Influence of citric acid on calcium sulfate dihydrate crystallization in aqueous media

Abstract

The crystallization of Calcium sulfate dihydrate produced by the reaction between pure Ca(OH) 2 suspension and H 2 SO 4 solution was investigated at different pH values, temperatures and citric acid concentrations. Crystal size distributions, filtration rates and zeta potentials of gypsum were determined as a function of citric acid concentrations at pH 3.5 and 65°C. The influence of citric acid on the morphology of gypsum was also investigated and discussed. The average particle size of gypsum was reached to maximum in the presence of approximately 2500 ppm citric acid concentration, where the minimum cake resistance and maximum filtration rate were obtained. In the presence of citric acid, various crystal morphologies such as tabular, platelike, double-taper leaf-like and flower-like, etc., were obtained. The change of morphology is related to the preferential adsorption of citric acid on different crystallographic faces.

Gypsum Crystallization in the Presence of Cr3+ and Citric Acid

“…In our previous paper, we demonstrated the effect of citric acid on gypsum crystallization in aqueous media at different pH values, temperatures, and citric acid concentrations [12]. In this study, we found that the pH did not affect the average particle size but it had a great effect on the gypsum shape at 20°C.…”

Physical and Adsorptive Characterization of Precipitated Magnesium Silicate from Rice Hull Ash Silica

“…The laboratory filtration data were used to calculate the cake parameters based on Darcy's law [13]. The inverse of time rate change of the filtrate volume during filtration is expressed as: A plot of dh/dV as the dependent variable and V as the independent variable results in a straight line where K p and B are the slope and intercept, respectively.…”

Effect of trace metals on reactive crystallization of gypsum

“…In this study, we found that pH does not affect the average particle size but it has great effect on the shape of gypsum at 20°C. It was also deduced that citric acid plays an important role for gypsum morphology (size and shape) at pH 3.5 and 65°C and approximately 2500 ppm citric acid concentration was determined as an optimum concentration in terms of average crystal size, crystal shape, and filtration characteristics [8].…”

“…The laboratory filtration data were used to calculate the cake parameters based on Darcy's law [15]. Details of this method were presented in our previous paper [8].…”