engleski

Efficiency of the Rinsing Agent on the Reduction of B2O3 Mass Fraction in Magnesium Oxide from Seawater

This study has examined the combined method of rinsing the magnesium hydroxide precipitate (3+2) in which alkalised distilled water with pH = 12.50 is used in the decanting procedure in the first phases, followed by fresh distilled water with pH = 5.30. In multiple rinsing on filter paper (up to three times) the alkalised distilled water with pH = 12.5 and/or combined rinsing method (2+3) was applied, i.e. after the precipitate had been rinsed 2 times by alkalised distilled water, it was rinsed with fresh distilled water (up to 3 times). The purpose of the study was to establish the efficiency of these methods of rinsing the seawater-derived magnesium hydroxide precipitate on reduction of the mass fraction of boron(III) oxide in calcined magnesium oxide, as the properties of seawater-derived high-temperature sintered magnesium oxide are greatly affected by the B2O3 fraction. The experimental results indicate that it suffices to perform the rinsing on filter paper by alkalised distilled water with pH = 12.50 two times. This method of rinsing attains the total reduction of the B2O3 fraction by approx. 61 % relative to the B2O3 fraction in samples prepared without rinsing of the magnesium hydroxide precipitate (B2O3 = 0.2533 mass %). If, together with rinsing on filter paper, the combined method (2+3) is applied, the mass fraction of B2O3 in calcined magnesium oxide is reduced by approx 69 % relative to the not-rinsed sample.

magnesium oxide ; rinsing agent ; mass fraction B2O3 ; substoichiometric precipitation

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