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The energy demand in Malaysia has shown a dramatic increase over the last few years: with natural gas and coal being the primary contributors. Nevertheless, due to declining in fossil fuel reserves coupled with negative environmental impacts, shifting to sustainable renewable energy for meeting the future energy demand is recommended. Since Malaysia is rich with natural resources, utilization of biomass energy (bioenergy/biofuel) as the alternative energy is promising to be further explored. Therefore, this review paper intents to discuss the current scenario of different types of biomass energy in Malaysia along with the up-to-date local biomass energy–related environmental policy (from 2016 onwards). In addition, challenges and barriers for large-scale implementation of the biomass energy in Malaysia are to be discussed. Overall, this review paper is interesting as it can assist in promoting the biomass utilization as energy source, and to ensure the future growth of biomass energy market in the country along with its effective implementation while alleviating poor disposal problem and to create job employment opportunities. Furthermore, a collective effort to expand potential biomass feedstocks, apart from oil palm, should be emphasized to encourage the renewable energy production diversification in the nation.

Bamboo is the fastest-growing plant and is abundant in Malaysia. It is employed as a starting material for activated carbon production and evaluated for its potential in CO2 capture. A single-stage phosphoric acid (H3PO4) activation is adopted by varying the concentrations of H3PO4 between 50 and 70 wt.% at a constant temperature and holding time of 500°C and 120 min, respectively. The bamboo-based activated carbons are characterized in terms of product yield, surface area, and porosity, as well as surface chemistry properties. Referring to the experimental findings, the prepared activated carbons have BET surface area of >1000 m2 g-1, which implies the effectiveness of the single-stage H3PO4 activation. Furthermore, the prepared activated carbon via 50 wt.% H3PO4 activation shows the highest BET surface area and carbon dioxide (CO2) adsorption capacity of 1.45 mmol g-1 at 25°C/1 bar and 9.0 mmol g-1 at 25°C/30 bar. With respect to both the characterization analysis and CO2 adsorption performance, it is concluded that bamboo waste conversion to activated carbon through H3PO4 activation method is indeed promising.

The volumetric adsorption kinetics of carbon dioxide (CO2) onto the synthesized palm kernel shell activated carbon via single-stage CO2 activation and commercial Norit® activated carbon were carried out at an initial pressure of approximately 1 bar at three different temperatures of 25, 50, and 100 °C. The experimental kinetics data were modelled by using the Lagergren’s pseudo-first-order model and pseudo-second-order model. Comparing these two, the non-linear pseudo-second-order kinetics model presented a better fit towards CO2 adsorption for both adsorbents, owing to its closer coefficient of determination (R2) to unity, irrespective of the adsorption temperature. In addition, kinetics analysis showed that the corresponding kinetics coefficient (rate of adsorption) of both activated carbons increased with respect to adsorption temperature, and thereby, it indicated higher mobility of CO2 adsorbates at an elevated temperature. Nevertheless, CO2 adsorption capacity of both activated carbons reduced at elevated temperatures, which signified exothermic and physical adsorption (physisorption) behaviour. Besides, process exothermicity of both carbonaceous adsorbents can be corroborated through activation energy (Ea) value, which was deduced from the Arrhenius plot. Ea values that were in range of 32–38 kJ/mol validated exothermic adsorption at low pressure and temperature range of 25–100 °C. To gain an insight into the CO2 adsorption process, experimental data were fitted to intra-particle diffusion model and Boyd’s diffusion model, and findings revealed an involvement of both film diffusion and intra-particle diffusion during CO2 adsorption process onto the synthesized activated carbon and commercial activated carbon.

Bamboo is the fastest-growing plant and is abundant in Malaysia. It is employed as a starting material for activated carbon production and evaluated for its potential in CO

In this study, a binary mixture of petroleum coke and palm kernel shell had been investigated as potential starting materials for activated carbon production. Single-stage potassium carbonate (K2CO3) activation under nitrogen (N2) atmosphere was adopted in this research study. Effect of several operating parameters that included the impregnation ratio (1-3 wt./wt.), activation temperature (600-800 °C), and dwell time (1-2 hrs) were analyzed by using the Box-Behnken experimental design. Influence of these parameters towards activated carbon yield (Y1) and carbon dioxide (CO2) adsorption capacity at an atmospheric condition (Y2) were investigated. The optimum conditions for the activated carbon production were attained at impregnation ratio of 1.75:1, activation temperature of 680 °C, and dwell time of 1 h, with its corresponding Y1 and Y2 is 56.2 wt.% and 2.3991 mmol/g, respectively. Physicochemical properties of the pristine materials and synthesized activated carbon at the optimum conditions were analyzed in terms of their decomposition behavior, surface morphology, elemental composition, and textural characteristics. The study revealed that the blend of petroleum coke and palm kernel shell can be effectively used as the activated carbon precursors, and the experimental findings demonstrated comparable CO2 adsorption performance with commercial activated carbon as well as that in literatures.

