Removal of bovine serum albumin and methylene blue using a hybrid membrane of single walled carbon nanotube-banana peel protein: Fabrication and characterization

An environmentally friendly, facile and nondestructive method was developed for the fabrication of nano-bio hybrid membranes. Single-walled carbon nanotubes (SWNTs) were self-assembled via a one-step fabrication procedure using a protein extract from banana peel waste as a biological glue. A large fraction of the protein extract consisted of aliphatic and polar/amphiphilic residues. The hydrophobic functional groups of the protein extract were probably responsible for the binding of the extract to the SWNTs, with this binding involving π-π stacking and hydrophobic interactions, while hydrophilic groups of the protein extract possibly provided an ionic environment for the SWNT-protein hybrids. These hybrids were easily transplanted onto membrane support for use in water treatment. Due to the non-destructive assembly of SWNTs and proteins extracted from the banana peel, the hybrid membranes maintained the electrical conductivity of the SWNTs and hydrophilicity of the protein extract. Water contact angle and porosity values of the hybrid membrane were found to depend on the SWNT and protein contents. Specifically, the porosity and water permeate flux increased with increasing protein content. The SWNT-protein hybrid membrane was successfully used to reject the cationic dye methylene blue and the protein bovine serum albumin, results demonstrating the filtration capability of this membrane.