Preparation and UV/Vis Spectroscopic Characterization of N,N‐Disubstituted 2‐Amino‐5‐arylazoselenazoles and Some of Their Carbocyclic and Heterocyclic Analogues

By coupling of aryldiazonium salts 5 with N,N‐disubstituted 2‐amino‐5H‐selenazoles 4 deeply coloured 5‐arylazo‐substituted 2‐amino‐selenazoles 6a—6l have been prepared and their solvatochromic properties determined by means of UV/Vis spectroscopy, and compared with the ones of several other arylazosubstituted N,N‐dialkylanilines 7a—7d , 2‐(N,N‐dialkylamino)‐thiophenes 8a—8e , and 2‐(N,N‐dialkylamino)‐thiazoles 9a—9c .     

Enhanced degradation of azo dyes wastewater by S-scheme heterojunctions photocatalyst g-C3N4/MoS2 intimately coupled Rhodopseudomonas palustris with chitosan modified polyurethane sponge carrier

With the development of azo dyes in every aspect of life, azo dyes have brought serious harm to human beings and ecological environment. In this study, a new intimately coupling photocatalysis and biodegradation (ICPB) system was reported: The rod-like graphite carbon nitride-molybdenum disulfide (RCM) of S-scheme was prepared by hydrothermal method and loaded onto the exterior surface of chitosan modified polyurethane sponge (CPU), and Rhodopseudomonas palustris (R. palustris) with metabolic versatility, significant survivability and decomposition to toxic and nonbiodegradable organics was combined inside the carrier. The rod-like RCM and egg-like R. palustris in the CPU were observed, the 13.1° and 27.6° characteristic peaks of g-C₃N₄ and 33.4° and 57.6° characteristic peaks of MoS₂ were detected, N–H, NC, C–S–Mo, N–Mo bonds were confirmed, and E_g = 2.42 eV were calculated in RCM, which confirmed the successful preparation of R. palustris/RCM@CPU. The doping ratio of MoS₂ was 6%, RCM dosage was 0.2 g and chitosan doping ratio was 0.5%, R. palustris/RCM@CPU system showed high degradation efficiency. The removal rates of Congo red, methyl orange and carmine were 99.5%, 97.5% and 99.5%, respectively. The significant removal of R. palustris/RCM@CPU system on azo dyes was due to that the RCM of S-scheme produced strong oxidizing superoxide radical (^.O₂⁻), hydroxyl radical (^.OH) and hole (h⁺), and could oxidize azo groups and benzene rings of azo dyes to form alkane compounds, which were mineralized by R. palustris. The close cooperation among CPU adsorption, RCM oxidation and R. palustris mineralization effectively enhanced the degradation efficiency of R. palustris/RCM@CPU system for a variety of azo dyes. This study would propose a new means for the degradation efficiency of azo dye wastewater.