Abstract

BACKGROUND Bio-oils can be effectively used for the preparation of bio-based materials owing to their chemical compositions. In this study, brown macroalgal-derived bio-oil was used for the synthesis of graphene oxide-carbon dot composite by a simple hydrothermal process. RESULTS A simple and facile hydrothermal process was explored for the preparation of green-emitting graphene oxide-carbon dot (GO-CD) composite from brown macroalgal biomass-derived bio-oil as carbon source in water medium at 170 degrees C for 4 h. An aqueous solution of the prepared GO-CD composite exhibited green emission under ultraviolet (UV) radiation exposure. Raman spectroscopy and transmission electron microscopy analyses confirmed the successful formation of GO-CD composite. Physicochemical characterizations such as phase structure and optical properties of the GO-CD were investigated by X-ray diffraction, UV-visible and photoluminescence analyses. The effects of the GO-CD composite on the seed germination of mung bean were studied. It was found that, compared with the control (100/0 vol% water; total length of plant similar to 20 cm), the 75/25 vol% water/GO-CD ratio treatment resulted in better plant growth (total length of plant similar to 25 cm) under the studied conditions. Further increase in GO-CD concentration above the optimum level resulted in a decrease in plant growth but did not have a significant effect on the mass, root and leaf mass development. CONCLUSION Brown macroalgal bio-oil-derived graphene oxide-carbon dot composite were explored for the seed germination of mung bean and the results showed that a low concentration enhanced the plant growth. (c) 2019 Society of Chemical Industry