CaTiO3/g-C3N4 heterojunction-based composite photocatalyst: Part I: Experimental design, kinetics, and scavenging agents' effects in photocatalytic degradation of gemifloxacin

Comparative photocatalytic degradation of cationic rhodamine B and anionic bromocresol green using reduced ZnO: A detailed kinetic modeling approach

The photocatalytic degradation of rhodamine B (RhB), a cationic dye, and bromocresol green (BCG), an anionic dye, was investigated using oxygen vacancy-enriched ZnO as the catalyst. These dyes were selected due to their differing charges and molecular structures, allowing for a deeper exploration of how these characteristics impact the degradation process. The catalyst was prepared by reducing ZnO with 10% H2/Ar gas at 500 °C, and the introduction of oxygen vacancies was confirmed using various characterization techniques. A detailed kinetic model was developed to track dye degradation, accounting for adsorption and photocatalytic degradation simultaneously, both in solution and on the catalyst surface. The model incorporated the effect of pH on adsorption by considering the dissociation behavior of the dyes and their respective pKa values. The study revealed that degradation primarily occurs on the catalyst surface at acidic pH, while at basic pH, degradation is more pronounced in the solution. DFT calculations supported these findings, showing that the electrostatic potential of the dyes shifts depending on pH, influencing their interaction with hydroxyl radicals or the catalyst surface. Quantum yield calculations indicate peak values of 6.32 10-5 molecules per photon for RhB at pH 11, and 4.20 10-5 for BCG at pH 3.

Establishing robust ZnO-sodium alginate nanocomposite for dye wastewater treatment: characterization, RSM methodology, and mechanism evaluation

In today's world, water is a highly valued resource, and enhancing the quality of this natural endowment is a significant concern and a worldwide endeavor. This study sought to purify real wastewater and water tainted with methylene blue (MB) by immobilizing ZnO nanoparticles onto an alginate matrix using a straightforward approach and a three-dimensional structure. After analyzing the impact ofH 2 O 2 , it was determined that 93.84% of MB was successfully removed (time = 120 min, dye concentration = 15 mg/L, catalyst amount = 2.5 g). The effects of inorganic ions and water types were investigated to simulate real wastewater conditions, and the catalyst performed satisfactorily. Alginate played a significant role in selectively removing dye, and the catalyst effectively removed 80.36% of MB and, in contrast, 20% of methyl orange (MO). The practical application of the catalyst was evaluated in textile wastewater treatment, and the catalyst showed satisfactory performance. An average 2.49% reduction in dye removal was observed after five stages of using the catalyst, demonstrating the beads' excellent stability. The composites were subjected to free radical trapping experiments to ascertain the active species. According to the results,h + and · OH acted as the main reaction species in the degradation of MB. At the end, the synergistic mechanism of adsorption and degradation in MB removal was presented.

Photocatalytic activity of self-heterojunctioned intermediate phases in HCl protonated and HNO3 deconjugated g-C3N4 nanostructures

This research involved the different acid-treatment conditions of graphitic carbon nitride and its modified nanostructures through thermal polycondensation of urea at various temperatures. X-ray diffraction patterns revealed that processing at a lower temperature than 500 °C resulted in melem and its derivatives, indicating incomplete transformation of urea to g-C3N4. However, treatment at higher temperatures and the HCl acid treatment led to the formation and expansion of g-C3N4 networks, as evidenced by notable differences in peak intensities observed in their Fourier-transform infrared and Raman spectra. Scanning electron microscopy analysis illustrated a transition from the granular morphology of melamine to the layered structure characteristic of g-C3N4. The nanoparticle morphology observed in the HNO3 acid treatment sample was attributed to the deconjugation of nanosheets through the highly oxidative acid medium. The most suitable photocatalytic activity for Methylene Blue (MB) degradation under UV and visible light illumination was observed for the samples prepared at 550 °C and HCl post-processed nanostructures. It is proposed that the enhanced photocatalytic activity observed in these samples is most likely attributed to the reduced recombination of photogenerated charge carriers facilitated by heterojunctions formed between different intermediate phases. These findings highlight the potential of modified g-C3N4 and its derivatives as promising photocatalytic materials for water purification applications.

Advances in multifunctional metal-organic framework (MOF)-based nanoplatforms for cancer starvation therapy

Cancer remains a significant threat to human health today. Even though starvation therapy and other treatment methods have recently advanced to a new level of rapid development in tumour treatment, their limited therapeutic effectiveness and unexpected side effects prevent them from becoming the first option in clinical treatment. With rapid advancement in nanotechnology, the utilization of nanomaterials in therapeutics offers the potential to address the shortcomings in cancer treatment. Notably, multifunctional metal-organic framework (MOF) has been widely employed in cancer therapy due to their customizable shape, adjustable diameter, high porosity, diverse compositions, large specific surface area, high degree of functionalization and strong biocompatibility. This paper reviews the current progress and success of MOF-based multifunctional nanoplatforms for cancer starvation therapy, as well as the prospects and potential barriers for the application of MOF nanoplatforms in cancer starvation therapy.

