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).

A new series of furo[2,3-b]pyridine derivatives bearing aryl substituents were synthesized in two steps, where, the cyano-(2H)-pyridones (1a-l) were converted to the corresponding nicotinonitriles (2a-l), followed by the Thorpe-Ziegler ring cyclization to the furo[2,3-b]pyridine derivatives (3a-l). All new compounds were characterized by 1D-NMR experiments (1H and 13C) and 2D-NMR experiments (COSY, HMBC and HSQC), as well as ESI-MS and HR-ESI-MS data. The new compounds were screened for their antioxidant activities by 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) free radical assay. The highest radical scavenging effect was observed for nicotinonitriles 2d, 2h and 2l and furo[2,3-b]pyridines 3b, 3f and 3j by methanolic solvent at 4.0 mg/mL concentration. Remarkably, all nicotinonitriles and furo[2,3-b]pyridine exhibited a significant radical scavenging activity after 24 and 48 hours compared with 0.5 hour.

This study aims to assess the ability of old, immobilized fresh, and free fresh green microalgae (a Bracteacoccus sp.) to remove methyl orange (MO) dye from aqueous solutions. The effects of four factors, including initial MO concentration (5–25 mg L⁻¹), adsorbent dose (0.02–0.10 g mL⁻¹), temperature (4–36 °C), and contact time (5–95 min), were examined. The Box–Behnken design (BBD) was used to determine the number of required experiments and the optimal conditions expected to provide the highest removal percentage of MO dye from aqueous solutions. The experimental data were applied to four isotherm models (Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Temkin isotherm models) and three kinetic models (pseudo–first–order, pseudo–second–order, and Elovich kinetic models). The results indicate that the highest removal of MO (97%) could be obtained in optimal conditions consisting of an initial MO concentration of 10.0 mg L⁻¹, an adsorbent dose of 0.10 g mL⁻¹, a temperature of 20 °C, and a contact time of 75 min. Moreover, the experimental data were best fitted by the Langmuir and Temkin isotherm models and followed a pseudo-second-order kinetic model. The interaction between MO and the Bracteacoccus sp. was confirmed by UV and ESI/MS analyses, indicating that MO removal occurred via both sorption and degradation processes.

Currently, different sources of contamination threaten water quality in Damietta, Egypt. The aim of this study was to assess the pollution, hydrogeochemistry and suitability for use in agriculture of water collected atseven stations along the Damietta branch of the Nile River. In addition to pH, temperature, dissolved oxygen (DO), and electrical conductivity (EC), levels of Mg2+, Ca2+, K+, Na+, Cl−, HCO3−, SO42− and CO32− were measured. From the highest to the lowest, the concentrations of cations were Na+ > Ca2+ > Mg2+ > K+, whereas those of anions were HCO3− > SO42− > Cl− in water samples collected at seven stations along the Damietta branch. Moreover, water quality indexes, such as sodium percentage (Na%) ranged between 21.6 and 71.4, Kelly's ratio from 0.37 to 3.85, sodium adsorption ratio (SAR) varied from 1.73 to 61.8, residual sodium carbonate (RSC) found to be in range of 0.2 to 3.8. Also, the potential salinity (PS) and permeability index (PI), magnesium hazard (MH), were calculated. Most samples (71%) belonged to the Mg–Ca–Na–HCO3 watertype. Fertilization wastes were identified as the main contributors of alkaline earth metals, whereas ion exchange was the main source of alkali metals. This work also provides information on distinguishing geochemical behaviors and the pollution of water samples.