Isotherm, Thermodynamic and Kinetic Studies of Selective CO2 Adsorption on Chemically Modified Carbon Surfaces

Abstract

Detailed assessments of adsorption properties (isotherm, thermodynamics and kinetics) were carried out on chemically modified activated carbon (AC). Some pretreatment methods prior amination have been used to improve the CO 2 selective capture of AC in our previous works. Here, the inter-relationships among the adsorption properties were further investigated and reported. It was found that CO 2 molecules bind onto the heterogeneous surfaces of AC in a monolayer pattern as experimental data fit Freundlich isotherm rather than Langmuir. However, Redlich-Peterson, a 3-parameter model provided the best fit. The highest degree of precision of Chi-square analysis professed it as the most efficient error function for the isotherm study. Values of standard entropy showed to be the most significant thermodynamic limiting parameter in the adsorption process, as physisorption was found predominant for CO 2 collection at the interface. This observation was corroborated with temperature programmed desorption (TPD) analysis where ca. 86% of adsorbed CO 2 were desorbed below 500°C. The kinetic study indicated that CO 2 -AC interaction follows pseudo-second order while the higher R 2 of intraparticle diffusion over Elovich equation confirmed the deduction made from the thermodynamic study. Conclusively, the study of adsorption properties in this work provides useful information for designing proper adsorption reactor and subsequent regeneration of CO 2 -laden adsorbents at environmental levels.

Assessment of Ag Nanoparticles Interaction over Low-Cost Mesoporous Silica in Deep Desulfurization of Diesel

“…The Langmuir model fitting for sulfur adsorption results with this material at 298, 308 and 318 K is depicted in Figure S4 of the Supplementary Material. The positive value for ΔH° indicates an endothermic process and its magnitude reaches the region defined for chemisorption in literature (≥40 kJ/mol) [54,55], thus suggesting predominantly chemical interactions between S-compounds and AgNO3/MCM-41 M adsorbent. Although the process is not spontaneous, it can be noticed that there is a tendency of increasing spontaneity by increasing the adsorption temperature, since the total free energy (ΔG°) of the system decreases.…”

“…The effect of temperature in S-compounds adsorption was studied by varying the temperature from 298, 308 and 318 K. The obtained thermodynamics parameters describe the variation or the transformation of a system. The standard free energy (∆G • , kJ/mol), standard enthalpy change (∆H • , kJ/mol) and standard entropy change (∆S • , kJ/mol K) can be calculated from the following Equations [54]:…”

Sustainable Biomass Glucose-Derived Porous Carbon Spheres with High Nitrogen Doping: As a Promising Adsorbent for CO2/CH4/N2 Adsorptive Separation

“…Among them, ACSs-N displayed the best performance, and its CO 2 capacity was 3.03 mmol g −1 at 25 • C and 1 bar, which is comparable to or higher than those of other state-of-the-art porous carbon adsorbents (see Table S1). It is well known that the favorable CO 2 capacity arose from two critical factors: (i) Highly microporous structure, especially the narrow micropores (<1 nm), which could greatly accommodate CO 2 molecules into pores; and (ii) heteroatom incorporation, especially N-doping, which could increase the surface basicity to enhance the bonding force with acidic CO 2 molecules [23,28,29,32]. However, the high micro-porosity is often inverse with the N content.…”

“…Among them, porous carbon absorbents have manifested many advantages, including easy preparation, low cost, large surface area, controllable porosity and surface functionality, hydrophobicity, and resistance to both bases and acids. One attractive aspect for porous carbon adsorbents is that they can be prepared by using various cheap carbon precursors, such as waste plastic polyethylene terephthalate [19], carbon black [24,25], coal [26][27][28], oil sands coke [29], and various biomass [30][31][32]. Among these precursors, biomass materials stand out for their environmental friendliness, wide availability, low cost, and renewability, and have been extensively used as a precursor for the preparation of gas-selective adsorbents.…”

Effects of Injection Pressure on Geological CO2 Storage in the Northwest Taiwan Basin

“…The behavior was assessed in terms of the pressure accumulation, CO 2 plume migration, risk of leakage from a fault and mechanical displacement (Li et al, 2013). More recent research on CO 2 capture technologies and mobility in the saline aquifers, like Yang et al (2014), Jean et al (2016), Wu et al (2016), and Adelodun et al (2016), further improves the confidence in carrying out CO 2 capture and storage in Taiwan in the foreseeable future. Li et al (2013) concluded that the aquifer at depths from 1500 m to 2000 m could safely contain a large amount of CO 2 for a long period of time (Li et al, 2013).…”