Slow Release of Menthol Using Sorbents Developed from Microwave Graphene Oxide

Menthol is a key ingredient in many of the traditional Thai aroma products such as potpourri and herbal air freshener. However, it suffers from the rapid evaporation and sublimation loss. In this work, microwave graphene oxide (mGO) has been prepared as sorbent and tested for the slow release of menthol. Menthol was loaded into microwave graphene oxide at loading ratios of 1:0.5 and 1:1. The release performance of the mGO as compared to traditional essential oil reed diffuser and the pure menthol was studied by monitoring the menthol weight loss at the temperature of 80°C until all of the menthol evaporated using thermogravimetric analysis. It was found that mGO can significantly slow down the menthol release rate compared to that of the pure menthol by up to eight times slower. The interaction and adsorption mechanism of the menthol-loaded microwave graphene oxide was also studied using Fourier Transform Infrared Spectroscopy (FTIR) which indicates that menthol adsorbs strongly onto the mGO leading to the slow release rate.