Immersion Well Reactors

These reactors are among the most efficient for photochemical reactions since the lamps are effectively surrounded by the solution to be irradiated. The lamps are contained in double-walled immersion wells made of quartz, allowing water cooling and/or filtering of excitation radiation. Various flask designs enable reactions to be conducted under anaerobic conditions at low or constant temperature.

Lamps

WARNING: All the lamps contain Mercury and must be disposed of in
accordance with local Health and Safety Regulations.

UV lamps

Two basic types of mercury lamps (low and medium pressure) are used.

Low pressure lamps emit over 90% of their radiation at 254nm, the remainder is visible light.

Medium pressure lamps produce predominantly 365-366nm radiation with smaller amounts also in the ultraviolet region at 254, 265, 270, 289, 297, 302, 313 and 334nm.

Significant amounts of radiation are produced in the visible region at 405-408, 436, 546 and 577-579nm.

Daylight lamp

Daylight lamp produces predominantly visible radiation in the range of 400-700nm.

WARNING: The lamp also produces dangerous UV radiation.

The lamp must allowed to cool after use, this can take up to 30 minutes with the cooling water flowing through the immersion well. If you attempt to start when hot the lamp will not light.

^a Photons/s measured by ferrioxalate actinometery in quartz immersion well

Radiated heat produced by lamps

Tests have been carried out to measure the rise in temperature on the surface of the immersion well with the cooling water circulating and lamp operating.

The cooling water temperature was 20°C at 2 litres per minute in all tests. Ice was introduced into the cooling water, this only lowered the temperature on the surface by 5-10°C. Increasing the water flow rate did not result in lower temperatures.

The low pressure lamps were not tested because of their low operating temperature approximately 80°C on the surface of the lamp. If cooling is used then there is little change in the temperature at the immersion well wall. If used without cooling water the immersion well wall will be approximately the same temperature as the lamp.

Water cooling must be provided with UV and Daylight Lamps.

Power Supplies

Arc sources possess negative voltage-current characteristics and conventional low-impedance power supplies cannot be used.  Lamps must be operated from reactive-type supplies having a large resistance or inductance in series.  This provides extra power to initiate the arc and reduce the power for continuous operation.  Recommended power supplies for lamps are listed below.  Input voltage 200-240VAC, 50-60Hz. The correct power supply for the lamp must be used to prevent damage to the equipment.

Immersion Wells

These are double-walled vessels made of quartz or borosilicate glass which house the irradiation lamp.  Inlet and outlet tubes provide for air or water cooling, when using a Medium Pressure UV or Daylight Lamp liquid cooling MUST be provided to ensure safe operation of the lamp. It is recommended that a flow sensor, such as PRC2, be used that will turn the lamp off if the cooling liquid flow is restricted.  A PTFE tube extends to the bottom of the annular space to allow coolant liquid to flow upwards from the bottom of the well.  The space between the walls allows filtering of certain wavelengths with coolant liquids such as cobalt, nickel, copper sulphate, sodium nitrate solutions.

Cutting off Radiation below 300nm

Small quartz immersion well reactor components RQ125: Use small borosilicate glass immersion well 3220 in place of the standard quartz immersion well 3210.

Large quartz immersion well reactor components RQ400: Use glass filter sleeve 3408

Full details of liquid cut-off filter solutions are supplied with instruction manuals.

Reaction Flasks

  

Three types of reaction flasks are available.  All are made of borosilicate glass and are fitted with one central ground socket to take an immersion well and other smaller sockets for a reflux condenser or drop-in funnel, sampling port etc.  Flasks may be supported by conventional laboratory stands and clamps.

Reaction flasks may be supplied in other capacities and/or with other fitments to suit the individual requirements. Please contact us with your requirements.

These are cylindrical flasks with a partially flattened bottom for a magnetic stirrer bar.This type of flask may be immersed in a container of liquid ice slush, etc. for low/constant temperature irradiations.

                  

Standard Flasks 400ml and below

Are provided with one angle socket (10/19) and one vertical socket (14/23).  PTFE tubing for gaseous agitation may be led through the 10/19 socket. Accessories such as gas entry tube, maybe supplied. Prices on request email your requirements to martin@photochemicalreactors.co.uk

Larger Capacity Standard Flasks

The 1000ml and 2000ml flasks are fitted with:

• B70 centre socket to house large quartz immersion well Model 3230
• Vertical socket joint B19/26 to fit condenser
• SQ18 screw thread fitting for nitrogen gas mixing of the reactant liquid
• Angle socket joint B14/23 for the insertion of a thermometer or resistance probe

Both flasks are supplied complete with accessories: screw-thread fittings and gas-entry tube.  Extended cone for thermometer or temperature measurement probe.

Gas Inlet and Flow Through Flasks

              

Gas Inlet Flask

These are similar to the standard flasks but have a sintered glass disc (medium porosity) fitted to the bottom of the flask to permit gas agitation and allow the reaction mixture to be kept under an inert or reactive atmosphere.

A glass-PTFE stopcock is attached at the bottom.

Flow Through Flask

This type of flask is provided with two vertical sockets (14/23 and 10/19) and upper exit tube fitted with glass-PTFE stopcock.

Two tubes are fitted at the base, one with a sintered glass disc (medium porosity) and glass-PTFE stopcock to permit gas agitation and allow the reaction mixture to be kept under an inert or reactive atmosphere and one fitted with glass-PTFE stopcock for use as a liquid entrance tube and drain tube.

Options

Reflux Condenser

A Davies double-surface reflux condenser, overall length 275mm with 14/23 cone joint, prevents “reactant creep” and loss of vapour when low boiling point liquids are used.  This will fit all types of reaction flasks, excluding 1000 and 2000ml capacities.

Immersion Well Reactor Components

The following lists describe a number of reactor components, the combination included in each model having proved effective since the models RQ125 and RQ400 were introduced in 1976.