Optical characteristics of the sensor membrane
Fig. 4 shows the absorbance spectra of immobilized methyl orange
on hydrolyzed cellulose acetate film and aqueous solution at
different pHs (4–12). As can be seen from Fig. 4, the dissolved form
and immobilized methyl orange show two clear maximums in the
visible region. In order to pH monitoring 464 nm was selected.
With the increase in solution pH, the absorbance of sensor and
solution were decreased. However, the absorbance changes of the
optical sensor by pH variation are greater than the soluble form.
This behavior increases the sensitivity of the optical sensor