Before salt splitting may be used to produce dilute NaOH and dilute HCl solutions from salty brines, scaling ions such as Ca2+ and Mg2+ needs to be removed to increase the operating live of the membranes in bi-polar double membrane electrodialysis (BPMD). This is generally done by chemical precipitation through the addition of Ca(OH)2 to precipitate Mg(OH)2 and NaCO3 to precipitate CaCO3 under alkaline conditions (pH>10). It is possible to selectively precipitate first the Mg(OH)2 and then the CaCO3. The resulting solids are considered non-hazardous waste and is an underutilised secondary resource. We propose that these wastes be dissolved in the dilute acid produced by salt splitting to provide cations for ion-exchange treatment of zeolite adsorbents after thermal treatment. Adsorbents will therefore have a sodium (baseline), or a modified calcium or magnesium framework. Although some zeolites have previously been evaluated in modified calcium framework, this will be the first test work on magnesium frameworks.
Thermal treatment of the baseline zeolites at 200 \u00b0C (activation), 400 \u00b0C (crystallinity improvement and framework ordering) and 500 \u00b0 (calcination and strengthening) will be done in a muffle furnace and characterized for comparison with the baseline samples.
Framework modification will follow using ion exchange in a temperature controlled shaker table. Thermally enhanced zeolite doses will be placed in flasks and aqueous solutions of known MgCl2 or CaCl2 concentration and volume will be introduced. Samples of the aqueous solutions will be taken before and after the ion exchange experiments to determine the efficacy of the ion exchange by analysis of the Ca, Mg and Na content using ICP-OES. The duration of the ion exchange will be 2 to 4 hours for Ca ions and 4 to 8 hours for Mg ions. Mg\u00b2\u207a exchange is expected to require longer contact times than Ca\u00b2\u207a due to the larger hydrated radius and lower diffusion coefficient of Mg\u00b2\u207a in zeolite micropores, which has been shown to be approximately an order of magnitude lower than that of Ca\u00b2\u207a in crystalline zeolites. The zeolites with modified frameworks will then be tested and compared with the baseline products produced in WP1.
Baseline CO\u2082 adsorption performance will be established using static gas adsorption isotherms. Adsorbents will then undergo controlled thermal treatment and ion exchange with Ca\u00b2\u207a and Mg\u00b2\u207a cations. Adsorption performance will be correlated with structural, textural and compositional characterisation using established techniques including SEM, TEM, BET surface area analysis, ICP-OES, XRF and FIR spectroscopy.<\/p>\n\n\n\n
Aim <\/p>\n\n\n\n
To improve CO\u2082 adsorption capacity and selectivity of mineral\u2011derived adsorbents through systematic thermal treatment and ion exchange using earth\u2011abundant cations sourced from waste streams.<\/p>\n\n\n\n
Objectives <\/p>\n\n\n\n
Baseline CO\u2082 adsorption and selectivity data for mineral\u2011derived adsorbents; A systematically characterised suite of thermally treated and ion\u2011exchanged adsorbents (Na\u207a, Ca\u00b2\u207a and Mg\u00b2\u207a forms); Quantitative evaluation of improvements in CO\u2082 adsorption capacity and selectivity; Structure\u2013property relationships linking cation chemistry and thermal history to adsorption performance; One review paper on adsorbent enhancement through thermal and chemical treatment; One peer\u2011reviewed journal publication on adsorption enhancement through combined thermal and chemical treatment; Conference dissemination of outcomes<\/p>\n\n\n\n
Significance <\/p>\n\n\n\n
Ideal Candidate <\/p>\n\n\n\n
Minimum requirements: A Bachelor\u2019s degree with first-class honours or upper second-class honours in Chemical Engineering, Environmental Engineering, Metallurgical Engineering, or a closely related discipline.<\/p>\n\n\n\n
Applicants holding a Master\u2019s degree with peer-reviewed journal publications and research experience in hydrometallurgy, extractive metallurgy, metal extraction, or the development of novel leaching and separation reagents will be highly regarded.<\/p>\n\n\n\n
Applicants must meet the minimum academic entry requirements for admission to the Doctor of Philosophy program at Curtin University (https:\/\/www.curtin.edu.au\/research\/postgraduate), including the English language proficiency requirements (e.g. IELTS overall score of 6.5, with no band below 6.0). Detailed information is available at: https:\/\/www.curtin.edu.au\/study\/offering\/course-research-doctor-of-philosophy\u2014mining-and-metallurgical-engineering\u2013dr-mmengr\/<\/a><\/p>\n\n\n\n This project is open to International and Domestic applicants. <\/p>\n\n\n\n Scholarship <\/p>\n\n\n\n If you are identified as the preferred candidate for this project, you may be considered for an RTP scholarship<\/a>. <\/p>\n\n\n\n Enquires and How to Apply <\/p>\n\n\n\n For enquires about this opportunity contact Dr Lina Hockaday<\/strong> at\u00a0Lina.Hockaday@curtin.edu.au<\/a><\/p>\n\n\n\n