Fe3O4/PVDF catalytic membrane treatment organic wastewater with simultaneously improved permeability, catalytic property and anti-fouling.

Fe3O4/Polyvinylidene fluoride (PVDF) three-channel hollow fiber catalytic membrane was successfully fabricated via non-solvent induced phase inversion and used for organic wastewater degradation in this work. The effects of Fe3O4 nanoparticles addition on the surface and cross-section morphologies, hydrophilicity and thermal properties of the catalytic membrane were characterized by the field emission scanning electron microscopy (SEM), water contact angle and thermogravimetric analysis (TGA), respectively. The obtained catalytic membrane exhibited good hydrophilicity, a high pure water flux of 175.8 L m-2 h-1 and a high removal of methylene blue (up to 97.6%) with Fenton catalytic reaction. Meanwhile, the catalytic membrane shows excellent anti-fouling property due to the presence of Fenton reaction. Our results show that Fe3O4/PVDF three-channel hollow fiber catalytic membrane was a promising alternative for the degradation of organic contaminants.

Strain-insensitive temperature sensing with a dual polarization fiber grating laser.

In this paper, a strain-insensitive temperature sensor based on a dual polarization fiber grating laser is demonstrated. The laser is fabricated by inscribing two wavelength-matched Bragg gratings in an Er-doped fiber. It emits single-longitudinal-mode output in wavelength domain and generates a RF-domain signal as a beat note between the two polarization modes. A temperature sensor has been exploited by monitoring the beat frequency. The measured temperature sensitivity is -78.46 kHz/°C. Theoretical analysis suggests that the temperature response is a result of both the differences in thermo-optic coefficient and thermal expansion between the core and cladding. In contrast, the sensor is almost insensitive to applied axial strain. We found that the strain insensitivity is due to the compensation between the strain-induced birefringence change and the effect of the elongation/material index change. The proposed sensor can be applied for reliable and precise measurement of temperature independently, towards the applications in structural integrity, oil-well monitoring, aerospace engineering, and process control.