Effect of surface, structural and textural properties of graphenic materials over cooperative and synergetic adsorptions of two chloroaromatic compounds from aqueous solution

Graphenic materials have been recently applied for adsorption processes due to their high efficiency and their easy capability of surface modification. In the present study two different graphene oxides, two reduced graphene oxides under inert atmosphere and one reduced graphene oxide under ammonia atmosphere were used as adsorbents for removing two chloroaromatic compounds from water: 2,4-dichlorophenol and 2,4-dichlorophenoxyacetic acid. Hydrogen bonds and pi-pi interactions have been detected by Attenuated Total Reflectance infrared spectroscopy in the solids with adsorbed species. Besides, two direct relationships between their adsorption capacities and graphenic surface, textural and structural properties were found. In order to obtain real adsorption information, some experiments with the presence of both pollutants at the same time were performed. From these mixture experiments, when graphene oxide was used as adsorbent some cooperative effects between pollutants were detected. Based on XRD results and an innovative comparison between different infrared techniques, the importance of interlayer spaces during adsorption was demonstrated. Otherwise, synergetic interactions between pollutants were revealed as the main adsorption forces when reduced graphene oxides were used, being their aromatic structures a decisive factor in their final adsorption capacity.