Dyes degradation using atmospheric pressure dielectric barrier discharge pencil plasma jet

Abstract

The dye degradation efficacy of the cold plasma pencil jet is presented in the present investigation. Air plasma is produced in the cylindrical coaxial dielectric barrier discharge configuration. Electrical characterization of plasma is performed and the plasma species are identified using optical emission spectroscopy. For the dye degradation study using air plasma, six different types of dyes (erythrosine, metanil yellow, sudan I, crystal violet, rhodamine B, and Indigo) are chosen. The degradation of dyes is analyzed using UV visible spectroscopy, total organic carbon, and chemical oxygen demand. The results showed complete degradation of all the dyes in UV visible analysis with minimum time for indigo (3 minutes) and maximum time for erythrosine (45 minutes). Moreover, erythrosine (k = 1.08 mg L-1 min-1) and sudan I (k= 3.46 mg L-1 min-1) follows zero-order degradation kinetic and metanil yellow (k = 0.094 min-1), crystal violet (k = 0.25 min-1), rhodamine B (k = 0.17 min-1), Indigo (k = 0.81 min-1) follows first-order degradation kinetics. Also, substantial enhancement in mineralization and reduction in chemical oxygen demand of all the dyes occurs after plasma treatment. The toxicity of plasma degraded dye solution toward freshwater algae species (Chlorella Sorokiniana and Chlorella Pyrenoidosa) are significantly low compared to virgin dyes solutions. The study reveals that pencil plasma jet substantially degrade dyes as well as converts the dyes solutions non-toxic.