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Particle oxidation model of synthetic FeS and sediment acid‐volatile sulfide
Author(s) -
Di Toro Dominic M.,
Mahony John D.,
Gonzalez Adrian M.
Publication year - 1996
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620151211
Subject(s) - ionic strength , particle (ecology) , chemistry , dispersity , reaction rate constant , particle size , sulfide , reaction rate , oxygen , kinetics , ionic bonding , inorganic chemistry , ion , organic chemistry , catalysis , geology , oceanography , physics , quantum mechanics , aqueous solution
Abstract A model is proposed for the kinetics of the oxidation of acid‐volatile sulfide (AVS). It is based on a surface oxidation reaction that erodes the particle surface until the particle disappears. A monodisperse particle size distribution is assumed with a reaction rate that is proportional to the surface area remaining and a dimensional exponent that relates the surface area to the particle volume. The model is fit to time course data from a number of experiments conducted using synthetic FeS at various pHs, oxygen concentrations, and ionic strengths. The reaction rate constants are modeled using a surface complexation model. It is based upon the formation of two activated surface complexes with molecular oxygen, one of which is charged. The complexation model provides a good fit to the variation of the reaction rate constant with respect to O 2 , pH, temperature, and ionic strength. The dimensional exponent v increases with pH from values characteristic of plates and needles to values reflecting more spherical particles, presumably due to coagulation. However the increase in v with respect to O 2 at high concentrations is unexplained.