Physical and chemical studies of chlorophyll in microemulsions. Progress report

Technical Report · Tue Jan 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/6890397· OSTI ID:6890397

Studies designed to provide fundamental information on both the nature of photoreactions in microemulsions and the utility of these media as solvents for absorbers of solar energy were conducted. As a test system, the photoreduction of absorbed dye (principally methyl red) sensitized by chlorophyll a in an anionic mineral oil in water microemulsion was investiged. Using ascorbate as the water soluble reducing agent and pigment concentrations of up to eight per drop (10mM), the reaction exhibits a pseudo zero order dependence on methyl red. The effect of sensitizer, ascorbate concentration and light intensity on the quantum yield was examined, as well as the effect of varying the microemulsion charge type, product catalysis, and the use of synthetic porphyrin sensitizers. In microemulsions containing up to eight chlorophyll molecules per microdroplet, the quantum yield remains constant over five orders of magnitude concentration. The intrinsic quantum yield is independent of droplet surface charge, but is dependent on pH. One of the products of the chemical reduction of methyl red, N, N-dimethyl-p-phenylenediamine (DMPD), increases the limiting quantum yield two to three fold. Synthetic porphyrins have been found to act as sensitizers, and a number of tetrapyridyl porphyrin derivatives containing one to four carbon chains of varying length have been made and examined. The results show that the quantum yield increases with increasing chain length for the monoalkyl compounds, and also indicate the possible involvement of a sensitizer orientation effect. The transport of oil soluble electroactive species in nonionic microemulsions has been found to exhibit percolation behavior, which has potential photogalvanic applications.

• Research Organization: Drexel Univ., Philadelphia, PA (USA). Dept. of Chemistry
• Sponsoring Organization: USDOE
• DOE Contract Number: AS02-77ER04452
• OSTI ID: 6890397
• Report Number(s): DOE/ER/04452-3
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500 -- Photochemistry
AMINO ACIDS
ASCORBIC ACID
AZO COMPOUNDS
AZO DYES
CARBOXYLIC ACIDS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHLOROPHYLL
COLLOIDS
DATA
DISPERSIONS
DYES
EMULSIONS
EQUIPMENT
ESTERS
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INDICATORS
INFORMATION
METHYL RED
MICROEMULSIONS
MINERAL OILS
NUMERICAL DATA
OILS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
REDUCTION
SOLAR ABSORBERS
SOLAR EQUIPMENT
SOLVENTS
SYNTHESIS
VITAMINS
YIELDS