Figure 3.

Kinetic analysis of ACC from CaCl₂ and Na₂CO₃ solutions. (a) Schematic of the microfluidic device used for the kinetics measurements. The colored rectangles along the primary microchannel indicate the positions where XAS spectra were recorded and correspond to reaction times of 10, 130, 1100, and 2200 ms. (b) Ca K-edge XANES spectra of solvated calcium ions (Ca²⁺) (60 mM CaCl₂) in droplets, Ca K-edge XANES spectra of impurity-free ACC under 80% humidity, and Ca K-edge XANES spectra measured at increasing reaction times. (c) Relative contribution from free calcium ions (Ca²⁺) and ACC as a function of time. Data were obtained from an LCF of each spectrum from the reference spectra.