Influence of precursor pH on the structure and photo-Fenton performance of Fe/hydrochar

Fe/hydrochar was one-pot synthesized by a hydrothermal method under different pH conditions. The structure, composition and chemical state of the obtained samples were analyzed by different characterization methods. It was found that the precursor pH affected the morphology, surface area, surface Fe content and organic groups of the products. The catalytic performance of the samples for the photo-Fenton decolorization of Orange II with visible light irradiation and the role of dissolved Fe in this process were investigated. The result indicated that the Fe/hydrochar prepared at pH 2 exhibited the highest catalytic activity because of its strong visible light adsorption, high surface Fe content, and rich oxygen-containing groups. The light irradiation accelerated the leaching of Fe and regeneration of Fe2+, and the contribution of homogeneous reactions increased dramatically with reaction time, thus promoting the formation of OH in solution. A possible mechanism for the Fe3+/Fe2+ cycle at the catalyst/water interface was proposed.