RESEARCH NOTE: Ozone Degradation Of Selected Non-Agricultural Herbicides

Abstract

This research note investigates the efficiency of ozone for the degradation of threeherbicides,imazapyr[2-I4-isopropyl-4-methyI-Soxo-2-imidazolin-2-yll-nicotinic acidl, triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acidl and diuron [3-(3,4-dichlorophenyll-1,l-dimethylurea under controlled laboratory conditions. Experiments were conducted at pH 7.5, in a bubble contactor column, with a raw lowland surface water spiked with initial active ingredient concentrations of 2 pgl". The ozone doses applied and consumed were 4.79 and 2.9 mg 4L", respectively, and resulted in removals of 53%, 48% and 90% of imazapyr, triclopyr and diuron, respectively.

Physicochemical processes

“…Byproducts formed included deethylatrazine and deisopropylatrazine. Lambert et al ( 1993) observed removals of 53, 48, and 90% for the herbicides imazapyr, triclopyr, and diuron, respectively, at pH 7.5 and an ozone dose of 4.8 mg/L, For ozonation of process streams, Beulker and Jekel ( 1993a and b) observed that ozonation of pulp mill eflluents at pH 2 reduced COD, DOC, and color, whereas ozonation at alkaline pH caused an increase in color. The color increase was thought to be due to the polymerization of organics.…”

Catalytic efficiency and stability of cobalt hydroxide for decomposition of ozone and p-chloronitrobenzene in water

“…Ozone has recently received much attention in water treatment technology, due to its high capacity for oxidation and disinfection. The ozonation process is a proven technology for 2 removing various types of environmental pollutants, such as dyes, herbicides and other pesticides in aqueous solution [1][2][3]. It is well known that the reaction of ozone with organic substrates follows two reaction mechanisms [4]: (1) molecular ozone oxidation (direct reaction), and (2) free radical oxidation (indirect reaction).…”