Decolorization of Reactive Black 5 using a dielectric barrier discharge in the presence of inorganic salts

Abstract

Inorganic salts improve the coloration of textiles, which increases the pollution load of dye-house effluent in general. Decolorization of the reactive textile dye C.I. Reactive Black 5 was studied using Advanced Oxidation Processes (AOPs) in a non-thermal plasma reactor, based on the coaxial water falling film Dielectric Barrier Discharge (DBD). The initial dye concentration in the solution was 40.0 mg L-1. The effects of the addition of different high concentrations of inorganic salt (NaCl, Na2SO4 and Na2CO3) on the degree of decolorization were studied. The dye solution was recirculated through the DBD reactor with an applied energy density of 45.0-315 kJ L-1. The influence of residence time was investigated after 5 min and 24 h of plasma treatment. Decolorization of the dye was monitored spectrophotometrically. The pH value and the conductivity of the dye solution were measured after each recirculation. The most effective decolorization of over 90 % was obtained with the addition of NaCl (50 g L-1) with an applied energy density of 135 kJ L-1 and after a residence time of 24 h of plasma treatment. Decolorization of the solutions containing inorganic salts Na2SO4 and Na2CO3 were lower than for the solution without salt.

Neorganske soli poboljšavaju bojenje tekstila. Povećana koncentracija soli u otpadnoj vodi koja potiče iz tekstilne industrije dodatno opterećuje otpadnu vodu u celini. U okviru ovog rada proučavano je obezbojavanje reaktivne tekstilne boje reaktivno crno 5 koristeći unapređeni oksidacioni proces (AOP) pomoću koaksijalnog reaktora na bazi netermičke plazme. Reaktor radi na principu dielektričnog barijernog pražnjenja (DBD), pri čemu je jedan sloj dielektrika tanak sloj tretirane vode koji se konstantno obnavlja (protočni tip reaktora). Početna koncentracija boje u tretiranom rastvoru je bila 40,0 mg L-1. Proučavan je uticaj različitih visokih koncentracija neorganskih soli (NaCl, Na2SO4 i Na2CO3) na stepen obezbojenja. Rastvor boje je sedam puta recirkulasan kroz DBD reaktor, što odgovara primenjenoj gustini energije od 45 do 315 kJ L-1. Procenat obezbojenja rastvora boje je meren posle 5 min i posle 24 h od tretmana plazmom. Obezbojavanje boje je praćeno pomoću spektrofotometrijskog merenja. Posle svake recirkulacije rastvora boje merene su promena pH vrednosti i provodljivost rastvora. Najefikasnije obezbojenje od preko 90 % dobijeno je u sistemu sa dodatkom 50 g L-1 NaCl, pri primenjenoj gustini energije od 45 kJ L-1 i posle 24 sata od plazma tretmana. Obezbojenja rastvora boje koji sadrže neorganske soli Na2SO4 i Na2CO3 bila su niža nego kod rastvora boje bez dodatka soli.