White LED active α-Fe2O3/rGO photocatalytic nanocomposite for an effective degradation of tetracycline and ibuprofen molecules

Super antioxidant and high antibacterial ability bi-functional xylitol/2-hydroxypropyl-β-cyclodextrin carbon dots with hydroxyl-functionalized for rainbow trout preservation

In 2020, Rainbow trout production reached 959,600 tons, representing 4 % of the global trout output. However, microbial contamination and lipid and protein oxidation spoil around 15 % of total aquatic products. Traditional food preservatives, used for their antibacterial or antioxidant properties, often fall short due to the disparity between the radical-scavenging ability of antioxidants and the ROS-generating capability of antimicrobial agents. This study developed bifunctional xylitol-based carbon dots (xβ-CDs) using 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD), which exhibited both super antioxidant and high antibacterial activities. The incorporation of xylitol into xβ-CDs substantially enhanced their functional performance. The xβ-CDs displaying remarkable inhibition of DPPH (1-Diphenyl-2-trinitrophenylhydrazine), ABTS (2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate), and ·OH radicals (96.31 %, 99.74 %, and 99.72 %, respectively), rivaling the antioxidant capacity of vitamin C (VC). The xβ-CDs also effectively combated spoilage bacteria by compromising the cell wall and membrane integrity, reducing total protein, AKP, and ATP enzyme levels by 51.25 %, 70.08 %, and 57.80 %, respectively. Moreover, storage tests revealed that xβ-CDs extended the shelf life of Rainbow trout fillets by 3 days. These results indicate that xylitol/2-hydroxypropyl-β-cyclodextrin carbon dots offer a promising approach to preventing bacterial infections, protein oxidation, and lipid oxidation in rainbow trout.

Synthesis of superparamagnetic Fe3O4-graphene oxide-based material for the photodegradation of clonazepam

The global concern over water pollution caused by contaminants of emerging concern has been the subject of several studies due to the complexity of treatment. Here, the synthesis of a graphene oxide-based magnetic material (GO@Fe3O4) produced according to a modified Hummers' method followed by a hydrothermal reaction was proposed; then, its application as a photocatalyst in clonazepam photo-Fenton degradation was investigated. Several characterization analyses were performed to analyze the structure, functionalization and magnetic properties of the composite. A 23 factorial design was used for the optimization procedure to investigate the effect of [H2O2], GO@Fe3O4 dose and pH on clonazepam degradation. Adsorption experiments demonstrated that GO@Fe3O4 could not adsorb clonazepam. Photo-Fenton kinetics showed that total degradation of clonazepam was achieved within 5 min, and the experimental data were better fitted to the PFO model. A comparative study of clonazepam degradation by different processes highlighted that the heterogeneous photo-Fenton process was more efficient than homogeneous processes. The radical scavenging test showed that O 2 · - was the main active free radical in the degradation reaction, followed by hydroxyl radicals (•OH) and holes (h+) in the valence layer; accordingly, a mechanism of degradation was proposed to describe the process.

Graphene-based photocatalysts for degradation of organic pollution

Compared with the traditional wastewater treatment technology, semiconductor photocatalysis is a rapidly emerging environment-friendly and efficient Advanced Oxidation Process for degradation of refractory organic contaminants. Single-component semiconductor photocatalysts exhibit poor photocatalytic performance and cannot meet the requirements of wastewater treatment. The combination of semiconductor photocatalysts and Graphene can effectively improve the photocatalytic activity and stability of semiconductor photocatalysts. This review focuses on the synergistic effect of several types of semiconductors with Graphene for photocatalytic degradation of organic pollutants. After a brief introduction of the photodegradation mechanism of semiconductor materials and the basic description of Graphene, the synthesis, characterization and degradation performance of various Graphene-based semiconductor photocatalysts are emphatically introduced.

