Abstract

Abstract
Recently, developing bio-based carbon materials due to the surface chemistry and a large spectrum of pore structures have received much attention. In the present work, a series of activated carbon (AC) adsorbents were synthesized from the compost derived by the mechanical/biological treatment of municipal solid wastes and evaluated regarding their CO2 uptake. The AC samples were characterized by sulfuric acid and calcination by N-2 at 400 and 800 degrees C. Then, the CO2 uptake capacities were evaluated by dynamic breakthrough experiments in a temperature range of 40-100 degrees C and pressures up to 3 bar. The presented data were properly described by Langmuir model and it was revealed that the CMSW-S-800 sample, treated with sulfuric acid and activated at 800 degrees C, has the highest CO2 uptake capacity with an amount adsorbed around 2.6 mol/kg at 40 degrees C. In the next step, a mathematical model has been developed to match the experimental dynamic breakthrough data and design a pressure swing adsorption (PSA) cyclic process to evaluate the capacity and potential of the best AC sample for CO2 adsorption. The results arising from this work showed a possible route for the application of the compost as a source of activated carbon for the sorption of greenhouse gases.

Abstract
In this study, municipal solid waste composts obtained from mechanical biological treatment has been considered as a source of adsorbents for CO2 capture. Three samples derived from the maturated compost in the municipal solid wastes were modified to produce activated carbon. The first sample was treated with sulfuric acid, the second one was thermally treated at 800? C and the last one was modified chemically and thermally with sulfuric acid and at 800? C. Then, the CO2 uptake capacity of prepared samples was measured through breakthrough adsorption experiments at the post combustion operational conditions to collect isotherm data. Also a fixed bed adsorption mathematical model was developed by applying mass and energy balances. Results showed the municipal solid wastes have an excellent capacity to be considered as source of adsorbent for CO2 capture also the mathematical model is able to predict breakthrough data. © 2020 Taylor & Francis Group, London, UK.

Abstract
A fixed bed adsorption mathematical model has been developed to describe the kinetic separation of hexane isomers when they flow through a packed bed containing the microporous Metal-Organic Framework (MOF) ZIF-8 adsorbent. The flow of inert and adsorbable species through the fixed bed is modeled with fundamental differential equations according to the mass and heat conservation laws, a general isotherm to describe adsorption equilibrium and a lumped kinetic mass transfer mechanism between bulk gas phase and the porous solid. It is shown that a proper combination of two characteristic times (the residence time of the gas in the fixed bed, tfb and the characteristic time of diffusion of solutes into the pores tdif) can lead to very different dynamics of fixed bed adsorbers where in a limiting case can gives rise to a spontaneous breakthrough curves of solutes. The numerical simulations of an experimental breakthrough curve with the developed mathematical model clearly explain the complete separation between linear n-Hexane (nHEX) and the respective branched isomers: 3-Methyl-Pentane (3MP) and 2, 2-Dimethyl-Butane (22DMB). The separation is due to significant differences in the diffusivity parameters tdif between 3MP and 22DMB and the residence time of the gas mixture tfb within the fixed bed. This work shows the importance of mathematical modelling for the comprehension and design of adsorption separation processes. © 2018, Springer International Publishing AG, part of Springer Nature.