Recyclable NiO/sepiolite as adsorbent to remove organic dye and its regeneration

In this study, the impregnation synthesis of NiO/sepiolite and its application for dye removal during wastewater treatment is introduced. The NiO/sepiolite materials act as an adsorbent/catalyst. It comprises a unique combination of adsorption and high-temperature gas flow regeneration (the NiO/sepiolite acts as a catalyst at this stage, using regeneration rate as evaluation index of catalytic activity of NiO/sepiolite) in a single unit, in which the NiO/sepiolite was regenerated and reused for the next round adsorption of dye. An aqueous solution of methylene blue was used to evaluate the adsorption and regeneration performance of the adsorbent/catalyst. The regeneration rate reached 74% when the reaction time and temperature were 7 min and 350 °C, respectively. The effects of the regeneration temperature and volume fraction of O(2) on the regeneration rate were investigated. And the regeneration reaction kinetics was provided. The combination of adsorptive and catalytic properties in the NiO/sepiolite composites received interesting results for removing refractory biodegradable organic pollutants. This work provides new insights for the removal of dye from wastewater using Ni catalysts supported on natural low-cost clay.