Abstract
In present work, we examine the photocatalytic properties of S-doped TiO2 (S1, S2) compared to bare TiO2 (S0) in present work. The photocatalytic tests were performed in alkaline aqueous solutions (pH = 10) of three differently substituted phenols (phenol (I), 4,4′-isopropylidenebisphenol (II), and 4,4′-isopropylidenebis(2,6-dibromophenol) (III)). The activity of the catalysts was evaluated by monitoring I, II, III degradation in the reaction mixture. The physicochemical properties (particle size, ζ-potential, Ebg, Eu, E0cb, E0vb, σo, KL) of the catalysts were established, and we demonstrated their influence on degradation reaction kinetics. Substrate degradation rates are consistent with first-order kinetics. The apparent conversion constants of the tested compounds (kapp) in all cases reveal the sulfur-loaded catalyst S2 to show the best photocatalytic activity (for compound I and II S1 and S2 are similarly effective). The different efficiency of photocatalytic degradation I, II and III can be explained by the interactions between the catalyst and the substrate solution. The presence of bromine substituents in the benzene ring additionally allows reduction reactions. The yield of bromide ion release in the degradation reaction III corresponds to the Langmuir constant. The mixed oxidation-reduction degradation mechanism results in higher degradation efficiency. In general, the presence of sulfur atoms in the catalyst network improves the degradation efficiency, but too much sulfur is not desired for the reduction pathway.
Highlights
Publisher’s Note: MDPI stays neutralThe depletion of water resources is one of the key problems of the modern world
The contamination of industrial wastewater has become a major issue due to the tremendous diversity of potential micro-pollutants originating from industrial products such as plastics, agrochemicals, pharmaceuticals, or household chemicals, which can seep into the ground and surface waters
SC doped nanopowders were synthesized in a solid-phase method where metatitanic acid (MA) and thiourea (TU) were triturated in an agate mortar to obtain a homogeneous mass, further annealed in an air atmosphere at 500 ◦ C for 1 h
Summary
The depletion of water resources is one of the key problems of the modern world. The overuse of water and its growing pollution has caused the scarcity of water resources. The contamination of industrial wastewater has become a major issue due to the tremendous diversity of potential micro-pollutants originating from industrial products such as plastics, agrochemicals, pharmaceuticals, or household chemicals, which can seep into the ground and surface waters. Aromatic hydrocarbons are one of the most toxic, but still utilised widely in petrochemical, chemical, and pharmaceutical industries. The presence of aromatic compounds in aqueous environments creates serious problems due to complex mechanisms of their toxicity, persistence in the environment, and significant bioaccumulation. The increasing public concern with these environmental pollutants brings upon the need to develop novel treatment methods, in which solar-lightinduced photocatalytic degradation of micro-pollutants gains growing attention. The utilisation of colloidal semiconductors and introducing catalysts to promote specific redox processes on semiconductor surfaces were developed in the last decades
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