Recent Advances in Carbon-Based Materials for Adsorptive and Photocatalytic Antibiotic Removal

Antibiotics have been a primary environmental concern due to their widespread dispersion, harmful bioaccumulation, and resistance to mineralization. Unfortunately, typical processes in wastewater treatment plants are insufficient for complete antibiotic removal, and their derivatives in effluent can pose a threat to human health and aquatic communities. Adsorption and photocatalysis are proven to be the most commonly used and promising tertiary treatment methods. Carbon-based materials, especially those based on graphene, carbon nanotube, biochar, and hierarchical porous carbon, have attracted much attention in antibiotic removal as green adsorbents and photocatalysts because of their availability, unique pore structures, and superior physicochemical properties. This review provides an overview of the characteristics of the four most commonly used carbonaceous materials and their applications in antibiotic removal via adsorption and photodegradation, and the preparation of carbonaceous materials and remediation properties regarding target contaminants are clarified. Meanwhile, the fundamental adsorption and photodegradation mechanisms and influencing factors are summarized. Finally, existing problems and future research needs are put forward. This work is expected to inspire subsequent research in carbon-based adsorbent and photocatalyst design, particularly for antibiotics removal.

Highly Efficient Solar Light Driven g-C3N4@Cs0.33WO3 Heterojunction for the Photodegradation of Colorless Antibiotics

This study facilitates the synthesis of a graphitic carbon nitride/cesium tungsten oxide (g-C₃N₄@Cs_0.33WO₃) heterojunction using a solvothermal method. The photocatalytic activities of the prepared samples were examined for the photodegradation of colorless antibiotics, namely tetracycline, enrofloxacin, and ciprofloxacin, as well as cationic and anionic dyes, such as methyl orange, rhodamine B, neutral red, and methylene blue, under full-spectrum solar light. We have purposely selected different kinds of wastewater pollutants of colorless antibiotics and cationic and anionic organic dyes to investigate the potential application of this heterojunction toward different groups of water pollutants. The results revealed that the g-C₃N₄@Cs_0.33WO₃ heterojunction showed an outstanding photocatalytic activity toward all the pollutants with concentrations of 20 ppm each at pH 3 by photocatalytically removing 97% of tetracycline within 3 h, 98% of enrofloxacin within 2 h, 97% of ciprofloxacin within 2.25 h, 98% of methylene blue in 1 h, 99% of rhodamine B within 2 h, 99% of neutral red in 1.25 h, and 95% of methyl orange in 2 h. These findings indicate that the developed photocatalyst possesses excellent photocatalytic properties toward seven different water pollutants that make it a universal photocatalyst. The developed g-C₃N₄@Cs_0.33WO₃ oxide heterojunction also presented a photocatalytic performance better than those of reported solar light active photocatalysts for photodegradation of rhodamine B and tetracycline. The efficient photocatalytic performance of the heterojunction can be ascribed to its extended light-absorbing ability, effective charge separation and fast charge transfer properties, and a high surface area. Moreover, an active species detection experiment also confirmed that superoxide radicals, hydroxyl radicals, and holes played significant roles in the photocatalysis of the organic dyes and tetracycline.

Synthesis and characterization of SnO2/rGO nanocomposite for an efficient photocatalytic degradation of pharmaceutical pollutant: Kinetics, mechanism and recyclability

The SnO₂ and SnO₂/rGO nanostructures were successfully synthesized using the facile hydrothermal synthesis technique. The prepared nanostructures were well studied using different techniques such as XRD, XPS, UV-DRS, FT-IR, EDX, SEM and HR-TEM analysis. The crystalline nature of SnO₂ and SnO₂/rGO was confirmed by the XRD technique. The formation of highly pure SnO₂ and SnO₂/rGO nanostructures was confirmed by EDX analysis. The morphological results show the good agglomeration of several spherical nanoparticles. The optical properties were studied through the UV-DRS technique and the bandgap energies of SnO₂ and SnO₂/rGO are estimated to be 3.12 eV and 2.71 eV, respectively. The photocatalytic degradation percentage in presence of SnO₂ and SnO₂/rGO against RhB was found to be 96% and 98%, respectively. The degradation of TTC molecules was estimated as 90% and 88% with SnO₂/rGO and SnO₂, respectively. The degradation of both RhB and TTC molecules was well suited with the pseudo-first-order kinetics. The results of successive experiments clearly show the enhancement in the photocatalytic properties in the SnO₂/rGO nanostructures.