode materials are explained in the following review, with carbon-made electrodes, specially activated carbon highlighted in regards to their improvement of the typical power and energy densities of ECs. Supercapacitive materials, remarkably transition metal oxides are revealed by the potential to further develop EC performance through synergistic effects and asymmetric design. Recently, several chemically deposited metal oxide thin film electrodes as well as ruthenium oxide, manganese oxide, cobalt oxide, nickel oxide, iron oxide, ferrites etc., have been evaluated in supercapacitors. This review presents supercapacitor performance data of metal oxide thin film electrodes on activated carbon offered by electroless plating as a suitable, fast and economical technique. The supercapacitors demonstrated the specific capacitance (Sc) principles, which are relatively comparable with bulk electrode values; therefore, it is likely that metal oxide films will continue to play a major role in supercapacitor technology and are expected to significantly develop the capabilities of these devices in the near future. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical capacitors (ECs), also known as pseudocapacitors or supercapacitors (SCs), is receiving great attention for its potential applications in electric and hybrid electric vehicles because of their ability to store energy, alongside with the advantage of delivering the stored energy much more rapidly than batteries, namely power density. To become primary devices for power supply, supercapacitors must be developed further to improve their ability to deliver high energy and power simultaneously. In this concern, a lot of effort is devoted to the investigation of pseudocapacitive transition-metal-based oxides/hydroxides such as ruthenium oxide, manganese oxide, cobalt oxide, nickel oxide, cobalt hydroxide, nickel hydroxide, and mixed metal oxides/hydroxides such as nickel cobaltite and nickel–cobalt oxy-hydroxides. This is mainly due to the fact that they can produce much higher specific capacitances than typical carbon-based electric double-layer capacitors and electronically conducting polymers. This review presents supercapacitor performance data of metal oxide thin film electrodes by microwave-assisted as an inexpensive, quick and versatile technique. Supercapacitors have established the specific capacitance (Cs) principles, therefore, it is likely that metal oxide films will continue to play a major role in supercapacitor technology and are expected to considerably increase the capabilities of these devices in near future. [Copyright &y& Elsevier]

Theworldwide demand of activated carbon is expected to increaseby 58% until 2016 [FredoniaWorld Activated Carbon;2013; p 415], owing to tighter pollution controls andincreased production of consumer goods. To cope up with high demand,new sustainable and energy efficient processes are being explored.Microwave assisted production of activated carbon from biomass feedstockuse selective heating which makes the process energy efficient andsustainable in nature. Recent studies used domestic microwave ovenwith open loop temperature control to prepare activated carbon, withouttaking into consideration the dielectric properties of biomass andactivating agents, and safety issues. As a result, these studies donot provide necessary information for the scale-up of the reactorfor high throughputs. In this research, the critical issues in thepresent research are analyzed, and appropriate remedies have beensuggested to overcome them, as a step forward toward the scale-upof technology for industrial scale production. [ABSTRACT FROM AUTHOR]

Abstract: Oil palm empty fruit bunch pellets were subjected to pyrolysis in a multimode microwave (MW) system (1kW and 2.45GHz frequency) with and without the MW absorber, activated carbon. The ratio of biomass to MW absorber not only affected the temperature profiles of the EFB but also pyrolysis products such as bio-oil, char, and gas. The highest bio-oil yield of about 21wt.% was obtained with 25% MW absorber. The bio-oil consisted of phenolic compounds of about 60–70 area% as detected by GC–MS and confirmed by FT-IR analysis. Ball lightning (plasma arc) occurred due to residual palm oil in the EFB biomass without using an MW absorber. The bio-char can be utilized as potential alternative fuel because of its heating value (25MJ/kg). [Copyright &y& Elsevier]

Abstract: Oil palm shell biomass contains a high amount of lignin and thus has the potential to be converted into value-added products. If this biomass is not utilised efficiently, significant loss of valuable chemical products may occur, which otherwise can be recovered. In this paper, a new technique using an overhead stirrer to pyrolyse biomass under microwave (MW) irradiation was investigated. The ratio of biomass to activated carbon was varied to investigate its effect on the temperature profile, product yield and phenol content of the bio-oil. Interestingly, the microwave pyrolysis temperature could be controlled by varying the biomass to carbon ratio. The highest bio-oil yield and phenol content in bio-oil were obtained at a biomass to carbon ratio of 1:0.5. Chemical analyses of bio-oil were performed using FT-IR, GC–MS and 1H NMR techniques. These results indicate that bio-oil consists mainly of aliphatic and aromatic compounds with high amounts of phenol in the bio-oil. Thus, MW pyrolysis with a stirrer successfully produced high-phenol bio-oil compared to other methods. This significant increase in bio-oil quality could either partially or wholly replace petroleum-derived phenol in many phenol-based applications. [Copyright &y& Elsevier]

Abstract: The purpose of this paper was to carry out microwave induced pyrolysis of oil palm biomass (shell and fibers) with the help of char as microwave absorber (MA). Rapid heating and yield of microwave pyrolysis products such as bio-oil, char, and gas was found to depend on the ratio of biomass to microwave absorber. Temperature profiles revealed the heating characteristics of the biomass materials which can rapidly heat-up to high temperature within seconds in presence of MA. Some characterization of pyrolysis products was also presented. The advantage of this technique includes substantial reduction in consumption of energy, time and cost in order to produce bio-oil from biomass materials. Large biomass particle size can be used directly in microwave heating, thus saving grinding as well as moisture removal cost. A synergistic effect was found in using MA with oil palm biomass. [ABSTRACT FROM AUTHOR]

