Facet engineering of minerals for effective oil-water separation

Minerals have been growing as an emerging 'hot' topic in separating water -in -oil emulsions. Whether the intrinsic structure of minerals could precisely regulate water-mineral interactions for enhancing emulsions separation efficiency is still ambiguous. Here, taking half -hydrated gypsum as a case, this study reveals the crystal facet -dependent potential mechanism of minerals in water -in -oil emulsions separation. We show that the (204) facet of half -hydrated gypsum is more susceptible to water -induced degradation and hydration reaction. With combined experimental and theoretical studies, the facet -dependent mechanism for oil-water separation are revealed; the (204) facet that exhibited weak internal hydrogen bond and strong binding energy with water accelerated the dissolution and recrystallization of half -hydrated gypsum, thus enhancing oil-water separation efficiency. Through engineering, half -hydrated gypsum with a higher surface fraction of the (204) facet achieved much higher separation efficiency (99.9%), surpassing those of minerals in disclosed literature. This investigation not only contributes significantly to the comprehension of interactions at the minerals -water interface but also illuminates novel perspectives and avenues for the utilization of facet engineering in advancing research on mineral surface properties.