Sodium Alginate-Based Functional Materials toward Sustainable Applications: Water Treatment and Energy Storage

Most synthetic materials used in water treatment and energy storage are nonbiodegradable and nonrenewable, causing the generation of massive electronic wastes and discarded separation materials. Sodium alginate (SA) has the features of abundant sources, low cost, renewability, and biodegradability. To achieve sustainable development and minimize environmental impact, SA is well designed into high-performance hydrogels, aerogels/foams, films, and binders used in water treatment and energy storage components via low-energy, low-toxicity, and low-cost ways. This review summarizes the preparation methods of SA composites and highlights the advantages of composites applied in water treatment and energy storage. In water treatment, challenges and solutions to the separation, regeneration, and waste disposal process of SA composites are introduced, aiming to simplify the separation process, reduce secondary pollutants, and achieve high-value utilization of waste. Conventional and nonbiodegradable components in energy storage materials were replaced with renewable SA to improve electrochemical performances, decrease manufacturing costs, and reduce the generation of solid-state electronic wastes. Finally, a summary and perspectives are proposed.