The main objective of this study is to investigate the effect of filler content and filler size on the water absorption behaviour of phenolic composites filled with oil palm shell flour, rice husk flour and coconut shell flour. Lignocellulosic phenolic composites with three different filler sizes (<38 µm, 38-75 µm and 75-150 µm) and at three different filler loadings (30%, 45% and 55%) were prepared using a two-roll mill before being hot pressed. A pure Novolak sample was produced via the same method. The water absorption rate at different times, the diffusion coefficients, and the kinetic parameters k and n of the samples were calculated. All the samples exhibited a Fickian diffusion mechanism The water absorption rate and the quantity of water absorbed by the composites increased noticeably with increasing filler loading due to the hydrophilic nature of the lignocellulosic fillers. However, filler size does not significantly influence these properties. [ABSTRACT FROM AUTHOR]

Gas separation technology by adsorption processes has been widely applied in many related industries, such as petrochemicals, biochemical, environmental technology, oil and gas industries. Oil palm solid waste, the palm shell, was utilized to prepare carbon molecular sieve (CMS) by carbonization for air separation. The effect of different carbonization temperatures on the pore structures and adsorptive properties for oxygen and nitrogen was investigated. CO2 was used as the probing adsorbate at 298 K to characterize the micropore volume and surface area of the CMS. The efficiency in kinetic based separation of air, i.e. selective adsorption of oxygen from nitrogen, was evaluated from the adsorption capacity curves. Results showed that within 1 min of time, one of the samples had shown excellent separation capability, and the O2/N2 selectivity as high as 48 could be obtained. This kinetic selectivity of air was greatly influenced by the carbonization temperatures. The excessive heat at high temperatures has reduced the micropore volume and surface area of the adsorbents, but it has enhanced the oxygen-selective pathway compared with nitrogen. However, the excellent selectivity has affected the overall adsorption capacity to become lower due to the reduction in micropore volume. This study has identified the palm shell as the potential starting material in the preparation of CMS. [Copyright &y& Elsevier]

• Power level was a major parameter in affecting performance of torrefied products. • Dielectric materials and particle size affect significantly heating rate. • 150 to 250 W was sufficient to produce a good quality torrefied products. • Clean-products derived from microwave heating technique can be obtained. • Dedicated operating conditions in MW heating resulted in high EROI (6.1 to 34). Microwave (MW) heating offers numerous advantages over conventional heating. Its characteristics of fast internal heating, volumetric heating, and low energy consumption enable microwave torrefaction (MWT) of biomass to be performed. The purpose of this article is to review the current state of MWT of biomass. A brief explanation of MWT, including experimental setups and the effects of several important parameters, are reviewed and discussed. Potential future directions and challenges regarding MWT are also discussed. It is known that the MW power level, types of MW absorbers (catalyst), and particle size can significantly influence the performance of torrefied biomass in terms of energy and mass yields, mass loss, H/C and O/C ratios, fuel ratio, and high heating value. The effect of operating condition on products derived from MWT needs to be further investigated in order to make the technology feasible and reliable. Overall, MWT has the potential to serve as energy-efficient method to improve the performance of biomass. [ABSTRACT FROM AUTHOR]

High temperature thermal plasma has a major drawback which consumes high energy. Therefore, non-thermal plasma which uses comparatively lower energy, for instance, microwave plasma is more attractive to be applied in gasification process. Microwave-induced plasma gasification also carries the advantages in terms of simplicity, compactness, lightweight, uniform heating and the ability to operate under atmospheric pressure that gains attention from researchers. The present paper synthesizes the current knowledge available for microwave plasma gasification on solid fuels and waste, specifically on affecting parameters and their performance. The review starts with a brief outline on microwave plasma setup in general, and followed by the effect of various operating parameters on resulting output. Operating parameters including fuel characteristics, fuel injection position, microwave power, addition of steam, oxygen/fuel ratio and plasma working gas flow rate are discussed along with several performance criteria such as resulting syngas composition, efficiency, carbon conversion, and hydrogen production rate. Based on the present review, fuel retention time is found to be the key parameter that influences the gasification performance. Therefore, emphasis on retention time is necessary in order to improve the performance of microwave plasma gasification of solid fuels and wastes. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) prepared by two-stage microwave-induced physical activation of oil palm shell have been coated using electroless plating technique to form nanocomposite material. The composite materials were calcinated at different temperature of 300, 400 and 500 °C for one hour. The nanocomposite materials were evaluated as potential electrodes for supercapacitors. Using the composite electrodes in a two-electrode symmetrical capacitor, the properties of the composite electrodes were investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Results from electrochemical measurements show that the nanocomposite electrodes exhibit superior capacitive performance compared with the AC electrode. The specific capacitance have been found to increase by 85–205% with respect to the AC electrode. In addition, the specific capacitance as well as the energy density were found to reduce with the increment of the calcination temperature. The composite electrode calcinated at 300 °C offers the maximum enhancement of 205% in both specific capacitance and energy density. [ABSTRACT FROM AUTHOR]

