Abstract
Toxic wastewater remains an important and ongoing challengeChallenges in industrial societies. The natural and eco-friendlyEco-friendly diatomaceous earth with nano-scale pores has demonstrated excellent removal capability of wastewater contaminated with dyes, heavy metalMetals ions, and oil pollutants. However, adsorbents with micro-scale pores exhibit high adsorption capacity but low permeability, making it difficult to optimize both adsorption capacity and flow efficiency. To overcome this limitation, we fabricated multi-scaleMulti-scale, hierarchically porous absorbents using natural diatomite as raw materialsMaterials. Through the combination of the freeze casting method and 3D-printed sacrificial template, porous adsorbents with adjustable multi-scaleMulti-scale channel widths (in the range of 300–500 nm, 10–30 μm, and 0.5–3 mm) were successfully fabricated. By designing the geometry of the porous structuresPorous structures, we can optimize the adsorption efficiency and the mechanical strength of adsorbents. The designed channels meander the fluid paths and the micropores and nanopores further enhance the accessibility of adsorption sites in hierarchically porous adsorbents.