Environmentally friendly bacterial cellulose hydrogel-derived aerogel and membrane for efficient water purification

Simultaneously removing various contaminants from contaminated water with a low energy consumption remains challenging. Herein, we employed bacterial cellulose hydrogel (BCH) as a substrate and synthesized ZnO nanoflowers within its three-dimensional network via an in-situ synthesis approach, resulting in the formation of BCH/ZnO. Subsequently, the BCH/ZnO was processed through freeze-drying and heat-drying to fabricate a composite aerogel (BCA/ZnO-3) and a composite membrane (BCM/ZnO-3), respectively. The BCA/ZnO-3 exhibited remarkable adsorption capacities towards various contaminants and demonstrated a treatment capacity of 773.8 L m −2 in an injection-driven filter for real contaminated water. Meanwhile, the BCM/ZnO-3 was applied in ultrafiltration (UF) system with hydraulic pressure. At 2.5 bar, it exhibited a flux of 29.19 L m −2 h −1 and had a treatment capacity of 674 L m −2 for contaminated water. Moreover, the BCM/ZnO-3 showed a favorable antifouling performance and reusability. Experimental results and theoretical calculations revealed that both BCA/ZnO-3 and BCM/ZnO-3 perform UF and adsorption based on size screening, electrostatic interaction and hydrogen bonding. These processes simultaneously eliminated microorganisms, heavy metals, and small organic molecules (e.g., dyes and antibiotics). Moreover, these environmentally friendly materials can biodegrade in natural environments and have less environmental impact than other adsorptive membranes. Overall, the biohydrogel-based materials are promising alternatives to conventional petroleum-based membranes, offering effective and energy-efficient solutions for diverse water purification needs.