Confined synthesis of ultrafine ZrO2 anchoring composites in switchable and microchannel-like space for fluoride removal

The continuous phase films in high internal phase emulsions (HIPEs), which seems to be a microchannel-like space, are benefit for confined synthesis of ultrafine adsorbent. Herein, switchable and microchannel-like space in the continuous phase of oil-in-water HIPEs is developed for fabricating ultrafine ZrO 2 anchoring cross-linked enzyme aggregates (CLEAs-ZrO 2 ), and then as-prepared composites were applied as defluoridation adsorbent. Bis(3-aminopropyl)tetramethyldisiloxane oleic acid surfactant (BTOA) can realize reversible emulsification and demulsification in response to CO 2 /N 2 switch, endowing with simple collection of products and continuous preparation. This confinement effect is expected of resulting in a 28 % increase in adsorption capacity and 33 % reduction in synthesis time. In addition, the adsorption capacity of CLEAs-ZrO 2 is nearly 4.2 times higher than that of commercially available defluoridants. In fluorine-containing industrial wastewater, the removal efficiency of fluoride ion (F - ) reaches 93 %, and the corresponding partition coefficients ( K d ) achieves the value of 31.1 L g −1 . By analyzing with XPS spectra and in-situ FT-IR spectroscopy, a strong Zr-F bonding interaction between CLEAs-ZrO 2 and F - in the solution boosts this specific adsorption. This work presents a novel method for constructing switchable confinement system, but also offers a promising defluoridation adsorbent for industrial effluents.