A drop-casting route toward porous alumina ceramic balls driven by pseudo-boehmite solution and sodium alginate crosslinked network

Abstract

Geometric structure design is an effective strategy for the Al₂O₃ ceramics to develop their potential in many application regions. Here, we propose a facile drop casting route to take advantage of both the network (pseudo-boehmite, PB) and egg-box (sodium alginate, SA) structure to prepare porous Al₂O₃ balls, enabling these ceramics with macroscale size, network structure, and proper densities. With the Al₂O₃ particles as the framework materials, PB solution penetrated the calcium alginate network under proper acidic and Ca²⁺ ionic environment, facilitating the construction of the 3D porous structure for the aimed Al₂O₃ ceramic balls. After the frozen drying and TEOS immersion, Al₂O₃ ceramic balls can be obtained through a heat treatment at 1200 °C for 2 h, with 65.21 % porosity, 1.32 g/cm³ density and ∼3 mm diameter. Moreover, these obtained ceramic balls exhibit selective adsorption on the methylene blue (MB) dyes and reusability for times. Our proposed simple drop-casting method can provide Al₂O₃ ceramic balls with tailored ball sizes and porous network structure, illustrating prosperous prospects in the application fields of catalyst support, adsorption, separation and purification.