Radiation chemistry of aqueous solutions of dicyandiamide. [Gamma radiation or pulsed electron beam]

Journal Article · Thu Jan 25 04:00:00 EST 1979 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100465a003· OSTI ID:6281019

Draganic, Z D; Draganic, I G; Sehested, K

Oxygen-free aqueous solutions of dicyandiamide, DCDA, were exposed to /sup 60/Co ..gamma.. rays or a pulsed 10-MeV electron beam. Fast kinetic spectrophotometry was used for the study of free-radical intermediates, and computer simulation of the reaction mechanism for evaluation of experimental data. The hydrated electron reacts by addition, k(e/sub aq//sup -/ + DCDA) = 1.1 x 10/sup 10/M/sup -1/s/sup -1/; the anion radical (NH/sub 2/C(=NH)NHCN)/sup -/ absorbs in the UV region with lambda/sub max/<255nm and an epsilon (255) of 1150 M/sup -1/cm/sup -1/. It disappears with 2k = 1 x 10/sup 9/M/sup -1/s/sup -1/ by forming a product which absorbs with lambda/sub max/<255nm and an epsilon (255) of 2400 M/sup -1/cm/sup -1/. The hydrogen atom also reacts by addition, k(H + DCDA) = 2.7 x 10/sup 6/ M/sup -1/s/sup -1/, and the radical intermediate has a lambda/sub max/ of 350nm and an epsilon (350) of 1250 M/sup -1/cm/sup -1/; it disappears with 2k greater than or equal to 10/sup 9/M/sup -1/s/sup -1/. Hydroxyl radicals react both by addition and by abstraction, k(OH + DCDA) = 5.6 x 10/sup 6/M/sup -1/s/sup -1/, and two transients with lambda/sub max/ at 450 and 355nm appear. It is estimated that about 90% of OH radicals react by abstraction. It has also been found that the radical-anion SO/sub 4//sup -/ reacts efficiently with DCDA and the product of this reaction, NH/sub 2//sup +/C(=O)NHCN, absorbs light with a lambda/sub max/ of 355nm and epsilon (355) of 1150 M/sup -1/cm/sup -1/. The OH adduct of DCDA has a lambda/sub max/ of 450nm and epsilon (450) of 1700 M/sup -1/cm/sup -1/; it disappears by a second-order process with 2k less than or equal to 4 x 10/sup 9/M/sup -1/s/sup -1/. The search for stable radiolytic products in the kilorad-megarad dose range has shown the presence of only a few smaller molecules and in low yields.

• Research Organization: Boris Kidric Inst. of Nuclear Sciences, Beograd, Yugoslavia
• OSTI ID: 6281019
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:2; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
ANIONS
AQUEOUS SOLUTIONS
BEAMS
CARBONIC ACID DERIVATIVES
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
CYANAMIDES
DATA
DATA FORMS
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
GAMMA RADIATION
GRAPHS
HYDRATION
HYDROXYL RADICALS
INFORMATION
IONIZING RADIATIONS
IONS
ISOLATED VALUES
KINETICS
LEPTON BEAMS
LEPTONS
MIXTURES
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARTICLE BEAMS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOLYSIS
REACTION INTERMEDIATES
REACTION KINETICS
SOLUTIONS
SOLVATED ELECTRONS
SOLVATION
SPECTRA
SPECTROPHOTOMETRY