Insights into the rapid elimination of antibiotics from aqueous media by tunable C3N4 photocatalysts: Effects of dopant amount, co-existing ions and reactive oxygen species

Selective adsorption of high ionization potential value organic pollutants in wastewater

It is imperative to devise effective removal strategies for high ionization potential (IP) organic pollutants in wastewater as their reduced electron-donating capacity challenges the efficiency of advanced oxidation systems in degradation. Against this backdrop, leveraging the metal-based carbon material structure meticulously, we employed metal-pyridine-N (M-N-C, M=Fe, Co, and Ni) as the electron transfer bridge. This distinctive design facilitated the ordered transfer of electrons from the adsorbent surface to the surface of high IP value pollutants, acting as a "supplement" to compensate for their deficient electron-donating capability, thereby culminating in the selective adsorption of these pollutants. Furthermore, this adsorbent also demonstrated effective removal of trace emerging contaminants (2 mg/L), displayed robust resistance to various salts, exhibited reusability, and maintained stability. These findings carry substantial implications for future carbon-based material design, offering a pathway toward exceptional adsorption performance in treating water pollution.

Enhancing photocatalytic wastewater treatment: investigating the promising applications of nickel ferrite and its novel nanocomposites

Water contamination ranks highest among the challenges posed by the rapidly increasing environmental contamination, which is thought to be the most pressing issue globally. The development of innovative techniques for the successful removal of diverse types of undesirable pollutants from wastewater would therefore yield a huge return on investment. Nowadays, the removal of many organic and synthetic pollutants from the environmental matrix is anticipated to be possible by photocatalytic degradation, owing to its low energy consumption, high catalytic activity, and low overall cost. In this context, magnetic nanoparticles received greater attention as photocatalytic materials from the scientific community in wastewater treatment for the removal of different kinds of pollutants due to their specific properties. The present study provides an overview of the recent advances in water treatment using nickel ferrite nanoparticles and their nanocomposites as photocatalysts. Furthermore, a proposed mechanism for these photocatalysts to generate active free radicals under visible and ultraviolet light has been described. The review concludes that photocatalysts based on NiFe2O4 have potential applications in water purification technologies. However, more research is still needed to determine their practical application in water treatment facilities.

Enhanced degradation of enoxacin using ferrihydrite-catalyzed heterogeneous photo-Fenton process

The ferrihydrite-catalyzed heterogeneous photo-Fenton reaction shows great potential for environmental remediation of fluoroquinolone (FQs) antibiotics. The degradation of enoxacin, a model of FQ antibiotics, was studied by a batch experiment and theoretical calculation. The results revealed that the degradation efficiency of enoxacin reached 89.7% at pH 3. The hydroxyl radical (∙OH) had a significant impact on the degradation process, with a cumulative concentration of 43.9 μmol L-1 at pH 3. Photogenerated holes and electrons participated in the generation of ∙OH. Eleven degradation products of enoxacin were identified, with the main degradation pathways being defluorination, quinolone ring and piperazine ring cleavage and oxidation. These findings indicate that the ferrihydrite-catalyzed photo-Fenton process is a valid way for treating water contaminated with FQ antibiotics.

Adsorption-photocatalysis synergy of reusable mesoporous TiO2-ZnO for photocatalytic degradation of doxycycline antibiotic

The potentials of mesoporous TiO2-ZnO (3TiZn) were explored on photocatalytic degradation of doxycycline (DOX) antibiotic, likewise the influence of adsorption on the photocatalytic process. The 3TiZn was characterized for physical and chemical properties. Stability, reusability, kinetic and the ability of 3TiZn to degrade high concentration of pollutant under different operating conditions were investigated. Photocatalytic degradation of DOX was conducted at varied operating conditions, and the best was obtained at 1 g/L catalyst dosage, solution inherent pH (4.4) and 50 ppm of DOX. Complete degradation of 50 ppm and 100 ppm of DOX were attained within 30 and 100 min of the reaction time, respectively. The stability and reusability study of the photocatalyst proved that at the tenth (10th) cycle, the 3TiZn is as effective in the degradation of DOX as in the first cycle. This may be attributed to the fusion of the mixed oxides during calcination. The 3TiZn is mesoporous with a pore diameter of 17 nm, and this boosts it potential to degrade high concentration of DOX. It was observed that the adsorption capacity of 3TiZn enhance the photocatalytic process. It can be emphasized that 3TiZn portrayed a remarkable catalyst stability and good potentials for industrial application.

