Optimization and Evaluation of Alkali-Pretreated Paeonia Ostii Seed Coats as Adsorbent for the Removal of Mb From Aqueous Solution

A novel effi cient adsorbent, alkali-pretreated Paeonia ostii seed coats (AP-PSC), was investigated for the removal of methylene blue (MB) dye from solution. Orthogonal array design was applied to optimize the process parameters viz. alkali concentration, liquid-solid ratio (LSR) and pretreatment time. The results revealed that the optimal pretreatment conditions were at 0.8% (w/w) NaOH with LSR of 0.35 L g-1 treating for 50 min. Equilibrium and kinetic studies indicated that Langmuir isotherm and Pseudo-second-order models described the experimental data well. The maximum adsorption capability was of 368.2 mg g-1 for MB at 25oC. Thermodynamic parameters suggested that the AP-PSC adsorption process was physical, endothermic and spontaneous. Furthermore, the adsorption process was infl uenced by several interactive mechanisms, including ion-exchange, as well as Van der Waals forces and hydrogen bonds that occur concomitantly. It was concluded that AP-PSC may be potential as an effi cient adsorbent to remove MB from solution.