Radiation synthesis for a highly sensitive colorimetric hydrogel sensor-based p(AAc/AMPS)-TA for metal ion detection

Abstract The copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid AMPS with acrylic acid AAc using gamma radiation technique was performed in different co-monomer concentration. The effect of AMPS concentrations on the gel fraction (%) and swelling behavior were investigated. It is found that as AMPS concentrations increases both gel fraction (%) and swelling degree of p(AAc/AMPS) hydrogel samples increase. The p(AAc/AMPS) (1:2 wt%) hydrogel were selected to be loaded with tannic acid (TA) to give p(AAc/AMPS)-TA that are used as colometric sensor due to its high swelling properties (320 g/g). The colorimetric detection of 10 of (Mg2+, Cu2+, Co2+, Mn2+, Ni2+, Cr6+, Cd2+, Hg2+, Fe3+ and Sr2+) metal ions is run in water solution. The colometric sensor of p(AAc/AMPS)-TA hydrogel has been doped with 10 analyst with concentration range between 103-M and 5 x 104-M for 60 min. The final deprotonated M+n-p(AAc/AMPS)-TA intermediate has shown a clear change in the color. The change in the color of M+n-p(AAc/AMPS)-TA is due to electron transition in the electronic properties of complex induced by Internal Charge Transfer (ICT) mechanism. The change in naked color eye and optical property where an obvious change in the vis-spectrum has been investigated. The obtained result showed a good selectivity of p(AAc/AMPS)-TA toward Cr6+ 10 fold than Hg2+. Therefore, the p(AAc/AMPS)-TA hydrogel could be proposed as a colometric sensor of determining the hazardous metal in solution.