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This study investigates the synthesize of activated carbon for carbon dioxide adsorption using palm kernel shell (PKS), a by-product of oil palm industry. The adsorbent synthesis involved a simple two-step carbonization method. Firstly, PKS was activated with potassium oxide (KOH), followed by functionalization with magnesium oxide (MgO). Surface analysis revealed that KOH activated PKS has resulted in a high specific surface area of 1086 m 2 /g compared to untreated PKS (435 m 2 /g). However, impregnation of MgO resulted in the reduction of surface area due to blockage of pores by MgO. Thermogravimetric analysis (TGA) demonstrated that PKS-based adsorbents exhibited minimal weight loss of less than 30% up to 500 °C, indicating their suitability for high-temperature applications. CO 2 adsorption experiments revealed that PKS-AC-MgO has achieved a higher adsorption capacity of 155.35 mg/g compared to PKS-AC (149.63 mg/g) at 25 °C and 5 bars. The adsorption behaviour of PKS-AC-MgO was well fitted by both the Sips and Langmuir isotherms, suggesting a combination of both heterogeneous and homogeneous adsorption and indicating a chemical reaction between MgO and CO 2 . Thermodynamic analysis indicated a spontaneous and thermodynamically favourable process for CO 2 capture by PKS-AC-MgO, with negative change in enthalpy (- 0.21 kJ/mol), positive change in entropy (2.44 kJ/mol), and negative change in Gibbs free energy (- 729.61 J/mol, - 790.79 J/mol, and - 851.98 J/mol) across tested temperature. Economic assessment revealed that the cost of PKS-AC-MgO is 21% lower than the current market price of commercial activated carbon, indicating its potential for industrial application. Environmental assessment shows a significant reduction in greenhouse gas emissions (381.9 tCO2) through the utilization of PKS-AC-MgO, underscoring its environmental benefits. In summary, the use of activated carbon produced from PKS and functionalised with MgO shows great potential for absorbing CO 2 . This aligns with the ideas of a circular economy and sustainable development., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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 2 capture. A single-stage phosphoric acid (H 3 PO 4 ) activation is adopted by varying the concentrations of H 3 PO 4 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 m 2 g -1 , which implies the effectiveness of the single-stage H 3 PO 4 activation. Furthermore, the prepared activated carbon via 50 wt.% H 3 PO 4 activation shows the highest BET surface area and carbon dioxide (CO 2 ) 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 CO 2 adsorption performance, it is concluded that bamboo waste conversion to activated carbon through H 3 PO 4 activation method is indeed promising., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The volumetric adsorption kinetics of carbon dioxide (CO 2 ) onto the synthesized palm kernel shell activated carbon via single-stage CO 2 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 CO 2 adsorption for both adsorbents, owing to its closer coefficient of determination (R 2 ) 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 CO 2 adsorbates at an elevated temperature. Nevertheless, CO 2 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 (E a ) value, which was deduced from the Arrhenius plot. E a 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 CO 2 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 CO 2 adsorption process onto the synthesized activated carbon and commercial activated carbon., (© 2020. Springer-Verlag GmbH Germany, part of Springer Nature.)

Accelerating greenhouse gas emission particularly carbon dioxide (CO 2 ) in the atmosphere has become a major concern. Adsorption process has been proposed as a promising technology for CO 2 adsorption from flue gas, and the carbonaceous adsorbent is a potential candidate for CO 2 adsorption at atmospheric pressure and ambient temperature. Biochar derived from palm kernel shell waste was applied as a potential precursor for activated carbon production. This research study employed the response surface methodology coupled with Box-Behnken design to optimize the parameters involved in producing exceptional activated carbon with high yield (Y 1 ) and CO 2 adsorptive characteristics (Y 2 ). Specifically, parameters studied include the activation temperature (750-950 °C), holding time (60-120 min), and CO 2 flow rate (150-450 mL/min). The activated carbon at the optimum conditions was characterized using various analytical instruments, including elemental analyzer, nitrogen (N 2 ) physisorption analyzer, and field emission scanning electron microscopy. Overall, utilization of biochar as the activated carbon precursor is practical compared with the traditional non-renewable materials, due to its cost efficiencies and it being more environment-friendly ensuring process sustainability. Besides, this research study that incorporates physical activation with CO 2 as the activating agent is attractive, because it directly promotes CO 2 utilization and capture, in addition to the absence of any chemicals that may result in the secondary pollution problems.

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 (CO 2 ) 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 CO 2 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 CO 2 flow rate of 450 cm 3 /min. The synthesised activated carbon has been characterised by diverse analytical instruments including thermogravimetric analyser, scanning electron microscope, as well as N 2 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 CO 2 uptake is comparable to the synthesised activated carbon from conventional dual-stage activation, commercial activated carbon and other published data from literature.

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]

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]

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]

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]