Determination of adsorption capacity, regeneration ability, and aggregation tendency toward inorganic and organic pollutants of metal-doped carbon-silica composites in multicomponent systems

The main aim of the study was to develop a method for determining the adsorption capacity, regeneration ability, and aggregation tendency of metal-doped carbon-silica composites (iron-doped, C/Fe/SiO2, and manganese-doped, C/Mn/SiO2) against heavy metals and selected organic substances. The properties of these composites were compared with those of metal-free silica-carbon composite (C/SiO2). Inductively coupled plasma-optical emission spectrometry (ICP-OES) and high-pressure liquid chromatography were used to determine the adsorbed amounts and the desorption degree of organic/inorganic pollutants. Potentiometric titrations and electrophoretic mobility measurements were conducted to understand the mechanisms that were driving adsorption and particle aggregation. The size of the aggregates formed in the systems as well as the stability of the examined suspension were estimated by using ultraviolet-visible spectrophotometry. The performed experiments showed that the selected combination of methods is appropriate to determine the potential of metal-doped carbon-silica composites as adsorbents as well as the ease of their removal with adsorbed contaminants from aqueous solutions by sedimentation. Graphical Abstract