The Precipitation of Alkaline-Earth Metal Polyacrylate Hydrate Powders from Aqueous Solution: Ionic Equilibria,Precipitate Compositions and Morphologies |
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| Authors: | A. Packter S. Sabir |
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| Abstract: | The precipitation of barium, strontium, calcium and magnexium polyacryate hydrates was studied from equivalent aqueous solutions of initial concentrations 0.03 M to 0.30 M at ambient temperature: sodium polyacrylate (m. wt = 30,000 to 300,000) was added to metal chloride solution. The final yields of precipitate increased with decreasing solubility and/or peptisation (Ba > Sr > Ca > Mg) and increasing molecular weight of the polyacrylate; the precipitates had the compositions [BaA(COO)2 · 1–2H2O]n, [SrA(COO)2 · 1–2 H2O]n, [CaA(COO)2 · 2 H2O]n and [MgA(COO)2 · 2 H2O]n. The final yields of the precipitates from sodium polyacrylate solutions were far lower and these had the compositions [Na2αM1-αCA(COO)2 · 2 H2O]n; A = CH CH2 CH . The metal polyacrylate hydrate powders consisted of microcrystalline ‘spherules’; their average diameters were from 0.03–0.05 μm (for lower m. wt products) to 0.01 to 0.02 μ,m (for higher m. wt products). |
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