The volumetric adsorption kinetics of carbon dioxide (CO

The feasibility of biomass-based activated carbons has received a huge attention due to their excellent characteristics such as inexpensiveness, good adsorption behaviour and potential to reduce a strong dependency towards non-renewable precursors. Therefore, in this research work, eco-friendly activated carbon from palm kernel shell that has been produced from one-stage physical activation by using the Box-Behnken design of Response Surface Methodology is highlighted. The effect of three input parameters—temperature, dwell time and gas flow rate—towards product yield and carbon dioxide (CO2) uptake at room temperature and atmospheric pressure are studied. Model accuracy has been evaluated through the ANOVA analysis and lack-of-fit test. Accordingly, the optimum condition in synthesising the activated carbon with adequate CO2 adsorption capacity of 2.13 mmol/g and product yield of 25.15 wt% is found at a temperature of 850 °C, holding time of 60 min and CO2 flow rate of 450 cm3/min. The synthesised activated carbon has been characterised by diverse analytical instruments including thermogravimetric analyser, scanning electron microscope, as well as N2 adsorption-desorption isotherm. The characterisation analysis indicates that the synthesised activated carbon has higher textural characteristics and porosity, together with better thermal stability and carbon content as compared to pristine palm kernel shell. Activated carbon production via one-step activation approach is economical since its carbon yield is within the industrial target, whereas CO2 uptake is comparable to the synthesised activated carbon from conventional dual-stage activation, commercial activated carbon and other published data from literature.

The increase in carbon dioxide (CO2) concentration in atmosphere brings in major concern nowadays. Accordingly, a study on the volumetric CO2 adsorption by using the palm kernel shell-based activated carbon synthesized via direct activation at 850 °C for 1 h has been investigated. The adsorbents are characterized using various analytical techniques to analyze the elemental, surface, and textural characteristics. Referring to the physiochemical analysis, it verifies that the proposed activation method effectively converts the palm kernel shell to value-added activated carbon material. The synthesized palm kernel shell-based activated carbon shows comparable CO2 adsorption capacity and CO2/nitrogen selectivity with the commercial grade activated carbon. The regeneration study that has been carried out via pressure swing indicates easy regenerability and good stability after the multiple adsorption-desorption cycles. The experimental CO2 adsorption isotherm data is examined by using several isotherm models – Langmuir, Freundlich, and Sips, by using non-linear regression method. The findings reveal that the Sips model mathematically represents the CO2 adsorption, irrespective of adsorption temperature. Besides, heterogeneity characteristics of gas-solid adsorption is further confirmed through the isosteric heat of adsorption (Qst) value that decreases with increasing surface loading.

The activated carbon is acknowledged as a promising adsorbent to be applied in various applications due to its low cost, well-developed pore structures, and high adsorption capacity. At present, the increasing abundance of oil palm wastes has resulted in various environmental problems. Accordingly, these agro wastes can be employed as potential low-cost precursors for the activated carbon production. This review paper presents a comprehensive overview on the recent advancement in the utilisation of oil palm wastes as the origin of the activated carbon production, specifically from the year 2011 to the present. Throughout this review paper, a strong emphasis is put on the recent activation methodology towards the oil palm residues. This includes the types of thermal heating mode: conventional furnace-heating and microwave-heating. The experimental designs applied in fabricating the activated carbons from the oil palm wastes are discussed. Overall, this review paper assists researchers to move forward in exploring a simple and economically-viable technique to produce oil palm wastes-based activated carbon with outstanding physiochemical properties and excellent adsorption capacity.

Functionalization of activated carbon as electrode materials for supercapacitor application has attracted much attention nowadays, due to integration of electrostatic and Faradaic reaction mechanism that contributes to high performance supercapacitor system. Thus, this review article aims to provide an up-to-date information on the recent development of nitrogen-functionalized activated carbon and the corresponding techniques (post-modification and in-situ doping) used for the functionalization process. The characteristics of the functionalized activated carbon such as the specific surface area and N-contents, as well as the performance particularly in terms of the gravimetric capacitance has also been discussed. Further, perspective of future work particularly on the nitrogen-functionalized activated carbon has been described at the end of this review paper. Overall, it is hoped that this review paper can enhance the research area on the activated carbon as electrode materials for the supercapacitor applications.