Corrosive characteristics of lignocellulosic bioethanol on metals, such as mild steel, copper, and aluminum were studied by static immersion test at room temperature. Effect of metals on degradation of fuel properties, such as pHe, total acid number, acidity, density, viscosity, calorific value, flash point, and color changes were evaluated. Moreover, the transformation of water content and oxidation products in the fuel were investigated. Effect of fuel blends on corrosion rate, chemical structure of metals, and morphology of corrosion product were also examined. Results showed that the corrosion of metals in E50 (50% bioethanol and 50% gasoline) is high compared with E25 and E0. Moreover, degradation of fuel properties and compositional changes in E25 and E50 were high compared with E0. The corrosion rate of aluminum in E50 (0.216 mpy) was lower than copper (0.441 mpy) and mild steel (0.487 mpy). Moreover, the corrosion rate of aluminum in E25 (0.096 mpy) was also lower than copper (0.285 mpy) and mild steel (0.297 mpy). It was discovered that corrosion of materials and degradation of fuel properties were 2.4 times high in higher ethanol blends (above E25) compared with lower ethanol blends (up to E25). Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Corrosive behavior of biodiesel–diesel–ethanol (BDE) fuel blends upon exposure to metals, namely, mild steel, copper and aluminum was studied by static immersion at room temperature and 60 °C. The change of fuel properties, i.e., total acid number, density, viscosity, calorific value, flash point, and color changes were investigated. Moreover, fuel compositional changes, such as water content, oxidation product level, and metal elements in the fuel blends were examined. Finally, the effect of fuel blends on corrosion rate (CR), morphology of corrosion products, and chemical structure of metals were studied. Results revealed that the CR of metals in BDE fuels is in the order: aluminum < mild steel < copper at both temperature conditions. The degradation of fuel properties and corrosion rate of metals in BDE fuel blends are lower than neat biodiesel (B100), whereas higher than petro–diesel (B0). Corrosiveness of B20D75E5 is lower than B20D70E10 upon exposure to metals. [ABSTRACT FROM AUTHOR]

Bioethanol fuel obtained from biomass and bioenergy crops has been proclaimed as one of the feasible alternative to gasoline fuel, as it is considered to be clean, renewable and green. In this review, the bioethanol production techniques from different lignocellulosic biomass, and its potential ethanol yield are studied. Moreover, this paper has reviewed the effects of bioethanol fuel blends on spark ignition engine combustion characteristics (i.e. cylinder pressure, cylinder temperature, flame speed, combustion efficiency, combustion duration, heat release rate, knocking and cold start); engine performance parameters (i.e. torque, brake power, brake specific fuel consumption, brake mean effective pressure, brake thermal efficiency and volumetric efficiency); and emission characteristics (i.e. carbon monoxide, oxides of nitrogen, carbon dioxide, unburned hydrocarbon and other unregulated emissions). Recently, many researchers produced bioethanol from herbaceous, industrial and municipal solid wastes (MSW) instead of agriculture and woody biomass. Most of the engine test results showed a remarkable improvement in engine performance and enhanced combustion characteristics for bioethanol fuel. In addition, the carbon monoxide and unburned hydrocarbon emissions decreased. Conversely, carbon dioxide and oxides of nitrogen emissions were not significantly reduced. Furthermore, there was no significant reduction of unregulated emissions, such as aromatics, acetaldehyde, and carbonyls. [ABSTRACT FROM AUTHOR]

In this study, coal solids were subjected to Microwave (MW) pyrolysis conditions. Coconut Activated Carbon (CAC) solids used as a MW absorber was distributed uniformly over coal solids to reduce hotspots. Three process parameters; CAC loading, MW power and N 2 flow rate were studies on pyrolysis heating performance. The highest coal-tar yield of 18.59 wt% was obtained with 600 W, 75 wt% CAC loading and 4 Liter per Minute (LPM) of N 2 flow rate. This improved coal-tar yield is mainly of the fact that higher MW power and CAC loading produced sustained pyrolysis conditions for longer duration for the complete conversion of pyrolysis solids. The coal-tar was composed mainly of aromatics (naphthalenes, benzenes and xylene) and saturated aliphatics (alkanes and alkenes) hydrocarbons. The gas produced from pyrolysis of coal is mainly of H 2 40.23–65.22 vol%. [ABSTRACT FROM AUTHOR]

The energy insecurity from oil and natural gas and increased CO 2 emission from fossil fuels is driving societies to look for sustainable and renewable energy supply. The huge coal resources can serve as a potential source for fuels. Bio-energy from biomass has been recognized as renewable energy to reduce CO 2 emission. Although fast pyrolysis has emerged as the most promising technology to convert organic materials to liquid fuels at shorter duration but it still faces some technical challenges in improving product yield, its quality and process energy efficiency. Microwave assisted pyrolysis of coal and biomass in the presence of microwave absorber provides distinctive environment to resolve these challenges. The microwave absorber can indirectly heat coal and biomass particles which are relatively microwave transparent and influence product yield and its quality by contributing as a catalytic precursor. The microwave heating of coal or biomass particles with microwave absorber shows efficient heating and sufficient contact of volatile or gas phase species with specific microwave absorber can improve fuel quality. [ABSTRACT FROM AUTHOR]

Highlights: [•] Microwave hydrothermal hydrolysis with CO2 was carried out for SPW. [•] Batch fermentation and distillation was carried out. [•] GC and FTIR confirmation of distilled ethanol was done. [•] Maximum of 43.8% glucose and 15.6gethanol per 100g SPW was obtained. [•] Lower energy consumption was observed for combined pretreatment and hydrolysis. [ABSTRACT FROM AUTHOR]

