Imaging adsorption of iodide on single Cu2O microparticles reveals the acid activation mechanism

• Published in: Journal of hazardous materials 2021-10, Vol.420, p.126539-126539, Article 126539
• Main Authors: Huang, Wei, Li, Hua, Yu, Ling, Lin, Ying, Lei, Yuting, Jin, Luyue, Yu, Haili, He, Yi
• Format: Article
• Language: English
• Subjects: Acid activation mechanism; Cuprous oxide; Iodine adsorption; Kirkendall effect; Single-particle imaging
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.126539

Imaging an adsorption reaction taking place at the single-particle level is a promising avenue for fundamentally understanding the adsorption mechanism. Here, we employ a dark-field microscopy (DFM) method for in situ imaging the adsorption process of I- on single Cu2O microparticles to reveal the acid activation mechanism. Using the time-lapsed DMF imaging, we find that a relatively strong acid is indispensable to trigger the adsorption reaction of I- on single Cu2O microparticle. A hollow microparticle with the increase in size is obtained after the adsorption reaction, causing the enhancement of the scattering intensity. Correlating the change of the scattering light intensity or particle size with adsorption capacity of I-, we quantitatively analyze the selective uptake, slightly heterogeneous adsorption behavior, pH/temperature-dependent adsorption capacity, and adsorption kinetics as well as isotherms of individual Cu2O microparticles for I-. Our observations demonstrate that the acid-initiated Kirkendall effect is responsible for the high-reaction activity of single Cu2O microparticles for adsorption of I- in the acidic environment, through breaking the unfavorable lattice energy between Cu2O and CuI as well as generating high-active hollow intermediate microparticle. [Display omitted] •A method is proposed for imaging adsorption of I- on single Cu2O microparticles.•The adsorption of I- follows pseudo-first-order kinetic and D-R isotherm models.•The activation mechanism is attributed to the acid-initiated Kirkendall effect.•This imaging method facilitates understanding of the structure-activity relationship.