Multicomponent Adsorption of Pesticides onto Activated Carbon Fibers

Abstract

The adsorption equilibria of pesticides and metabolites (atrazine, deethylatrazine, deisopropylatrazine and simazine) are studied onto activated carbon fibers -ACF-with a broad pore size distribution (32% mesopore volume, 68% micropore volume). Mono-and multi-component isotherms have been determined for low concentrations, from 0.23 × 10 −6 to 9.52 × 10 −6 mol L −1 . Single solute isotherms, modeled by Freundlich and Langmuir models, tend to prove the influence of the adsorbate's solubility in the adsorption capacity of activated carbon fibers. Binary solute isotherms confirm the strong influence of pesticide solubility on the competitive adsorption mechanism: the competition is higher in the case of adsorbates of different solubilities (atrazine and DEA or DIA for example). Multicomponent experimental data were modeled by extended Langmuir-based equations and the Ideal Adsorbed Solution theory. Whereas the first ones failed to model accurately binary adsorption due to restrictive hypothesis, the IAS model showed a good agreement between experimental and predicted data. It emphasised also the difficulty in satisfying the hypothesis of the model in the case of highly adsorbed compounds. Finally, the simultaneous adsorption of atrazine and NOM (in a natural water, DOC = 18.2 mg L −1 ) shows no adsorption competition effects between natural organic matter and atrazine. This is due to the presence of secondary micropores (0.8-2 nm) and mesopores in the ACF, which limit a pore blockage phenomenon by NOM.

Adsorption of atrazine on hemp stem-based activated carbons with different surface chemistry

“…Comparing the correlation coefficients of the three equations indicates that the equilibrium experimental data for HAC and HAC N 2 are best fitted by the Langmuir-Freundlich equation, while atrazine adsorption onto HAC HNO 3 and HAC NH 3 is described by the Langmuir equation. Langmuir monolayer adsorption was also reported for atrazine adsorption onto activated carbon prepared from rubber tire waste (Gupta et al 2011) and commercial activated carbon fibers (Faur et al 2005). However, in most reports the sorption isotherms of atrazine for various adsorbents were best fitted by the Freundlich model (Kovaios et al 2006;Tang et al 2012;Labeau et al 1999).…”

Detoxification of pesticide waste via activated carbon adsorption process

“…In the case of a binary or multi-components system, adsorption capacities of each individual pesticide were noted proportionally less with another, indicating the existence of competition for available sites, with non-equal adversary to the heterogeneity of carbon surface. Accordingly, pesticide with the greatest ionic potential saturation value may effectively occupy most of the active sites hindering further adsorption of other pesticides by possessing a lower affinity [51].…”

Competition of Reactive red 4, Reactive orange 16 and Basic blue 3 during biosorption of Reactive blue 4 by polysulfone-immobilized Corynebacterium glutamicum

“…However, single component isotherm data revealed that PIPC showed good biosorption capacity towards all three reactive dyes. Therefore direct sites competition may be the predominant competition mechanism [22], with all reactive dyes competing with each other in occupying the same amine group.…”