High efficient Cefixime removal from water by the sillenite Bi12TiO20: Photocatalytic mechanism and degradation pathway

International audienceWater pollution is a significant concern that affects the environment and human health. Antibiotics are among the most dangerous types of pollutants spreading in our time because of their harmful effects, such as generating antibiotic-resistant bacteria. Therefore, it is necessary to attain an eco-friendly and efficient method for treating those hazardous compounds. This study proposes a clean approach for removing antibiotics from pharmaceutical wastewater, using an efficient photocatalyst Bi12TiO20 (BTO) synthesized by the sol-gel method. Several characterizations were carried out to identify the obtained catalyst, such as XRD, BET, Raman, FESEM, EDX with elemental mapping, TEM, UV–Vis, and PL, in which the space group of BTO crystals was discovered to be I23, with a bandgap of 2.9 eV. To evaluate the photocatalytic properties of the catalyst BTO, Cefixime (CFX) was chosen as a pollutant example. The photocatalytic efficiency was optimized using an artificial neural network (ANN) method with a deep learning technique. The ANN network was trained using experimental data with various BTO dosages and CFX initial concentrations at varying pH. The results have shown that the BTO catalyst can lead to 94.93% CFX degradation and 87.66% mineralization within only 3 h, this efficiency was very high compared to other catalysts used in previous studies. The relative importance of different photocatalytic parameters was estimated using ANN data, the highest effective parameter was the initial CFX concentration. Then, the by-products were analyzed using GC-MS, and a pathway for CFX degradation was suggested. The mechanism of the degradation was also investigated in the presence of scavenger agents. The results showed that the CFX molecules had been degraded totally into tiny molecules, proving the efficient performance of this catalyst. These findings make this sillenite an effective catalyst for removing antibiotics from the aquatic environment. © 2021 Elsevier Lt

Techno-economic studies for a pilot-scale Bi12TiO20 based photocatalytic system for pharmaceutical wastewater treatment: From laboratory studies to commercial-scale applications

International audienceThis work proposes an appropriate method for cleaning pharmaceutical wastewater from hazardous compounds like cephalosporin and also conducts innovative full design criteria for commercial-scale applications associated with full economic evaluation. The sillenite Bi12TiO20 (BTO) was used as a catalyst in this approach, and it was chosen based on previous studies. First, the BTO catalyst was characterized and tested before proposing it as an alternative solution. The catalyst BTO has been characterized using various characterization techniques such as XRD, TEM, BET, XPS and DRS. This catalyst was found to be a nanoparticles sillenite type with a space group cubic structure type I23 agglomerated in grains form with particle size around 3–15 μm and a surface area of 8.84 m2/g; its bandgap was found to be at ~2.9 eV. After characterization, the catalyst BTO was tested for the removal of three different antibiotics, which are Cefixime (CFX), Cefaclor (CFC), Cefuroxime (CFRM), and it has shown efficient photocatalytic activity with rates of 94%, 81%, and 69.71% within 210 min for CFX, CFC and CFRM; respectively. After that, a photocatalytic treatment system was proposed as a large scale of the previous process. An integrated economic assessment for treating 1 L/min antibiotic polluted effluents using this pilot scale design was presented to examine the system's commercial potential. The findings of batch experimental testing and pilot-scale designs proved the viability of employing BTO sillenite in a large-scale demonstration for pharmaceutical wastewater treatment as a sustainable and cost-effective photocatalytic system. © 2022 Elsevier Lt

Bismuth Sillenite Crystals as Recent Photocatalysts for Water Treatment and Energy Generation: A Critical Review

International audiencePhotocatalysis has been widely studied for environmental applications and water treatment as one of the advanced oxidation processes (AOPs). Among semiconductors that have been employed as catalysts in photocatalytic applications, bismuth sillenite crystals have gained a great deal of interest in recent years due to their exceptional characteristics, and to date, several sillenite material systems have been developed and their applications in photoactivity are under study. In this review paper, recent studies on the use of Bi-based sillenites for water treatment have been compiled and discussed. This review also describes the properties of Bi-based sillenite crystals and their advantages in the photocatalytic process. Various strategies used to improve photocatalytic performance are also reviewed and discussed, focusing on the specific advantages and challenges presented by sillenite-based photocatalysts. Furthermore, a critical point of certain bismuth catalysts in the literature that were found to be different from that reported and correspond to the sillenite form has also been reviewed. The effectiveness of some sillenites for environmental applications has been compared, and it has demonstrated that the activity of sillenites varies depending on the metal from which they were produced. Based on the reviewed literature, this review summarizes the current status of work with binary sillenite and provides useful insights for its future development, and it can be suggested that Bismuth sillenite crystals can be promising photocatalysts for water treatment, especially for degrading and reducing organic and inorganic contaminants. Our final review focus will emphasize the prospects and challenges of using those photocatalysts for environmental remediation and renewable energy applications. © 2022 by the authors. Licensee MDPI, Basel, Switzerland