Keratin Waste Transformation: An Eco-friendly Approach to Water Treatment

Keratin, a byproduct of the global livestock, poultry, and wool industries, is one of the most prevalent strong-structural non-food proteins. Despite being biodegradable, the high sulfur content poses a risk to the environment and complicates direct disposal due to pollution concerns. Utilizing keratin waste as a reusable biosorbent can reduce the amount of direct environmental dumping. However, controlled regeneration and disposal through chemical treatment are required to prevent secondary pollution due to its sulfur-rich nature and the buildup of adsorbed contaminants. Therefore, repurposing waste that is high in keratin as a biosorbent for water purification is an environmentally conscious and sustainable management approach. Keratin has a wellestablished ability to adsorb contaminants due to its large surface area and functional groups such as hydroxyl, thiol, amino, and carboxyl that facilitate contaminant binding. However, there are disadvantages to the native form of keratin, including low regeneration, poor stability, and a low adsorption capacity. Since these materials have been the subject of recent research, keratin extraction from biomass and its application as a bio-adsorbent in a range of keratin-based nanocomposites, including biofilms, crosslinked polymers, sponges, membranes, and hydrogels, are covered in this review. In terms of their adsorption capacity (qmax), removal efficiency (%), regeneration efficiency (%), adsorption kinetics, isotherm parameters, surface area, and structural integrity following repeated adsorption-desorption cycles, these advancements have enhanced the stability, reusability, and binding effectiveness of keratin materials. With an emphasis on innovative extraction techniques and strategies for overcoming challenges in the development of efficient and sustainable keratin-based materials for water treatment applications, this review methodically examines well-known and frequently cited research articles.