Electrical properties of chitosan films with metal ion

Metal ion, unlike other types of pollutant, can easily enter the human body but very difficult to degrade. Metal ions in trace amount is essential nutrient, however consumption at high dose may cause disorder in plant and animals, as well as fatality due to toxicology. The purpose of this study is to measure and determine the electrical properties of chitosan film with metal ion. Intrinsically, chitosan plays important role in the adsorption process of metal ion in the water. The experiment was conducted by soaking chitosan film with dimension of 8 mm by 8 mm into copper, cadmium and zinc ions solutions for 20 minutes at various concentrations. The selections and concentration of metal ion were determined according to the level of toxicity in drinking water that allowed by EPA regulations for common contaminants. The soaked chitosan was then attached onto the interdigitated electrode that connected to LCR meter. The principle of chitosan film measurement is based on determination of the impedance, capacitance, and resistance. When the concentration metal ion was set at 50 mg/L, zinc possess the highest resistance whilst the highest capacitance value is given by copper ions. The standard deviation of capacitance value for chitosan film with copper, cadmium and zinc are 7.01 nF, 74 nF and 48 nF respectively. The results were then elaborated and analysed through Nyquist plot to identify the circuit arrangement between chitosan film and interdigitated electrode. The dielectric material and conductivity pattern show that polarization occur at low frequency that lead to decrement in dielectric constant and dielectric loss. The absence of semicircle in Nyquist graph indicates the arrangement between the chitosan film and interdigitated electrode is in series. The finding of this study shows the potential of chitosan as portable metal ion sensor due to its ability to provide authentic amount of ions in the water through detection of samples’ electrical changes in real-time.

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