This study introduced a novel microwave torrefaction (MWT) strategy combining optimal briquetting conditions and oxidative MWT (OMWT) to create briquettes using empty fruit bunch (EFB)-starch binder for enhanced physical and fuel properties. An analysis was conducted to evaluate the impacts of compaction pressure (20–80 MPa), EFB-to-starch binder mixing ratios (90:10, 80:20, and 70:30 by wt%), and drying duration (50–150 min) on the final moisture content, unit density, and physical properties of the EFB-starch binder briquettes. This study also investigated the influences of heating duration (5–15 min), microwave (MW) power levels (200–400 W), and oxygen (O 2) concentration (0–6 vol%) on the physical and fuel properties of oxidative MW-torrefied EFB-starch binder briquettes. The optimal briquetting parameters were determined using a compaction pressure of 80 MPa, mixing ratio of 80:20 (wt%), and drying duration of 120 min. Meanwhile, the optimal conditions for the OMWT process to produce satisfactory physical appearance and competitive compressive strength with higher heating value were a heating duration of 10 min, MW power level of 300 W, and O 2 concentration of 6 vol%. Consequently, this process demonstrated an enhanced MWT method using minimal charcoal-activated carbon (C-AC) in an oxidative environment. [Display omitted] • A novel time-saving and practical OMWT with minimum C-AC was achieved. • Longer duration and higher MW power levels increased electromagnetic intensity. • An increased O 2 concentration led to intense reaction and devolatilization. • OMWT severely affected the physical properties of the MW-torrefied briquettes. • Fully oxidative MW-torrefied briquette exhibited poor physical properties. [ABSTRACT FROM AUTHOR]

Abstract: A new technique to pyrolyse biomass in microwave (MW) system is presented in this paper to solve the problem of bio-oil deposition. Pyrolysis of oil palm shell (OPS) biomass was conducted in 800W and 2.45GHz frequency MW system using an activated carbon as a MW absorber. The temperature profile, product yield and the properties of the products were found to depend on the stirrer speed and MW absorber percentage. The highest bio-oil yield of 28wt.% was obtained at 25% MW absorber and 50rpm stirrer speed. Bio-char showed highest calorific value of the 29.5MJ/kg at 50% MW absorber and 100rpm stirrer speed. Bio-oil from this study was rich in phenol with highest detected as 85 area% from the GC–MS results. Thus, OPS bio-oil can become potential alternative to petroleum-based chemicals in various phenolic based applications. [Copyright &y& Elsevier]

This article presents simulation results of a solar cooling system that consists of a parallel-flow double-effect water-lithium bromide absorption chiller and parabolic trough solar collector. Parametric study of the cooling system is carried out considering a reference double-effect absorption chiller from Broad Company with nominal cooling capacity of 1163 kW. The aim for the analysis is to properly size the solar collector field and study the interaction of different operating conditions and parameters on the operation and performance of the system. Based on the operational constrains of the reference chiller, such as the minimum chilled water temperature and the cooling power, a solar collector field of 1350 m2 (1.16 m2/kW) is obtained from the range of 800–1800 m2. The reference system is then optimized where the exergy efficiency (second law efficiency) is maximized considering the flow rates of the external working fluid and solution distribution ratio of the parallel-flow double-effect absorption chiller as the decision variables. The system optimization is performed considering the risk of solution crystallization at various locations within the chiller. The optimum parameters together with other operating conditions are normalized per unit chiller nominal cooling capacity so that these values can be applied to other similar system configurations with different chiller nominal capacities. The reference system is simulated at optimum condition using a typical day climate data of Kuala Lumpur, Malaysia. The system achieved cooling effect in the range of 798–1223 kW under solar radiation levels of 600–944 W/m2. The procedure presented in this paper can be applied in sizing the solar collector field and evaluating the performance of similar systems under various climatic conditions having minimum solar radiation around 500 W/m2. • Detailed parametric study of solar driven double-effect H 2 O–LiBr absorption system. • Operating conditions of the system are optimized. • The optimal collector area required for cooling is found to be 1.16 m2/kW. • The maximum system exergy efficiency was found to be 6.9% at optimal conditions. [ABSTRACT FROM AUTHOR]

• Botryococcus sp. grown in domestic sewage produced 3.2 g/L of dry biomass. • Botryococcus produced 94.1 wt% of biodiesel using tungstated zirconia catalyst. • Lipid extracted residues yield 41 wt% of biochar after pyrolysis at 500 °C. • Thermogravimetric curve show that the metallic iron synthesis was found at 990 °C. • Botryococcus is a potential material for conversion of hematite to metallic iron (Fe). This study focused on a novel approach for biodiesel production and metallic iron synthesis using biochar obtained from the biomass residue of green microalgae Botryococcus sp. Hematite (Fe 2 O 3) is one of the most important iron ore used in steelmaking industries. Thus, we proposed this work for the development of algal biorefinery concept at commercial scale. This work contains two phases; in the first phase, the alga was successfully cultivated on the domestic wastewater at large scale using a low-cost photobioreactor, which provided significant biomass and lipid yield. To reduce the cost involved in biomass harvesting, an auto-flocculation technique was implemented and harvested 94.8% of biomass without adding any flocculants. The biodiesel extraction was performed in an ultrasonic bath with a frequency of 25 kHz using a tungstated zirconia as a heterogeneous acid catalyst, which produced 94.1 wt% of biodiesel yield. The kinetic studies were investigated at various reaction temperature and confirmed that the reaction followed a pseudo-first-order kinetic model. The activation energy and pre-exponential factor for the transesterification reaction were found to be 45.3861 kJ mol−1 and 2.6956 min−1, respectively. In the second phase, the lipid extracted residue was converted to biochar through pyrolysis process, and the yield obtained was 41 wt%. The obtained biochar was utilized for metallic iron synthesis, and this reaction was carried out in a thermogravimetric analyzer equipped with Fourier-transform infrared spectroscopy. The results showed that the reduction behaviors was occurred in a stepwise manner rendering to the temperature and the metallic iron synthesis was found at 990 °C. [ABSTRACT FROM AUTHOR]

