Dissolution kinetics of borogypsum in di-ammonium hydrogen phosphate solutions

Abstract

This work examines the dissolution kinetics of borogypsum in di-ammonium hydrogen phosphate solutions ((NH4)(2)PO4) in a batch reactor. The parameters selected were the reaction temperature (15-53 degrees C), di-ammonium hydrogen phosphate concentration (1-4 M), stirring speed (50-800 rpm), and solid/liquid ratio (1/50-1/5). The dissolution rate increased by increasing the temperature (from 0.32 to 0.82), di-ammonium hydrogen phosphate concentration (from 0.35 to 0.821), and by decreasing solid-to-liquid ratio (from 0.77 to 0.24). The dissolution rate increased up to stirring speed of 600 rpm (from 0.135 to 0.56), and then decreased with increasing stirring speed (from 0.56 to 0.351). The dissolution rate was described by first-order pseudo-homogeneous reaction model. The activation energy of this study was calculated as 42.103 kJ mol(-1). A kinetics model including the used parameters in this study was suggested as follows: -ln(1-x) = 223.63C(0.911)(S/L)(-0.7689)W(0.6212)e((-5064.2/T))t (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.