Earnshaw Medal
Earnshaw 2009 Nominees: Thomas Cummins, DCU
Optical Sensors for Heavy Metal Ion Monitoring
This project investigates the use of optical sensors for the determination of heavy metal ions. Measurement of the sensors detection of Cu2+ ions is made via a shift in the absorbance peak for the complex. Experimental work began with testing in solution, whereupon successful dyes could be used in solgels. Three complexes were used in this work; phosphine oxide (OPR3), dilithium phthalocyanine (Li2Pc) and 4-(2-pyridylazo)resorcinol (PAR). Testing of the three sensor dyes results with PAR being incorporated into a thin film by the sol-gel process, using 3-aminopropyltrimethoxysilane (APTMS) and phenyltriethoxysilane (PTEOS) sols. Testing of the performance parameters of the optical sensor are carried out, with comparisons made to the current HMI monitoring devices in the optical sensors field. The resulting value for the sensitivity range minimum of 1.16 mg/l for the sensor covers the limit set by WHO standards of copper in drinking water of 2 mg/l. Future work includes the optimisation of the solgel process to maximise performance parameters of the sensor.
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