The accelerating demand of energy in the world has resulted in increasing numbers of installation of coal-fired power plants. With growth in coal burning power stations, huge amounts of coal bottom ash considered as hazardous materials are anticipated to be produced. At present, coal ash residues are conventionally disposed in an on-site disposal system such as land-fill and in ash pond without any commercialization purposes. The massive generation of coal bottom ash in power plants causes a variety of environmental pollutions, with regards to presence of alkaline heavy metals and their leaching problems. In addition, huge accumulation of bottom ash results in handling and storage problems, such as inadequate spaces or facilities to hold the coal burning residues. Accordingly, a review on the prospect of coal bottom ash utilization as adsorbent material is elaborated. The physical and chemical properties of the bottom ash are discussed for a good understanding of the physiochemical characteristics and sui...

The increase of carbon dioxide (CO2) concentration in the ambient air has become the key factor in the pace of temperature rise, and accordingly, is a primary contributor towards global warming scenario. In view of this, the quick mitigation efforts associated with capturing CO2 from fossil fuel combustion source must be implemented to alleviate environmental catastrophic events in future. Therefore, the purpose of this paper was to review the role and performances of activated carbon in capturing anthropogenic CO2 flue gas prior to emission to air. Throughout this paper, the activated carbons which were proposed to be a separation medium for CO2 capture are evaluated in terms of equilibrium adsorption capacity as well as the surface modification. The utilization of the activated carbons instead of current state-of-art technology, which is the chemical absorption is promising as it avoids higher energy penalty encountered in regeneration process and the consumption of corrosive chemical such as aqueous amine-based solvent. In addition, the investigation on the potential of activated carbons for post-combustion CO2 capture is expected to confer scientists with critical information related to the future direction of the activated carbons in an industrial application, and as an alternative to conventional amine scrubbing process.

The aim of this study was to produce a low-cost activated carbon derived from rubber-seed shells using potassium hydroxide (KOH) as chemical agent. The effect of preparation conditions such as impregnation ratio (1:1 and 1:2), carbonization temperature (500, 600 and 700°C) and duration (90, 120, 150, 180 and 210 minutes) on the produced activated carbon were investigated. Sample B1 was identified to yield activated carbon with the largest surface area, total pore volume and diameter. The results from adsorption test found that under the effect of initial concentration, the optimum sample is capable of removing 98.8% of Zn 2+ and 99% of Cu 2+ at low concentration of 200 ppm. Under the effect of stirring rate, 99.7% of Zn 2+ and 99.6% of Cu 2+ is removed at stirring rate at 400 rpm. Finally under the effect of contact time, 99.6% of Zn 2+ and 94% of Cu 2+ removal is achieved at time of 45 minutes. The obtained results show that agriculture waste product from rubber-seed shell is a promising low cost precursor for the production of activated carbon and it can be effectively used as an adsorption material.

The bifunctional Graphene Oxide-Copper (GO-Cu) coated nickel mesh that was fabricated through layer-by-layer approach was used as a working electrode in carbon dioxide (CO2) electro-reduction process for ethanol production. The findings confirmed smooth and well-dispersed deposition of Cu-nanoparticles onto GO, and less corrosion behavior in 0.1M potassium carbonate (K2CO3) solution. Besides, linear sweep voltammetry and chronoamperometry analysis was performed to determine the electro-reduction activity of the fabricated electrode. Novelty of this study covers a working electrode production that possesses high durability and stability while maintaining good current and proton conductivity, as well as high efficiency and selectivity towards desirable product.

The goal of the study was to produce a low-cost activated carbon from agricultural residues via single stage carbon dioxide (CO2) activation and to investigate its applicability in capturing CO2 flue gas. The performance of the activated carbon was characterized in terms of the chemical composition, surface morphology as well as textural characteristics. The adsorption capacity was investigated at three temperatures of 25, 50 and 100 °C for different types of adsorbate, such as purified carbon dioxide and binary mixture of carbon dioxide and nitrogen. The purified CO2 adsorption study showed that the greatest adsorption capacity of the optimized activated carbon of 1.79 mmol g−1 was obtained at the lowest operating temperature. In addition, the adsorption study proved that the adsorption capacity for binary mixtures was lower due to the reduction in partial pressure. The experimental values of the purified CO2 adsorption were modelled by the Lagergren pseudo-first-order model, pseudo-second-order model, and intra-particle diffusion model. Based on the analysis, it inferred that the adsorption of CO2 followed the pseudo-second-order model with regression coefficient value higher than 0.995. In addition, the adsorption study was governed by both film diffusion and intra-particle diffusion. The activation energy that was lesser than 25 kJ mol−1 implied that physical adsorption (physisorption) occurred.

