Cm. Miller et Rl. Valentine, OXIDATION BEHAVIOR OF AQUEOUS CONTAMINANTS IN THE PRESENCE OF HYDROGEN-PEROXIDE AND FILTER MEDIA, Journal of hazardous materials, 41(1), 1995, pp. 105-116
Hydrogen peroxide has been used as an oxidant to degrade contaminants
in solutions and soils. A poor understanding of the numerous variables
that are involved makes it difficult to determine dominant contaminan
t removal mechanisms. Our primary objective was to examine the relatio
nship between contaminant (quinoline and nitrobenzene) degradation rat
e and the rate of hydrogen peroxide decomposition on filter media. Bot
h batch and continuous flow column experiments were conducted. In gene
ral, the rate of contaminant degradation was proportional to the rate
of hydrogen peroxide decomposition, but the mass of contaminant remove
d depended on the amount of hydrogen peroxide decomposed, filter mediu
m concentration, and filter medium characteristics. For increasing fil
ter medium concentration and equivalent loss of hydrogen peroxide, the
mass of contaminant degraded was found to decrease. In addition, acid
-hydroxylamine treatment of the selected filter medium, to examine the
role of reducible metal oxide coatings, resulted in greater contamina
nt removals than the parent material despite a slower hydrogen peroxid
e decomposition rate. The observed hydrogen peroxide decomposition and
contaminant oxidation results are consistent with a reaction scheme w
hose central elements include: (1) a rate limiting filter medium surfa
ce catalyzed reaction initiating hydrogen peroxide decomposition with
the formation of a reactive intermediate, (2) a competing reaction of
the intermediate with the filter medium surface, and (3) reaction of t
he same intermediate with the aqueous organic contaminant. Loss of qui
noline and nitrobenzene is most likely a solution phase reaction becau
se sorption of these compounds was small over the pH range 7-8 and oxi
dation efficiency did not increase with increasing filter medium conce
ntration, which would be expected if the reactions were occurring on t
he surface. Finally, enhanced oxidation of quinoline and nitrobenzene
on the treated material is explained by more efficient use of the reac
tive intermediates for contaminant oxidation due to a reduction in the
number of scavenging sites associated with reducible metal oxide coat
ings.