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https://hdl.handle.net/1959.11/14781
Title: | Apparent inhibition of thermal decomposition of hydrogencarbonate ion by poly(acrylic acid): The effect of molar mass and end-group functionality | Contributor(s): | Al-Hamzah, Ali (author); Fellows, Chris (author) | Publication Date: | 2014 | DOI: | 10.1016/j.desal.2013.10.021 | Handle Link: | https://hdl.handle.net/1959.11/14781 | Abstract: | The thermal decomposition of the hydrogencarbonate ion has been previously described by a bimolecular mechanism or a unimolecular mechanism. In this work the Gibbs free energy of the competing reactions for both the unimolecular and bimolecular mechanisms was calculated for typical concentrations found in thermal desalination plants. Activity coefficients were estimated using the Pitzer equations. At low temperature the bimolecular mechanism is thermodynamically favored, while above 80 °C the unimolecular mechanism is favored, consistent with observations of alkaline scale formation in thermal desalination plants. The rate coefficient of thermal decomposition of HCO₃⁻ at 97.2 °C in the absence and presence of 10 ppm of poly(acrylic acid) (PAA) with different end groups and molar mass was determined. PAA was found to retard the rate of decomposition by up to 49% and for all end groups of PAA the rate coefficient of thermal decomposition of 40 ppm HCO₃⁻ increased with increasing molar mass. The results are consistent with PAA preventing heterogeneous decomposition of HCO₃⁻ on interfaces. The rate of partitioning of PAA to these interfaces should increase with decreasing molar mass and resulting mobility of PAA, and may also be affected by self-assembly behavior. | Publication Type: | Journal Article | Source of Publication: | Desalination, 332(1), p. 33-43 | Publisher: | Elsevier BV | Place of Publication: | Netherlands | ISSN: | 1873-4464 0011-9164 |
Fields of Research (FoR) 2008: | 030603 Colloid and Surface Chemistry 030602 Chemical Thermodynamics and Energetics 030304 Physical Chemistry of Materials |
Fields of Research (FoR) 2020: | 340603 Colloid and surface chemistry 340602 Chemical thermodynamics and energetics 340302 Macromolecular materials |
Socio-Economic Objective (SEO) 2008: | 961101 Physical and Chemical Conditions of Water for Urban and Industrial Use | Socio-Economic Objective (SEO) 2020: | 180205 Measurement and assessment of estuarine water quality 180306 Measurement and assessment of freshwater quality (incl. physical and chemical conditions of water) |
Peer Reviewed: | Yes | HERDC Category Description: | C1 Refereed Article in a Scholarly Journal |
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Appears in Collections: | Journal Article School of Science and Technology |
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