Enhanced tetracycline degradation with TiO2/natural pyrite S-scheme photocatalyst

In this study, TiO2 nanoparticles were employed as a photocatalyst for the degradation of tetracycline (TC) under visible light irradiation. The TiO2 nanoparticles were decorated on natural pyrite (TiO2/NP) and characterized using XRD, FTIR, and SEM-EDX methods. This study evaluated the impacts of various operational parameters such as pH, catalyst dosage, initial TC concentration, and light intensity on TC removal. The findings revealed that under optimal conditions (pH 7, catalyst: 2 g/L, TC: 30 mg/L, and light intensity: 60 mW/cm2), 100% of TC and 84% of TOC were removed within 180 min. The kinetics of TC elimination followed a first-order model. The dominant oxidation species involved in the photocatalytic elimination of TC was found to be ·OH radicals in the TiO2/NP system. The reuse experiments showed the high capability of the catalyst after four consecutive cycles. This study confirmed that the TiO2/NP system has high performance in photocatalytic TC removal under optimized experimental conditions.

Antibacterial Carbon Dots: Mechanisms, Design, and Applications

The increase in antibiotic resistance promotes the situation of developing new antibiotics at the forefront, while the development of non-antibiotic pharmaceuticals is equally significant. In the post-antibiotic era, nanomaterials with high antibacterial efficiency and no drug resistance make them attractive candidates for antibacterial materials. Carbon dots (CDs), as a kind of carbon-based zero-dimensional nanomaterial, are attracting much attention for their multifunctional properties. The abundant surface states, tunable photoexcited states, and excellent photo-electron transfer properties make sterilization of CDs feasible and are gradually emerging in the antibacterial field. This review provides comprehensive insights into the recent development of CDs in the antibacterial field. The topics include mechanisms, design, and optimization processes, and their potential practical applications are also highlighted, such as treatment of bacterial infections, against bacterial biofilms, antibacterial surfaces, food preservation, and bacteria imaging and detection. Meanwhile, the challenges and outlook of CDs in the antibacterial field are discussed and proposed.

One-pot hydrothermal fabrication of 2D/2D BiOIO3/BiOBr Z-scheme heterostructure with enhanced photocatalytic activity

A 2D/2D BiOIO₃/BiOBr Z-scheme heterostructure was firstly synthesized by a simple one-pot hydrothermal process and it was used to effectively remove rhodamine B under irradiation of Xe and LED light. The BB-15 heterostructure has an optimal apparent rate constant k of 0.046 min^-1 (0.17 min^-1), which is ∼6.2 (89.7) and 3.5 (3.5) times that of BiOIO₃ and BiOBr under the irradiation of Xe light (LED light). The enhanced photocatalytic activity can be attributed to the following points: (1) the face-to-face and tight contact in 2D/2D BiOIO₃/BiOBr heterostructures provides more migration channels for photogenerated carriers which facilitates the transfer and separation of photogenerated carriers; (2) the Z-scheme photocarrier transport path not only hastens the separation and transfer efficiency of photocarriers in space but also maintains a robust redox capacity; (3) the presence of IO₃^-/I^- redox couple and built-in electric field further encourage the separation and transfer of photocarriers and enhance the photocatalytic activity of the composite. And the O₂^-, h⁺, and OH are active species, which are responsible for the photodegrade process of RhB under irradiation of Xe light. This study provided an easy and reliable strategy to design and prepare an efficient bismuth-containing heterojunction, the characterization and evaluation experiment results proved its effectiveness for solar utilization and environmental purification.

