Abstract
The continuous increase of anthropogenic carbon dioxide (CO2) emission has a wide range of impacts on human life. This phenomenon has burst a range of research trends towards the capturing and storing of CO2, subsequently, high performance carbon-capture materials include the liquid-based, membranes, and solid adsorbents have been reported. In particular, the solid-based carbon capture materials garnered attention in recent years owing to their variety of advantages over other adsorbents. Among them, magnesium oxide (MgO) based adsorbents are recognized as promising group of sorbent materials for CO2 adsorption and storage at intermediate temperatures. One of the main advantages of using MgO is its theoretical low costs and abundance in resource. However, real production cost is still high due to: a) higher CO2 capture operation temperatures, b) costly synthesis methods, and c) lack of clear adsorption mechanisms. This dissertation is dedicated to (1) develop a MgO based-solid adsorbent technique, (2) establish a control mechanism of room temperature CO2 adsorption. In this study, a rational design and synthesis methods of MgO based nanocomposites for room temperature CO2 adsorption were explored. Here, MgO based composites synthesized using electrospinning, an economical and an efficient method on synthesizing nanofibers. These electrospun MgO composites can be easily functionalized to match with the application making it easy to adopt for commercialization. The synthesized MgO based nano composites were in the range of 1µm-600 nm after calcinated at 300 ? for two hours. The resultant sorbents reported adsorption capacity of 3.9 wt% at 30 ? and increased adsorption of 14wt% and 15.5 wt%, at its’ 3-months and 6-months aging period at ambient conditions within 90 minutes which is a novel trend identified by this research. The electrospinning allows the ease of material combination. By taking advantage of this, anions of magnesium such as chlorine, sulfate, and phosphates have incorporated into the electrospinning solution to synthesis doped MgO composites. The samples were evaluated thoroughly as follows. The structural properties of the nanocomposites were investigated by iii using X-ray diffraction (XRD), evincing the presence of MgO with magnesium-based hydrides, carbonates, and monoclinic magnesium malate tetrahydrate. Scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) were used to evaluate surface morphology and sample composition. The surface area of the samples were analyzed by Brunauer-Emmett-Teller (BET) technique. The samples which recorded the highest adsorption was undergone the CO2 gas sensing. The resultant CO2 capture capacities analyzed via Thermo gravimetric analysis (TGA) measurements. The highest reported adsorption was recorded for the 10% Chlorine doped MgO material, at 30 ? recording 5.59 wt% (mmol/g) CO2 adsorption within 90 minutes. This reported CO2 adsorption capacity is the highest recorded capacity to date for electrospun MgO based CO2 capture materials at 30?. The best performed samples were then subjected to CO2 sensing and was reported to have gas sensing at 300 ? exposing 500ppm CO2 conditions. This thesis is composed of five (5) chapters and brief details of each chapters are present in chapter 1. This report presents with mechanisms of CO2 adsorption to the electrospun MgO composites at room temperature. The novel approach and the scientific apprehension enable a broad range of real-world applications for the MgO based CO2 capture, CO2 mineralization, sensing networks, and monitoring of inhouse CO2 levels.