Solid Barium Sulfate Formation from Aqueous Solution: Re-examination of Key Literature and Kinetics of This Classic System in Search of a Minimum Mechanism of Formation

Abstract

The formation of solid barium sulfate, (BaSO4) n , known as barite when a crystalline solid in space group Pnma, is a classic system with a range of applicability in and consequences for the petroleum and other industries. Herein, we search for a minimum mechanism for (BaSO4) n formation via, first, a critical review of the literature since the 1950s, literature revealing that (BaSO4) n formation is an early, important model system with which to study nucleation, growth, and any accompanying aggregation. The literature also teaches that solid (BaSO4) n forms via non-classical, continuous nucleation, as first identified in 1997. Second, key literature kinetics data sets are reanalyzed in light of five classes of established minimum mechanisms for particle and solid formation. The resulting working hypothesis for (BaSO4) n formation is a 4-step mechanism consisting of nucleation (A → B), autocatalytic growth (A + B → 2B), bimolecular aggregation (B + B → C), and secondary autocatalytic aggregation (B + C → 1.5 C), with rate constants k 1, k 2, k 3, and k 4, respectively, and where A = precursor, B = smaller particles, and C = larger particles. Also provided are sections on caveats, engineering models, remaining questions, suggestions for moving forward, and a short summary.

Impact of Solution {Ba2+}:{SO42–} on Charge Evolution of Forming and Growing Barite (BaSO4) Crystals: A ζ─Potential Measurement Investigation

“…Most likely, the initial signal was more strongly influenced by nucleation besides particle growth. This is in agreement with the findings of MacHale and Finke (2023), 79 who showed (based on the data of Turnbull (1953) 80 ) that for initial Ω barite = 361, nucleation dominated growth at t < 90 s. Though our initial Ω barite was higher (i.e., Ω barite = 1000), the difference in timing of nucleation at these high supersaturation values is small, 81−83 i.e., induction time is less sensitive to the degree of supersaturation at Ω barite > 316, it is likely that nucleation dominated growth at roughly t < 90 s in our (stoichiometric) systems with an initial Ω barite = 1000 as well.…”

Unveiling Step-by-Step the Bottom-Up Kinetics and Growth Mechanism of Laser-Induced Colloidal Gold Nanoparticles

“…The removal of gold species from the formed nanocrystals increases the number of particles in the solution and provides new growth sites. This is a physical process possibly induced by collisions of the crystal with the impeller (magnetic stirring bar), vessel walls, and other nanocrystals or by fluid shear (see Figure for a pictorial representation of step III). , This process is subsequently followed by the incorporation of monomer units (atomic species) into the fragmented particles, leading to the slow growth observed in step III (Figure c,f).…”

“…This is a physical process possibly induced by collisions of the crystal with the impeller (magnetic stirring bar), vessel walls, and other nanocrystals or by fluid shear (see Figure 6 for a pictorial representation of step III). 43,44 This process is subsequently followed by the incorporation of monomer units (atomic species) into the fragmented particles, leading to the slow growth observed in step III (Figure 7c,f). However, at longer irradiation times, the particle concentration reaches a threshold value and then decreases continuously (Figure 7d, step III, t = 5−9 min) as a consequence of the rapid monomer consumption related to the growth of a large number of fragmented particles in a short period of time.…”

Effect of Solution Stoichiometry on BaSO4 Crystallization from Turbidity Measurements and Modeling

“…Due to its reliance on a two-step crystallization process involving classical nucleation theory and a bulk first order growth rate, the model of Dai et al has been criticized . There, the authors advocate for a model including a four step mechanism based on slow, continuous nucleation followed by autocatalytic surface growth, bimolecular aggregation, and then secondary, size-dependent autocatalytic aggregation of smaller and larger particles. We have chosen our current approach, based on Dai et al, as it provides a direct form of quantification of our type of measurements.…”