SORPTIVE-CATALITIC ROLE OF ACTIVATED CARBON IN THE PROCESS OF REMOVING CRYSTAL VIOLET FROM THE AQUEOUS SOLUTION IN THE PRESENCE OF HYDROGEN PEROXIDE

Activated carbons play an important role in the processes of purifying waters, wastewaters and gases. While analyzing the effectiveness of these processes mainly the sorptive properties of the activated carbons are considered, taking no account of their catalytic abilities. According to the data presented in the literature, activated carbons catalyze the decomposition of oxidants such as hydrogen peroxide or ozone creating the hydroxyl radical, which is the strongest oxidating factor. This reaction may be used to oxidate the organic impurities in the aqueous solutions. In the activated carbon - oxidant - organic impurities system most probably both the processes of sorption and catalytic oxidation of the organic compounds take place. In this paper the effectiveness of removing the crystal violet from the aqueous solution in the presence od various activated carbons and hydrogen peroxide was examined (C-d=20 mg/dm(3), CH2O2(1) = 375 mg/dm(3). CH2O2(2) = 3750 mg/dm(3), m(ac)= 0.5 g, t = 160 min). In the research the commercial activated carbon WDex, activated carbon WDex oxidated with hydrogen peroxide and activated carbon WDex saturated with crystal violet and regenerated with Fe2+/H2O2 i Fe2+/CaO2 (sorption - oxidation of adsorbed compounds) were used. It has been observed that in specified conditions the effectiveness of removing the dye in the presence of carbon and oxidant is greater (72 mg/g) than the sorptive abilities of the activated carbons (34 mg/g). It has been also concluded that the efficiency of the process depends on the type of the activated carbon used, the amount of the hydrogen peroxide and the method of carrying out the process. It has been also show that the effectiveness of removing crystal violet from the aqueous solution is greater when the process is carried out in the activated carbon - crystal violet - hydrogen peroxide system than in case of removing the dye by the sorption on activated carbon - regeneration of the activated carbon - subsequent regeneration (56 mg,/g). The results of the research confirm both the sorptive and catalytic properties of the activated carbons in the analyzed process.