Dye adsorption and photo-induced recycling of hydroxypropyl cellulose/molybdenum disulfide composite hydrogels

A novel environmental friendly dye adsorbent composited of hydroxypropyl cellulose (HPC) and molybdenum disulfide (MoS2) were fabricated, which can be recycled and reused by illumination due to the photo-catalytic properties of MoS2. In order to promote a more homogeneous dispersion of MoS2 nanosheets in HPC, MoS2 was functionalized with HPC chains through esterification. The successful functionalization of MoS2 was confirmed by FTIR, XRD, XPS characterizations. The morphologies of the HPC and HPC-MoS2/HPC hydrogels were compared by SEM. The obtained HPC-MoS2/HPC hydrogels exhibited enhanced adsorption performance toward methylene blue. An adsorption improvement of HPC hydrogel had been brought by the incorporation of HPC-MoS2 sheets. Adsorption kinetics was then imitated by Lagergren pseudo-first-order and pseudo-second-order models. Adsorption isotherms were imitated by Langmuir isotherm and Freundlich isotherm. The photo-regeneration experiments of HPC-MoS2/HPC hydrogel after absorption showed that the absorbent can be activated easily by illumination with little loss of dye adsorbing capacity.