Association of Triorganotin Compounds with Dissolved Humic Acids

Abstract

Sorption to dissolved organic matter (DOM) may influence significantly the fate and the effects of organic pollutants in the aquatic environment. To date, most studies on DOMwater partitioning have focused on neutral hydrophobic compounds. Very little is known on the binding of hydrophobic organic cations to DOM. In this study, the association of triorganotin compounds (TOTs) with dissolved Aldrich and Suwannee River humic acids has been systematically investigated as a function of pH and sodium perchlorate concentration. The organotin compounds studied include the two widely used biocides tributyltin (TBT) and triphenyltin (TPT) as well as other trialkyltin compounds of various hydrophobicities. Between pH 3 and pH 9, for both TBT and TPT, the overall DOM-water distribution ratio (D DOM ) was strongly pH-dependent and exhibited a maximum close to the acidity constant (pK a ) of the compounds. The observed pH dependence of D DOM could be described successfully with a semiempirical discrete log K spectrum model. It was found that, over the whole pH range investigated, sorption was governed by complexation of the corresponding TOT cation (TOT + ) by negatively charged ligands (i.e., carboxylate and phenolate groups) of the humic acids. The determining factors of the TOT + binding are postulated to be (i) complex formation between the tin atom and the deprotonated ligands and (ii) hydrophobic interactions. Significant differences in D DOM of TBT were observed between Suwannee River and Aldrich humic acid. D DOM values of TOTs determined for Aldrich humic acid were in the same range as particulate organic matter-water distribution ratios reported in the literature for soils and sediments.

Ultraviolet degradation of methyltins: Elucidating the mechanism by identification of a detected new intermediary product and investigating the kinetics at various environmental conditions

“…First, methyltins can reacts with humic acid to form polymeric species (Omar and Bowen, 1982) as humic acid, a ubiquitous class of electrolytes, can form the complexes with organotin compounds in natural waters through chelation and hydrogen bonding (Oloughlin et al, 2000;Giacalone et al, 2006), which influence strongly the degradation rates of methyltins. For example, Arnold et al (1998) found that triorganotin cation can form the complexes with negatively charged ligands (i.e., carboxylate and phenolate groups) of the humic acids over the pH range 5.7-9.3. Second, humic acid and its UV degradation products (Garbin et al, 2007) can bind with free radicals and thus function as a powerful free radical scavenger.…”

Evaluating the impacts of some environmentally relevant factors on the availability of bisphenol A with negligible-depletion SPME

“…Schwarzenbach and co-workers investigated the partition in liposome-water system of a series of substituted phenols and anilines with pH dependent results (Escher and Schwarzenbach, 1996;Escher et al, 2002) and Arnold et al also found that the association of triorganotin compounds with dissolved humic acids was strongly pH dependent (Arnold et al, 1998). A few studies on the association of chlorophenols with various DOM were reported.…”

Comparative Study of Tributyltin Adsorption onto Mesoporous Silica Functionalized with Calix[4]arene, p-tert-Butylcalix[4]arene and p-Sulfonatocalix[4]arene

“…Adsorption using sorbents is among the widely employed methods to remove pollutants. Systematic examinations of the adsorption of TBT on various absorbents like natural sediments [11][12][13], pure minerals [14,15], organic matters [16] and black carbons [13,17] have been carried out.…”