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Photocatalytic degradation of phenolic compounds and algal metabolites in water
Thesis (PhD)--University of Pretoria, 2014.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2014
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| _version_ | 1867613645608845312 |
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| access_status_str | Open Access |
| author2 | Chirwa, Evans M.N. |
| author_browse | Chirwa, Evans M.N. |
| author_facet | Chirwa, Evans M.N. |
| collection | Thesis |
| dc_rights_str_mv | © 2014 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD)--University of Pretoria, 2014. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/40191 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:26.678Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/40191 Photocatalytic degradation of phenolic compounds and algal metabolites in water Chirwa, Evans M.N. altimipemu@yahoo.com Bamuza-Pemu, Emomotimi Emily Degradation Algal infestation Water Soluble organic compounds Water reservoirs in South Africa Advanced oxidation process (AOP) Photocatalytic degradation Phenolic compounds Algal metabolites in water UCTD Thesis (PhD)--University of Pretoria, 2014. Algal infestation in water bodies causes the release of soluble organic compounds that impact negatively on the taste and odour of the water. With increasing pollution in water bodies and increasing nutrient loading from agricultural activities, most water reservoirs in South Africa and around the world have become affected by this problem. In this study, an advanced oxidation process (AOP), namely, photocatalysis was evaluated for its potential to degrade aromatic compounds; and taste and odour causing bi-cyclic compounds originating from algae. Semiconductor photocatalysis is an environmentally friendly technology requiring no chemical inputs which is capable of completely mineralising organic pollutants to CO2 and H2O thereby eliminating production of unwanted by-products. Although processes involved in the photo-degradation have been reported for a wide range of pollutants, the degradative pathway in this process has not been fully established. In this study, compounds including phenol, 2-chlorophenol, 4-chlorophenol and nitrophenol were successfully eliminated from simulated wastewater. Degradation of geosmin at an environmentally significant initial concentration of 220 ng/L to levels below the lowest detectable concentration was achieved with an optimum catalyst concentration of 60 mg/L at a rate of 14.78 ng/L/min. Higher catalysts loading above 60 mg/L resulted in a decrease in degradation rates. An increase in initial geosmin concentration resulted in a decrease in rates. Ionic species commonly found in surface waters (HCO3 -, and SO4 2-) significantly reduced the efficiency of geosmin degradation. Degradation of geosmin produced acyclic intermediates from ring fission tentatively identified as 3,5-dimethylhex-1-ene, 2,4-dimethylpentan-3-one, 2-methylethylpropanoate and 2-heptanal. The results obtained indicate that the degradation of organic pollutants in aqueous solution is as a result of synergic action from hydroxyl radicals, positive holes and direct photolysis by UV radiation, though the predominant pathway of degradation is via hydroxyl radicals in solution. Major aromatic intermediates of phenol degradation include catechol, resorcinol and hydroquinone produced in the order catechol > resorcinol > hydroquinone. All three are produced within 2 minutes of photocatalytic reaction of phenol and remain in solution until all phenol is degraded in aerated systems. Production of resorcinol in non-aerated systems is transient, further supporting the hydroxyl radical dominant reaction pathway. gm2014 Chemical Engineering unrestricted 2014-06-17T12:59:08Z 2014-06-17T12:59:08Z 2014-04-08 2014 Thesis Bamuza-Pemu, EE 2014, Photocatalytic degradation of phenolic compounds and algal metabolites in water, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/40191> D14/4/107/gm http://hdl.handle.net/2263/40191 en © 2014 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Degradation Algal infestation Water Soluble organic compounds Water reservoirs in South Africa Advanced oxidation process (AOP) Photocatalytic degradation Phenolic compounds Algal metabolites in water UCTD Photocatalytic degradation of phenolic compounds and algal metabolites in water |
| title | Photocatalytic degradation of phenolic compounds and algal metabolites in water |
| title_full | Photocatalytic degradation of phenolic compounds and algal metabolites in water |
| title_fullStr | Photocatalytic degradation of phenolic compounds and algal metabolites in water |
| title_full_unstemmed | Photocatalytic degradation of phenolic compounds and algal metabolites in water |
| title_short | Photocatalytic degradation of phenolic compounds and algal metabolites in water |
| title_sort | photocatalytic degradation of phenolic compounds and algal metabolites in water |
| topic | Degradation Algal infestation Water Soluble organic compounds Water reservoirs in South Africa Advanced oxidation process (AOP) Photocatalytic degradation Phenolic compounds Algal metabolites in water UCTD |
| url | http://hdl.handle.net/2263/40191 |