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Quartz Dissolution as Influenced by pH and the Presence of a Disturbed Surface Layer
Author(s) -
Henderson J.H.,
Syers J. K.,
Jackson M. L.
Publication year - 1970
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197000042
Subject(s) - quartz , dissolution , chemistry , amorphous solid , solubility , particle size , layer (electronics) , surface layer , particle (ecology) , grinding , analytical chemistry (journal) , mineralogy , inorganic chemistry , chromatography , metallurgy , crystallography , materials science , organic chemistry , oceanography , geology
Quartz particles (10 to 2 microns in diameter, produced by grinding) released 45 ppm of SiO 2 to a buffer solution of pH 7 during a 48 hr period. The grinding of quartz particles produced a disturbed surface layer with solubility properties intermediate between crystalline quartz (6 ppm SiO 2 ) and amorphous silica (120 ppm SiO 2 ). Removal of the disturbed layer by treatment with 1 N HF lowered the SiO 2 dissolution from 45 to 3 ppm. Use of 12 N HF decreased the amount of SiO 2 dissolved to 2 ppm, a result found to coincide with a preferential dissolution of the finer quartz particles in addition to the removal of the disturbed surface layer. The rate of dissolution of SiO 2 from quartz particles, subsequent to treatment with 1 N HF, increased with decrease in particle size, from 1 to 3 ppm for quartz particles 50 to 20 microns in diameter to 30 to 44 ppm for particles 2 to 0.2 microns in diameter, during each of three consecutive 14‐day extractions with pH 7 buffer solution. The amount of SiO 2 dissolved from quartz in buffer solutions increased in the pH range of 4 to 10, from 0.6 ppm of SiO 2 at pH 4 to 19 ppm at pH 10 during a 14‐day period of extraction from quartz particles, 10 to 2 microns in diameter. Quartz particles, subsequent to the removal of the disturbed surface layer, removed SiO 2 from pH 4 and pH 8 buffer solutions prepared with more SiO 2 in solution than would be released from quartz in the respective solution.