Effect of Organic and Mineral Soil Fractions on Sorption Behaviour of Chlorophenol and Triazine Micropollutants

• Published in: Arhiv za higijenu rada i toksikologiju Vol. 60; no. 1; pp. 43 - 52
• Main Authors: Stipičević, Sanja, Fingler, Sanja, Drevenkar, Vlasta
• Format: Journal Article
• Language: English; Croatian
• Published: Croatia Versita 01.03.2009; Institute for Medical Research and Occupational Health
• Subjects: Adsorption; ametrin; ametryn; atraton; atratone; atrazin; atrazine; chlorophenolate anions; Chlorophenols - chemistry; didealkilirani atrazin; didealkylated atrazine; Freundlich isotherm; Freundlichova izoterma; Herbicides - chemistry; hidroksiatrazin; humic acid; huminska kiselina; Hydrophobic and Hydrophilic Interactions; hydroxyatrazine; klorfenolatni anioni; mineral surface; mineralna površina; Minerals - analysis; organic matter; organska tvar; Pesticides - chemistry; Soil - analysis; Soil Pollutants - chemistry; Soil Pollutants - isolation & purification; Triazines - chemistry
• ISSN: 0004-1254; 1848-6312; 0004-1254
• DOI: 10.2478/10004-1254-60-2009-1898

This article compares the sorption behaviour of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, chlorotriazine atrazine, methylthiotriazine ametryn, methoxytriazine atratone, hydroxyatrazine, and didelakylated atrazine in a topsoil and an aquifer sediment before and after removal of sorbent organic matter and in humic acid. Freundlich isotherm coefficients Kf and 1/n and free energy change (δG°) were calculated for all compounds in all sorbents. According to sorbent pH values, chlorophenolate anions and uncharged triazine species dominated in all sorption experiments with topsoil and aquifer sediment. In experiments with humic acid, chlorophenols, atrazine, and didealkylated atrazine existed almost completely as neutral species, whereas protonated species dominated for hydroxyatrazine, atratone, and ametryn. In addition to a hydrophobic partition, sorption of all compounds in native soil and sediment sorbents includes specific, more polar interactions, which greatly depend on sorbate acidity/basicity, specific properties of the sorbent organic matter and of mineral surface, as well as on the system pH. A significantly greater sorption intensity of all compounds in "organic-free" than in the native aquifer sediment confirmed the importance and possible dominance of mineral surface in the sorption process. Sorption intensity of chlorophenol and triazine compounds in humic acid was closely related to compound hydrophobicity. Greater sorption of almost completely protonated hydroxyatrazine than of the more hydropohobic but uncharged atrazine indicated different humic acid reaction sites for two compounds and consequently different sorption mechanisms. Uspoređena je sorpcija 2,4,6-triklorfenola, 2,3,4,6-tetraklorfenola i pentaklorfenola te različito supstituiranih triazinskih spojeva - klortriazina atrazina, metiltiotriazina ametrina, metoksitriazina atratona i razgradnih produkata atrazina hidroksiatrazina i didealkiliranog atrazina — u površinskom tlu i sedimentu vodonosnika prije i nakon uklanjanja organske tvari te u huminskoj kiselini. Izračunani su koeficijenti Freundlichove izoterme Kf i 1/n te izmjena slobodne energije (δG°) za sve spojeve i sorbense. U skladu s pH-vrijednostima sorbensa u svim su sorpcijskim pokusima s nativnim tlom i sedimentom prevladavali klorfenolatni anioni i neutralni triazinski spojevi. U pokusima s huminskom kiselinom klorfenoli, atrazin i didealkilirani atrazin postojali su kao neutralne vrste, dok su hidroksiatrazin, atraton i ametrin bili većim dijelom protonirani. Sorpcija svih spojeva u prirodnom tlu i sedimentu uključuje uz hidrofobnu particiju i specifične polarnije interakcije ovisne o kiselosti/bazičnosti sorbata, specifičnim svojstvima organske tvari i mineralne površine sorbensa te o pH-vrijednosti sustava. Intenzitet sorpcije svih spojeva u sedimentu iz kojeg je uklonjena organska tvar bio je značajno veći od sorpcije u prirodnom sedimentu, što potvrđuje važnost i moguću dominantnu ulogu mineralne površine u sorpcijskom procesu. Intenzitet sorpcije klorfenola te klortriazina, metiltiotriazina i metoksitriazina u huminskoj kiselini korelirao je s hidrofobnosti spojeva. Veća sorpcija gotovo potpuno protoniranog hidroksiatrazina od hidrofobnijeg, ali neutralnog atrazina upućuje na različita reakcijska mjesta za ova dva spoja, a time i na različite mehanizme sorpcije u huminskoj kiselini.