Bamboo-Based Biofoam Adsorbents for the Adsorption of Cationic Pollutants in Wastewater: Methylene Blue and Cu(II)

[Image: see text] Human health is being threatened by cationic pollutants in wastewater, for example, methylene blue (MB) and Cu(II). Our research team successfully fabricated biofoam adsorbents from recycled bamboo waste that removed cationic pollutants via introducing bamboo fiber sources, i.e., bamboo fiber, bamboo α-cellulose fiber, and bamboo nanocellulose fiber, into a polyurethane (PU) foam matrix. The biofoam adsorbent with 1 g of nanocellulose (PUN(1)) presented high removal efficiencies for MB (95.52%) and Cu(II) (100%) in low cationic pollutant concentration aqueous solutions. The biofoam adsorbent with 1 g of bamboo fiber (PUB(1)) also displayed excellent removal efficiency for MB (98.61%) at pH 11. Meanwhile, 100% removal of Cu(II) was obtained by PUB(1) at pH 7 (initial content = 15 mg/L). Furthermore, the PUN(1) sample had excellent reusability, evidenced by 61.25% removal of MB after five adsorption–desorption cycles, suggesting that PUN(1) is a promising renewable adsorbent for cationic pollutants. In addition, PUB(1) is a low-cost adsorbent with good adsorption efficiencies for MB in weak alkaline solutions and Cu(II) in neutral aqueous solutions.