In Zone Refining, a short molten zone travels slowly through an elongated sample of a crystalline material, achieving exceptional purification through controlled phase transitions.
A molten zone traversing a solid sample has two liquid-solid interfaces: a melting interface and a freezing interface.
At the melting interface the composition does not change, but at the freezing interface, the impurities favor the liquid phase because the crystal structure tends to exclude molecules that do not readily fit into the crystal lattice.
Passing the molten zone(s) through the sample many times concentrates the impurities at one end, leaving the opposite end highly purified.
The sample is contained in one (or two) disposable, thin-walled Teflon sample tubes. These tubes are filled with the sample and clamped on each end in the tube transport mechanism.
The transport mechanism slowly moves the tubes downward, passing them through the four heating and four cooling zones of the temperature regulated metal blocks.
After the tubes move downward the distance of one hot zone and one cold zone (two centimeters), the transport mechanism is reversed and the tubes are quickly moved upward to the original position.
The net result of this motion is that the molten and crystalline zones migrate slowly and continuously upward with respect to the tubing.
With a typical zone rate of 2 cm/hr and with four active zones, each portion of the sample is subjected to one purifying phase transition per hour.
Usually within 18 hours of automatic operation (18 recrystallizations), the sample is purified. After the sample tube is cooled, it is removed from the MiniZone.
From sample loading to recovery, a streamlined workflow for ultra-purification
Fill the thin-walled Teflon sample tube with your material and clamp it in the transport mechanism.
Configure the temperature zones and zone rate based on your material's melting characteristics.
The MiniZone automatically cycles the molten zones through your sample for up to 18 hours.
Cut the cooled tube into sections. The purified material is concentrated at one end, impurities at the other.
Contact us to schedule a demonstration and learn how the MiniZone II can enhance your purification workflow.
Contact Us