Metal-doped perovskite BiFeO3/rGO nanocomposites towards the degradation of acetaminophen in aqueous phase using plasma-photocatalytic hybrid technology

Determinants for an Efficient Enzymatic Catalysis in Poly(Ethylene Terephthalate) Degradation

The enzymatic degradation of the recalcitrant poly(ethylene terephthalate) (PET) has been an important biotechnological goal. The present review focuses on the state of the art in enzymatic degradation of PET, and the challenges ahead. This review covers (i) enzymes acting on PET, (ii) protein improvements through selection or engineering, (iii) strategies to improve biocatalyst–polymer interaction and monomer yields. Finally, this review discusses critical points on PET degradation, and their related experimental aspects, that include the control of physicochemical parameters. The search for, and engineering of, PET hydrolases, have been widely studied to achieve this, and several examples are discussed here. Many enzymes, from various microbial sources, have been studied and engineered, but recently true PET hydrolases (PETases), active at moderate temperatures, were reported. For a circular economy process, terephtalic acid (TPA) production is critical. Some thermophilic cutinases and engineered PETases have been reported to release terephthalic acid in significant amounts. Some bottlenecks in enzyme performance are discussed, including enzyme activity, thermal stability, substrate accessibility, PET microstructures, high crystallinity, molecular mass, mass transfer, and efficient conversion into reusable fragments.

Norfloxacin mineralization under light exposure using Sb-SnO2 ceramic anodes coated with BiFeO3 photocatalyst

Advanced Oxidation Processes have been proven to be an efficient way to remove organic pollutants from wastewaters. In this work, a ceramic electrode of Sb-SnO₂ (BCE) with a layer of the photocatalytic material BiFeO₃ (BFO-BCE), has been characterized electrochemically and further tested for norfloxacin photo-electrooxidation in the presence and absence of light. The electrode photoactivity was highly enhanced thanks to the presence of BiFeO₃, as confirmed by Linear Sweep Voltammetry, chronoamperometry and potentiometry, and Electrochemical Impedance Spectroscopy. Additionally, working in galvanostatic mode, a high mineralization of norfloxacin was achieved after 240 min, reaching 62% at 25 mA cm^-2 under light conditions. This value is comparatively higher than the 40% achieved with the BCE. The oxidation byproducts were followed by ionic chromatography and HPLC analysis, which also allowed us to propose an oxidation pathway of the norfloxacin molecule. Finally, some indicators of the reactor performance such as the Mineralization Current Efficiency and the specific energy consumption were analyzed, revealing that lower current densities (8.3 mA cm^-2) led to higher current efficiencies, and that light improved both the current efficiency and energy consumption.

Mechanism and efficiency of photocatalytic triclosan degradation by TiO2/BiFeO3 nanomaterials

Hierarchical porous TiO₂ photocatalytic nanomaterials were fabricated by impregnation and calcination using a peanut shell biotemplate, and TiO₂/BiFeO₃ composite nanomaterials with different doping amounts were fabricated using hydrothermal synthesis. The micromorphology, structure, element composition and valence state of the photocatalyst were analyzed using a series of characterization methods, including X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), BET surface area (BET), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance (UV-vis), fluorescence spectroscopy (PL) and other technological means. Finally, the degradation mechanism and efficiency of BiFeO₃ composite photocatalyst on the target pollutant triclosan were analyzed using a xenon lamp to simulate sunlight. The results showed that TiO₂/BiFeO₃ catalyst fabricated using a peanut shell biotemplate has a specific surface area of 153.64 m²/g, a band gap of 1.92 eV, and forms heterostructures. The optimum doping amount of TiO₂/BiFeO₃ catalyst was 1 mol/mol, and the degradation rate was 81.2%. The main active substances degraded were ·O₂^-and ·OH. The degradation process measured is consistent with the pseudo-first-order kinetic model.