TREATMENT OF 1,2-DIBROMO-3-CHLOROPROPANE AND NITRATE-CONTAMINATED WATER WITH ZERO-VALENT IRON OR HYDROGEN PALLADIUM CATALYSTS/

The abilities of zero-valent iron powder and hydrogen with a palladium catalyst (H-2/Pd-alumina) to hydrodehalogenate 1,2-dibromo-3-chloropr opane (DBCP) to propane under water treatment conditions (ambient temp erature and circumneutral pH) were compared. DBCP reacted with iron po wder (100-200 mesh, 36 g/l) in HERES-buffered water (pH = 7.0) with a tin of 2.5 min and in different groundwaters (pH = 8.2-8.7) with a t(1 /2) ranging from 41-77 min. Dissolved O-2 and NO3- slowed the transfor mation, whereas sulfate and nitrite had little effect. Iron removed 60 mg/l of nitrate within 14 min with nitrite as an intermediate. In 75 mi groundwater containing 22.5 mg 1% Pd-alumina catalyst under 10% H-2 partial pressure, DBCP was transformed to propane within minutes. The rate in groundwater was slower by about 30% compared to Milli-Q(tm) w ater. SO42-, NO3-, Cl- or O-2 added to Milli-Q water only slightly inh ibited DBCP transformation by H-2/Pd-alumina, while SO32- had a much s tronger inhibitory affect. Copyright (C) 1996 Elsevier Science Ltd