Fabrication of SA-SiOSUB2/SUB capsules with 3D microscopic re-entrant structures via one-step titration-gel method for the removal of methylene blue from water

摘要

In this paper, the eco-friendly sodium alginate-silicon oxide capsule (SASC) with a brilliantly wide pH toleranceproperty was obtained via the one-step titration-gel method and in-situ sol-gel progress. The spherical droplets with SA andtetraethyl orthosilicate (TEOS) casting mixture were directly injected into the calcium chloride (CaCl2) solution. The effectsof SiO2 nanoparticles (SiO2 NPs) on the morphology and adsorptive properties of the capsules were investigated. The interfaceof the SASC with micro-porous fracture aperture and microscopic re-entrant structures help to provide a stronger interactionbetween MB and surface channel thus increased its removed capacity during the courses of adsorption. The maximumabsorption amount of the SASC against methylene blue (MB) was found to be 350.80 mg/g at 25 °C and the solutionpH value of 8, which had a 12.82% enhancement compared with the neat capsule. The adsorptive performance of the preparedcapsules was literally fitted the pseudo-second-order kinetic equation and Langmuir absorption isothermal model. Moreover,the pH of the MB solution was evidently declined after adsorption, indicating that the adsorption mechanism of the capsulesagainst MB might be dominated by ion-exchange and electrostatic attraction. This facile method which was used to generatefree-standing spherical support structures with specialized morphology might be more suitable for removing cationic pollutantsfrom alkaline wastewater.