Rapid removal of Auramine-O and Methylene blue by ZnS:Cu nanoparticles loaded on activated carbon: A response surface methodology approach

Abstract

The focus of this research is on the rapid ultrasound-assisted removal of Methylene blue (MB) and Auramine-O (AO) dyes from aqueous solutions using ZnS:Cu nanoparticles loaded on activated carbon (ZnS:Cu-NP-AC) as a low cost and environmental friendly adsorbent. The adsorbent was characterized by FE-SEM, FTIR and XRD. The effect of variables such as adsorbent dosage, sonication time, initial concentration of MB, and initial concentration of AO on the removal percentages of MB and AO dyes were simultaneously investigated by central composite design (CCD) under response surface methodology (RSM) while pH was optimized separately. It was shown that the adsorption of AO and MB follows the pseudo-second-order rate equation, while the Langmuir model explains equilibrium data. A small amount of the adsorbent was able to remove more than 99.5% of both dyes rapidly with high adsorption capacity in single component system (106.9 mg/g for MB, and 94.2 mg/g for AO) and in binary-component system (51.7 mg/g for MB, and 38.1 mg/g for AO). It is worth to note that the optimum adsorption of MB and AO dyes occurred at neutral pH, which is an advantage of our work.