Sorption Kinetics of 2,4-D and Diuron Herbicides in a Urea-Fertilized Andisol

Abstract

Sorption kinetics studies of herbicides, using different models, are an important tool for determining the mechanisms and kinetic parameters that explain the bioavailability and environmental behavior of these compounds. However, little is known about the combined effects of fertilizers and herbicides and how it could modify these processes on the soil. The aim of this study was to evaluate the sorption kinetics of diuron and 2,4-D in an Andisol treated with urea using various kinetic models. The experiments were carried out in batch, independently for each herbicide, with urea application in an equivalent dose of 200 kg N ha −1 and artificial pH modifications. The results showed no differences in sorption kinetics due to urea for diuron; however 2,4-D showed differences with urea and changes in pH conditions. The data fitted well with the pseudo-second-order model (R 2 > 0.996), showing a maximum soil adsorption capacity of 11.9, 10.8, and 9.61 mg kg −1 for diuron, 2,4-D, and 2,4-D-urea, respectively. The initial adsorption rate was similar for both herbicides, but a significant increase in the rate constant was observed for 2,4-D at acid pH. We conclude from the Elovich and Weber-Morris models that both herbicides were adsorbed mainly during the first stage, followed by lower adsorption in the slower second stage. According to these models, mass transfer across the boundary layer, and to a lesser degree intraparticle diffusion mechanisms, controlled sorption kinetics for both herbicides. The results suggest that urea application could influence sorption process of acid herbicides for pH changes in soils.

Gene-Centric Model Approaches for Accurate Prediction of Pesticide Biodegradation in Soils

“…Despite being relatively low leverage and low identifiable, sorption parameters ( K FP and n FP ) were not considered for reduction due to the importance of sorption of pesticide in soil . Moreover, these two parameters could be directly measured through sorption kinetic experiments − (not performed in the current work). Additionally, the analysis suggests that parameter a CO 2 can be eliminated due to its low impact on model outputs.…”

Adsorption of Phenoxyacetic Herbicides from Water on Carbonaceous and Non-Carbonaceous Adsorbents

“…The fate and transport of the phenoxy herbicides (adsorption/desorption) in the subsurface are affected by a complex, time-dependent interplay between adsorption and mineralization processes, which are influenced by both the water and organic matter content of the soil as well as its pH. Research on the adsorption of phenoxyacetic acids concerned soils with different degrees of mineralization, different contents of organic materials, different geological origins, and different locations [ 50 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 ]. The problem of adsorption and transport of herbicides in the soil has been recently very carefully described and discussed in the review by Paszko et al [ 153 ].…”

Nanocellulose–organic montmorillonite nanocomposite adsorbent for diuron removal from aqueous solution: optimization using response surface methodology

“…At low concentrations, it presents the characteristics of the Freundlich isotherm. 59 The Sips isothermal adsorption model showed that the maximum adsorption capacity of diuron was 69.04 mg g À1 . The R 2 values of the three isotherm models are greater than 0.90, which indicates that they are applicable for explaining the adsorption mechanism.…”