Haider, Muhammad Hamza Ali (2024)
Osmotic Energy Harvesting using Polymeric Cation Selective Membranes.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00026751
Ph.D. Thesis, Primary publication, Publisher's Version
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Osmotic Energy Harvesting using Polymeric Cation Selective Membranes | ||||
Language: | English | ||||
Referees: | Ensinger, Prof. Dr. Wolfgang ; Hofmann, Prof. Dr. Jan Philipp | ||||
Date: | 7 March 2024 | ||||
Place of Publication: | Darmstadt | ||||
Collation: | ix, 123 Seiten | ||||
Date of oral examination: | 14 February 2024 | ||||
DOI: | 10.26083/tuprints-00026751 | ||||
Abstract: | A nanopore with a charged surface can preferentially transport counterions, due to the presence of overlapping double layers. A charged nanoporous membrane can be utilised in various applications, such as heavy metal ion filtration and osmotic energy harvesting. The osmotic energy harvesting technique requires a porous membrane that performs either osmosis or selective ion transportation. The efficiency of the osmotic energy harvesting system is crucially dependent upon the membrane’s performance. In this thesis, two different cation selective membranes were fabricated for the application of osmotic energy harvesting: a sub-nanometre polyimide membrane and an acrylic acid hydrogel PET membrane (HP membrane). The membranes were negatively charged and selectively transported cations down the concentration gradient. The PI membrane was fabricated using the soft-etching technique. To achieve this, PI foil with latent tracks, was immersed inside DMF solution. DMF dissolves the polymeric material within the PI foil resulting in the fabrication of the pore in the sub-nanometre range. The HP-membrane was fabricated by incorporating acrylic acid hydrogel within a porous PET support membrane with sub-micrometre-sized pores. The performances of the membranes were analysed in various conditions, e.g, various concentration folds, pH, fluence, exposure to multivalent cation and time dependent investigation. The PI membrane exhibited the highest power output of 0.45 μW, while the HP membrane exhibited the maximum power of 1.10 μW. Acidic medium and multivalent cations were extremely detrimental to the membranes. A sharp decline in power output was observed in the acidic or multivalent cation solutions. A gradual increase in the power output was observed with the increase in concentration folds but subsequently declined after a certain value of concentration fold. The power output increased up to a certain fluence, after which a decline in power was observed. In the thesis, cation and anion transport behaviour in the negative and positively charged conical nanopore was investigated. The conical nanopore was fabricated within PET foil using the asymmetrical etching technique. Due to the etching, pore’s surface carry a net negative surface charge and can be modified to positive via electrostatic self-assembly of PAH. Monovalent cations did not invert the surface charge of the unmodified conical nanopore. However, exposure to multivalent cations resulted in either surface charge neutralisation or inversion. The surface charge of the modified conical nanopore was neutralised or inverted by certain monovalent and multivalent anions such as HCO3-, H2PO4- and HPO42-. |
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Status: | Publisher's Version | ||||
URN: | urn:nbn:de:tuda-tuprints-267512 | ||||
Classification DDC: | 500 Science and mathematics > 500 Science 500 Science and mathematics > 540 Chemistry |
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Divisions: | 11 Department of Materials and Earth Sciences > Material Science > Material Analytics | ||||
Date Deposited: | 07 Mar 2024 12:41 | ||||
Last Modified: | 08 Mar 2024 07:32 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/26751 | ||||
PPN: | 51607346X | ||||
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