Optimization of the Adsorption Process of Methylene Blue Dye by Apatites Using a Factorial Design

In recent years, a number of scientific studies have focused on the preparation and use of grafted HAp. In this context, we have prepared HAp grafted with AMP molecules at different grafting rates in order to precisely improve certain physico-chemical properties to increase the adsorbed amount of methylene blue dye. These materials were synthesized by wet process according to the precipitation method which is carried out by the neutralization of various reagents of calcium ions Ca(OH) 2 and phosphate NH 4 H 2 PO 4 at 25 °C in an aqueous medium. The prepared materials HAp and HAp-AMP were characterized by XRD, FTIR, and BET to determine their physicochemical properties. Adsorption of MB dye by apatite matrices was monitored by a factorial design method using Design-Expert software to study the influence of variation and efficiency of different MB concentrations, pH and stirring time between adsorbent and ad-sorbate to determine optimal conditions for maximum adsorbate retention. The highest removal of MB (328.78 mg.g -1 ) was obtained for an initial concentration of 460 mg.L -1 , and a contact period of 135.5 min at 298 K.