Advanced oxidation of acridine orange by aqueous alkaline iodine

ABSTRACT

The advanced oxidation process is certainly used for the dye waste water treatment. In this continuation a new advanced oxidation via aqueous alkaline iodine was developed for the oxidation of acridine orange [AO] [3, 6 -bis [dimethylamino] acridine zinc chloride double salt]. Oxidation Kinetics of AO by alkaline solution of iodine was investigated spectrophotometrically at lamda[max] 491 nm. The reaction was monitored at various operational parameters like several concentrations of dye and iodine, pH, salt electrolyte and temperature. The initial steps of oxidation kinetics followed fractional order reaction with respect to the dye while depend upon the incremental amount of iodine to certain extent whereas maximum oxidation of AO was achieved at high pH. Decline in the reaction rate in the presence of salt electrolyte suggested the presence of oppositely charged species in the rate determining step. Kinetic data revealed that the de-colorization mechanism involves triodate [I3[-]] species, instead of hypoidate [OI[-]] and hypiodous acid [HOI], in alkaline medium during the photo-excitation of hydrolyzed AO. Alleviated concentration of alkali result in decreasing of rate of reaction, clearly indicate that the iodine species are active oxidizing species instead of OH radical. Activation parameters at elevated temperatures were determined which revealed that highly solvated state of dye complex existed into solution. Reaction mixture was subjected to UV/Visible and GC mass spectrum analysis that proves the secondary consecutive reaction was operative in rate determining step and finally dye complex end into smaller fragments