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The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes
Thesis (MSc) -- University of Stellenbosch, 1994.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867614037478473731 |
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| access_status_str | Open Access |
| author | Gerber, Heloise |
| author2 | Sanderson, R. D. |
| author_browse | Gerber, Heloise Sanderson, R. D. |
| author_facet | Sanderson, R. D. Gerber, Heloise |
| author_sort | Gerber, Heloise |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc) -- University of Stellenbosch, 1994. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/58614 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:45:40.057Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/58614 The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes Gerber, Heloise Sanderson, R. D. Schneider, D. F. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Reverse osmosis Dissertations -- Chemistry Thesis (MSc) -- University of Stellenbosch, 1994. In title the p of p-aminophenyl is in subscript. The aim of this study was to prepare p‑aminophenyl ethers of poly(vinyl alcohol) (PVOH) as precursors for making ultrathin composite reverse osmosis membranes. p‑Aminophenyl ethers of PVOH were prepared by chemical modification of PVOH rather than by copolymerisation. Copolymerisation of phenyl vinyl ether with vinyl acetate was also investigated, but the results were not promising. Aryl phenyl ethers cannot be prepared from alcoholates and aryl halides by the Williamson ether synthesis, but the ether was successfully prepared in a three‑step synthesis. Firstly, the alcohol group of PVOH was converted into a good leaving group by the formation of p‑toluenesulphonate esters (tosylates). Secondly, the ether bond was formed by nucleophilic substitution of the tosylate by a phenolate group, sodium p‑acetamidophenolate. Direct etherification of unprotected p‑aminophenol was not possible, because both N‑ and O‑alkylation occur simultaneously. To ensure that only O‑alkylation took place, the amine was protected beforehand by acetylation and the acetyl group was then recovered after substitution at the free amine by acid hydrolysis. ^1H n.m.r. spectroscopy was used to characterise the compounds. Ultrathin composite membranes were made by an interfacial polycondensation reaction between a p‑aminophenyl ether of PVOH and isophthaloyl chloride and then tested for their reverse osmosis performance. Tubular reverse osmosis membranes were prepared by a three‑step procedure, during which the porous support membrane was immersed in an aqueous precursor solution of the modified PVOH polymer, followed by contacting with an organic solution of the diacid chloride cross‑linking agent. During cross‑linking it was necessary to make use of an acid scavenger to neutralise the hydrochloric acid formed. In the case, however, addition of an acid scavenger, sodium hydroxide or triethyl amine, to the aqueous precursor solution or the organic solution of diacid chloride, respectively, resulted in precipitation of the precursor or cross‑linking agent from solution. This necessitated the introduction of a third step in the membrane fabrication process, during which the membrane was immersed in a solution of the acid scavenger after, either before or after contacting with the diacid chloride cross‑linking agent. Tubular membranes gave retentions of 31.37 ± 1.24 to 46.54 ± 2.18 % and fluxes of 17.23 ± 1.46 to 33.91 ± 3.45 l/m²h depending on the method of fabrication, when tested with 2 000 ppm sodium chloride at 2 MPa and 20°C. When the membranes, made according to method 2 which involved contacting the polymer coated porous support membrane with an organic solution of isophthaloyl chloride followed by immersing in an organic solution of triethyl amine acid scavenger, were tested with 2 000 ppm magnesium sulphate feed solutions, retentions of 69.48 ± 3.33 % and fluxes of 18.8 ± 2.02 l/m²h were obtained. Masters 2012-08-27T11:39:03Z 2012-08-27T11:39:03Z 1994 Thesis http://hdl.handle.net/10019.1/58614 en Stellenbosch University 142 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Reverse osmosis Dissertations -- Chemistry Gerber, Heloise The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes |
| title | The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes |
| title_full | The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes |
| title_fullStr | The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes |
| title_full_unstemmed | The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes |
| title_short | The synthesis of p-aminophenyl ethers of poly(vinyl alcohol) reverse osmosis membranes |
| title_sort | synthesis of p aminophenyl ethers of poly vinyl alcohol reverse osmosis membranes |
| topic | Reverse osmosis Dissertations -- Chemistry |
| url | http://hdl.handle.net/10019.1/58614 |
| work_keys_str_mv | AT gerberheloise thesynthesisofpaminophenylethersofpolyvinylalcoholreverseosmosismembranes AT gerberheloise synthesisofpaminophenylethersofpolyvinylalcoholreverseosmosismembranes |