I am using wave length of 270nm on UV with glass cuvette to determine the absorbance of phenol after adsorption with composite of Chitosan from crab shell and activated neem leave at varying concentration of 1-20ppm. After 48 hrs of adsorption, I discovered that the absorbance value was greater than that of the blank. In other words my final concentration was higher than the initial concentration of phenol. What could be responsible please?
The final OD may not be only due to phenol but other chemical having same absorbance. Otherwise the interaction of phenol and chitosan might be influencing the absorbance. In final sample you are not getting pure phenol for quantification.
Even when I used commercial chitosan I still had the same result. But with Methylene blue solution the result was perfect
You can check the absorbance spectrum curve for a wide wavelength. Do seperately with phenol and final sample. Probably both curve will not give similar spectral signature near 270nm. You try from 200-800/900 mm.
The XRF result of the adsorbent showed the presence of P, Ca, Fe, Ni, Sr, Rh and Ag. could these have formed ionic interaction in the solution with the phenol that may have affected the absorbance result of my final sample?
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