Highlights • Synechocystis sp. grown in municipal wastewater produced 94.5 tones dry biomass ha−1 year−1. • It was estimated that 2–3 US$ required to produce 1 kg of algal biomass. • Tungstated zirconia catalyst supported for high biodiesel yield of 90.5%. • Synechocystis biodiesel fuel properties fitted with ASTM D6751 specification. • Lipid extracted residues produced 0.19 g bioethanol/g residue. Abstract Currently, the most important barrier in algal cultivation is growth nutrients cost. In the present study, the isolated alga Synechocystis PCC6803 was acclimatized under laboratory conditions using municipal wastewater and taken for large-scale cultivation in an open raceway pond. At the semi-continuous mode, the alga produced the highest biomass yield of 0.21 g L−1 d−1 and it was estimated that the algae could be able to produce 94.5 tones dry biomass ha−1 year−1. A low-cost study was conducted to harvest the maximum biomass recovery. The result shows that a combined use of iron (III) chloride and biopolymer enhanced the harvesting process and the maximum biomass recovery was achieved up to 98.7%. In addition, the biomass production cost was thoroughly explored, and it was estimated that the microalgae Synechocystis biomass production cost was approximately 2–3 US$ per kg of biomass. Meanwhile, to reduce the lipid extraction cost, a direct transesterification was performed using tungstated zirconia as a heterogeneous catalyst and the highest biodiesel yield of 90.5% was obtained. In addition, the biodiesel fuel properties were analyzed, and the results revealed that most of the fuel properties found within ASTM D6751 limits. Furthermore, the lipid extracted residues was explored for bioethanol extraction, and 0.186 g bioethanol/g residue was obtained. This is the first study to demonstrate the alga Synechocystis cultivation in an open raceway pond using municipal wastewater successfully and produced two potential biofuels. [ABSTRACT FROM AUTHOR]

Highlights • Microwave acid hydrolysis was carried out using H 2 SO 4 and HCl for SPW. • A maximum of 88% glucose yield and 3.1 g ethanol per 10 g SPW was obtained. • Energy consumption to produce 1 g glucose and 1 g bioethanol fuel was calculated. • A minimum of 31. 77 kJ was used to produce 1 g bioethanol fuel from SPW. Abstract Microwave assisted acid hydrolysis (H 2 SO 4 and HCl with >0.5 mol/L) to produce bioethanol from sago pith waste (SPW) was studied. The energy consumption for microwave hydrolysis at different energy inputs and acid concentration were calculated. The overall energy consumption for bioethanol fuel production from SPW was assessed. A maximum of 88% glucose yield and 80% ethanol yield (3.1 g ethanol per 10 g SPW) were obtained using 1.0 mol/L H 2 SO 4. Microwave hydrolysis using 1.0 mol/L H 2 SO 4 consumed the minimum energy of 8.1 kJ to produce 1 g glucose from SPW when energy input was fixed at 54 kJ (900 W for 1 min). In general, 1 g glucose can produce 16 kJ. The overall energy consumption for fuel grade bioethanol production from SPW was 31.77 kJ per g ethanol, which was slightly higher than the lower heating values of ethanol (26.74 kJ/g ethanol). [ABSTRACT FROM AUTHOR]

Highlights • Horse manure is thermogravimetrically analysed at 1–10 °C/min under inert environment. • The TGA data is analysed using model-free FWO, KAS, Friedman and Kissinger methods. • The determined activation energy for horse manure is between 149 and 200 kJ/mol. • Horse manure shows highest conversion rate at pyrolysis temperature of 290–330 °C. • FWO, KAS and Friedman methods are reliable in determining the kinetic parameters. Abstract Horse manure is a biowaste with bioenergy recovery potential for heat and power generation. However, there is no kinetics data in literature to date. In this work, a kinetic study of the pyrolysis process of horse manure is investigated through the use of thermogravimetric analyses. The samples were heated over a range of temperature from 298 to 927 K with four different heating rates of 1, 2, 5 and 10 K/min. The weight loss was measured by a thermogravimetric analyser in an inert atmosphere. The differential thermal gravimetric (DTG) thermogram shows that the highest reaction rate occurred at between 290.2 and 329.6 °C where the devolatilisation process was initiated to overcome the activation energy barrier of the manure. The activation energy and pre-exponential factor obtained by the Kissinger method, assumed to be constant throughout the whole pyrolysis process are 149 kJ/mol and 3.3 × 1012 s−1, respectively. The activation energy calculated from the non-isothermal Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods are 199.3, 200.2 and 194.6 kJ/mol, whereas the pre-exponential values are 9.3 × 1018, 1.8 × 1019 and 3.6 × 1020 s−1, respectively. The kinetic parameters determined based on interval conversional fraction shows good agreement. The high volatile and low ash content in horse manure indicates the potential for bioenergy recovery. The results of the kinetic study can be used for modelling devolatilisation and designing thermochemical conversion processes. [ABSTRACT FROM AUTHOR]

