Micro-Octahedron Cu2O-Based Photocatalysis-Fenton for Organic Pollutant Degradation: Proposed Coupling Mechanism in a Membrane Reactor

Mathematical Modeling of NaCl Scaling Development in Long-Distance Membrane Distillation for Improved Scaling Control

Membrane distillation is a novel membrane-based separation technology with the potential to produce pure water from high-salinity brine. It couples transport behaviors along the membrane and across the membrane. The brine in the feed is gradually concentrated due to the permeate flux across the membrane, which is a significant factor in initiating the scaling behavior on the membrane surface along the feed flow direction. It is of great interest to investigate and estimate the development of scaling on the membrane surface. This work specifically focuses on a long-distance membrane distillation process with a sodium chloride solution as the feed. A modeling approach has been developed to estimate the sodium chloride scaling development on the membrane surface along the flow direction. A set of experiments was conducted to validate the results. Based on mathematical simplification and analytical fitting, a simplified model was summarized to predict the initiating position of sodium chloride scaling on the membrane, which is meaningful for scaling control in industrial-scale applications of membrane distillation.

Chitosan-Integrated Curcumin-Graphene Oxide/Copper Oxide Hybrid Nanocomposites for Antibacterial and Cytotoxicity Applications

This study deals with the facile synthesis of a single-pot chemical technique for chitosan-curcumin (CUR)-based hybrid nanocomposites with nanostructured graphene oxide (GO) and copper oxide (CuO) as the antibacterial and cytotoxic drugs. The physicochemical properties of synthesized hybrid nanocomposites such as CS-GO, CS-CuO, CS-CUR-GO, and CS-CUR-GO/CuO were confirmed with various advanced tools. Moreover, the in vitro drug release profile of the CS-CUR-GO/CuO nanocomposite exhibited sustained and controlled release during different time intervals. Also, the antibacterial activity of the CS-CUR-GO/CuO hybrid nanocomposite presented the maximum bactericidal effect against Staphylococcus aureus and Escherichia coli pathogens. The hybrid nanocomposites revealed improved cytotoxicity behaviour against cultured mouse fibroblast cells (L929) via cell adhesion, DNA damage, and proliferation. Thus, the chitosan-based hybrid nanocomposites offer rich surface area, biocompatibility, high oxidative stress, and bacterial cell disruption functionalities as a potential candidate for antibacterial and cytotoxicity applications.

In Situ Synthesis of Cu2O Nanoparticles Using Eucalyptus globulus Extract to Remove a Dye via Advanced Oxidation

Water pollution, particularly from organic contaminants like dyes, is a pressing issue, prompting exploration into advanced oxidation processes (AOPs) as potential solutions. This study focuses on synthesizing Cu2O on cellulose-based fabric using Eucalyptus globulus leaf extracts. The resulting catalysts effectively degraded methylene blue through photocatalysis under LED visible light and heterogeneous Fenton-like reactions with H2O2, demonstrating reusability. Mechanistic insights were gained through analyses of the extracts before and after Cu2O synthesis, revealing the role of phenolic compounds and reducing sugars in nanoparticle formation. Cu2O nanoparticles on cellulose-based fabric were characterized in terms of their morphology, structure, and bandgap via SEM-EDS, XRD, Raman, FTIR, UV-Vis DRS, and TGA. The degradation of methylene blue was pH-dependent; photocatalysis was more efficient at neutral pH due to hydroxyl and superoxide radical production, while Fenton-like reactions showed greater efficiency at acidic pH, primarily generating hydroxyl radicals. Cu2O used in Fenton-like reactions exhibited lower reusability compared to photocatalysis, suggesting deterioration. This research not only advances understanding of catalytic processes but also holds promise for sustainable water treatment solutions, contributing to environmental protection and resource conservation.

Enhancing Fenton-like Degradation of Organic Pollutants at Neutral pH by Multivalent Cu NCs/HAp Nanocatalysts

Heterogeneous Fenton-like catalysis is a widely used method for the degradation of organic pollutants. However, it still has some limitations such as low activity in the neutral condition, low conversion rates of metals with different valence states, and potential secondary metal pollution. In this study, a Fenton-like nanocatalyst was first created by generating ultrasmall copper nanoclusters (Cu NCs) on the surface of hydroxyapatite (HAp) through a process of doping followed by modification. This resulted in the formation of a composite nanocatalyst known as Cu NCs/HAp. With the help of hydrogen peroxide (H2O2), Cu NCs/HAp exhibits an outstanding Fenton-like catalytic performance by efficiently degrading organic dyes such as methylene blue under mild neutral conditions. The removal rate can reach over 83% within just 30 min, demonstrating ideal catalytic universality and stability. The improved Fenton-like catalytic performance of Cu NCs/HAp can be ascribed to the synergistic effect of the multivalent Cu species through two simultaneous reaction pathways. During route I, the embedded Cu NCs with a core-shell Cu0/Cu+ structure can undergo sequential oxidation to form Cu2+, which continuously activates H2O2 to generate hydroxyl radicals (•OH) and singlet oxygen (1O2). In route II, Cu2+ produced from route I and initially adsorbed on the surface of HAp can be reduced by H2O2, thus regenerating Cu+ species for route I and achieving a closed-loop reaction. This work has confirmed that Cu NCs loaded on HAp may be an alternative Fenton-like catalyst for degradation of organic pollutants and environmental remediation, opening up new avenues for potential applications of other Cu NCs in future water pollution control.

Insights into the Degradation Mechanisms of TCH by Magnetic Fe3S4/Cu2O Composite

Unique Fe₃S₄/Cu₂O composites were constructed with high Fenton-like photocatalytic activity through the impregnation coprecipitation method. The structure, morphology, optical, magnetic, and photocatalytic properties of the as-prepared composites were explored in detail. The findings suggest that small Cu₂O particles were grown on the surface of Fe₃S₄. The removal efficiency of TCH by Fe₃S₄/Cu₂O was 65.7, 4.75, and 3.67 times higher than that of pure Fe₃S₄, Cu₂O, and the Fe₃S₄ + Cu₂O mixture, respectively, when the mass ratio of Fe₃S₄ and Cu₂O was 1:1 at pH 7.2. The synergistic effect between Cu₂O and Fe₃S₄ was the main factor for TCH degradation. The Cu⁺ species from Cu₂O increased the Fe³⁺/Fe²⁺ cycle during the Fenton reaction. ^•O₂^- and h⁺ were the main active radicals; however, ^•OH and e^- played the second role in the photocatalytic degradation reaction. Moreover, the Fe₃S₄/Cu₂O composite retained good recyclability and versatility, and could be conveniently separated by a magnet.