Lactone radical transformed methyl mercaptan-adsorbed activated carbon into graphene oxide modified activated carbon.

Activated carbon was a widely-used adsorbent. However, it was usually classified as a hazardous waste after saturation adsorption for one pollution. For the first time, this article reported a regeneration method for the activated carbon saturated with methyl mercaptan. The regenerated carbon was partially transformed into graphene-oxide fragment with a thickness of 0.9-1.0 nm after a hydrothermal treatment at 180 °C. Electron paramagnetic resonance revealed that lactone group was transformed into lactone radical under the hydrothermal condition. The spins were increased from 4.54E+17-1.24E+18. The formed radical effectively reacted with the adsorbed methyl mercaptan and re-distributed the amorphous activated carbon to form lamellar graphene oxide. As a result, the spins were decreased from 1.24E+18-8.73E+17. At the same time, the amount of lactone group was decreased from 0.71 to 0.42 mmol/g. The regenerated activated carbon thus regained ability to adsorb methyl mercaptan. The main result of this paper puts forward a simple and low-cost method to obtain graphene oxide modified activated carbon from the regeneration of hazardous waste carbon. This conclusion makes contribution to the development of "zero-waste" conception.