Structural and Optical Properties of Bi12NiO19 Sillenite Crystals: Application for the Removal of Basic Blue 41 from Wastewater

This article covers the structural and optical property analysis of the sillenite Bi12NiO19 (BNO) in order to characterize a new catalyst that could be used for environmental applications. BNO crystals were produced by the combustion method using Polyvinylpyrrolidone as a combustion reagent. Different approaches were used to characterize the resulting catalyst. Starting with X-ray diffraction (XRD), the structure was refined from XRD data using the Rietveld method and then the structural form of this sillenite was illustrated for the first time. This catalyst has a space group of I23 with a lattice parameter of a = 10.24 Å. In addition, the special surface area (SSA) of BNO was determined by the Brunauer-Emmett-Teller (BET) method. It was found in the range between 14.56 and 20.56 cm2·g−1. Then, the morphology of the nanoparticles was visualized by Scanning Electron Microscope (SEM). For the optical properties of BNO, UV-VIS diffusion reflectance spectroscopy (DRS) was used, and a 2.1 eV optical bandgap was discovered. This sillenite′s narrow bandgap makes it an effective catalyst for environmental applications. The photocatalytic performance of the synthesized Bi12NiO19 was examined for the degradation of Basic blue 41. The degradation efficiency of BB41 achieved 98% within just 180 min at pH ~9 and with a catalyst dose of 1 g/L under visible irradiation. The relevant reaction mechanism and pathways were also proposed in this work

Polyaniline/Bi₁₂TiO₂₀ Hybrid System for Cefixime Removal by Combining Adsorption and Photocatalytic Degradation

Sillenite catalysts have shown efficient photocatalytic activity for the removal of various pollutants from water in previous studies, thus enhancing their activity by combining them with other materials will be very promising for environmental applications. In this context, an interesting hybrid system containing Polyaniline (PANI) as an adsorbent and Bi12TiO20 (BTO) sillenite as a catalyst was proposed in this work. Cefixime (CFX) has been selected as a pollutant for this study, and its removal was evaluated using PANI (adsorption), PANI and BTO (combined system) and the hybrid system Bi12TiO20/Polyaniline (BTO/PANI). First, the impact of PANI adsorption was investigated on its own; after that, the solution was filtered to separate the adsorbent from the liquid in order to re-treat the solution using photocatalysis (combining adsorption with photocatalysis). At the same time, a similar technique was used involving the hybrid system BTO/PANI. The results show that the hybrid system can remove a very high Cefixime concentration of 30 mg/L, almost 100%, within only 2 h, and this is better than previous investigations. These results indicate that it is possible to combine photocatalysis and adsorption processes to control water pollution

Structural and electrochemical characterizations of Bi12CoO20 sillenite crystals: degradation and reduction of organic and inorganic pollutants

International audienceThe present contribution is to synthesize and characterize a new material photocatalyst. It also explores the possibility of using it to remove organic and inorganic pollutants in water. In this context, the sillenite Bi12CoO20 (BCO) in pure phase was synthesized by the combustion sol-gel method. The phase was identified by X-ray diffraction (XRD) then it was refined in the cubic symmetry in the space group (I23 N degrees 197) using the Rietveld refinement method; the lattice constant was accurately determined. A direct optical bandgap of 2.56 eV was evaluated using the UV-Visible diffuse reflectance. The electrochemical properties were investigated for the first time. A flat band potential of E-fb = 0.62 V-SCE was found with a p-type character; the hole density N-d = 54.2 x 10(17) cm(-3) extends the depletion width at 27 nm. The photocatalytic activity of BCO nanoparticles was tested to eliminate organic and inorganic pollutants namely the Basic red 46 (BR46) and hexavalent chromium Cr(VI). An acceptable rate was observed within 3 h for both contaminants

Exploring the Synthesis of Novel Sillenite Bi12SnO20: Effect of Calcination Temperature on the Phase Formation and Catalytic Performance

International audienceSillenite materials have been the focus of intense research in recent years due to their unique properties and distinct structure with the I23 space group. This electronic structure has reflected high-quality applications and results for some environmental processes such as photocatalysis. This paper investigates the synthesis of a new sillenite, Bi12SnO20, and its characteristics, emphasizing its potential for photocatalytic applications. The sillenite Bi12SnO20 has been synthesized through the co-precipitation method by mixing the appropriate ratio of Bi and Sn ions. The obtained particles after precipitation and drying were characterized by thermogravimetric analysis (TGA) and then calcined at different temperatures based on this analysis. The phase has been identified by structural analysis using X-ray diffraction (XRD), and its morphology after identification was carried out by scanning electron microscopy (SEM). The calcination temperature has been found to have a critical role in obtaining the phase, where the phase was found to be formed at temperatures between 310 and 400 °C and changed to other phases within higher temperatures. The physicochemical properties of this sillenite were also studied by Fourier-transform infrared spectroscopy (FTIR) and UV Visible Spectrometer (UV-Vis). To study the obtained phases at different calcination temperatures, performance testing was performed under visible light to remove different contaminants, which are Tetracycline, Bisphenol A, and Rhodamine B. The phase Bi12SnO20 obtained at 350 °C with a catalyst dose of 1 g/L showed the highest performance for removing these pollutants with concentrations of 20 mg/L, with an efficiency of almost 100% within 2 h. This work will be useful as an important resource and strategy for the development of this sillenite material in its pure phase