Intimately coupled photocatalysis and biodegradation for effective simultaneous removal of sulfamethoxazole and COD from synthetic domestic wastewater

The inefficiency of conventional biological treatment for removing sulfamethoxazole (SMX) is posing potential risks to ecological environments. In this study, an intimately coupled photocatalysis and biodegradation (ICPB) system consisting of Fe³⁺/g-C₃N₄ and biofilm was fabricated for the treatment of synthetic domestic wastewater containing SMX. The results showed that this ICPB system could simultaneously remove 96.27 ± 5.27% of SMX and 86.57 ± 3.06% of COD, which was superior to sole photocatalysis (SMX 100%, COD 4.2 ± 0.74%) and sole biodegradation (SMX 42.21 ± 0.86%, COD 95.1 ± 0.18%). Contributors to SMX removal in the ICPB system from big to small include LED photocatalysis, biodegradation, LED photolysis, and adsorption effect of the carrier, while COD removal was largely ascribed to biodegradation. Increasing initial SMX concentration inhibits SMX removal rate, while increasing photocatalyst dosage accelerates SMX removal rate, and both had no impact on COD removal. Our analysis of biofilm activity showed that microorganisms in this ICPB system maintained a high survival rate and metabolic activity, and the microbial community structure of the biofilm remained stable, with Nakamurella and Raoultella being the two dominant genera of the biofilm. This work provides a new strategy to effectively treat domestic wastewater polluted by antibiotics.

Nickel ferrite nanoenabled graphene oxide (NiFe2O4@GO) as photoactive nanocomposites for water treatment

Nanocomposite materials can enhance the capabilities of water treatment processes such as photocatalysis. In this work, novel light-driven nanocatalysts were synthesized by using nickel ferrite (NiFe₂O₄) to nanoenable graphene oxide (GO) substrates. GO is an emerging 2D nanomaterial with high conductivity and adsorption properties. Moreover, the electric properties of GO improve photocatalytic performance by promoting charge carrier separation. Results of the characterization of the nickel ferrite nanoenabled graphene oxide (NiFe₂O₄@GO) nanocomposites demonstrate that homogeneous and stable photocatalysts were produced. The as-synthesized nanocatalysts enabled complete decolorization of the colored water matrix in short irradiation times of 150 min using minimal catalyst loading at 0.5 g L^-1. The selective hook and destroy mechanism reduced the competitive effect of co-existing ions in solution. Furthermore, the use of specific scavengers helped to elucidate the degradation mechanisms of organic dye methylene blue by NiFe₂O₄@GO nanocomposites.

Design a new photocatalyst of sea sediment/titanate to remove cephalexin antibiotic from aqueous media in the presence of sonication/ultraviolet/hydrogen peroxide: Pathway and mechanism for degradation

The aim of the current study was directed to develop a new sea sediment/titanate photocatalyst to remove cephalexin from aqueous media in the presence of ultraviolet (UV) light, hydrogen peroxide (H₂O₂), and ultrasonic waves. The influence of furnace temperature (300, 350, 400, and 500 °C), furnace residence time (1, 2, 3, and 4 h), and ratio of sea sediment: titanium (0-6 v: w) on the physicochemical properties and the cephalexin removal by the sea sediment/titanate photocatalyst was explored. The technique of FTIR, SEM/EDX, XRD, BET, BJH, and Mapping was used to determine the physicochemical properties of the generated photocatalyst. The maximum cephalexin removal (94.71%) was obtained at the furnace temperature of 500 °C, the furnace residence time of 2 h, and the sea sediment: titanium ratio of 1:6 (=12 mL TiO₂/2 g sea sediment). According to the acquired results, the surface area of the optimized catalyst, namely Cat-500-2-12, was computed to be 52.29 m²/g. The crystallite size of titanium oxide on the optimum photocatalyst was calculated ~17.68 nm. The FTIR test confirmed the presence of C=C, O-H, C=O, C-S, and C-H functional groups in the photocatalyst. The transformation pathway for the degradation of cephalexin by the developed system was drawn. The present investigation showed that the developed technique (sea sediment/titanate-UV-H₂O₂-ultrasonic) could be used as a promising alternative for attenuating cephalexin from aqueous solutions.