Sorption Kinetics and Equilibria of Organic Pesticides in Carbonatic Soils from South Florida

Abstract

A batch reactor was used to determine sorption kinetic parameters (k2, F, and K*) and the equilibrium sorption coefficient (K). The two-site nonequilibrium (TSNE) batch sorption kinetics model was used to calculate the kinetic parameters. Two probe organic pesticides, atrazine [2-chloro-4-ethylamino-6-isopropylamino-s-triazine] and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] were studied using three carbonatic soils from South Florida (Chekika, Perrine, and Krome), one noncarbonatic soil from Iowa (Webster), and one organic soil (Lauderhill) from South Florida. Carbonatic soils contained more than 600 g kg(-1) CaCO3. Sorption is initially very fast up to 3 h and then slowly reaches equilibrium. All soil-chemical combinations reached sorption equilibrium after about 24 h and all sorption isotherms were linear. The sorption kinetics data were well described by the TSNE model for all soil-chemical combinations except for the marl soil data (Perrine-Atrazine), which were better described by the one-site nonequilibrium (OSNE) model. Diuron, with higher K, undergoes slower sorption kinetics than atrazine. The Lauderhill soil containing organic carbon (OC) of 450 g kg(-1) exhibited slowest sorption kinetics for both pesticides. An inverse relationship between k3 and K was observed for atrazine and diuron separately in Chekika, Webster, and Lauderhill soils but not in Perrine and Krome soils. The sorption kinetic parameters were used to distinguish the sorption behavior between atrazine and diuron and to identify differences between soils. Normalizing the sorption coefficient (K) to OC showed that atrazine and diuron had K oc values in carbonatic soils that were a third of reported literature values for noncarbonatic soils. Using existing literature K oc values in solute transport models will most likely underestimate the mobility of atrazine, diuron, and other neutral organic chemicals in carbonatic soils.

Direct and residual effects on diuron behaviour and persistence following two-phase olive mill waste addition to soil: Field and laboratory experiments

“…Indeed, the diuron sorption (k f ) values were highly and significantly (R 2 = 0.991; p b 0.001) correlated with the TOC content. While some workers report significant associations between the K f for diuron and TOC content (Liyanage et al, 2006;Cabrera et al, 2007;Cabrera et al, 2008a,b), other studies have found no such correlation (Oliver et al, 2005;Nkedi-Kizza et al, 2006).…”

Modeling the sorption kinetic of metsulfuron-methyl on Andisols and Ultisols volcanic ash-derived soils: Kinetics parameters and solute transport mechanisms

“…Two-site nonequilibrium model (TSNE) [21]. Among the nonequilibrium processes influencing sorption, the possible division of sorption sites into two types exists.…”

“…Taking into account the scarce or null antecedents into the literature about the kinetic behavior of MSM in soils, especially in volcanic ash-derived soils, and the broad and increasing use of sulfonylurea herbicides in the world's agriculture, this work has been aimed at the application and discussion of two type of kinetic models: those that allow to establish principally kinetic parameters and modeling of sorption process, such as pseudo-first-and pseudosecond-order [18], and some ones frequently used to describe solute transport mechanisms of organic compounds on soils or different sorbents intended for remediation purposes [17,[19][20][21][22]. Such information is necessary for understanding and modeling leaching of target herbicides for preventing potential contamination of water resources.…”

Sorption of Selected Aromatic Substances—Application of Kinetic Concepts and Quantum Mechanical Modeling

“…1 and 2 is analogous to the work by Nkedi-Kizza et al (2006) with the difference that they implemented forward and backward reactions (k +/− ) for the mass transfer reaction in the two-site model, instead of using a transfer rate as in Eq. 2:…”

“…When applying the two-site model with forward and backward reactions, k − corresponds to ω (k + =k − • (1−f)/f, resulting from the kinetic sorption reaction at t=∞), c ∞ to c 0 ·ω/k, and the exponent k 2 /β to k used here (Nkedi-Kizza et al 2006). …”