Solar Degradation of Sulfamethazine Using rGO/Bi Composite Photocatalysts

Abstract

Heterogeneous photocatalysts for water decontamination were obtained by the optimized synthesis of bismuth-functionalized reduced graphene oxide (rGO/Bi) using the Hummer method and microwave treatment. Sulfamethazine (SMZ) was used as model pollutant to evaluate the photocatalytic efficacy. Photocatalysts were characterized by VP-SEM, HRTEM, XDR, XPS, RAMAN, and FTIR analyses, which confirmed the effective reduction of GO to rGO and the presence of bismuth as a crystalline phase of Bi2O3 polydispersed on the surface. Their performance was influenced by the rGO/Bi ratio, microwave temperature, and treatment time. The as-obtained 5%rGO/Bi composite had the highest photocatalytic activity for SMZ degradation under visible light irradiation (λ > 400 nm), achieving 100% degradation after only 2 h of treatment. The degradation yield decreased with higher percentages of rGO. Accordingly, the rGO/Bi catalysts efficiently removed SMZ, showing a high photocatalytic activity, and remained unchanged after three treatment cycles; furthermore, cytotoxicity tests demonstrated the nontoxicity of the aqueous medium after SMZ degradation. These findings support the potential value of these novel composites as photocatalysts to selectively remove pollutants in water treatment plants.

Characteristics and Behavior of Different Catalysts Used for Water Decontamination in Photooxidation and Ozonation Processes

“…FTIR results for 5% rGO/Bi reveal a major reduction in the stretching vibration of C=O groups, confirming the GO reduction. In this case, peaks below 1000 cm −1 can be assigned to metal-oxygen vibrations, showing that Bi is well-functionalized on the rGO surface [80]. Raman spectra results for 5% rGO/Bi composite also indicate that GO in rGO/Bi sample is well deoxygenated and reduced.…”

“…In this way, rGO has been combined with different metal oxides (TiO 2 , ZnO, Cu 2 O, Bi 2 WO 6 , etc.) and found to be a very effective photocatalyst for the degradation of different pollutants from water and to prevent corrosion and leaching of the metal oxide nanoparticles in water [80,81,123]. A series of rGO/TiO 2 [81] and rGO/Bi composites [80] with different rGO contents were exhaustively characterized, and their structural, chemical, and electronic properties were compared with their photocatalytic activity in the degradation of organic pollutants in aqueous solution.…”

“…% rGO-TiO 2 composites were used as photocatalysts for ethylparaben (EtP) degradation from water under UV radiation [80]. Direct photolysis of EtP under UV radiation alone achieves 61.5% degradation after 40 min of irradiation (Table 13).…”

“…Textural characteristics and bandgap energy (Eg) of rGO/metal oxide catalysts (adapted from[80,81]). …”

Magnetic Nanoparticles of Fe₃O₄ Biosynthesized by <em>Cnicus Benedictus</em> Extract: Photocatalytic Study of Organic Dye Degradation and Antibacterial Behavior

“…Therefore, it is important to study, propose and promote the use of endemic plants in nanomaterial synthesis processes. On the other hand, the applications of the Fe3O4 nanoparticles in the field of the degradation of organic pollutes and environmental remediation has been extensively studied due to their photocatalytic properties and the emerging needs for environmental remediation [32][33][34][35]. In this work, we reported an environmentally friendly alternative synthesis route of Fe3O4 nanoparticles with significant antibacterial and photocatalytic activity evaluated in Red Congo (CR) degradation.…”