Lignin-based membranes for health, food safety, environmental, and energy applications: current trends and future directions

Polymer-based membrane technologies aim to address critical needs for separation, purification, transport, wound healing, contaminant removal, and more. While robust performance from these membranes is a priority, there is also a pressing need for sustainable, cost-effective solutions for membrane materials to replace perfluorinated and petroleum-derived polymers, which pose significant environmental concerns. Lignin, the second most naturally abundant polymer and a waste by-product of pulp and paper industries and cellulosic biorefineries, offers immense potential to drive sustainable materials revolution. This largely underutilized biopolymer possesses many physical and chemical attributes, making it suitable for biomedical, environmental, and energy applications. For instance, lignin and its functionalized derivatives offer antimicrobial, antioxidant, ultraviolet (UV)-blocking, and barrier properties, which are essential for slow drug release, wound healing with reduced stress, combating antibiotic resistance, and sterile food packaging/preservation. On the other hand, lignin’s 3D, hyperbranched architecture, phenolic units, and facile functionalization opportunities enable unique physical, mechanical, thermal, chemical, and ion transport/separation characteristics, critical for clean water and clean energy technologies. Therefore, by transforming lignin-rich biomass feedstock and industrial waste into value-added, efficient products, we can potentially address global needs for clean water, safe food, affordable healthcare, and renewable energy, as outlined in the United Nations’ Sustainable Development Goals. This mini-review highlights recent advancements in lignin-based membrane designs for biomedical, environmental, and energy applications, alongside a brief discussion on rooms for improvement in this emerging field via lignin valorization.