Publication: Conversion of waste slags into functional oxide materials and their application in carbon dioxide capture
| datacite.subject.fos | oecd::Engineering and technology::Chemical engineering | |
| dc.contributor.author | Zaza Hazrina Hashim | |
| dc.date.accessioned | 2025-05-15T02:39:39Z | |
| dc.date.available | 2025-05-15T02:39:39Z | |
| dc.date.issued | 2023-02-01 | |
| dc.description.abstract | Slag is a by-product of the smelting process for ores and scrap metals. The issue of excessive slag waste generated in the iron and steel industries has spurred an investigation on slag utilization. Blast furnace slag (BFS) is recovered by melting and separation from blast furnaces that produce molten pig iron, while dephosphorization slag and desiliconization slag are generated during the purification of steel to reduce the phosphorus and silicon content, respectively, and mostly consist of CaO, FeO, SiO2 and other minor oxides. In addition, CO2 emitted from the iron and steel industry accounts for about 5-7% of the total CO2 emissions worldwide, and its separation and recovery is a challenge. Chapter 1 provides background information on global warming and CO2 emissions from the iron and steel industries, as well as carbon capture and sequestration using calcium looping technologies. The problem statement, research objectives, scope of the study, and contents of the thesis are also addressed. Chapter 2 summarizes the iron and steel making process and discusses global steel slag production, chemical composition of steel slag, and CO2 emissions from the steel industry. Carbon capture and sequestration using calcium looping technology, examples of the use of waste slags as CO2 adsorbents and some methods to control sintering of CaO-based adsorbents are also addressed. In chapter 3, the general methodology for converting waste slags into metal oxide composites is addressed, which includes i) synthesis of CaO-Ca12Al14O33 composite adsorbent from blast furnace slag, ii) synthesis of CaO-Fe2O3-SiO2 composite adsorbent from dephosphorization slag, and iii) synthesis of CaO-mesoporous silica composite adsorbent from desiliconization slag. It also describes the chemicals and materials, the methods used to evaluate the CO2 adsorption performance, and the details of the equipment used in the experiments. Chapter 4 describes the structure and CO2 adsorption performance of the CaO-based oxide composites synthesized from three types of slag (blast furnace slag, dephosphorization slag, and desiliconization slag) using various acids (HCl, HNO3, formic acid, acetic acid, and citric acid). In Part I, a CaO-Ca12Al14O33 composite is synthesized from blast furnace slag using HCl and HNO3 as dissolving acids. It is found that the sample synthesized using HNO3 shows a superior CO2 adsorption performance compared to that synthesized using HCl due to easy removal of nitrate ions by a thermal treatment. In Part II, a CaO-Fe2O3-SiO2 composite is synthesized from dephosphorization slag using three kinds of acids (formic acid, HCl and HNO3) and a pore-forming agent (P123). The composite synthesized with formic acid shows the highest CO2 adsorption of 17 wt% under a flow of 10% CO2/N2 and at 700 °C. It is found that the use of organic acids and the addition of a pore-forming agent are effective for the synthesis of an efficient CO2 adsorbent. In Part III, a CaO-mesoporous silica composites are synthesized from desiliconization slag using three types of organic acids (formic acid, acetic acid, and citric acid). The sample synthesized with acetic acid shows a high CO2 adsorption uptake of about 21 wt% and reusability. It is considered that the use of acetic acid promotes the separation of crystalline CaO and SiO2 particles by the reaction of acetate ions and leached Ca2+ ions to form calcium acetate, which suppresses the sintering during CO2 adsorption and improves the durability of the adsorbent | |
| dc.identifier.uri | https://erepo.usm.my/handle/123456789/21635 | |
| dc.language.iso | en | |
| dc.title | Conversion of waste slags into functional oxide materials and their application in carbon dioxide capture | |
| dc.type | Resource Types::text::thesis::doctoral thesis | |
| dspace.entity.type | Publication | |
| oairecerif.author.affiliation | Univerisiti Sains Malaysia |