Numerical desirability function for adsorption of methylene blue dye by sulfonated pomegranate peel biochar: Modeling, kinetic, isotherm, thermodynamic, and mechanism study

Sulfonated pomegranate ( Punica granatum ) peel biochar (SPPBC) was developed via thermal activation with sulfuric acid (H 2 SO 4 ) to act as a promising biochar material for the adsorptive removal of toxic cationic dye namely methylene blue (MB) dye from contaminated water. A Box-Behnken design (BBD) and numerical desirability function were adopted to optimize the input adsorption variables (SPPBC dosage, temperature, pH, and contact time). The maximum removal of the MB dye can be accomplished by simultaneous significant interaction between SPPBC dosage with solution pH, SPPBC dosage with time, SPPBC dosage with temperature, solution pH with time, and time with temperature. The numerical desirability function identified the highest MB dye removal (93.9%) can be achieved at the following optimum numerical adsorption conditions: SPPBC dosage 0.18 g, temperature 49 °C, pH 9.7, and time 4.3 h. Equilibrium data were well fitted to the Temkin and Langmuir isotherm models. The maximum recorded adsorption capacity of SPPBC for MB dye adsorption by using Langmuir isotherm model was 161.9mg/g. This research work reveals the possibility of converting lignocellulose pomegranate peel into a renewable and environment-friendly biochar via a relatively fast acid-activation process with the great potential to be promising adsorbent for removal of MB dye.