Global depletion of fossil fuels, growing awareness on the effects of carbon emissions and greenhouse gases and, the need for renewable energy, has increased the attention towards biocoke research and active engagement with various research groups and industrial players. Biocoke production and utilisation is crucial as it contributes to the efficient management of agricultural residue and municipal solid waste. The technologies involved in the biocoke production and the viability of Malaysia's agricultural waste as a feedstock was described in this paper. In addition, the paper provided background information about the biocoke characteristics and the feedstocks that dictate quality. Comparisons of commercial coal coke and biocoke production technologies that may be applicable to Malaysia were also addressed. Moreover, the paper demonstrated the challenges towards Malaysia's biocoke commercialisation despite its viability from biomass feedstocks characteristics, availability, and evidence of calorific value estimations. [ABSTRACT FROM AUTHOR]

Industrial gas turbine fueled by blended palm olein is a promising option for electricity generation in next generation of gas turbines. In order to evaluate combustion performance of palm olein and blended diesel in a combustion chamber, detailed experimental investigations were done to evaluate the combustion performance of diesel and palm olein blended fuels. The experimental studies were conducted for 100% diesel and blending diesel with 10, 20, 30, 40, 50 and 60% palm olein (PO). The combustion performances were evaluated for blended oil and compared with diesel. The emission of NO ranged from 30-55ppm while the soot emissions were high for high blended fuel. A maximum blending ratio of 30% PO was recommended to be used in gas turbines in order to avoid any modification in the spray combustion system so that it can be utilized in existing gas turbine systems. The computational fluid dynamic modeling of the combustor was also done, and a comparison was made between the experimental and computational results. This can be helpful in future parametric studies of the combustor performance under different operating conditions. An acceptable level of comparison between numerical simulations and experimental findings was obtained as far as the flame structure is concerned. For high blended fuel, it was found out that increasing amount of soot particles can damage the blades of the turbine which ultimately requires early monitoring and maintenance scheduling. [ABSTRACT FROM AUTHOR]

Biodiesel proliferation as a sustainable fuel has led to a glut of crude glycerol as co-product. This scenario made a previously lucrative co-product in the food and pharmaceutical sectors into a bioresource waste. The present study investigates the utilisation of a microwave-assisted pyrolysis technique to convert crude glycerol from biodiesel waste into usable bioenergy source. Operating conditions ranged from a temperature of 300–800 °C at carrier gas flow rates of 100–2000 mL/min, with the effects of carbonaceous catalyst on the selectivity of reaction pathway being investigated. Within the aforementioned conditions, the proportion of products phases is mainly dependent on the residence time inside the quartz reactor, followed by the reaction temperature. This is due to the combined factors of the reaction sequence and provision of activation energy to change product phases. The third factor of carbonaceous catalyst shows a predisposition towards hydrogen gas selectivity, leading to a lower overall gaseous product mass when factoring in products from all phases. An analysis of the energy content revealed that overall energy profit increases with decreasing temperature and increasing residence time. This concurs with solid energy content increasing in the same conditions, while it increases for liquid and gaseous products with decreasing temperature and flow rate, respectively. The conversion of waste into portable and energy profit positive products through pyrolysis makes crude glycerol a potential candidate for bioenergy production of bio-oil and syngas. [ABSTRACT FROM AUTHOR]

In this study, an integrated biomass conversion concept of producing liquid biofuels from brown marine macroalga Padina tetrastromatica was investigated. The algal biomass was collected from the Mandapam coastal region and processed under laboratory. Various parameters were studied to extract crude lipids from the biomass. A kinetic study was conducted for extracting the lipids from the biomass, which follows the first order kinetics and the lipid yield was 8.15 wt.%. The activation energy; Ea = 34.314 kJ mol −1 and their thermodynamic parameters were determined. Since the crude algal lipids contain high amount of free fatty acids, a sequential transesterification technique was examined and 7.8% of biodiesel (78 mg/g algal biomass) yield was obtained. The biodiesel was analyzed by 1 H and 13 C–NMR spectroscopy and the conversion yield was estimated. Further, the biodiesel fuel properties were investigated and found that all the features fit the required ASTM D6751 specification limits. The residual biomass after lipid extraction was further explored for bioethanol production through the anaerobic fermentation process. The ethanol yield obtained after saccharification and fermentation were estimated and 161 mg/g residue biomass was reported. The theoretical yield of conversion of hydrolysate to bioethanol was estimated and found to be 83.4%. Therefore, this study demonstrates that macroalga P. tetrastromatica biomass has great potential to produce liquid biofuels such as biodiesel and bioethanol. [ABSTRACT FROM AUTHOR]

Fruit wastes of mango endocarp and waste fruits peel from banana, orange and watermelon were pyrolysed respectively and subjected to different analyses to examine their thermal behaviour, chemical functional group, elemental and proximate content. The fruit wastes were dominated by volatile matter (52–67 wt%) containing aliphatic hydrocarbons, fatty acids and lignocellulosic components that can be recovered as potential fuel or chemical feedstock via pyrolysis. The wastes were also detected to have considerable amounts of fixed carbon (30–36 wt%), thus showing potential to be pyrolysed to produce biochar for use as activated carbon or catalyst support. The wastes can be pyrolysed at ≥ 400 °C to convert the majority of the waste content into volatiles for recovery as useful bio-oil and bio-gas, and the remaining solid mass can be recovered as bio-char. The results demonstrate that the fruit wastes show exceptional promise as a feedstock for pyrolysis conversion into potentially useful products. [ABSTRACT FROM AUTHOR]

