Application In Wastewater Treatment Research Articles

UV-initiated polymerization of cationic organic flocculants and its application and mechanism in coal mine wastewater treatment

In this study, in order to improve the flocculation efficiency of natural organic flocculant in coal mine wastewater, guar gum (GG) and [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (DMC)were used to synthesize a type of graft copolymer of GG with DMC (GG-g-DMC) with flocculating function by free radical polymerization under ultraviolet (UV) light initiation conditions. Performance testing and structural characterization of the composites including FTIR, NMR, XRD, SEM, TG, and XPS were conducted to verify the synthesis of the graft polymer. The GG-g-DMC was applied to treat coal mine wastewater, according to the sedimentation index and the optimal flocculation solution was determined, and the flocculation settling mechanism was studied using focused beam reflectance measurement (FBRM), Zeta potentiometer and adhesion force meter. The results indicated that GG-g-DMC synthesis by UV-initiated polymerization was feasible and the settling effect increased significantly; 0.5 mg/g(s) GG-g-DMC 4 was excellent in all aspects, its sedimentation speed reached 20.64 cm/min, the light transmittance was 95.00%, and the compression layer thickness was 1.89 cm; the mechanism is mainly the synergy of charge neutralization, bridging, and improve hydrophobicity.

Valeriana jatamansi root extract a potent source for biosynthesis of silver nanoparticles and their biomedical applications, and photocatalytic decomposition

ABSTRACT This study aimed to synthesize silver nanoparticles (VJ@AgNPs) using Valeriana jatamansi root extract and assess their antibacterial, antioxidant, and antibiofilm properties against Escherichia coli, Staphylococcus aureus, and Streptococcus mutans. Various chemical and physical characterization methods were employed to analyze the synthesized VJ@AgNPs. UV-Visible spectroscopy confirmed the presence of VJ@AgNPs with a peak absorption at 426 nm, while FT-IR results indicated the involvement of phyto-compounds from V. jatamansi in the reduction and stabilization of these nanoparticles. High-resolution transmission electron microscopy revealed well-dispersed spherical nature with an average size of 29.1 ± 2.06 nm, and X-ray diffraction confirmed their crystalline structure. The biosynthesized VJ@AgNPs exhibited significant antibacterial activity against all tested pathogens, with substantial inhibition zones at 50 and 100 μg/mL concentrations. Additionally, VJ@AgNPs displayed potent antibiofilm activity and antioxidant capacity in scavenging assays. Furthermore, these VJ@AgNPs showed promise in photocatalytic degradation, effectively removing 95% of RhB dye within 75 minutes under solar light irradiation, following pseudo-first-order kinetics. This suggests their potential application in wastewater treatment for organic dye removal. The biocompatible and environmentally friendly nature of VJ@AgNPs underscores their potential as therapeutic agents against bacterial infections and oxidative stress-related diseases.

Transition metals-doped g-C3N4 nanostructures as advanced photocatalysts for energy and environmental applications

Graphitic carbon nitride (g–C3N4)–based heterostructured photocatalysts have received significant attention for its potential applications in the treatment of wastewater and hydrogen evolution. The utilization of semiconductor materials in heterogeneous photocatalysis has recently received great attention due to their potential and eco-friendly properties. Doping with metal ions plays a crucial role in altering the photochemical characteristics of g-C3N4, effectively enhancing photoabsorption into the visible range and thus improving the photocatalytic performance of doped photocatalysts. As an emerging nanomaterial, nanostructured g-C3N4 represents a visible light-active semiconducting photocatalyst that has attracted significant interest in the photocatalysis field, particularly for its practical water treatment applications. To the best of our knowledge, investigations of functionalized photocatalytic (PC) materials on 3d transition metal-doped g-C3N4 remain unexplored in the existing literature. g-C3N4 based heterohybrid photocatalysts have demonstrated excellent reusability, making them highly promising for wastewater treatment applications. This paper describes the overview of numerous studies conducted on the heterostructured g-C3N4 photocatalysts with various 3d metals. Research studies have revealed that the introduction of element doping with various 3d transition metals (e.g., Ti, Mn, Fe, Co, Ni, Cu, Zn, etc.) into g-C3N4 is an efficient approach to enhance degradation efficacy and boost photocatalytic activity (PCA) of doped g-C3N4 catalysts. Moreover, the significance of g-C3N4 heterostructured nanohybrids is highlighted, particularly in the context of wastewater treatment applications. The study concludes by providing insights into future perspectives in this developing area of research, with a specific focus on the degradation of various organic contaminants.

