Processing brines to recover strategic mineral salts using evaporation ponds requires large surface areas and are slow, even in arid climates. Here we show a novel membrane macropore storage mechanism that induces fast salt crystallisation in mesoporous top-layers in inorganic asymmetric membranes, stemming from 789 million nucleation points per metre square of surface area. During membrane pervaporation, dissolved salts are retained mainly in the macropores of the substrate which subsequently provide ideal conditions for crystal nucleation and growth on the membrane surface upon drying. This novel pore storage mechanism is attained owing to the solution flow modulation of the mesoporous titania and gamma-alumina layers that is counterbalanced by the flow of water during pervaporation. Therefore, pore size control is imperative to avoid flooding in the macroporous substrate. This work further shows the fundamental properties of the salt storage mechanism described by a single salt production coefficient, and a global salt production coefficient for metal chloride salts. This technology could potentially be considered for unlocking and process strategic global minerals from brines.

使用蒸发池处理盐水以回收战略性矿物盐需要大的表面积并且速度缓慢，即使在干旱气候下也是如此。在这里，我们展示了一种新的膜大孔存储机制，该机制在无机不对称膜的介孔顶层中诱导快速盐结晶，源于每平方米表面积 7.89 亿个成核点。在膜渗透蒸发过程中，溶解的盐主要保留在基材的大孔中，这为干燥后膜表面的晶体成核和生长提供了理想的条件。由于介孔二氧化钛和γ-氧化铝层的溶液流动调制在渗透蒸发过程中被水流抵消，因此实现了这种新颖的孔隙存储机制。所以，孔径控制对于避免大孔基材中的水淹是必不可少的。这项工作进一步显示了由单一产盐系数和金属氯化物盐的全局产盐系数描述的盐储存机制的基本特性。这项技术有可能被考虑用于从盐水中解锁和加工全球战略矿物。