promising solid adsorbents that can be utilized to capture CO2 due to its numerous benefits, such as inexpensive, easy for regeneration, insensitiveness towards the moisture, high CO2 adsorption capacity at ambient condition, high specific surface area, adequate pore size distribution, high mechanical strength, as well as low in energy requirement (4). Based on the benefits possessed by activated carbon, it has been widely employed in various applications, be it in gas or liquid phase. However, exploitation of the activated carbons in capturing CO2 has not been extensively evaluated. The potential of activated carbon in CO2 capture depends on few criteria such as types of activation method and nature of starting materials, which in turn affects the porosity and surface chemistry of the synthesized activated carbon (5). The chemical activation method includes the ammonia treatment and impregnation technique that have been extensively employed nowadays is uninvited as it imposes hazardous impacts towards the environment and also, results in pore blockage that may possibly lessen the adsorption capacity. Plaza et al. (2) proved that impregnation of activated carbon with amine-based compounds is not a suitable approach for CO2 capture at room temperature, as it reduces the surface area and block the microporous structure that is accountable for physical adsorption process. Specifically, the impregnated activated carbon with polyethylenimine (PEI) solvents which had BET surface area of 90 m 2 /g can only capture CO2 up to 4.9 wt%, as compared to virgin activated carbon that had total surface area of 1,762 m 2

The present study investigates the optimization of hydrogen (H2) production with in-situ catalytic adsorption (ICA) steam gasification by using a pilot-scale fluidized bed gasifier. Two important response variables i.e. H2 composition (in percent volume fraction, %) and H2 yield (in g kg−1 of biomass) are optimized with respect to five process variables such as temperature (600 °C–750 °C), steam to biomass mass ratio (1.5–2.5), adsorbent to biomass mass ratio (0.5–1.5), superficial velocity (0.15 m s−1–0.26 m s−1) and biomass particle size (350 μm–2 mm). The optimization study is carried out based on Response Surface Methodology (RSM) using Central Composite Rotatable Design (CCRD) approach. The adsorbent to biomass mass ratio is found to be the most significant process variables that influenced the H2 composition, whereas temperature and biomass particle size are found to be marginally significant. For H2 yield, temperature is the most significant process variables followed by steam to biomass mass ratio, adsorbent to biomass mass ratio and biomass particle size. The optimum process conditions are found to be at 675 °C, steam to biomass mass ratio of 2.0, adsorbent to biomass mass ratio of 1.0, superficial velocity of 0.21 m s−1 that is equivalent to 4 times the minimum fluidization velocity, and 1.0 mm–2.0 mm of biomass particle size. The theoretical response variables predicted by the developed model fit well with the experimental results.

The objective of this research is to synthesize the microporous activated carbon and test its applicability for CO2gas capture. In this study, coconut shell-based and commercial activated carbon is used as the solid adsorbent. Based on the findings, it shows that the gas adsorption capacity is correlated to the total surface area of the materials. In addition, reduction in the adsorption capacity with respect to temperature proves that the physisorption process is dominant. Higher carbon dioxide (CO2) adsorption capacity in comparison to nitrogen (N2) capacity contributes to higher CO2/N2selectivity, and confirms its applicability in the post-combustion process. Utilization of abundance agricultural wastes and one-step physical activation process is attractive as it promotes a cleaner pathway for activated carbon production, and simultaneously, reduces the total operating cost.

CO 2 (Carbon dioxide) emissions are one of the greenhouse gases that cause global warming. The power generation industry is one of the main emitters of CO 2 , and the emissions are expected to increase in the coming years as there seems to be no abatement in the consumption of fossil fuels for the production of electricity. Thus, there is a need for CO 2 adsorption technologies to mitigate the emissions. However, there are several disadvantages associated with the current adsorption technologies. One of the issues is corrosion and the need for specialized equipment. Therefore, alternative and more sustainable materials are sought after to improve the viability of the adsorption technology. In this study, several types of agricultural wastes were used as activated carbon precursors for CO 2 adsorption process in a TGA (thermogravimetric analyser). The adsorption was also modelled through a pseudo-first order and second order model, Elovich's kinetic model, and an intra-particle diffusion model. From the correlation coefficient, it was found that pseudo-second order model was well-fitted with the kinetic data. In addition, activation energy below than 42 kJ/mol confirmed that the physisorption process occurred.

