Yin Yiming, Li Tianshu, Zuo Kuichang, Liu Xitong, Lin Shihong, Yao Yiqun, Tong Tiezheng
Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, Colorado80523, United States.
Department of Civil and Environmental Engineering, George Washington University, Washington, District of Columbia20052, United States.
Environ Sci Technol. 2022 Nov 15;56(22):16315-16324. doi: 10.1021/acs.est.2c06560. Epub 2022 Oct 28.
Developing engineered surfaces with scaling resistance is an effective means to inhibit surface-mediated mineral scaling in various industries including desalination. However, contrasting results have been reported on the relationship between scaling potential and surface hydrophilicity. In this study, we combine a theoretical analysis with experimental investigation to clarify the effect of surface wetting property on heterogeneous gypsum (CaSO·2HO) formation on surfaces immersed in aqueous solutions. Theoretical prediction derived from classical nucleation theory (CNT) indicates that an increase of surface hydrophobicity reduces scaling potential, which contrasts our experimental results that more hydrophilic surfaces are less prone to gypsum scaling. We further consider the possibility of nonclassical pathway of gypsum nucleation, which proceeds by the aggregation of precursor clusters of CaSO. Accordingly, we investigate the affinity of CaSO to substrate surfaces of varied wetting properties calculating the total free energy of interaction, with the results perfectly predicting experimental observations of surface scaling propensity. This indicates that the interactions between precursor clusters of CaSO and substrate surfaces might play an important role in regulating heterogeneous gypsum formation. Our findings provide evidence that CNT might not be applicable to describing gypsum scaling in aqueous solutions. The fundamental insights we reveal on gypsum scaling mechanisms have the potential to guide rational design of scaling-resistant engineered surfaces.
开发具有抗结垢性能的工程表面是抑制包括海水淡化在内的各种行业中表面介导的矿物结垢的有效手段。然而，关于结垢潜力与表面亲水性之间的关系，已有相互矛盾的报道。在本研究中，我们将理论分析与实验研究相结合，以阐明表面润湿性对浸入水溶液中的表面上非均相石膏（CaSO₄·2H₂O）形成的影响。源自经典成核理论（CNT）的理论预测表明，表面疏水性的增加会降低结垢潜力，这与我们的实验结果相反，我们的实验结果是亲水性更强的表面更不易发生石膏结垢。我们进一步考虑了石膏成核的非经典途径的可能性，该途径是通过CaSO₄前体簇的聚集进行的。因此，我们通过计算相互作用的总自由能来研究CaSO₄对不同润湿性的基底表面的亲和力，结果完美地预测了表面结垢倾向的实验观察结果。这表明CaSO₄前体簇与基底表面之间的相互作用可能在调节非均相石膏形成中起重要作用。我们的研究结果提供了证据，表明CNT可能不适用于描述水溶液中的石膏结垢。我们揭示的关于石膏结垢机制的基本见解有可能指导抗结垢工程表面的合理设计。
