Adsorption ofs-Triazines by Soil Organic Matter

Abstract

The adsorption of sevens-triazines from aqueous solutions by organic soil colloids was determined at pH levels from 1.0 to 5.2. Maximum adsorption occurred at pH levels in the vicinity of the pKAvalues of the respective compounds. The amounts adsorbed were dependent upon the molecular structures of the compounds and the pH of the suspension and were, in order of decreasing adsorption, as follows: 2-methoxy-4,6-bis(diethylamino)-s-triazine (hereafter referred to as tetraetatone) = 2,4-bis(isopropylamino)-6-methylmercapto-s-triazine (prometryne) = 2-hydroxy-4,6-bis(isopropylamino)-s-triazine (hereafter referred to as hydroxypropazine) > 2-methoxy-4-diethylamino-6-ethylamino-s-triazine (hereafter referred to as trietatone) > 2-methoxy-4,6-bis(isopropylamino)-s-triazine (prometone) > 2-methoxy-4,6-bis(ethylamino-s-triazine (simetone) > 2-chloro-4,6-bis(isopropylamino-s-triazine (propazine). Approximately 52% of the prometone adsorbed by the organic matter was desorbed with two extractions of 0.1N NaCl. It was concluded that the adsorption of thes-triazines was due to complexing of the triazine molecules with functional groups on the organic colloids and/or adsorption ofs-triazine cations by ion exchange forces.

Atrazine Adsorption by Some Soil Samples in Relation to Their Constituents

“…Atrazine adsorption is seen to follow the titration curve closely, suggesting that undissociated carboxyl and phenol groups constitute the sites for atrazine adsorption. The importance of carboxyl and phenol groups as adsorption sites for various s-triazines has been pointed out previously (Weber et al, 1969;Hayes, 1970, Stevenson, 1972Adams, 1973;Senesi & Testini, 1982). although Muller-Wegener (1977) found a significant, but negative, correlation between ametryne adsorption and the phenol group content.…”

“…to adsorb atrazine and other striazines has been demonstrated repeatedly (Walker & Crawford, 1%8;Weber et al, 1969;Hayes, 1970;Stevenson, 1972;hluller-Wegener, 1977;Streibig, 1979;Sencsi & Testini, 1982). The results of the present investigation, shown by dots in Fig.…”

Filtration of triazine herbicides by polymer-clay sorbents: Coupling an experimental mechanistic approach with empirical modeling

“…Most studies on atrazine adsorption by soil or soil organic matter (Kovaios et al, 2006;Weber et al, 1969) suggest that hydrophobic partitioning and/or hydrogen bonds are involved.…”

Simple regression models for the qualitative prediction of atrazine and terbuthylazine leaching

“…Considering the negative correlation between adsorption and leachability, this finding appears to confirm the well-documented strong relationship between soil organic matter and adsorption of s-triazine herbicides. Numerous studies have shown that soil organic matter is the most important soil factor as far as atrazine adsorption or bioactivity is concerned (Talbert & Fletchall, 1965;Weber Weed & Ward, 1969;Harrison et at., 1976;Anderson, Stephenson & Corke, 1980;Nel & Reinhardt, 1984;Ehlers, Reinhardt & 1987. In several studies strong links between the mobility of terbuthylazine in soil and the soil organic matter content have Downloaded by [University of Connecticut] at 19:46 11 October 2014 S.…”