Development of eco-friendly green and chemical routes for exfoliation of graphite as effective antibacterial agent

Abstract

Liquid phase exfoliation (LPE) has emerged as an effective technique for producing large scale 2D nano-sheets. In present study, graphite has been exfoliated by using chemical and green routes. The adopted methods are cost effective, eco-friendly, time saving and utilize less toxic solvents for producing high quality exfoliated graphite (EG). Herein, graphite exfoliation has been achieved by using NaOH, HCl, natural acids (lemon juice) and plant extract (mint extract). In chemical route, exfoliation of graphite using NaOH has given excellent results as compared to HCl. By using NaOH, d-spacing value has been increased from 3.30 to 3.37 nm and sheets with average thickness of 14.8 nm have been achieved. In green route, mint extract gives better result as compared to lemon juice. The bioactive constituents of plant extracts penetrate between graphitic layers results in weakening of van der waals forces which facilitates exfoliation. Using mint extract, d-spacing value has been increased from 3.30 to 3.36 nm. Thin sheets with average thickness of 10.79 nm has been obtained. Overall exfoliation using NaOH and mint extract gives excellent result. The higher ID/IG ratio for exfoliated graphite using NaOH and mint extract is 0.77 and 0.88, respectively as compared to pure graphite which confirmed the degree of exfoliation. Exfoliation of graphite enhances the surface properties of nano-sheets leading to the enhanced antibacterial activity against Pseudomonas Aeruginosa as compared to pure graphite. The exfoliated graphite using mint extract showed the best antibacterial activity.