Uptake of Sulfadiazine Sulfonamide from Water by Clinoptilolite

Zhaohui Li,Christie Stockwell,Hanlie Hong,Skylar Minegar,Jacqueline Niles

doi:10.1155/2013/648697

Abstract

The interactions between sulfadiazine (SDZ), a sulfonamide antibiotic, and clinoptilolite, a hydrophilic zeolite, were investigated under batch experimental conditions. The uptake of SDZ on the zeolite followed a linear sorption isotherm under neutral pH conditions. Higher SDZ uptake on the zeolite was observed when solution pH was below the or above the values of SDZ, while minimal SDZ uptake was observed when the solution pH was between the and values of SDZ. These observations suggested that hydrophobic interaction between SDZ and the zeolite was minimal due to the hydrophilic nature of the substrate. Electrostatic interactions and ion bridging were attributed to the elevated SDZ uptake under low and high pH conditions. As SDZ had a low value, the hydrophilic nature of the substrate prevented extensive uptake of SDZ, which could contribute to its extensive detection in the environment, including surface water and wastewater.

Highlights

The worldwide use of veterinary antibiotics poses a continuous threat to the environment
The goal of this study was to investigate the interactions between SDZ and clinoptilolite, a tectosilicate found in many volcanic soils with high external cation exchange capacity (ECEC) and total cation exchange capacity (TCEC), in order to better understand the fate and transport of SDZ in the environment and to understand the effect of solution chemistry on the removal of SDZ by high charged zeolite minerals
The data of SDZ uptake by zeolite were fitted to several kinetic models, but only the pseudo-second-order kinetics fitted the data well (Figure 2)

Summary

Introduction

The worldwide use of veterinary antibiotics poses a continuous threat to the environment. Used extensively in human and animal medicine, sulfonamide antibiotics (SAs) were highly stable towards hydrolysis, resulting in accumulations in the environment [1]. Neutral and cationic SAs interacted primarily with external surfaces, instead of intercalating into the swelling clay mineral montmorillonite [2]. Conflicting results were reported on the stability of adsorbed SAs to solid surfaces. Adsorption of SAs to mineral soil colloids was weaker and resulted in a stronger desorption from clay-size fractions [3]. High Kd values were reported for SAs sorption on pure clays, while organic matter had higher affinities for neutral SAs than smectite clays [7]

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Conclusion