Synthesis and urea sustained-release behavior of an eco-friendly superabsorbent based on flax yarn wastes

► Superabsorbent composite is synthesized from biological waste of textile industry. ► Homogeneous graft copolymerization in a low-cost NaOH/urea solution. ► The product is amphoteric with excellent urea loading and release capability. ► The superabsorbent composite is biodegradable and environment-friendly.