Facet-mediated interaction between humic acid and TiO2 nanoparticles: implications for aggregation and stability kinetics in aquatic environments. Issue 6 (10th May 2019)

• Record Type: Journal Article
• Authors: Zhang, Hui; Wang, Weimin; Zhao, Huanxin; Zhao, Lixia; Gan, Li-Yong; Guo, Liang-Hong
• Is Part Of: Environmental science. Volume 6:Issue 6(2019)
• Page Start: 1754
• Page End: 1764
• Publication Date: 2019-05-10
• Subjects: Environmental sciences -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c9en00231f
• Languages: English
• ISSNs: 2051-8153

Abstract

Abstract : Humic acid improves TiO2 nanocrystal stability in a facet dependent manner due to the facet-specific SRHA coordination on the TiO2 surface. Abstract : Interfacial interactions between TiO2 nanocrystals and the surrounding environmental media play a critical role in dictating their environmental behaviors. Here two specific-faceted TiO2 crystals, {101} facet and {001} facet, were adopted to investigate facet-mediated aggregation kinetics in aquatic environments. In pristine electrolyte solution (NaCl and CaCl2 ), {001} TiO2 exhibited higher stability than {101} TiO2 due to the abundant –OH groups on the {001} facet surface. The presence of Suwannee river humic acid (SRHA) significantly improved the stability of TiO2 nanocrystals in a facet dependent manner, in which {101} TiO2 exhibited a more remarkable improvement in stability than {001} TiO2 . At a high SRHA concentration (10 mg L −1 ), both faceted TiO2 displayed comparable stability. The adsorption experiments and attenuated total reflectance Fourier transformation infrared spectroscopy demonstrated that {101} TiO2 induced more pronounced adsorption of SRHA molecules than {001} TiO2, probably driven by the efficient bidentate coordination of –COO– groups in SRHA on the {101} facet. This facet-affected colloidal stability behavior would deepen our understanding on nanomaterial transport and exposure in natural waters.