Investigating film structure of membrane-based colorimetric sensor for heavy metal detection

A stable and relatively long lifetime optical membrane sensor for determination of heavy metal ions was prepared by covalent immobilization of dithizone (DTZ) on cellulose acetate membrane. Present work was aimed at gaining a quantitative understanding of the influence of membrane morphologies towards the immobilization of DTZ on the membrane surface. Experimental results indicated that the developed membrane by using 1 wt.% chitosan and 17 wt.% cellulose acetate showed to have the highest binding capacity and high binding stability up to 90 days of measurement. The prepared DTZ-membrane sensor exhibited quick (within 1 min) color change and was found to be capable of displaying distinctive color changes responses to the presence of mercury, copper, and zinc in aqueous solutions. The color intensity increases with increasing metal ions concentration, showed the potential practical applications for on-site quick detection of metal ions.

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