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Caption : fig. s1. nh<sub>3</sub> adsorption isotherms of (a) c-hap and (b) p-hap. co<sub>2</sub> adsorption isotherms of (c) c-hap and (d) p-hap. squares, circles, diamonds, and triangles represent first adsorption isotherm, second adsorption isotherm, third adsorption isotherm, and irreversible adsorption, respectively.

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Caption : fig. s2. acetaldehyde adsorption isotherms of c-hap (circles) and p-hap (triangles). open and solid symbols represent adsorption and desorption processes, respectively. red dashed line represents monolayer volume. adsorption curves were extrapolated (black dashed lines) to estimate irreversible multilayer after desorption process (10.9 for c-hap and 2.9 for p-hap). monolayer adsorption volume of acetaldehyde (0.49 mol/kg) was calculated from the bet specific surface area and molecular cross-sectional area of 0.228 nm<sup>2</sup>. adsorption profiles show large adsorption amounts with a large hysteresis loop between the adsorption and desorption processes. irreversible and reversible adsorption behaviors can be attributed to catalytic reactions at both oh<sup>−</sup> basic sites and surface p–oh brønsted acidic sites. 

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Caption : fig. s3. ir spectra of c-hap (blue line) and p-hap (red line) after acetaldehyde vapor adsorption. bands at 2900 cm<sup>−1</sup> are assigned to c–h group vibrations and those at 1390−1470 cm<sup>−1</sup> and around 1550 cm<sup>−1</sup> are assigned to carboxylatess1,s2,s3 from chemical species generated after acetaldehyde adsorption. acetaldehyde band (1709−1711 cm<sup>−1</sup>) is absent from spectra of both c-hap and p-hap. noise between 1300 and 1900 cm<sup>-1</sup> is attributed to water vapor. band intensities increased with increasing amount of adsorbed acetaldehyde. large adsorption amounts indicate that acetaldehyde undergoes catalytic reaction over apatite surface.