INTERACTION OF HUMIC SUBSTANCES WITH BIPYRIDYLIUM HERBICIDES

Abstract

The binding or complexing of diquat (1,1-ethylene-2,2-bipyridylium dibromide) and paraquat (1-1′-dimethyl-4-4′-bipyridylium dichloride) by humic acid and fulvic acid has been studied by the gel filtration technique. Paraquat was complexed by humic compounds in greater amounts than was diquat, but the amounts of the two herbicides complexed by humic acid were higher than those complexed by fulvic acid. By infrared spectroscopic technique, evidence is presented for the formation of charge–transfer complexes between diquat or paraquat and humic compounds. The complexing of bipyridylium herbicides by humic substances should be of interest to those concerned with environmental problems.