Determination of growth and dissolution mass rate of boric acid crystals by a simple computer program

Growth and dissolution rates of boric acid were measured in a laboratory-sc ale fluidized-bed crystallizer under well-established conditions of supersa turation, undersaturation, temperature and fluidization. It was found that the overall growth rate of boric acid is controlled by both diffusion and r eaction steps. But reaction step is the main controller of the crystal grow th of boric acid. It was also determined that the dissolution region of bor ic acid, apart from other known materials is controlled by diffusion and re action steps. An improved computer program procedure was used to determine the effect of diffusion and reaction steps on the growth and dissolution ra tes of boric acid crystals. This simple program gives a high accuracy of de termination of the mass transfer coefficient, k(d), the surface reaction co nstant, k(r) and the surface reaction order r. The relative standard deviat ion between the equation R-G = k(r)(Delta C - R-G/F-d)(r) and those experim entally obtained and represented by the equation R-G = K-G(Delta C)(g) do n ot exceed 0.08 % for both growth and dissolution region. (C) 2000 Published by Elsevier Science B.V. All rights reserved.