Er3+ Carbon Paste Electrode Based on New Nano-composite

Our previous studies showed a strong interaction of N'-(2-hydroxy-1,2-diphenylethylidene) benzohydrazide (HDEBH) with Er3+ ions. To have a high performance sensor with enhanced mechanical resistant for determination of Er3+ ions in real samples, HDEBH was used as a sensing material in new composite carbon paste electrode. The carbon paste were made based on a new nano-composite including multi-walled carbon nanotube (MWCNT), nanosilica, and room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate [bmim]BF4. The constructed nano-composite electrode showed better sensitivity, selectivity, response time, response stability and lifetime in comparison with typical Er3+ carbon paste sensor. The best performance for nano-composite sensor was obtained with electrode composition of 20% HDEBH, 20% [bmim]BF4, 47% graphite powder, 10% MWCNT and 3% nanosilica. The new electrode exhibited a Nernstian response (19.6 +/- 0.3 mV decade(-1)) toward Er3+ ions in the range of 7.5x10(-8)-1.0x10(-2) mol L-1 with a detection limit of 6.0x10(-8) mol L-1. The proposed modified Er3+ sensor can be used over the pH range of 3.0 to 8.0.