This paper begins with a review on the current techniques used for the treatment and recovery of waste oil, which is then followed by an extensive review of the recent achievements in the sustainable development and utilization of pyrolysis techniques in energy recovery from waste oils. The advantages and limitations shown by the use of pyrolysis technique and other current techniques were discussed along with the future research that can be performed on the pyrolysis of waste oil. It was revealed that the current techniques (transesterification, hydrotreating, gasification, solvent extraction, and membrane technology) are yet to be sustainable or completely feasible for waste oil treatment and recovery. It was established that pyrolysis techniques offer a number of advantages over other existing techniques in recovering both the energetic and chemical value of waste oil by generating potentially useful pyrolysis products suitable for future reuse. In particular, microwave pyrolysis shows a distinct advantage in providing a rapid and energy-efficient heating compared to conventional pyrolysis techniques, and thus facilitating increased production rates. It was found that microwave pyrolysis of waste oil showed good performance with respect to product yield, reaction time, energy consumption, and product quality, and thus showing exceptional promise as a sustainable means for energy recovery from waste oils. Nevertheless, it was revealed that some important characteristics of the pyrolysis process have yet to be fully investigated. It was thus concluded that more studies are needed to extend existing understanding in the optimal reaction and process parameters in order to develop the pyrolysis technology to be a sustainable and commercially viable route for energy recovery from problematic waste oils. [ABSTRACT FROM AUTHOR]

Algae are considered promising renewable feedstocks for the production of alternative fuels. In this study, an indigenous strain of Scenedesmus bijugatus found commonly in the fresh water bodies was isolated and evaluated for biofuels production. The alga was successfully mass cultivated in the custom made vertical tubular photobioreactor (250 L capacity) at semi-continuous mode. During the cultivation period, the volumetric biomass and lipid productivity were assessed. The alga S. bijugatus produced 0.26 g L −1 d −1 of dry biomass and 63 mg L −1 d −1 of lipids, respectively. Algal biomass was harvested by a combined harvesting process involving coagulation and flocculation using Iron (III) sulfate and an organic polymer which resulted in 98% harvesting efficiency. Lipid extraction using hexane:diethyl ether (1:2 ratio) resulted in maximum extraction of lipids. This study also examined sequential stages of esterification and transesterification to convert lipids to biodiesel. The maximum biodiesel yield of 0.21 g/g of dry biomass was obtained through the acid base catalytic process. The biodiesel fuel properties were tested and observed that most of the properties complying with ASTM D6751 specifications. The lipid extracted residual biomass recorded a yield of 0.158 g of bioethanol per g. This study confirmed the potential of lipid extracted biomass for the production of bioethanol to improve the economic feasibility of microalgal biorefinery. [ABSTRACT FROM AUTHOR]

In this study, solid oil palm shell (OPS) waste biomass was subjected to microwave pyrolysis conditions with uniformly distributed coconut activated carbon (CAC) microwave absorber. The effects of CAC loading (wt%), microwave power (W) and N 2 flow rate (LPM) were investigated on heating profile, bio-oil yield and its composition. Response surface methodology based on central composite design was used to study the significance of process parameters on bio-oil yield. The coefficient of determination ( R 2 ) for the bio-oil yield is 0.89017 indicating 89.017% of data variability is accounted to the model. The largest effect on bio-oil yield is from linear and quadratic terms of N 2 flow rate. The phenol content in bio-oil is 32.24–58.09% GC–MS area. The bio-oil also contain 1,1-dimethyl hydrazine of 10.54–21.20% GC–MS area. The presence of phenol and 1,1-dimethyl hydrazine implies that the microwave pyrolysis of OPS with carbon absorber has the potential to produce valuable fuel products. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) have been reported to be responsible for many acute and chronic health effects and environmental degradations. In this study, coconut shell based porous carbon was produced through chemical activation with potassium hydroxide (PHAC) and chemically treated with ammonia (PHAC-AM) to improve the adsorption of benzene and toluene. The porous carbons were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nitrogen adsorption tests. Removal efficiencies and adsorption capacities of the activated carbon samples for benzene and toluene were carried out through batch studies. Langmuir, Freundlich and Temkin adsorption isotherms were tested for the adsorption process and the experimental data were best fitted by Langmuir model. Pseudo-second-order kinetic model best described the adsorption kinetics for the two VOCs on PHAC and PHAC-AM. The removal of benzene and toluene by PHAC are; 82.5 and 85.6%, while that of PHAC-AM are; 91 and 92.3% respectively with approximately 10% increase in the uptake after the ammonia treatment. After five cycles of adsorbents regeneration test, approximately 50% of benzene and toluene was still able to be removed. The results of this study revealed that ammonia treated activate carbon (PHAC-AM) is a sustainable adsorbent for treatment of VOCs in polluted waters. [ABSTRACT FROM AUTHOR]

This study explores an integrated approach on biodiesel and bioethanol production from the indigenous strain Botryococcus sudeticus. The alga was isolated from the freshwater pond and mass cultivated in 25 m 2 open raceway pond. A two-step combined harvesting technique such as coagulation and flocculation was standardized. The results showed that 150 ppm of ferric chloride and 15 ppm of organic polymer Poly-(D) glucosamine increases the harvesting efficiency and the biomass yield was achieved up to 99%. Based on the areal and volumetric biomass productivity, it is estimated that the alga B. sudeticus can produce 71.1 t ha −1 y −1 of dry biomass. The dry biomass was analyzed for its chemical compositions. The results revealed that, the alga accumulates 4.5% of hydrocarbon, 22.6% of lipid, 23% of carbohydrate and 19.5% of protein, respectively. Sequential stages of esterification and then transesterification were studied to convert the FFA and triglycerides into biodiesel. Triacylglycerides and free fatty acids were converted to alkyl esters with up to 89% efficiency and the biodiesel yield was estimated up to 0.195 g/dry biomass. Further, the exploitation of lipid extracted residual biomass was explored for bioethanol production. The results indicate that 0.165 g bioethanol/g residual biomass was obtained at 30 °C fermentation for 168 h. [ABSTRACT FROM AUTHOR]

