Photodiscoloration of Malachite Green Dye using Nitrogen Self-doped Graphene Oxide from Moringa oleifera Leaves

The present study focuses on the preparation of heteroatom doped/functionalized graphene from the Moringa Oleifera leaves by a simple torrefaction method and exploring it as a photocatalyst for the degradation of Malachite green dye. The prepared nitrogen self-doped graphene oxide (N-GO) was structurally analyzed using various analytical tools such as FT-IR, PXRD, Micro-Raman, UV-visible analysis, XPS, and HR-TEM. The study examined the influence of various experimental parameters such as the concentration of dye, amount of catalyst, pH of the medium, and contact time for the photo-discoloration of Malachite green dye. At optimum conditions (300 mg/L of catalyst, pH 7, and 6 mg/L of Malachite green dye), the prepared N-GO shows higher photocatalytic activity of 87% at 120 minutes of reaction. The experimental data fit very well with the Langmuir-Hinshelwood kinetic model with a rate constant of 0.087 min-1 and regression coefficient (R2) of 0.9916. The retention of almost 50% photocatalytic activity even after continuous 5 cycles of dye degradation indicates the reusability of the prepared photocatalyst. The results of the reactive species scavenging study concluded that hydroxyl radicals as the most active species involved in the catalytic process of the present study. A possible degradation mechanism is suggested by employing different scavengers in the experimental study. The study was further extended for the removal of Malachite green dye (81%) from simulated textile industry effluent. In conclusion, the study provided an entirely green approach towards the conversion of biomass into a biodegradable photocatalyst with strong prospects in industrial applications.

Photodiscoloration of Malachite Green Dye using Nitrogen Self-doped Graphene Oxide from Moringa oleifera Leaves Keywords:

Doped/Functionalized Graphene oxide , Malachite green , Sunlight , Kinetics , and Textile effluent