Calcination of CaCO 3 is a process of producing CaO – a widely used substance in high temperature applications. However, the efficiency of the process depends on the variable involved and the assumption made. Therefore, this paper aims to illustrate the effects of few variables on calcination and carbonation reaction of CaCO 3 via thermo-gravimetric analyzer (TGA) in order to optimize the process. In the present work, cockle shells were used as CaCO 3 sources. The experimental variables i.e. particle size, heating rate, calcination and carbonation temperature were employed. A minimum of two runs of experiments for each variable were conducted and the standard deviation for all of the runs are found to be less than 1. Analysis of XRD, XRF and EDX indicates the conversion of CaCO 3 in cockle shells to CaO after calcination. The optimum adsorptive capacity of synthesized CaO for CO 2 at the optimum conditions is 0.72 kg CO 2 /kg CaO.

In this work, a combined process of adsorption and gas hydrate formation is proposed as an alternative approach for the separation of carbon dioxide (CO2) content from gas stream. The objective of this research is to study adsorption isotherms of the CO2 gas onto the synthesized calcium oxide (CaO) via a static volumetric method at 2 °C at a different amount of water ratio (Rw). A large increment of CO2 adsorption was observed on the wetted sample due to formation of CO2 hydrates, particularly at high pressure. The highest adsorption capacity was obtained at Rw of 0.67. The experimental data of CO2 adsorption isotherms for Rw = 0 and Rw =0.67 are further analyzed by five isotherm models which are Langmuir, Freundlich, Redlich-Peterson (R-P), Toth and Sips. The Freundlich model satisfactorily describes the CO2 adsorption onto the dried sample, whilst the R-P model is best fitted for the wetted sample.

The feasibility of preparing activated carbon from single step carbon dioxide activation was studied. The optimization of the activated carbons were carried out to study the effects of precursors (coconut fiber, rice husk, coconut shell, palm kernel shell and palm mesocarp fiber), particle size (250-1000 μm), CO 2 flow rate (100-300 cm 3 /min), heating rate (5-25C/min), reaction temperature (500-900C) and residence time (15-90 mins) on the physical properties of the activated carbon. For the process parameter optimization, L 2 5 orthogonal array and “the-larger-the-better” response were employed to determine the optimum yield of the produced activated carbon. In addition, the proximate analysis, chemical compositions and the surface morphology of the raw materials and activated carbons were also discussed. The utilization of the agricultural residues as the activated carbon may help abating the environmental problems caused by irresponsible disposal of agro-wastes.

In this study, commercial Norit® SX2 activated carbon has been evaluated as a solid adsorbent for carbon dioxide (CO 2 ) capture at the post-combustion conditions, which are at an ambient pressure and low temperatures ( o C). The CO 2 equilibrium adsorption capacity is assessed through a static volumetric technique. This solid adsorbent is characterized in terms of elemental analysis, nitrogen physisorption, as well as surface morphology. The CO 2 adsorptive property of the commercial Norit® SX2 demonstrates a reduction in the amount of CO 2 adsorbed at an elevated temperature, and accordingly, it indicates that CO 2 adsorption is a physical adsorption process and demonstrates a behavior of an exothermic reaction, which consistent with the thermodynamics analysis. Different isotherm models are applied to mathematically model the CO 2 adsorption, and on basis of the regression coefficient (R 2 ), the Freundlich model provides a perfect fit to the experimental data, owing to closeness of the R 2 to unity. The result obtained in this study can serve as a benchmark while searching for inexpensive and superior activated carbon production in future studies.

Utilization of calcium-based adsorbent in carbon dioxide (CO2) separation from the gas stream through the calcination and carbonation process is extensively applied in the gas purification process, especially at the elevated reaction temperature. Typically, natural calcium carbonates (CaCO3) such as the limestone, magnesite and dolomite are widely consumed in the process due to their low cost and large abundance of these materials. However, in this research study, the potential of waste cockle shell as the CaCO3 sources were investigated. The main objectives of the work are to examine the influence of the process variables such as heating rate, particle size, temperature and residence time on the calcination rate. Therefore, Arrhenius equation was used to explain the process reactivity. The calcination process were carried out for various particles sizes (