Decolorization and mineralization of reactive dyes, by the $H_2O_2$/UV process with electrochemically produced $H_2O_2$

Abstract

Decolorization of Reactive Red 238, Reactive Orange 16, Reactive Black 5 and Reactive Blue 4 was studied in the UV/$H_2O_2$ process with $H_2O_2$ being produced electrochemically. The experimental results show that decolorization increased considerably when switching on the electrochemical production of $H_2O_2$. Complete decolorization (>99%) was achieved for all dyes under the applied experimental conditions, partial mineralization (49-85%) was obtained, which depends on the type of dye. Reactive Red 238 was used to investigate operational parameters and it was found that decolorization was influenced by the applied electrical current of the electrochemical cell and flow rate. Decolorization and mineralization of Reactive Red 238 can be described by pseudo-first order kinetics. It was found that the initial concentration of Reactive Red 238 has a negative influence on the pseudo-firstorder reaction constant.Z uporabo UV/$H_2O_2$ postopka, kjer smo $H_2O_2$ proizvedli elektrokemijsko, smo preučevali razbarvanje reaktivnih barvil Reactive Red 238, Reactive Orange 16, Reactive Black 5 in Reactive Blue 4. Iz eksperimentalnih rezultatov je razvidno, da se razbarvanje znatno poveča, ko vključimo elektrokemijsko proizvodnjo $H_2O_2$. Popolno razbarvanje vseh barvil (>99 %) smo dosegli pod uporabljenimi eksperimentalnimi pogoji, delna razgradnja (49-85 %) pa je bila odvisna od vrste barvila. Za ugotavljanje delovnih parametrov smo uporabili reaktivno barvilo Reactive Red 238. Na razbarvanje vplivajo: uporabljen električni tok ter hitrost pretoka. Razbarvanje in razgradnjo reaktivnega barvila Reactive Red 238 lahko opišemo z reakcijo psevdo-prvega reda, kjer ima začetna koncentracija barvila negativen vpliv na konstanto reakcije