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The increase in carbon dioxide (CO 2 ) concentration in atmosphere brings in major concern nowadays. Accordingly, a study on the volumetric CO 2 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 CO 2 adsorption capacity and CO 2 /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 CO 2 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 CO 2 adsorption, irrespective of adsorption temperature. Besides, heterogeneity characteristics of gas-solid adsorption is further confirmed through the isosteric heat of adsorption (Q st ) value that decreases with increasing surface loading. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 (< 120 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The increase of carbon dioxide (CO 2 ) 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 CO 2 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 CO 2 flue gas prior to emission to air. Throughout this paper, the activated carbons which were proposed to be a separation medium for CO 2 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 CO 2 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. [ABSTRACT FROM AUTHOR]

Abstract: CO2 (Carbon dioxide) emissions are one of the greenhouse gases that cause global warming. The power generation industry is one of the main emitters of CO2, 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 CO2 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 CO2 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. [Copyright &y& Elsevier]

Abstract: Calcination of CaCO3 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 CaCO3 via thermo-gravimetric analyzer (TGA) in order to optimize the process. In the present work, cockle shells were used as CaCO3 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 CaCO3 in cockle shells to CaO after calcination. The optimum adsorptive capacity of synthesized CaO for CO2 at the optimum conditions is 0.72 kg CO2/kg CaO. [Copyright &y& Elsevier]

Abstract: 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), CO2 flow rate (100-300 cm3/min), heating rate (5-25̊C/min), reaction temperature (500-900̊C) and residence time (15-90 mins) on the physical properties of the activated carbon. For the process parameter optimization, L25 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. [Copyright &y& Elsevier]

• K 2 CO 3 -activated carbon is obtained from mixtures of petroleum coke and palm shell. • Facile activation route through mechano-chemical K 2 CO 3 activation has been applied. • Box-Behnken design is used for optimization of yield and CO 2 adsorption capacity. • Optimized activated carbon shows a well-developed porosity and surface morphology. • Porous carbon from blend precursors has superior yield and CO 2 adsorption capacity. 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 (K 2 CO 3) activation under nitrogen (N 2) 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 (Y 1) and carbon dioxide (CO 2) adsorption capacity at an atmospheric condition (Y 2) 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 Y 1 and Y 2 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 CO 2 adsorption performance with commercial activated carbon as well as that in literatures. [ABSTRACT FROM AUTHOR]

This study aims to develop an inexpensive, environmentally-friendly adsorbent for capturing CO 2 using coconut shells, widely abundant in Asian agricultural waste. The raw coconut shell adsorbent (CS) has undergone dual functionalization utilizing Chlorella microalgae and magnesium oxide (MgO) to enhance its physicochemical properties. Through dual functionalization, minimizing the loss of surface area and reducing the temperature sensitivity often occurring during CO 2 adsorption is possible. The surface morphology, functional groups, and thermochemical properties of CS-hydrochar were characterized and evaluated. The characterization demonstrates the successful development of the ternary composite (HCS-A-Mg), with a specific surface area of 1045 m2/g and containing nitrogen and metal oxide functional groups. XRD analysis of HCS-A-Mg reveals crystalline peaks at 36.8°, 42.9°, and 63°, confirming the successful impregnation of MgO. The adsorption result showed that HCS-A-Mg exhibits a higher CO 2 adsorption capacity of 2.63 mmol/g, 50% higher than pristine hydrochar (HCS). The adsorption study revealed that the CO 2 adsorption capacity of HCS-A-Mg can be maximized to 3.23 mmol/g at 101 °C and 4.6 bar. Adsorption isotherms shows that the non-linear Sips model best describes the adsorption process, indicating a multilayer adsorption mechanism with profound surface heterogeneity of n = 2.3 for HCS-A-Mg, signifying higher accessibility of gas molecules deep into pores, enabling a variety of adsorption sites for CO 2 binding. Selectivity and reusability studies were conducted to validate the adsorbent applicability for industrial applications. HCS-A-Mg has higher CO 2 /N 2 selectivity by 41–57% and 0.05% loss of adsorption capacity after the 10th cyclic operation, suggesting their suitability for industrial applications. This finding underscores the potential of microalgae and magnesium oxide in advancing carbon capture technology and addressing environmental challenges. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper investigates the integrated catalytic adsorption (ICA) steam gasification of palm kernel shell for hydrogen rich gas production using pilot scale fluidized bed gasifier under atmospheric condition. The effect of temperature (600–750 °C) and steam to biomass ratio (1.5–2.5 wt/wt) on hydrogen (H2) yield, product gas composition, gas yield, char yield, gasification and carbon conversion efficiency, and lower heating values are studied. The results show that H2 hydrogen composition of 82.11 vol% is achieved at temperature of 675 °C, and negligible carbon dioxide (CO2) composition is observed at 600 °C and 675 °C at a constant steam to biomass ratio of 2.0 wt/wt. In addition, maximum H2 yield of 150 g/kg biomass is observed at 750 °C and at steam to biomass ratio of 2.0 wt/wt. A good heating value of product gas which is 14.37 MJ/Nm3 is obtained at 600 °C and steam to biomass ratio of 2.0 wt/wt. Temperature and steam to biomass ratio both enhanced H2 yield but temperature is the most influential factor. Utilization of adsorbent and catalyst produced higher H2 composition, yield and gas heating values as demonstrated by biomass catalytic steam gasification and steam gasification with in situ CO2 adsorbent. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]