When the vacuum freeze dryer is used for freeze drying of graphene, the principle of sublimation is used to first freeze the graphene solution into ice crystals, and then vacuumize the water to sublime out, and finally obtain flocculent solid graphene. The cold trap has a pre-freezing function, which can quickly pre-freeze the graphene solution, with fast cooling speed, low noise and high freeze-drying efficiency.
Graphene freeze-drying process and method:
1. The main engine and the vacuum pump are connected;
2. Pre-freeze the sample in a cold trap or other low temperature refrigerator;
3. When the pre-frozen samples are placed in the drying room, ensure that the air release valve is sealed, and turn on the vacuum pump;
4. Pay attention to the falling speed of the vacuum degree to determine whether the vacuum degree can reach below 20pa;
5. When vacuuming, be sure to keep the refrigerator turned on to ensure that the cold trap captures the sublimated moisture;
6. After the freeze-drying is completed, please release the air first (to prevent the vacuum pump from returning to the oil), then turn off the vacuum pump, turn off the refrigerator and power supply, and take out the dry product;
7. After defrosting in the cold trap, release the water, wipe off the residual water, and keep the table and the cold trap dry.