A Biodegradable Magnetic Nanocomposite as a Superabsorbent for the Simultaneous Removal of Selected Fluoroquinolones from Environmental Water Matrices: Isotherm, Kinetics, Thermodynamic Studies and Cost Analysis.

The application of a magnetic mesoporous carbon/ß-cyclodextrin-chitosan (MMPC/Cyc-Chit) nanocomposite for the adsorptive removal of danofloxacin (DANO), enrofloxacin (ENRO) and levofloxacin (LEVO) from aqueous and environmental samples is reported in this study. The morphology and surface characteristics of the magnetic nanocomposite were investigated by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) adsorption-desorption and Fourier transform infrared spectroscopy (FTIR). The N2 adsorption-desorption results revealed that the prepared nanocomposite was mesoporous and the BET surface area was 1435 m2 g-1. The equilibrium data for adsorption isotherms were analyzed using two and three isotherm parameters. Based on the correlation coefficients (R2), the Langmuir and Sips isotherm described the data better than others. The maximum monolayer adsorption capacities of MMPC/Cyc-Chit nanocomposite for DANO, ENRO and LEVO were 130, 195 and 165 mg g-1, respectively. Adsorption thermodynamic studies performed proved that the adsorption process was endothermic and was dominated by chemisorption.

Occurrence, quantification, and adsorptive removal of nodularin in seawater, wastewater and river water.

The presence of potent hepatotoxic cyanotoxins such as nodularin (NOD) in drinking water, groundwater, surface water, seawater and recreational waters presents a major risks to human and environmental health. Human exposure to cyanotoxins could lead to various health effects such as liver damage, jaundice, neurotoxicity and gastroenteritis. Therefore, it is critical to investigate their occurrence in environmental matrices. This study reports the use of tyre-based activated carbon (WTAC) as an adsorbent for preconcentration and removal of nodularin from environmental matrices prior to high performance liquid chromatographic analysis. The preconcentration and adsorption experiments were carried out in presence of other environmental components to consider the external effect on WTAC adsorption of nodularin. Under optimum conditions, the linear dynamic range was 0.05-70 µg L- 1 with a correlation coefficient of 0.9991. The LOD and LOQ (n = 10) in the absence and in the presence of humic acids were 0.012-0.025 µg L- 1 and 0.040-0.083, n = 10), respectively. The repeatability (n = 10) and reproducibility (n = 5) of the method expressed as relative standard deviation (%RSD) were 3.7 and 5.1%, respectively. The maximum adsorption capacity of WTAC was 345 µg g -1. Furthermore, the results demonstrated that the presence of humic acid has an effect on the nodularin adsorption to WTAC. However, high concentrations other coexisting ions such a Cl-, NO3-, PO43-, HCO3-, SO42- had no significant the effect on the adsorption process. The proposed technique was then used for a preconcentration and elimination of NOD trace levels in different water matrices. The results showed that the WTAC was an effective adsorbent for the preconcentration and removal of NOD from the complex matrices.