Sosa Ricardo D, Geng Xi, Reynolds Michael A, Rimer Jeffrey D, Conrad Jacinta C
Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204-4004, USA.
Lab Chip. 2019 Apr 23;19(9):1534-1544. doi: 10.1039/c9lc00061e.
Crystallization of mineral scale components ubiquitously plagues industrial systems for water treatment, energy production, and manufacturing. Chemical scale inhibitors and/or dissolvers are often employed to control scale formation, but their efficacy in flow conditions remains incompletely understood. We present a microfluidic platform to elucidate the time-resolved processes controlling crystallization and dissolution of barite, a highly insoluble and chemically resistant component of inorganic scale, in the presence of flow. In a growth environment, increasing the flow rate leads to a crossover from a transport-limited to a reaction-limited kinetic regime. In situ optical microscopy reveals that addition of diethylenetriaminepentaacetic acid (DTPA), a common dissolution agent, alters the morphology of barite crystals grown under flow. In a dissolution environment (i.e. alkaline solutions without barium sulfate), increasing the flux of DTPA, whether by increasing the flow rate or DTPA concentration, enhances the rate of dissolution of barite. Trends in the rate of barite dissolution with DTPA concentration and flow rate indicate an optimal combination of these parameters. The combined use of microfluidics and optical microscopy provides a robust and broadly-useful platform for capturing crystallization kinetics and morphological transformation under dynamic flow conditions.
矿物垢成分的结晶普遍困扰着用于水处理、能源生产和制造的工业系统。化学阻垢剂和/或溶解剂经常被用于控制垢的形成，但其在流动条件下的功效尚未完全了解。我们展示了一个微流控平台，用于阐明在流动情况下控制重晶石（无机垢的一种高度不溶且耐化学腐蚀的成分）结晶和溶解的时间分辨过程。在生长环境中，流速增加会导致从传输限制动力学 regime 转变为反应限制动力学 regime。原位光学显微镜显示，添加常见的溶解剂二乙烯三胺五乙酸（DTPA）会改变在流动条件下生长的重晶石晶体的形态。在溶解环境中（即不含硫酸钡的碱性溶液），无论是通过增加流速还是 DTPA 浓度来增加 DTPA 的通量，都会提高重晶石的溶解速率。重晶石溶解速率随 DTPA 浓度和流速的变化趋势表明了这些参数的最佳组合。微流控技术和光学显微镜的结合使用为在动态流动条件下捕捉结晶动力学和形态转变提供了一个强大且广泛适用的平台。
