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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 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 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.

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.

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.