ADSORPTION STUDIES OF DODECYLAMINE AT THE QUARTZ INTERFACE USING AN ELECTRODE-SEPARATED PIEZOELECTRIC SENSOR

The adsorption process of dodecylammonium chloride (DAC) from aqueous solutions onto a quartz crystal interface was investigated in situ usi ng an electrode-separated piezoelectric sensor (ESPS). Increasing amou nts of DAC adsorbed onto a quartz crystal surface resulted in linearly decreasing oscillating frequencies of the ESPS. The adsorption densit y can be monitored by the frequency decrease. The adsorption density o btained by calculation using the Sauerbrey equation in the ESPS method is greater than that in solution depletion method. A calibration coef ficient is added into the Sauerbrey equation to correct the influence of surface roughness of the quartz crystal on the adsorption density. The influence of solution properties on the adsorption density measure ment was discussed. A dependence of the adsorption density on pH was r eported.