Unsteady-state transfer of impurities during crystal growth of sucrose in sugarcane solutions

Unsteady-state inhibition of crystal growth caused by solution impurities

“…According to eqn (14), this variation of k À2 implies a more dramatic variation of the theoretical value of b from 4.8 to 50, which would change the nature of the carbonate impurity during barite crystal growth from ''active'' to ''very active''. 25 Experiments carried out at approximately constant supersaturation and non-sucrose content confirmed that crystal growth rates increase with time, as illustrated in Fig. 29 The existence of an induction time during surface recovery (Fig.…”

“…19,20 In general, impurities that strongly adsorb onto the crystal surface will be located at the surface terraces; 21 in these cases of immobile impurities (low values of b) significant inhibition of crystal growth will only occur in solutions of very low purity (high values of c i and q s ). Nevertheless, unsteady-state impurity action is reported in literature in cases such as changing crystal growth rates with time at constant supersaturation and impurity concentration, [22][23][24][25] or the growth rate hysteresis, i.e., different growth rates as the supersaturation is rising or decreasing. Nevertheless, unsteady-state impurity action is reported in literature in cases such as changing crystal growth rates with time at constant supersaturation and impurity concentration, [22][23][24][25] or the growth rate hysteresis, i.e., different growth rates as the supersaturation is rising or decreasing.…”

Determinação Da Influência Da Presença De Impurezas Na Supersaturação Crítica De Soluções De Sacarose

“…Martins et al (2009) dizem ser impossível uma modelagem genérica de soluções de sacarose contendo impurezas, pois os tipos e concentrações de impurezas encontrados nos xaropes de cana-de-açúcar variam de região para região e em uma mesma região variam de safra para safra, sendo necessário sempre um estudo específico de cada xarope. Os dados experimentais dos autores mostraram uma variação no coeficiente de solubilidade (definido como o quociente das solubilidades de sacarose em soluções impuras e puras na mesma temperatura, em (g de sacarose)/(100 g de água)) em soluções contento fécula, frutose e dextrano.…”

Inhibition of growth in solid solution–aqueous solution systems by non-incorporating impurities

“…It is clear that different initial supersaturation states of an aqueous solution with respect to a solid solution will result in different kinetic and compositional paths toward the complete inhibition of growth. This suggests that some reported phenomena, such as anomalous growth rates observed during the inhibition of crystallisation in some chemically complex systems ( (27] and references therein) and the development of heterogeneous element distributions onto mineral surfaces (28,29], might be related to the behaviour of crystal growth inhibition in SS-AS systems.…”