Optimization of Reactive Blue 21 removal by Nanoscale Zero-Valent Iron using response surface methodology

Since Reactive Blue 21 (RB21) is one of the dye compounds which is harmful to human life, a simple and sensitive method to remove this pollutant from wastewater is using Nano Zero-Valent Iron (NZVI) catalyst. In this paper, a Central Composite Rotatable Design (CCRD) was employed for response surface modeling to optimize experimental conditions of the RB21 removal from aqueous solution. The significance and adequacy of the model were analyzed using analysis of variance (ANOVA). Four independent variables—including catalyst amount (0.1–0.9 g), pH (3.5–9.5), removal time (30–150 s) and dye concentration (10–50 mg/L)—were transformed to coded values and consequently second order quadratic model was built to predict the responses. The result showed that under optimized experimental conditions the removal of RB21 was over 95%.