A Sharp Jump in Photocatalytic Activity of Elemental Sulfur for Dye Degradation in Alkaline Solution

Abstract

Elemental sulfur is a low‐cost and abundant substance as one of the largest by‐products of the oil industry which was widely used in many industrial activities. Cyclo‐octasulfur (S8) is one of the sulfur allotropes that is a very stable substance in standard conditions. In this study, we report a low‐cost and fast method for the degradation of methyl violet in water under visible light and also sunlight by using elemental sulfur (S8). The results show that sulfur is a good photocatalyst which operates under visible light and can be utilized for degradation of methyl violet. The photocatalytic degradation of methyl violet in acidic, neutral, and alkaline media was investigated, and it was found that the photocatalytic efficiency increases dramatically in alkaline solution. The effects of the initial concentration of the dye, photocatalyst dosage, solution pH, and photocatalyst reusability were investigated. The kinetics of the reaction were studied in detail, and the photocatalytic rate equation was presented.

Simultaneous photocatalytic Cr(VI) reduction and phenol degradation over copper sulphide-reduced graphene oxide nanocomposite under visible light irradiation: Performance and reaction mechanism

“…The modeling of the kinetic data with an appropriate kinetic model allows to determine the apparent rate constant and the order of reaction of the photocatalytic process. It is wellestablished that the rate (r) of a photocatalytic reaction for a single component can be defined using equation (2) [50,52]:…”

“…Although this pseudo first-order rate equation has been extensively used in the literature for modeling photocatalytic kinetic data, it is based on the Langmuir classical isothermal model, which assumes a homogeneous surface. However, the surface of a catalyst is rarely homogeneous and several studies have been carried out in this regard suggested the possibility to use modified Langmuir Freundlich isotherm (an isotherm for adsorption onto heterogeneous surface from liquid phase), Equation 3 [52].…”

“…s introduced recently in refs. [52,53]. By plotting the normalized concentration (C/C0) versus normalized time scale (t…”