Abstract

The objective of this study was to develop an iron oxide/activated hydrochar composite (FeOHC) capable of reducing or eliminating 2-chlorophenol from aqueous solutions through adsorption or oxidation processes. The study carried out the metal doping by two preparation techniques: (1) incipient wetness impregnation of original biomass via hydrothermal carbonization (FeOHC) and (2) coprecipitation of iron oxide on the hydrochar surface (FeOHC-C). The resulting materials were activated at 400 °C under a nitrogen atmosphere. The synthesized catalysts were characterized and evaluated for their capacity to remove 2- chlorophenol through adsorption/oxidation experiments. The results indicated that the synthesized materials exhibited mesoporous structures with surface areas ranging from 44 to 66 m² g⁻¹ and the presence of magnetite. Adsorption tests demonstrated significant capacity for 2-chlorophenol removal, evaluated through kinetic and isotherm models. Kinetic data showed that 2-chlorophenol adsorption capacity reached 7.71 and 5.14 mg/g within 24 hours. The Elovich model best described the kinetics for both materials. Equilibrium adsorption capacities ranged from 24.63 to 18.70 mg g⁻¹ with FeOHC having the highest capacity. The Sips isotherm model provided the best fit. Thermodynamic parameters suggested that the adsorption process can be considered of physical nature. Fenton reactions showed faster and greater 2-chlorophenol removal at pH 3.0, with no significant differences at pH 6.0. Reusability tests confirmed that the synthesized materials could serve as both adsorbents and self-regenerative catalytic systems for remediating water containing chlorinated compounds.