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Reactor for photo-electrochemical studies
MICROCHEMICAL
JOURNAL
Reactor
20, 113-114
(1975)
for Photo-Electrochemical
Studies
The equipment shown in Fig. 1 has been useful in studying the effect of ultraviolet radiation on the redox potential displayed by ferriin solutions (tris- 1, I 0-phenanthroline iron( I I I) blue complex). The sample is maintained at the desired temperature in a waterjacketed reaction kettle (Kontes Glass K296 1 10) fitted with a dense polyethylene lid machined on the pattern of the Leeds and Northrup coulometric analyzer cell lid (0675 13) and bored to suit the parts to be fitted. This is conveniently held in place by the same clamp which secures the standard reaction kettle head. The quartz finger for the lamp leaves enough room for operating a magnetic stirring bar beneath it. The glass sleeve supporting the uv lamp bears a sidearm with a septum socket through which cooling air for the lamp is introduced using a length of Teflon tubing extending down into the quartz finger, and a second sidearm through which the coolant escapes. The length of this sleeve is determined by the dimensions of the lamp. The uv lamp itself (Ultraviolet Products Inc.. Model PCQ) is silvered on all surfaces within the standard taper joint at the top. It is proposed to extend this silvering along the lamp to the top of the reaction kettle to minimize the irritating glare of the lamp (even though the glass sleeve is screening much of the harmful radiation) and possibly by internal reflections to direct some more of the light into contact with the solution being studied. Appropriate holes bored in the kettle lid admit the stem of a platinum gauze electrode X-mm diameter X 35mm cylinder length, which is arranged to surround the quartz finger at a distance of about 3 mm. The reference electrode is prepared in a Hildebrand half-cell vessel modified by replacing the tip by a male Lucr joint which engages the Teflon syringe needle shown. This needle thus serves as a Luggin capillary. It has been found that if the bore of the needle is distorted at the end by some such procedure as cutting off a short bit with not too sharp scissors, a plug of agar gel can be retained easily in the last few millimeters of the needle tubing. The cell has been used to prepare ferriin by electrolytic oxidation of ferroin (the corresponding iron red complex) either by replacing the 313 Copyright c 1975 by Academic Press. Inc. All rights of reproduction in any form reserved.
314
ATKINSON
FIG. 1. Reactor Assembly. K, reaction kettle: Q, quartz finger: H, polyethylene lid; C. coolant inlet; L, ultraviolet lamp; E, platinum electrode (cylindrical gauze): P, port ttypical) in lid; R, Teflon syringe needle for reference electrode.
quartz finger by a fritted glass sealing tube containing the counter-electrode, or by leaving the lamp in place and inserting a micro-scale gas dispersing tube (Ace Glass 9435C) on the end of a length of amber gum rubber tubing leading to a separate counter-electrode chamber. The apparatus conveniently holds 50 to 75 cm3 of sample, and is thus suited to small-scale preparations as well as studies of samples prepared in other equipment. ACKNOWLEDGMENTS The financial support of the National Research Council of Canada, and the technical assistance of Miss Dorothy McCulloch is gratefully acknowledged.
JOURNAL
Reactor
20, 113-114
(1975)
for Photo-Electrochemical
Studies
The equipment shown in Fig. 1 has been useful in studying the effect of ultraviolet radiation on the redox potential displayed by ferriin solutions (tris- 1, I 0-phenanthroline iron( I I I) blue complex). The sample is maintained at the desired temperature in a waterjacketed reaction kettle (Kontes Glass K296 1 10) fitted with a dense polyethylene lid machined on the pattern of the Leeds and Northrup coulometric analyzer cell lid (0675 13) and bored to suit the parts to be fitted. This is conveniently held in place by the same clamp which secures the standard reaction kettle head. The quartz finger for the lamp leaves enough room for operating a magnetic stirring bar beneath it. The glass sleeve supporting the uv lamp bears a sidearm with a septum socket through which cooling air for the lamp is introduced using a length of Teflon tubing extending down into the quartz finger, and a second sidearm through which the coolant escapes. The length of this sleeve is determined by the dimensions of the lamp. The uv lamp itself (Ultraviolet Products Inc.. Model PCQ) is silvered on all surfaces within the standard taper joint at the top. It is proposed to extend this silvering along the lamp to the top of the reaction kettle to minimize the irritating glare of the lamp (even though the glass sleeve is screening much of the harmful radiation) and possibly by internal reflections to direct some more of the light into contact with the solution being studied. Appropriate holes bored in the kettle lid admit the stem of a platinum gauze electrode X-mm diameter X 35mm cylinder length, which is arranged to surround the quartz finger at a distance of about 3 mm. The reference electrode is prepared in a Hildebrand half-cell vessel modified by replacing the tip by a male Lucr joint which engages the Teflon syringe needle shown. This needle thus serves as a Luggin capillary. It has been found that if the bore of the needle is distorted at the end by some such procedure as cutting off a short bit with not too sharp scissors, a plug of agar gel can be retained easily in the last few millimeters of the needle tubing. The cell has been used to prepare ferriin by electrolytic oxidation of ferroin (the corresponding iron red complex) either by replacing the 313 Copyright c 1975 by Academic Press. Inc. All rights of reproduction in any form reserved.
314
ATKINSON
FIG. 1. Reactor Assembly. K, reaction kettle: Q, quartz finger: H, polyethylene lid; C. coolant inlet; L, ultraviolet lamp; E, platinum electrode (cylindrical gauze): P, port ttypical) in lid; R, Teflon syringe needle for reference electrode.
quartz finger by a fritted glass sealing tube containing the counter-electrode, or by leaving the lamp in place and inserting a micro-scale gas dispersing tube (Ace Glass 9435C) on the end of a length of amber gum rubber tubing leading to a separate counter-electrode chamber. The apparatus conveniently holds 50 to 75 cm3 of sample, and is thus suited to small-scale preparations as well as studies of samples prepared in other equipment. ACKNOWLEDGMENTS The financial support of the National Research Council of Canada, and the technical assistance of Miss Dorothy McCulloch is gratefully acknowledged.