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Measurements of the solubility and metastable zone width (MSZW) of borax decahydrate (disodium tetraborate decahydrate) within chloride, sulfate and carbonate solutions were carried out. The MSZW was measured by the conventional polythermal method with turbidity technology. The results showed that the addition of impurities decreased solubility. The main factor reducing solubility is the common ion effect, but the salt effect is also significant in the complex system. The addition of impurities broadened the MSZW. The MSZW was wider at first, then decreased with the addition of NaCl, yet the MSZW widened with the addition of Na2SO4 within the concentration range studied. This can be explained by adsorption and diffusion. The data of solubility and MSZW were analyzed by applying the Van&rsquo, t Hoff equation and the classical 3D nucleation theory approach, respectively. By calculating the corresponding parameters, the experimental phenomena are further explained from the perspective of thermodynamics and dynamics.

Solubility and metastable zone width (MSZW) of aqueous sodium dichromate solutions in different concentration of sodium chromate were studied experimentally by the polythermal method using a turbidity monitoring technique. The effects of cooling rate R, saturation temperature T0 of sodium dichromate and concentration ci of sodium chromate on the MSZW were studied. The results show that the MSZW widens with increasing cooling rate R but it narrows with increasing saturation temperature T0 of sodium dichromate and concentration ci of sodium chromate. The experimental data were analyzed by using an equation, based on the classical three-dimensional nucleation theory, relating MSZW with cooling rate R.

The solubility and metastable zone width of boric acid in the simulated oilfield brine system of NaCl–KCl–CaCl2–H2O were studied at low temperature by the turbidity method. The nucleation kinetic constant A and the interfacial energy γ of boric acid were calculated with nucleation theory. Results showed that the solubility of boric acid in the simulated oilfield brine system was mainly determined by the coexisting salt of CaCl2 and decreased with increasing concentrations of CaCl2, even though the presence of NaCl and KCl has a salt-in effect on the solubility. However, the metastable zone width was affected by the three coexisting salts and it changes differently with the varied concentrations. The possible reason can be explained by the dependence of the interfacial energy γ on the slat concentration. On the basis of the above results, the crystallization behavior of boric acid during oilfield brine evaporation was investigated for the first time. It was deeply affected by the coexisting salts in brine.

The experiment data on the solubility and metastable zone width (MSZW) of sodium dichromate dihydrate have been determined in the temperature range from (290.45 to 319.76) K using the conventional polythermal method by turbidity monitoring technique. Based on the solubility data, the dissolution enthalpy and entropy of sodium dichromate dihydrate were calculated by the van’t Hoff equation. Two approaches were used to estimate the nucleation kinetics of sodium dichromate dihydrate from the MSZW data, the self-consistent Nývlt-like equation and the novel equation of three-dimensional nucleation theory. The notable factors affecting MSZW of sodium dichromate dihydrate such as cooling rate, initial composition, stirring rate, and presence of seed particles have been evaluated in this paper. It was observed that the MSZW of sodium dichromate dihydrate has an obvious decrease with the increase of initial composition, rotation frequency of stirring, and the mass of seed particles, respectively. Nevertheless, the...

The solubility and nucleation of borax decahydrate in the presence of Cl– and SO42– ions have been studied by two different methods: polythermal crystallization and isothermal crystallization. The results revealed that both anions had a salt-in effect on the solubility. A noticeable widening of the metastable zone was observed after the addition of the two anion impurities. For the isothermal crystallization, two different nucleation mechanisms were obtained. When the supersaturation ratio S > 1.3, the nucleation appears to be homogeneous, whereas at the supersaturation ratio S < 1.25, heterogeneous nucleation predominates. From the prolonged induction period in the presence of the two anions, we conclude that the nucleation of borax decahydrate was suppressed after the addition of impurities. The values of the interfacial energy γ calculated by isothermal method are lower than those obtained by polythermal method due to the underestimated values of ln S.

The solubility of sodium chromate tetrahydrate has been investigated in the temperature range from 290.15 K to 325.15 K using the conventional polythermal method by means of the laser technique. The metastable zone width (MZW) and the apparent nucleation order of sodium chromate tetrahydrate were calculated. The effects of cooling rate, initial composition, stirring rate, and seed particles on the MZW were also studied. The results show that the MZW of sodium chromate tetrahydrate first increases and then narrows with increasing initial composition. The MZW becomes wider by reducing the cooling rate and the mass of seed particles, whereas the MZW will be reduced by enhancing the rotation frequency of stirring and the diameter of seed particles.

The solubility and the metastable zone width of sodium tetraborate decahydrate in solutions containing lithium chloride have been measured at temperature a range of (20 to 35) °C. It is found that the lithium impurity has a salt-in effect on the solubility of sodium tetraborate decahydrate. The metastable zone width broadens with an increase of the impurity concentrations. This increase can be attributed to the absorption mechanism on the crystal surface. The apparent nucleation order of sodium tetraborate decahydrate with and without impurity was calculated by a modified regression method. The results show that the addition of lithium impurity has no great effect on the apparent nucleation order of sodium tetraborate decahydrate.

The solubility and ultra solubility of borax decahydrate both in pure and impure solutions have been determined in the temperature range from (0 to 30) °C by means of the conventional polythermal method using the laser technique. The metastable zone width and the apparent nucleation order of borax were calculated. The effects and the action mechanism of KCl on metastable zone property of borax were studied. It was found that the presence of KCl made an increase in the solubility and a decrease in the metastable zones of borax. However, the trends in the changes of metastable zone width at low impurity concentrations were different from high concentrations because of the adsorption equilibria on the crystals.