Sorption and leaching of diuron on natural and peat-amended calcareous soil from Spain
ABSTRACT The sorption and leaching processes of diuron from a 0.02 M CaCl2 aqueous solution at 25°C, by a calcareous soil from the Southeastern of Spain after organic carbon (OC) amendment with a commercial peat (from 0.18% to 4.61%) have been studied by using batch and soil column experiments. The experimental sorption isotherms may be classified as L type of the Giles classification which suggests, in general, a moderate affinity of the diuron molecules by the active sites of the adsorbents. Nevertheless, according to the slope of the initial portion of these isotherms, the affinity increases as the organic matter content increases. In order to calculate the adsorption capacity (Kf) of the samples for the herbicide diuron, the experimental data point were fitted to the Freundlich equation. The Kf values ranged between 2.17 mg kg−1 for the original soil (containing 0.18% OC) and 34.28 mg kg−1 for the peat-amended sample containing 4.61% OC. The breakthrough curves and distribution of diuron along the soil profile, obtained from the step-function type and pulse type experiments by using the soil column studies, indicate that the amount of diuron retained range from 359.3 mg kg−1 for the column filled with the original soil to 439 mg kg−1 for that filled with the peat-amended soil containing 4.61% OC. The amount of diuron desorbed (373.0 mg kg−1) from the soil containing the higher percentage of organic carbon (4.61%) was greater than that desorbed (300.8 mg kg−1) from the original soil, which might be due to the joining of diuron to the soluble fraction of the organic matter moving through the column.
Conference Paper: Effect of an organic residue on herbicide field dissipation[Show abstract] [Hide abstract]
ABSTRACT: The aim of this work was to study the effect of the application of a solid waste from olive oil production (alperujo) on the movement and persistence of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea]. The application of alperujo, fresh or composted, to the land has been shown to be an extremely effective contribution to increasing crop yields and to maintaining or improving soil fertility. An experimental olive grove located in Mengibar (Jaen, Spain) was divided into two plots: 1. Plot without organic amendment (blank) and 2. Plot treated with alperujo during 3 years at a rate of 17920 kg of alperujo ha-1. Diuron was applied to both plots at a rate of 2 kg ha-1a.i. Triplicates from each plot were sampled at three depths (0-10, 10-20 and 20-30 cm), air-dried, remains of olive leaves, grass roots, and stones removed and sieved through a 5 mm mesh sieve. Diuron was extracted with methanol 1:2 weight:volume ratio, the extracts were evaporated to dryness, resuspended in 2 mL of methanol, filtered and analyzed by HPLC. Higher amounts of diuron were detected at each sampling depth in plots treated with alperujo. The increase in soil organic matter content upon amendment with alperujo slightly increased sorption, suggesting that other factors beside sorption affect diuron degradation rate in organic amended soils. Keywords: olive oil production waste, diuron, soil, dissipation, field study. 1 Introduction Soil amendment with olive oil mill wastes increases soil organic matter affecting soil physico-chemical and biological environments and, consequently, affecting immobilization and degradation of herbicides. The increase in soil organic matter can increase sorption potential and reduce pesticide contamination of ground water [1, 2]. Under controlled laboratory conditions, an increase inWASTE MANAGEMENT 2008; 05/2008
[Show abstract] [Hide abstract]
ABSTRACT: The purpose of the study was to determine the process of adsorption and desorption of carbofuran at two different temperatures in two different types of Malaysian soils. The two types of soil used in this study were clay (high organic carbon content) and sandy clay (low organic carbon content). The recovery rates of carbofuran from sandy clay and clay soils were 98.7 and 76.1% respectively. The adsorption of carbofuran onto the soil corresponded well with the Freundlich isotherm. The results showed that adsorption of carbofuran decreases with increase in temperature at low initial concentration (10 µg). However, at higher initial concentrations (eg 50 µg), the influence of temperature on adsorption is not significant. The results show that the percentage adsorption of carbofuran is higher in clay than in sandy clay soils. The percentage carbofuran desorbed into the aqueous phase ranged from 57.4% to 89.8% in sandy clay and 51.7% to 75.9% in clay. The results clearly showed that carbofuran molecules were bound weakly to clay and sandy clay soils
[Show abstract] [Hide abstract]
ABSTRACT: Diuron sorption kinetic was studied in Andisols, Inceptisol and Ultisols soils in view of their distinctive physical and chemical properties: acidic pH and variable surface charge. Two types of kinetic models were used to fit the experimental dates: those that allow to establish principal kinetic parameters and modeling of sorption process (pseudo-first-order, pseudo-second-order), and some ones frequently used to describe solute transport mechanisms of organic compounds on different sorbents intended for remediation purposes (Elovich equation, intraparticle diffusion, Boyd, and two-site nonequilibrium models). The best fit was obtained with the pseudo-second-order model. The rate constant and the initial rate constant values obtained through this model demonstrated the behavior of Diuron in each soil, in Andisols were observed the highest values for both parameters. The application of the models to describe solute transport mechanisms allowed establishing that in all soils the mass transfer controls the sorption kinetic across the boundary layer and intraparticle diffusion into macropores and micropores. The slowest sorption rate was observed on Ultisols, behavior which must be taken into account when the leaching potential of Diuron is considered.Journal of hazardous materials 08/2013; 261C:602-613. DOI:10.1016/j.jhazmat.2013.07.073 · 4.33 Impact Factor