Optimization of Methylene Blue Adsorption on Agricultural Solid Waste Using Box-Behnken Design (BBD) Combined with Response Surface Methodology (RSM) Modeling

Tunics corm saffron (TCS) is a low-cost adsorbent that removes methylene blue (MB) from an aqueous solution. The TCS was characterized using FTIR and SEM analysis. The influence of MB adsorption variables such as TCS dose (0.4- 2.4 g L-1), contact time (0-120 min), MB dye concentration (100-500 mg L-1) was optimized Box-Behnken design (BBD) combined with response surface methodology (RSM) modeling. All three variables among the main parameters significantly affected the removal efficiency by applying the quadratic regression analysis. The results showed that the predicted values for MB adsorption were close to the experimental values and were in good agreement. Besides, the r(2) value (r(2)=0.970) indicates that the regression can predict response for the adsorption process in the studied range. The optimum BBD-RSM for MB removal of 89.48 % was recorded at a TCS dose of 1.78 g L-1, contact time of 56 min, MB dye concentration of 176 mg L-1 at solution pH of 5.4 temperature 21 degrees C. Excellent regeneration of TCS to remove MB in sixth consecutive adsorption-desorption cycles. This work highlights that TCS offers tremendous potential as a low-cost for organic dyes removal from wastewaters.