The present research aims to study the simulation of date palm waste gasification using ASPEN HYSYS. A steady state simulation of downdraft gasifier firing date palm leaves has been developed. The model is able to predict syngas composition with sound accuracy and can be used to find optimal operating conditions of the gasifier. Biomass is defined as an unconventional hypothetical solid component in HYSYS. A set of six reactor models simulates various reaction zones of the downdraft gasifier in accordance with its hydrodynamics. Biomass decomposition into constituents in the pyrolysis zone is modeled with a conversion reactor. The combustion of char and volatiles in the combustion zone are modeled with equilibrium and Gibbs reactor models respectively. The gasification zone is modeled with a Gibbs and equilibrium reactor. The results of simulation are validated against experimental results of a parametric variability study on a lab scale gasifier. The proportion of synthesis gas increase as temperature increases (concentration, molar fraction, and partial pressure). CO 2 and CH 4 in the product gases were also found to decrease with increasing temperature. At 800 °C, the exit gas reaches a stable molar composition (H 2 = 56.27%, CO = 21.71%, CO 2 = 18.24%, CH 4 = 3.78%). Increasing steam to biomass ratio increases CO 2 and H 2 at the expense of CO, governed by shift reaction. Steam induction increases the methane contents, thereby improves the heating value of the product gas. [ABSTRACT FROM AUTHOR]

The indigenous strain Botryococcus braunii TN101 was isolated and acclimatized under laboratory condition. Upstream and downstream process was thoroughly explored for biofuel production. During semi-continuous cultivation, the alga was grown under batch mode for 6 days; thereafter 40% of algal culture was harvested at every three days interval. At semi-continuous system, the indigenous strain grows well and produces high biomass productivity of 33.8 g m −3 day −1 . A two step combined harvesting process was designed using ferric iron and organic polymer Poly-( d )glucosamine and harvested 99.5% of biomass. Lipid extraction was optimized using different solvents, cyclohexane and methanol at 3:1 ratio supported for maximum extraction of lipids in Botryococcus up to 26.3%. Physicochemical properties of lipid was analyzed and found, saponification values 184, ester values 164, iodine values 92 and the average molecular weight of the lipids are 920 g mol −1 . The lipid contains 9.7% of FFA level, therefore, a simultaneous esterification and transesterification of free fatty acids and triacylglycerides were optimized for biodiesel production and the methyl ester yield was recorded up to 84%. In addition, an optimization study was carried out for the removal of pigments present in the biodiesel; the result revealed that 99% of pigments were removed from the biodiesel using activated charcoal. The biodiesel profile was analyzed by 1 H and 13 C NMR and GC–MS analyzer, methyl palmitate and methyl oleate was the major fatty acid found. Based on the areal and volumetric biomass productivity, it is estimated that the indigenous strain can produce 101 tons ha −1 year −1 of biomass. [ABSTRACT FROM AUTHOR]

The study explores on upstream and downstream process in Microcystis aeruginosa for biodiesel production. The alga was isolated from temple tank, acclimatized and successfully mass cultivated in open raceway pond at semi-continuous mode. A two step combined process was designed and harvested 99.3% of biomass, the daily dry biomass productivity was recorded up to 28 g m –2 day −1 . The lipid extraction was optimized and achieved 21.3%; physicochemical properties were characterized and found 11.7% of FFA, iodine value 72% and 99.2% of ester content. The lipid was transesterified by a two step simultaneous process and produced 90.1% of biodiesel; the calorific value of the biodiesel was 38.8 MJ/kg. Further, the physicochemical properties of biodiesel was characterized and found to be within the limits of American ASTM D6751. Based on the areal and volumetric biomass productivity estimation, M. aeruginosa can yield 84.1 tons of dry biomass ha −1 year −1 . [ABSTRACT FROM AUTHOR]

Highlights: [•] Ejector as an expansion device in vapor compression refrigeration system. [•] Modified ejector cycle for energy savings in air conditioning system. [•] Modified of ejector cycle can further improve the COP of standard refrigeration cycle. [•] The use of ejector as an expansion device is recommended for geographical areas which have high outdoor air temperature. [Copyright &y& Elsevier]

Highlights: [•] Dielectric properties of oil palm biomass (OPB) and biochar. [•] Penetration depth and dielectric properties are greatly influenced by frequency. [•] OPB is poor microwave absorber. [•] OPB alone did not attained high temperature under microwave heating. [Copyright &y& Elsevier]

Abstract: The present research work is probably the first attempt to focus on the kinetics of pyrolysis and combustion process for date palm biomass wastes like seed, leaf and leaf stem by using Thermogravimetric Analysis (TGA) technique. The physical properties of biomass wastes were also examined. Proximate and ultimate analysis of the date palm biomass was investigated. FT-IR analysis was conducted to determine possible chemical functional groups in the biomass. Results showed that date palm seed and leaf can be characterized as high calorific values and high volatile content biomass materials as compared to the leaf stem. Kinetic analysis of this biomass was also given a particular attention. It is concluded that these biomasses can become useful source of energy, chemicals and bio-char. [Copyright &y& Elsevier]