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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]

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]

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]