Polydopamine-functionalized natural cellulosic Juncus effusus fiber for efficient and eco-friendly Cr (VI) removal from wastewater

Biomass adsorbents have received extensive attention for the removal of heavy metals , but most of them had very limited adsorption capacity or needed to be modified with environmentally unfriendly chemicals to achieve acceptable performance. In this study, a green biomass adsorbent was fabricated using an abundant natural cellulosic Juncus effusus (JE) fiber and natural melanin polydopamine (PDA) through a simple mussel-inspired polymerization strategy. JE's unique hollow three-dimensional network structure provided an ideal scaffold substrate with abundant sites for dopamine polymerization deposition. This enabled the modified PDA@JE fibers to be rich in amino, hydroxyl, and other active adsorption sites, thereby endowing the PDA@JE fiber adsorbent with a promising Cr (VI) adsorption capacity of up to 145.8 mg / g. This capacity was significantly higher than that of most previously reported biomass-based adsorbents. Furthermore, 10–20 times the concentration of common interfering ions such as Ca 2+ , Cd 2+ , Cu 2+ , NO 3 - , Cl - , SO 4 2- and PO 4 3- had little effect on the adsorption efficiency. This study provided a green and general mussel-inspired strategy for preparing effective biomass adsorbent, offering a promising approach for utilizing natural cellulosic fibers in eco-friendly applications.