Lignin as an emerging material in membrane technology for water and wastewater treatment: A review

Water treatment using membranes is an attractive technology due to lower energy consumption and reduced environmental impact compared to other separation processes. However, there is a pressing need for new membrane materials with more sustainable life cycles. The use of biopolymers, such as lignin, in membrane fabrication is considered a sustainable alternative to conventional materials. Lignin is produced as a by-product of the wood processing industry and is therefore both inexpensive and abundant. It has been used as an adsorbent for various components in wastewater due to its many active sites and its ease of modification to suit various adsorption applications. Whilst the use of lignin in membrane fabrication is relatively recent, its application is attracting increasing attention due to the increased demand for biodegradable materials. This review critically examines the emerging role of lignin as a functional additive in the fabrication of membranes for water and wastewater treatment, with a focus on its potential to enhance antifouling characteristics. This review also discusses how lignin incorporation influences membrane surface and structural properties and covers the diverse techniques employed in the fabrication of lignin based membranes, highlighting the current limitations and outlining future directions to advance lignin-based membranes towards scalability.