Janus phenol–formaldehyde resin and periodic mesoporous organic silica nanoadsorbent for the removal of heavy metal ions and organic dyes from polluted water

Heavy metal ions and organic dyes are the main harmful substances in natural water bodies. At the same time, single-component treatment can be challenging to cope with the increasingly severe water pollution circumstances. In this work, Janus phenol–formaldehyde resin (PF) and periodic mesoporous organic silica (PMO) nanoparticles with an asymmetric structure are prepared, using PF microspheres as seeds and PMO for branch growth. The hydroxyl groups on the PF surface and the large specific surface area of PMO facilitate the efficient adsorption of heavy metal ions and organic dyes by utilizing chemical and physical properties, respectively. The maximum adsorption of Janus PF&PMO for Cd2+ in water reaches 17.07 mg/g. The adsorption behavior fits well with the pseudo-second-order kinetic model and Langmuir adsorption isotherm, suggesting monolayer and chemical adsorption as main mechanisms. Moreover, the adsorption of Janus PF&PMO for the organic dye methyl orange (MO) fits the pseudo-second-order kinetic model and Freundlich adsorption isotherm model with a maximum adsorption of 98.21 mg/g, suggesting monolayer and physical adsorption as main mechanisms. Therefore, Janus PF&PMO nano-adsorbent is expected to be used effectively in sewage treatment systems.Graphical abstractThe synthesized Janus-shaped nano-adsorbent demonstrated outstanding potentials for removing heavy metal ions and organic dye from polluted water.