Evaluation of Dry Anabasis aphylla Performance as Adsorbent for Methylene Blue Removal from Aqueous Solutions: Optimization and Kinetic Studies

In this study, the ability of dry Anabasis aphylla as an adsorbent for removing methylene blue (MB) from aqueous solutions was evaluated. The effects of several experimental factors such as, initial MB concentration (10?100 mg L? 1), adsorbent dosage (0.10?1.00 g), pH (2?10), and contact time (1?48 h) on MB removal were investigated at room temperature (20 ? 3 ?C). Moreover, the experimental data were applied to three kinetic models namely, pseudo-first order, pseudo-second order, and Elovich kinetic models. Furthermore, four common isotherm models namely, Langmuir, Freundlich, Dubinin?Radushkevich (D-R) and Temkin isotherm models were used to understand the adsorption mechanism of MB into dry A. aphylla. In addition, the efficiency of free dry A. aphylla to remove MB from aqueous solutions was compared with immobilized dry A. aphylla. The results reveal that the maximum removal efficiency (63%) of MB was obtained at optimum conditions including 10 mg L? 1 initial MB concentration, 0.40 g adsorbent dosage, initial pH of MB solution 4, and 2.0 h contact time. In addition, immobilized dry A. aphylla gives lower removal efficiency of MB (20%). MB removal by dry A. aphylla follows pseudo-second order and it is best fitted by Freundlich isotherm. The results of ATR-FTIR analysis of dry A. aphylla before and after MB adsorption confirm the MB binding with dry A. aphylla through adsorption process.