Bioremoval of Methylene Blue from Aqueous Solutions by Green Algae (<i>Bracteacoccus</i> sp.) Isolated from North Jordan: Optimization, Kinetic, and Isotherm Studies

Algae provide an alternative, sustainable, and environmentally beneficial method of dyetreatment. In this study, algae were successfully used to remove methylene blue (MB) from aqueous solutions. The effects of several parameters, such as initial concentration of MB (5–25 mg L−1), algae dosage (0.02–0.1 g mL−1), temperature (4, 20, and 30 °C), and contact time (24, 48, 72 and 84 h), on MB removal were investigated. In addition, the characterization of MB before and after treatment was achieved using UV-spectrophotometer and Liquid chromatography-mass spectrometry (LC-MS). The experimental data were applied to three kinetic models, namely pseudo-first-order, pseudo-second-order, and Elvoich. Moreover, Langmuir, Freundlich, Dubinin–Raduskevich (D–R), and Temkin isotherm models were tested. The maximum removal efficiency of MB (~96%) was accomplished at optimum conditions at the initial concentration of MB (15 mg L−1), temperature (30 °C), and algae dosage (0.06 g mL−1) after 60 min of contact time. The removal of MB follows the pseudo-second-order kinetic model (R2 > 0.999), and the experimental data is best fitted by the Langmuir isotherm model (R2 > 0.9300)