Experimental Design Modelling and Optimization of Triazine Herbicides Removal With Reduced Graphene Oxide Using Response Surface Method

Abstract

In this work, triazines were chosen as the organic micropollutants model, to develop a useful method for the removal of triazine products, using a reduced derivative of graphene oxide as adsorbent material. The pristine graphene oxide and its thermally reduced derivatives under mild conditions were tested, optimizing the GO reduction conditions by means of DOE coupled with the response surface methodology. For the reduction it was decided to choose the mildest and simplest conditions possible, using an air heat treatment in a common laboratory oven. The optimal reduction conditions deduced from the response surface were calculated at a reduction temperature of 110 °C maintained for 24 hours and rGO sample was employed in the adsorption of the triazines. All the adsorbent materials have been characterized before use, by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett- Teller (BET) surface area analysis. Triazine analyses were performed by HPLC. The data obtained from the adsorption isotherms have been fitted with the Langmuir and Freundlich models, and the Freundlich model was the best one, especially for the Atraton and the Prometryn. The maximum adsorption capacity obtained was 4.4 mg/g for Atrazine, 19.4 mg/g for Atraton and 18.4 mg/g for Prometryn, at room temperature.