Mesoporous Magnesium Oxide Adsorbent Prepared via Lime (Citrus aurantifolia) Peel Bio-templating for CO2 Capture

Abstract

The utilization of the lime (Citrus aurantifolia) peel as a template can improve the adsorbent’s structural properties, which consequently affect its CO2 uptake capacity. Herein, a mesoporous magnesium oxide (MgO-lime (Citrus aurantifolia) peel template (LPT)) adsorbent was synthesized using an LPT. MgO-LPT demonstrated improved structural properties and excellent CO2 uptake capacity. Moreover, another MgO adsorbent was prepared via thermal decomposition (MgO-TD) for comparison. The prepared adsorbents were characterized by N2 physisorption, Fourier transform infrared spectroscopy and thermogravimetric analysis. The CO2 uptake of these adsorbents was under 100% CO2 gas and ambient temperature and pressure conditions. MgO-LPT exhibited a higher Brunauer–Emmett–Teller surface area, Barrett–Joyner–Halenda pore volume, and pore diameter of 23 m2.g−1, 0.142 cm3.g−1, and 24.6 nm, respectively, than those of MgO-TD, which indicated the mesoporous structure of MgO-LPT. The CO2 uptake capacity of MgO-LPT is 3.79 mmol CO2.g−1, which is 15 times that of MgO-TD. This study shows that the application of lime peel as a template for the synthesis of MgO adsorbents is a promising approach to achieve MgO adsorbents with enhanced surface area and thus increased CO2 capture performance. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Fabrication of magnesium oxide adsorbent by cellulosic filter paper fibre bio-templating for CO2 adsorption application

“…This study showed a promising application of filter paper templating in tuning the physicochemical features of MgO. Additionally, in another study, the diverse selection of the magnesium precursor and preparation growth medium has been reported successfully influence the morphological development of the MgO, that tuned its physicochemical properties, particularly magnesium nitrate (precursor) and ethylene glycol (growth medium) [9,12,10]. With the magnesium nitrate and ethylene glycol utilisation together with filter paper usage as templating material, it is expected to influence the improvement of the MgO adsorption performance.…”

“…For the MgO solely, the alteration of the physicochemical features has been documented as achievable through the fabrication of MgO using an appropriate preparation method. As reported in previous studies, the conventional thermal degradation method has been reported to exhibit MgO with densely aggregated spherical-shaped morphological features with 1.65 μm particle size (average) [12,10]. With these morphological features, the MgO displayed a significantly low surface area of less than 15 m 2 /g, which could be considered as undesired structural feature in accomplishing high adsorption performance of the adsorbent.…”

“…As reported by a number of studies, besides filter paperinduced morphological structure, the morphological development of the MgO was also influenced by the chemical reagent/solvent used as a growth medium during the preparation stage. For instance, the polyol compound (e.g., ethylene glycol) used as a growth medium will role as a structure-directing (chelating) agent that chelated with the Mg-ion, forming an intermediate Mg-polyol (ethylene glycolate) complex in thin flake/sheet-like features [23,35,12,10]. The mechanism of possible filter paper-induced fibrous structure (direct loading of Mg-ion to FPT structure) and polyol-promoted thin flake-like structure MgO was proposed in Figure 5.…”

“…Various biomaterials have been subjected in the metal oxide adsorbent fabrication phase, such as eggshell membrane, flower petals, fruit peel, fibrous cotton wool, leaves, filter paper, etc [19-21, 12, 10]. According to previous research, the utilisation of biomaterial templating (bio-templating) has demonstrated strategic fabrication routes for the metal oxide adsorbent, particularly MgO, with enhanced physicochemical properties, which has significantly improved the adsorption performance of the MgO [19,12,10,22]. Considering the potential beneficial effect of fibrous biomaterial in developing hierarchicalstructured adsorbent, a cellulosic filter paper material has been reported to be a promising candidate [19].…”