Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Ammonium fluoride : transition metal purification
Dissertation (MEng)--University of Pretoria, 2017.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Published: |
University of Pretoria
2017
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613503354830848 |
|---|---|
| access_status_str | Open Access |
| author2 | Crouse, Philippus L. |
| author_browse | Crouse, Philippus L. |
| author_facet | Crouse, Philippus L. |
| collection | Thesis |
| dc_rights_str_mv | © 2017 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 | Dissertation (MEng)--University of Pretoria, 2017. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/62805 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:11.117Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| 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:2263/62805 Ammonium fluoride : transition metal purification Crouse, Philippus L. u25231635@tuks.co.za Lubbe, Salmon Yapi, Litha Ammonium fluoride LewatitTP207 Purolite S930plus Copper cation UCTD Engineering, built environment and information technology theses SDG-07 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Dissertation (MEng)--University of Pretoria, 2017. Pelchem NF3 plant produces an ammonium acid fluoride waste stream. The material of construction for the piping and stirrer fabrication in the plant is Monel. As a predominantly nickel-copper alloy, with minute quantities of carbon, manganese, silicon, sulfur and iron, these may leach into process fluids involved. The two biggest constituents of Monel contaminate the ammonium acid fluoride waste stream. Despite being the lesser of the two in terms of the composition of the Monel, copper is higher in concentration than nickel in the waste stream: the solubility of copper (II) cation in ammonium fluoride is higher than that of nickel (II) cation. Additionally, the ammonium acid fluoride is stored in steel barrels because of the relatively high process temperature that preclude the use of polymeric drums. This results in the leaching of iron from the steel drum to the solution. Pelchem expressed an interest in a suitable method of purification of ammonium fluoride, with specific interest of removing nickel (II) cation, copper (II) cation as well as iron (II) cation. The constraints to consider when selecting the appropriate methods are operating costs as well as the capital costs, but the most important factor to consider is the effectiveness of the method in removing the contaminant. In this regard, cationic exchange resins are very suitable, and they are very practical for industrial applications. In its simplest form, ammonium fluoride solutions are prepared by bubbling ammonia gas through solutions of hydrofluoric acid. Quite a few interesting uses of ammonium fluoride are available, these include as a chemical modifier in lead analysis, synthesis of beta zeolites, etc. The most prominent use is as a technical grade etchant in the electronics industry. The main aim of this research was to investigate ion exchange as a method of removing contaminants from Pelchem ammonium acid fluoride. Static equilibrium/selectivity experiments reveal that Purolite S930 Plus and Lewatit TP207 show a great affinity for the copper cation. For the limiting step of the reaction, the analysis includes apparent kinetics modelling contrasted with mass transfer modelling. In the case of reaction kinetics, Arrhenius and Van’t hoff equations were used to determine reaction parameters: the activation energies are 14 368 J∙mol-1 and 24 116 J∙mol-1, for Purolite and Lewatit respectively. The pre-exponential constants are 2 213 and 269 682 L2∙min-1∙mol-2 for Purolite and Lewatit in that order. The heats of reaction are -26 555 and -4 696 J∙mol-1 for Purolite and Lewatit respectively. Whilst the equilibrium pre-exponential constants are 75 057and 150 for Purolite and Lewatit respectively. Diffusivities for the two resins were found to be in reasonable agreement with those recorded in literature. They follow a temperature dependency trajectory. Weisz-Prater analysis of the observed reaction rate and the diffusion rate, in the two resins, reveals that intraparticle diffusion is the limiting step in the reaction. mi2026 Chemical Engineering MEng Unrestricted SDG-07: Affordable and clean energy SDG-09: Industry, innovation and infrastructure SDG-12: Responsible consumption and production 2017-10-13T13:41:26Z 2017-10-13T13:41:26Z 2017-09-08 2017 Dissertation Yapi, L 2017, Ammonium fluoride : transition metal purification, MEng Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/62805> S2017 http://hdl.handle.net/2263/62805 © 2017 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 | Ammonium fluoride LewatitTP207 Purolite S930plus Copper cation UCTD Engineering, built environment and information technology theses SDG-07 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Ammonium fluoride : transition metal purification |
| title | Ammonium fluoride : transition metal purification |
| title_full | Ammonium fluoride : transition metal purification |
| title_fullStr | Ammonium fluoride : transition metal purification |
| title_full_unstemmed | Ammonium fluoride : transition metal purification |
| title_short | Ammonium fluoride : transition metal purification |
| title_sort | ammonium fluoride transition metal purification |
| topic | Ammonium fluoride LewatitTP207 Purolite S930plus Copper cation UCTD Engineering, built environment and information technology theses SDG-07 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 |
| url | http://hdl.handle.net/2263/62805 |