Search

Emission of greenhouse gases is currently recognized as one of the most significant problems confronting societies all over the world. Human activities, such as the consumption of fossil fuels for the generation of heat and electricity, as well as other industrial operations and transportation, are the primary sources of greenhouse gas emissions. The implementation of adsorption technology for the capture of carbon are widely used to lower the greenhouse gas emissions mainly carbon dioxide (CO2). However, there are still insufficient research has been done on the performance of Meranti sawdust as a low-cost carbon for CO2 capture, particularly by using a greener activation agent. A mechanochemical activation method using potassium carbonate (K2CO3) is highlighted in this study, where the approach is simpler and more environmentally friendly. By using the Taguchi L9 orthogonal array, several variables (i.e., temperature, impregnation ratio, duration, N2 flow rate) have been investigated to determine the optimal operating conditions to obtain high yield activated carbon. From the findings, it is shown that the optimal conditions for the activated carbon production is at 700 °C, impregnation ratio of 3:1, carbonization time of 60 min, and N2 flow of 900 mL/min, with corresponding activated carbon yield is approximately 41 % and CO2 adsorption capacity of 2.8 mmol/g. The carbon materials are to be evaluated in terms of elemental composition, surface functionalities and morphologies, as well as textural characteristics. Overall, wood waste conversion to activated carbon aligns with SDG 9, SDG 12, as well as SDG 13. [ABSTRACT FROM AUTHOR]

BACKGROUND: Over the years, activated carbon has been widely used for environmental applications, including liquid or gas phase applications. However, there are many hurdles for researchers in the activated carbon field to overcome when it comes to non‐renewable materials, the utilization of individual precursors, and the complex multistep procedures of activated carbon synthesis. Therefore, in this study, the facile mechanochemical potassium carbonate (K2CO3) activation of blended precursors — palm kernel shell and petroleum coke — was investigated in terms of the activated carbon yield and carbon dioxide (CO2) adsorption capacity. RESULTS: The optimum configuration of the activated carbon production was found at temperature of 680°C, holding time of 60 min, and impregnation ratio of 1.75:1. The CO2 adsorption data at 25–120°C was best represented by the Sips model with R2 > 0.9999, where maximum CO2 adsorption capacity (qmax) was within the range of 2.24–4.32 mmol/g. The kinetic analysis was well‐represented by the pseudo‐second order model due to the high R2 and low sum of square of errors (ERRSQ) value. In terms of thermodynamic analysis, it showed that the CO2 adsorption process was physical, exothermic, and spontaneous at lower temperature. CONCLUSION: Overall, the integration of agricultural and industrial waste to value‐added activated carbon was feasible not only in reducing waste disposal problems but also in facilitating CO2 mitigation. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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: 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]