Quantitative analysis and kinetic modeling of ultrasound-assisted exfoliation and breakage process of graphite oxide

Ultrasonic exfoliation is the most widely used delamination technique for producing graphene oxide. In this work, the exfoliation of graphite oxide suspension is conveniently monitored via real-time measurement of viscosity and then quantitatively described by using the relative single-layer fraction (alpha) for the first time, by which the full exfoliation is achieved with a time scale of minutes. Lateral size evolution is demonstrated using lognormal distribution based on statistical analysis. With the quantization of relative single-layer fraction and lateral size distribution, a prototype database has been built to efficiently integrate experimental data tested under different process conditions (suspension concentration, ultrasonic frequency, and ultrasonic power density), which can be used as reference guides for process optimization and product control. The selection and breakage functions (S-i and B-ij) of ultrasound-assisted exfoliation are calculated and the breakage mechanisms of graphite oxide are found attributed mainly to sheet fracture. (C) 2019 Elsevier Ltd. All rights reserved.