A polymeric film as fluorescent sensor for detection of Pb2+ in aqueous solutions, synthesised from 1-vinylimidazole, poly(ethylene glycol) diacrylate and trimethylolpropane triacrylate has been described. The manuscript also describes the influence of pH and time on the fluorescence sensitivity of the polymeric film.
The Reaction of Interest:
I was using 10% VIM, 70% PEGDA and 20% TMTPA as described in section 2.2. The manuscript however, does not mention the specific amount of DMPA. I used 0.25 wt% following the observations in Journal of Applied Polymer Science 123(1) 2012. Removal of unreacted monomers was easy after keeping the UV-cured films in deionized water for 24 hours.
- Effect of pH: As described in section 3.3 of the manuscript, the effect of pH on Pb2+ sensing was investigated within the range of 3.0 to 6.0. The results were well replicated. The investigations were also carried out till pH 9 with suitable buffer, but the results show inconsistency in fluorescence intensities recorded, and in general, are found to be on the lower side. The variation of fluorescence intensities were more or less similar to that depicted in figure 4.
- The Table 1 lists the “Effect of foreign ions on the fluorescence intensity of 2.42×10-7 mol L-1 Pb(II) solution at optimum conditions”. Section 3.6 describes the implications. The only discrepancy found in the study was the exclusion of Al3+, although in section 3.8, the authors mention it as one of the most studied ions by sensing techniques. On examining the effect of Al3+ as a foreign ion, the tolerance level was found to be for relatively lower concentrations.
- The reusability of the sensor as described in section 3.8, is very good. However, the regeneration from distilled water was not found to be as quick (2 minutes).
- Using DMPA in 0.25 wt% concentration is sufficient for photo-polymerization process.
- Deionized water is recommended for regeneration of the membrane.