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Effect of citric acid and 1,2‐dihydroxybenzene 3,5‐disulfonic acid on crystallization of calcium sulfate dihydrate under simulated conditions of phosphoric acid production
Author(s) -
Rashad M. M.,
Mahmoud M. H. H.,
Ibrahim I. A.,
AbdelAal E. A.
Publication year - 2005
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.200410422
Subject(s) - citric acid , phosphoric acid , chemistry , crystallization , sulfuric acid , gypsum , inorganic chemistry , calcium , phosphate , nuclear chemistry , induction period , organic chemistry , catalysis , materials science , metallurgy
The effect of citric acid and 1,2‐dihydroxybenzene 3,5‐disulfonic acid (DHBDSA), as additives, on the crystallization of gypsum was studied under simulated conditions of the of phosphoric acid production. Calcium hydrogen phosphate and sulfuric acid were mixed with dilute phosphoric acid at 80 °C, and the turbidity of the reaction mixture was measured at different time periods to calculate the induction time of gypsum crystals formation. Addition of citric acid increased the induction time and decreased the growth efficiency while addition of DHBDSA decreased the induction time and increased the growth efficiency compared with in absence of additives. The crystals mean and median diameters were found to decrease in the presence of citric acid and increased in the presence of DHBDSA. The surface energy decreased with citric acid and increased with DHBDSA compared to the baseline (without additives). Interestingly, the majority of the formed crystals are tabular with DHBDSA and needle‐like type with citric acid and baseline