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

Photocatalysis 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

Application of Bi(12)ZnO(20) Sillenite as an Efficient Photocatalyst for Wastewater Treatment: Removal of Both Organic and Inorganic Compounds

International audienceThis work aims to synthesize and characterize a material that can be used as an effective catalyst for photocatalytic application to remove both organic and inorganic compounds from wastewater. In this context, sillenite BiZnO (BZO) in a pure phase was synthesized using the sol-gel method. Before calcination, differential scanning calorimetry (DSC) analysis was done to determine the temperature of the formation of the sillenite phase, which was found to be 800 °C. After calcination, the phase was identified by X-ray diffraction (XRD) and then refined using the Rietveld refinement technique. The results prove that BZO crystals have a cubic symmetry with the space group I23 (N°197); the lattice parameters of the structure were also determined. From the crystalline size, the surface area was estimated using the Brunauer-Emmett-Teller (BET) method, which was found to be 11.22 m/g. The formation of sillenite was also checked using the Raman technique. The morphology of the crystals was visualized using electron scanning microscope (SEM) analysis. After that, the optical properties of BZO were investigated by diffuse reflectance spectroscopy (DRS) and photoluminescence (PL); an optical gap of 2.9 eV was found. In the final step, the photocatalytic activity of the BZO crystals was evaluated for the removal of inorganic and organic pollutants, namely hexavalent chromium Cr(VI) and Cefixime (CFX). An efficient removal rate was achieved for both contaminants within only 3 h, with a 94.34% degradation rate for CFX and a 77.19% reduction rate for Cr(VI). Additionally, a kinetic study was carried out using a first-order model, and the results showed that the kinetic properties are compatible with this model. According to these findings, we can conclude that the sillenite BZO can be used as an efficient photocatalyst for wastewater treatment by eliminating both organic and inorganic compounds

Advanced Photocatalytic Treatment of Wastewater Using Immobilized Titanium Dioxide as a Photocatalyst in a Pilot-Scale Reactor: Process Intensification

International audienceIn many nations, particularly those experiencing water scarcity, novel approaches are being applied to clean wastewater. Heterogeneous photocatalysis is the most widely used of these approaches because it entails the decomposition of organic molecules into water and carbon dioxide, which is a more ecologically benign process. In our study, we studied the photocatalytic degradation process on the effluent flumequine. This treatment is made through a solar pilot reactor in the presence of immobilized titanium dioxide with three light intensities and two types of water as solvents. A variety of factors that might influence the rate of deterioration, such as flow rate, light intensity, and initial concentration, have been investigated. The maximal degradation of flumequine was achieved at more than 90% after 2.5 h under optimal conditions (an initial concentration of 5 mg/L, three lamp light intensities, and a flow rate of 29 L/h). By combining the oxidized agent H2O2 with this process, the photocatalytic activity was improved further to 97% under the same conditions. The mineralization of this product has also been tested using total organic carbon (TOC) analysis. A high mineralization rate has been recorded at around 50% for a high initial concentration (20 mg/L) at a flow rate of 126 L/h. The results demonstrated the highly effective removal of flumequine and the efficacy of this photocatalytic system

Synthesis and Characterization of ZnBi2O4 Nanoparticles: Photocatalytic Performance for Antibiotic Removal under Different Light Sources

International audienceThis work aims to synthesize a photocatalyst with high photocatalytic performances and explore the possibility of using it for antibiotic removal from wastewater. For that, the spinel ZnBi2O4 (ZBO) was produced with the co-precipitation method and its optical, dielectric, and electrochemical characteristics were studied. The phase has been determined and characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). For the ZBO morphology, a Scanning Electron Microscopy (SEM) has been used. Then, the optical and dielectric properties of ZBO have been evaluated by calculating refractive index n (lambda), extinction coefficient (k), dissipation factor (tan delta), relaxation time (tau), and optical conductivity (sigma opt) using the spectral distribution of T(lambda) and R(lambda). An optical gap band of 2.8 eV was determined and confirmed. The electrochemical performance of ZBO was investigated and an n-type semiconductor with a flat band potential of 0.54 V_SCE was found. The photocatalytic efficiency of ZBO was investigated in order to degrade the antibiotic Cefixime (CFX) under different light source irradiations to exploit the optical properties. A high CFX degradation of approximately 89% was obtained under solar light (98 mW cm(-2)) only after 30 min, while 88% of CFX degradation efficiency has been reached after 2 h under UV irradiation (20 mW cm(-2)); this is in line with the finding of the optical characterizations. According to the obtained data, solar light assisted nanoparticle ZBO can be used successfully in wastewater to remove pharmaceutical products

Disinfection of corona and myriad viruses in water by non-thermal plasma: a review

International audienceNowadays, in parallel to the appearance of the COVID-19 virus, the risk of viruses in water increases leading to the necessity of developing novel disinfection methods. This review focuses on the route of virus contamination in water and introduces non-thermal plasma technology as a promising method for the inactivation of viruses. Effects of essential parameters affecting the non-thermal discharge for viral inactivation have been exposed. The review has also illustrated a critical discussion of this technology with other advanced oxidation processes. Additionally, the inactivation mechanisms have also been detailed based on reactive oxygen and nitrogen species