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 Ca2+, Cd2+, Cu2+, NO3-, Cl-, SO42- and PO43- 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.