Characterization of CoCr2O4 semiconductor: A prominent photocatalyst in the degradation of basic blue 41 from wastewater

International audienceThe hazards of dyes on the water have driven researchers to develop strategies to remove them. Our choice for this study was photocatalysis. In view of this, semiconductor CoCr2O4 (CCO) by the co-precipitation method was synthesized and explored for its photo-catalytic efficiency by the possible elimination of basic blue 41 (BB41) by degradation in the visible light irradiation. The phase of synthesized CCO was refined and characterized structurally using X-ray diffraction (XRD) associated with the Rietveld method to illustrate the structural form of this spinel. The characteristic bands of CCO were identified for the vibrational groups using the FT-IR spectrum. Using the diffused reflectance data, an optical gap band of 1.65 eV was determined. The energy diagram resulting after the electrochemical study confirmed that the catalyst adopts the nature of n-type semiconductors. The photocatalytic degradation of BB41 by CCO as a function of time of irradiation, pH of BB41 solution, CCO dose and initial BB41 concentration was determined. The degradation percentage of 99% was studied for. 300 min but the efficiency decreased as the initial dye concentration was decreased. The photo-degradation mechanism and the compliance of pseudo-first-order models are discussed in this contribution. © 2021 Elsevier B.V

Photocatalytic performances of ZnCr2O4 nanoparticles for cephalosporins removal: Structural, optical and electrochemical properties

International audienceThe present contribution is about the synthesis of a composite photo-catalyst with remarkable activity and a narrow gap band to explore the possibility of using it for the removal of antibiotics in water. The synthesis of spinel ZnCr2O4 (ZCO) nanoparticles in pure phase by the combination of sol-gel methodology at 700 °C was achieved. The identification and characterization were done using characterization studies such as X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and UV–Visible spectroscopy techniques. The illustration of spinel structure was done with the help of lattice constants using XRD data. The optical and dielectric properties of ZCO were measured using the UV–Visible data. The photo-electrochemical property revealed the flat band potential value of 0.3 VSCE which ascribes the n-type semiconductor. The photocatalytic activity of ZCO nanoparticles under visible light source in degrading the three pharmaceutical products such as Cefaclor (CFR), Cefuroxime (CFRM) and Cefixime (CFX) of 66.9%, 55.2% and 80.1% was also successfully studied. © 2021 Elsevier B.V

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