MIL-101(Cr)-cobalt ferrite magnetic nanocomposite: synthesis, characterization and applications for the sonocatalytic degradation of organic dye pollutants.

In this study, for the first time, a novel magnetically recyclable MIL-101(Cr)/CoFe2O4 nanocomposite was prepared via a facile solvothermal method. The morphology, structural, magnetic and optical properties of the nanocomposite were characterized via field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), UV-visible spectroscopy (UV-visible) and BET surface area analysis. Furthermore, the sonocatalytic activity of the MIL-101(Cr)-based magnetic nanocomposite was explored for the degradation of organic dye pollutants such as Rhodamine B (RhB) and methyl orange (MO) under ultrasound irradiation in the presence of H2O2. Under optimized conditions, the degradation efficiency reached 96% for RhB and 88% for MO. The sonocatalytic activity of MIL-101(Cr)/CoFe2O4 was almost 12 and 4 times higher than that of the raw MIL-101(Cr) and pure CoFe2O4, respectively. The improved sonocatalytic performance of the as-prepared binary nanocomposite can be attributed to the relatively high specific surface area of MIL-101(Cr) and magnetic property of CoFe2O4, as well as the fast generation and separation of charge carriers (electrons and holes) in MIL-101(Cr) and CoFe2O4. In addition, the trapping tests demonstrated that ·OH radicals are the main active species in the dye degradation process. Moreover, the most influencing factors on the sonocatalytic activity such as the H2O2 amount, initial dye concentration and catalyst dosage were investigated. Finally, the nanocomposite was magnetically separated and reused without any observable change in its structure and performance even after four consecutive runs.

Evaluating workers' exposure to metalworking fluids and effective factors in their dispersion in a car manufacturing factory.

INTRODUCTION: Metalworking fluids (MWFs), which are widely used in metal working operations, can cause different adverse effects, e.g., dermal and respiratory disorders, and cancer. Evaluating workers' exposure to MWF mists and the effective factors in their dispersion were the purpose of this study. MATERIALS AND METHOD: Seventy-five out of 300 workers working in metalworking workshops were randomly selected. MWF concentrations were measured with the National Institute for Occupational Safety and Health (NIOSH) 5524 method. Air temperature and velocity were also determined as the predicted effective parameters on the level of exposure. RESULTS: The results indicated that exposure to MWF mists in one workshop was higher than in the other ones (p < .05). The findings also showed that temperature was an effective factor in the dispersion of MWF mists (p < .05). DISCUSSION: The exposure of almost all workers was under the threshold limit value of 5 mg/m(3), but it was over the value recommended by NIOSH of 0.5 mg/m(3). Air temperature was an effective factor in workers' exposure (r = .576).