Introduction of graphene-periodic mesoporous silica as a new sorbent for removal: experiment and simulation

Abstract

For the first time, a novel sandwich structure of graphene-periodic mesoporous silica (G-PMS) sorbent was introduced for the removal of acid blue (as a model analyte) from wastewater samples. Moreover, this procedure was investigated through static and column modes. The effect of different key factors affecting the adsorption of the target compound was studied in batch-based (static) conditions and optimized via response surface methodology using a Box–Behnken design. Parameters involved included the amount of sorbent, time for reaching adsorption equilibrium, and initial concentration of dye. Under the optimized conditions (amount of sorbent: 10 mg; acid blue concentration 60 ng mL−1; stirring rate of sample solution: 1400 rpm; contact time: 6 min), an acceptable adsorption capacity was obtained (21 mg g−1), and the adsorption isotherm was fitted with the Freudlich model. Moreover, G-PMS showed higher removal efficiency (R = 89.5%) compared to graphene (R = 62%). Furthermore, a flow-based (column) mode was also performed to study analyte removal using a fixed-bed column. Numerical simulation, using COMSOL Multiphysics, was applied to predict the breakthrough curves. An objective framework was suggested by this model to interpret the efficiency of the developed adsorption system. Eventually, the obtained results of this model can help to predict the possibility for designing and scaling-up the adsorption process.