Fabrication and morphology charaterization of spin-coated nafion thin films

Nafion thin films {\u3c2um) were fabricated using the spin coating technique. Substrate (silicon, silica and glass), concentration (5%, 10%, and 15% Nafion concentration), and spin coating angular velocity (1500rpm, 2000rpm, and 2500rpm) were chosen as the parameters. The deposition of the films onto the substrates was verified using energy-dispersive spectroscopy (EDX) and the surface morphology was characterized by scanning electron microscopy (SEM). The effects of varying the parameters were investigated. Surface morphological results show that the films followed the contour of the substrate onto which they are deposited and nanometer scratch-likes features appear at high magnification (x35000). Thickness measurements were graphed against the different parameters and results show that thickness of Nafion films decrease with increasing angular velocity and increase with increasing concentration. Results also show that silicon and silica produced thicknesses which are uniform while glass always achieved higher thicknesses than the two indicating that the kind of substrate affect the thickness of the deposited thin film

An exploratory study on the leachability of polybrominated diphenyl ethers (PBDEs) from computer monitor plastic casings using x-ray fluorescence spectroscopy (XRF)

Brominated flame retardants (BFRs) are chemicals commonly used in the industrial sector to suppress fire. Polybrominated diphenyl ethers (PBDEs) are a class of BFRs once widely used in many applications, which are required, since being listed under the Stockholm Convention, to be monitored and regulated. PBDEs can be found in waste from electric and electronic equipment (WEEE) and are known to leach out of such wastes. As part of the desire to protect the environment and both human and wild life, PBDEs and the ways to treat them from WEEE should be explored and studied, especially in a country such as the Philippines where contamination of PBDEs to the environment is a likely possibility due to the absence of treatment options and data to come up with such options that would help eliminate PBDEs from WEEE before stockpiling for future recycling. This study seeks to address the problem on the lack of data through the study of the leachability of PBDEs from WEEE in the form of computer monitor casings. In this study, the effect of parameters pH, contact time, and solvent type were investigated using X-ray fluorescence (XRF) spectroscopy. With regards to leachability, the study is divided to two parts: the first using 20% methanol in water and the second in pure methanol, dichloromethane (DCM), and toluene. Effect of pH was determined in 20% methanol experiments and the chosen pH settings were pH4 and normal (~pH7). Contact times were 1, 6, 24, 72, and 120 hours for tests in 20% methanol and 15 and 30 minutes for those in pure solvent. Based on the results, it is shown that pH and contact time had no leaching effect in 20% methanol and that, in general, leaching in methanol is nonexistent. Results also show that leaching happens in both DCM and toluene solvents, but that these solvents are not feasible for the treatment of computer monitor casings intended to be stockpiled for future recycling