Optimization of a low-cost adsorbent for dyes from treated avocado seed using full factorial design and central composite design

We prepared a natural adsorbent based on avocado seed after treatment with hexane. Our ‎adsorbent-treated avocado seed (TAS) had an amorphous structure, the material is ‎composed of tiny particles of different sizes, and a significant surface area of 3000 m2/g, with ‎a pHpzc 4.7. Mathematical models for the optimization of the adsorption process of basic ‎yellow 28 and tartrazine were developed. Starting with the full factorial design (FFD) for the ‎determination of the factors influencing the adsorption process, followed by the optimization ‎of these influencing parameters by the central composite design (CCD). In both processes, ‎only the pH, the dose of the adsorbent, and the concentration of dyes were studied as ‎influencing the adsorption according to the FFD results. The optimum conditions for the ‎adsorption of basic yellow 28 for a better yield > 99% is 169 mg of TAS in a solution of BY ‎‎28 of concentration 24.5 mg/L at a pH of 9.95. Similarly, for a better tartrazine elimination ‎yield of 91.11%, 350 mg of TAS was obtained in a tartrazine solution with a concentration of ‎‎10 mg/L and a pH of two. The pH, the mass of TAS, and the concentration of dyes must ‎therefore be carefully controlled when the adsorption process is implemented.‎