Nettle leaves-based sulfonated graphene oxide for efficient hydrolysis of microcrystalline cellulose

Abstract

A green preparation of porous graphitic carbon through iron based catalytic graphitization of nettle (Urtica dioica L.) as precursor for the synthesis of sulfonated graphene oxide to be used as catalyst was developed. The morphological and physicochemical properties of nettle-derived porous graphitic carbon (GI-Ntt), graphene oxide (GO-Ntt) and sulfonated graphene oxide (sGO-Ntt) were assessed with several characterization techniques. Layered soft-structure with surface area of 354.9 m2 g−1, mesopore volume of 0.13 m3 g−1 and presence of high densities of functional groups such as hydroxyl, epoxy, carbonyl, carboxyl and sulfonic acid group with the total acid sites density of 5.47 mmol g−1 on the surface of the sGO-Ntt were observed. Moreover, it is revealed that GO-Ntt and sGO-Ntt both possess extremely thin nanosheet-like structures with an irregular edges and transparent lamella appearance unlike the GI-Ntt. Using the sGO-Ntt as catalyst, hydrolysis of microcrystalline cellulose (MCC) without pretreatment in water as an environmentally benign solvent resulted in the maximum glucose yield and selectivity of 26.3% and 72.8%, respectively. The optimum experimental conditions were sGO-Ntt concentration ratio of 1 g g−1 of untreated microcrystalline cellulose at 160 °C for 3 h.