The solubility of a-CaSO4*0.5H2O was measured In concentrated phosphoric acid solutions containing approximately 40, 45, 50, and 55% P2Os at 80, 90, 100, and 110 °C, respectively. The weight percent solubility in terms of anhydrous calcium sulfate Is given by the equation % CaS04 = 2.879 181 03 + 0.01399258/-0.089 429 39( % P205) + 0.000 596 58(% P205)2 -0.000 11850/(% P2Os), where / Is the temperature (°C) and (% P2Os) Is the weight percent phosphorus pentoxldeIn solution. The endothermic heat of solution at saturation Is found to Increase with Increasing acid concentration.
The optimization of a technology for the Ti02-mediated solar photocatalysis of atrazine is described. The target users of this technology might be agrochemical dealers, manufacturers, and possibly farmers. Studies were performed to determine the ideal cover material for such a reactor based on UV light transmitting properties. The best cover material was a W transmitting acrylic. The Ti02 employed for this technology was bound to fiberglass mesh. The effects of mesh amount, stirring, water impurities, concentration of pesticide, and source of W light (mercury vapor lamp vs. solar) were also determined. The most efficient photocatlysis was achieved using five layers of mesh, a stirred reaction, water low in carbonate and other ions, a dilute waste stream, and solar irradiation rather than a mercury-vapor lamp. The formation and disappearance of eight intermediates were followed in a 2429 h indoor experiment comparing pure and formulated atrazine. A modified reaction mechanism was proposed based on studies of the detected intermediates.
The Influence of the common wet-process phosphoric acid Impurities [Al203 (1.50%), Fe203 (2.15%), and MgO (0.50%)] upon the solubility of -calcium sulfate hemihydrate In 40%, 45%, 50%, and 55% P20, phosphoric acid solutions at 80, 90, 100, and 110 °C, respectively, were measured. These additives were found to have very little Influence upon <*-CaSO4«0.5H2O solubility when the data are compared at equal water contents. The weight percent solubility In terms of anhydrous calcium sulfate Is given by the equation % CaS04 = -0.39820885 + 0.00442938/ + 0.00031947(% H20)2 + 0.00011517/(% H20), where / Is the temperature (°C) and % H20 Is the weight percent of water In the solution. Slight deviations In solubility are discussed In terms of enthalpy and entropy effects.
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