Bio-sorbent from castor oil polyurethane foam containing cellulose-halloysite nanocomposite for removal of manganese, nickel and cobalt ions from water

In order to mitigate the contamination of water with heavy metals, caused by mining dam failures in Brumadinho and Mariana in Brazil, eco-friendly bio-based castor oil polyurethane foams, containing a cellulose-halloysite green nanocomposite were prepared. Polyurethane foams containing none (PUF-0), 5%wt (PUF-5), and 10%wt (PUF-10) of the nanocomposite were obtained. The application of the material in aqueous media was verified through an investigation of the efficiency of adsorption, the adsorption capacity, and the adsorption kinetics in pH= 2 and pH= 6.5 for manganese, nickel, and cobalt ions. An increase of 5.47 times in manganese adsorption capacity was found after only 30 min in contact with a solution having this ion at pH= 6.5 for PUF-5 and 11.38 times for PUF-10 when both were compared with PUF-0. Adsorption efficiency was respectively 68.17% at pH= 2 for PUF-5% and 100% for PUF-10 after 120 h, while for the control foam, PUF-0, the adsorption efficiency was only 6.90%.