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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).

Targeted degradation of individual polycyclic aromatic hydrocarbon (PAH) constituents like anthracene, may offer cost effective and efficient cleaning of coal tar-contaminated sites. Thus, a reductive degradation procedure of anthracene using activated magnesium with anhydrous ethanol at room temperature was developed and optimized. To determine the optimum conditions for anthracene, such as effective magnesium concentrations, glacial acetic acid volumes, and exposure time for the anthracene reduction, the experiments were designed using the response surface methodology based on the central composite design. The design also minimized the number of experiments. The main product from anthracene reduction is 9,10-dihyrdoanthracene. Optimum conditions for 98% degradation capacity of anthracene (2.80 × 10 –3 mmol) were 30 mg of Mg powder (1.20 mmol), 60 μL of glacial acetic acid (1.05 mmol), and 30 min exposure time. When the optimized method was tested on the coal tar specimen, twice as many reagents (i.e., Mg and glacial acetic acid) were required to obtain a 90% degradation of anthracene and fluoranthene from the coal tar. This method of using activated Mg and anhydrous ethanol selectively reduces PAHs in coal tar; in particular anthracene and fluoranthene are most efficiently removed.

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