Fractional-order memristive dynamics in colloidal graphitic carbon nitride systems

We report on the synthesis and characterization of a colloidal graphitic carbon nitride (g-C_{3}N_{4}) system exhibiting complex memfractance behavior. The g-C_{3}N_{4} colloid was prepared through thermal polymerization of urea, followed by dispersion in deionized water. X-ray diffraction and scanning electron microscopy confirmed the successful synthesis of g-C_{3}N_{4}. Electrical characterization revealed nonpinched hysteresis loops in current-voltage curves, indicative of memristive behavior with additional capacitive components. The device demonstrated stable resistive switching between high (∼50kΩ) and low (∼22kΩ) impedance states over 500 cycles, as well as synaptic plasticity-like conductance modulation. To capture these complex dynamics, we employed a generalized memfractance model that interpolates between memristive, memcapacitive, and second-order memristive elements. This model, employing fractional-order derivatives, accurately fitted the experimental data, revealing the device's memory effects. The emergence of memfractance in this colloidal system opens new avenues for neuromorphic computing and unconventional information processing architectures, leveraging the unique properties of liquid-state memory devices.

Exquisitely designed TiO2 quantum dot/Bi2O2CO3 nano-sheet S-scheme heterojunction towards boosted photo-catalytic removal

The development of novel semiconductor photo-catalysts for the efficient degradation of antibiotics poses a considerable challenge in the context of ever-increasing environmental pollution. Herein, an S-scheme photo-catalyst consisting of TiO2 quantum dots (QDs, size ∼4-6 nm) anchored on Bi2O2CO3 nano-sheets was synthesised via a facile hydrothermal protocol. TiO2/Bi2O2CO3 (TB) nano-composite exhibits enhanced photo-catalytic removal of tetracycline, achieving ∼0.0158 min-1 photo-degradation rates using visible light, which is 3- and 53-fold greater than that of pristine TiO2 and Bi2O2CO3, respectively. The theoretical calculations substantiate that the built-in electric field in the TB nano-composite is conducive to the separation and transfer of photo-excited carriers. Notably, the generated superoxide radicals rather than hydroxyl were identified as the responsible species for tetracycline degradation. In addition, the corresponding degradation pathway and eco-toxicity analysis were also elucidated. In conclusion, this work contributes valuable insights and presents a feasible approach for the fabrication of S-scheme photo-catalysts (TiO2 QDs and bismuth-based nano-materials), thereby enabling the efficient removal of water pollutants.

A novel nanocomposite for photocatalytic rhodamine B dye removal from wastewater using visible light

Providing safe access to water and addressing the impact of waterborne diseases, which claim over two million lives annually, is a major contribution to water purification. The study introduces a novel nanocomposite, Ch/Fe3O4/α-MoO3, which exhibits outstanding photocatalytic efficacy under visible light. An in-depth investigation of the nanocomposite's synthesis, characterization, and photodegradation mechanisms reveals its outstanding capabilities. Photocatalytic activity is influenced by the catalytic dose, pH, dye concentration, and reaction time, according to the study. A response surface method is used to determine the optimal conditions for Rhodamine B degradation, which results in 96.3% removal efficiency at pH 8.5, dye concentration 25 mg/L, nanocomposite dose at 22 mg/L, and reaction time 50 min. As a result of its high surface area, biocompatibility, availability, and magnetization with iron compounds, Chitosan is an excellent substrate for enhancing the photocatalytic properties of MoO3 nanoparticles. A nanocomposite with an energy band of 3.18 eV exhibits improved visible light absorption. This study confirms the nanocomposite's recyclability and stability, affirming its practicality. Besides dye removal, it offers hope for the global quest for clean water sources by addressing a broader range of waterborne contaminants. By combining molybdenum and magnetite, nanocomposite materials facilitate the degradation of pollutant and bacteria, contributing positively to society's quest for clean and safe water. It emphasizes the role nanotechnology plays in preserving human health and well-being in combating waterborne diseases.

Silica wastes derived multifunctional coatings for formaldehyde photodegradation and autonomous indoor humidity buffering

To maintain a comfortable and healthy indoor environment without large amounts of energy consumption is of great importance. The progress of multifunctional indoor coatings with formaldehyde photodegradation and humidity buffering capability is necessary. From the viewpoints of circular economy, the preparation of effective photocatalysts (denoted as sFCC/GCN-x and ESF/GCN-y) via the decoration of recycling industrial wastes (i.e., spent fluid catalytic cracking catalysts (sFCC) and enhancement silica fume (ESF)) onto graphitic carbon nitride (GCN) by using a simple route is reported. The obtained results show that the prepared sFCC/GCN-0.15 and ESF/GCN-0.15 photocatalysts have the rate constants of formaldehyde degradation of 0.0075 and 0.0082 min-1, respectively, which are superior to that of pristine GCN (0.0044 min-1) under visible-light irradiation. The enhanced transfer kinetics of photogenerated electrons and declined recombination of electron-hole pairs may account for the surpassing photocatalytic performance. Results obtained from electron paramagnetic resonance spectra and Mott-Schottky plots indicate that the formation of ･O2- via the reaction of O2 with electrons generated on the conduction band is the major reaction pathway to photodegrade formaldehyde under visible light. To further assess the real applications of prepared photocatalysts, the sFCC/GCN-0.15 and ESF/GCN-0.15 are used to fabricate the multifunctional coatings (denoted as s- and E-coatings) with sFCC and ESF as the main compositions. Experimentally, the E-coatings could reach the formaldehyde degradation efficiency of ca. 84.5% after 3 h of visible light irradiation and excellent humidity buffering ability (293.8 g m-2) which is at least 10-folds higher than commercial coatings (28.9 g m-2). This notable progress of humidity buffering capacity on E-coatings can be attributed to their surface textural properties. Most importantly, this study exemplifies the valorization of inorganic silica wastes to produce sustainable and multifunctional coatings which may offer the practical and cost-effective applications in the indoor living space.