Thestrontian process is an obsolete chemical method to recover sugar frommolasses. Its use in Europe peaked in the middle of the 19th century. The namestrontian comes from the Scottish villageStrontian where the source mineralstrontianite (strontium carbonate) was first found.
Strontium carbonate is a recycled coreactant in this process.
Strontium carbonate iscalcined with carbon in the presence of steam to form strontium hydroxide. The strontium and carbon dioxide formed are rejoined later in the process, forming strontium carbonate once again.[1]
SrCO3 + C + H2O + O2 = Sr(OH)2 + 2 CO2
In a molasses solution kept near 100 °C,[2] the hydroxide reacts with soluble sugars to form water and the poorly soluble strontium saccharide which is filtered out, but kept awash in near-boiling water.
Sr(OH)2 + 2C12H22O11 = SrO(C12H22O11)2 + H2O
The saccharate liquid is cooled to 10 °C, cracking off one of the sugars
SrO(C12H22O11)2 = SrO(C12H22O11) + C12H22O11
The carbon dioxide (from the calcination) is bubbled through the saccharate solution, cracking off the second sugar and reforming the strontium carbonate, which is filtered off.
SrO(C12H22O11) + CO2 = SrCO3 + C12H22O11
The sugar is then extracted through evaporating the remaining solution.
There are two types of strontiumsaccharide: one at low temperature, the strontiummonosaccharide; and the second at high temperature, the strontiumdisaccharide.[3]
Molasses is the first stage output of several differentsugar production processes, and contains more than 50% sugar. The French chemistsHippolyte Leplay andAugustin-Pierre Dubrunfaut developed a process for extracting sugar from molasses, reacting them withbarium oxide, to give the insoluble barium-saccharates.[4] In 1849, they expanded their patent to include strontium salts. Apparently, this patent application had the only purpose to legally secure the so-calledbaryte process, since the strontian process from Leplay and Dubrunfaut probably wouldn't work as described.[5]
Only later, through the work ofCarl Scheibler (patents dated 1881, 1882, and 1883), was it possible to apply the strontian process on an industrial basis.[6][7]According to Scheibler the procedure must be carried out at boiling temperatures.
Yet by 1883, the demand for strontianite had begun to shrink. First, it was replaced by another strontium mineral (celestine), that could be imported from England, in a cheaper way. Second, the prices for sugar decreased so much, that the production from molasses was no longer worthwhile.[citation needed]
^Dinglers Polytechnisches Journal (in German). Vol. 248. 1883. pp. 426–428.
^J. Nicklès (1854). "Leplay's Verfahren zur Abscheidung des krystallisirbaren Zuckers aus der Melasse". Dinglers Polytechnisches Journal (Compilation) (in German).131 (XVII):47–50.