Regeneration and mass transfer simulation for remazol brilliant violet dye adsorption by pineapple peel–based adsorbent

The successful preparation of pineapple peel activated carbon (PineAC) using a low–cost and environmentally friendly method presented a promising alternative for the utilization of pineapple peel (PineP) waste. The remarkable regeneration capability of PineAC significantly enhances its possible reusable adsorbent for the effective Remazol Brilliant Violet 5 R (RBV 5 R) dye adsorption. The Polymath software was employed to gain deeper insights into the mass transfer process and optimize the adsorption kinetics. PineAC's performance was investigated using characterization techniques such as surface analyzer, Energy Dispersive X–ray (EDX), Fourier Transform Infrared (FTIR) spectroscopy, and X–Ray Diffraction (XRD) analysis. The optimal conditions for the adsorption of PineAC–RBV 5 R dye were at 60°C, in an acidic medium, and at 300 mg/L. The Langmuir isotherm model successfully described the monolayer behaviour of RBV 5 R dye adsorption onto PineAC at 30 and 45°C. In contrast, the Freundlich isotherm model was applicable at 60°C. The PineAC–RBV 5 R dye exhibited a maximum adsorption capacity (qmax) of 66.300 mg/g. The kinetic data demonstrated excellent agreement with the Polymath Mass Transfer (PMT) model, successfully capturing adsorption behavior. The rate constant, kPTM, displayed an increasing trend as the RBV 5 R initial concentration rose from 25 mg/L to 300 mg/L. Furthermore, the PMT model accurately predicted the adsorption surface area, aPMT, to be 466.6560 m2/g, closely matching the actual mesopores surface area of 547.8500 m2/g. This remarkable accuracy highlights the reliability and robustness of the PMT model in describing the adsorption process. PineAC–RBV 5 R dye adsorption exhibited consistent thermodynamic behaviour characterized by endothermic adsorption (ΔH°=28.49 kJ/mol), a physisorption mechanism (Ea=24.02 kJ/mol), and spontaneity (ΔG°=10.74 kJ/mol). The potential mechanisms involved in the PineAC–RBV 5 R dye adsorption included n–π interactions, hydrogen bonding, and π–π interactions. The regeneration effectiveness of PineAC–RBV 5 R dye adsorption was 72.30% for the third cycle without causing any surface morphological alterations in agreement with SEM images and EDX spectra. Investigating the adsorption mechanisms and the potential for further functionalization of PineAC could provide opportunities for enhanced performance and expanded applications in sustainable wastewater treatment.

Defects oriented hydrothermal synthesis of TiO2 and MnTiO2 nanoparticles as photocatalysts for wastewater treatment and antibacterial applications

Pure and manganese-doped titanium dioxide nanoparticles (MnTiO2-NPs) were synthesized by the defect-oriented hydrothermal approach. The synthesized material was then characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), and UV–visible spectroscopy (UV–Vis). The agar well diffusion method assessed the antibacterial efficiency of TiO2 and MnTiO2-NPs against E. coli and S. aureus. Zone of inhibition (ZOI) formed by pure TiO2 was observed as 12 mm and 11.5 mm against E. coli and S. aureus, while for MnTiO2-NPs it was observed as 19 mm (E. coli) and 21 mm (S. aureus). The concentration of synthesized nanoparticles (10 mg/ml, and 20 mg/ml) was used for antibacterial studies. The efficacy of the pure and MnTiO2-NPs as an active photocatalyst for the degradation of methylene blue (MB) dye was also assessed using a UV light. It was observed that the photodegradation efficiency of 1 g of MnTiO2-NPs was higher than the same amount of pure TiO2. The results suggest that the photocatalyst concentration directly impacts the photodegradation of MB dye. The pH value was found to influence the photodegradation of MB dye at higher pH values. Based on the obtained results, MnTiO2-NPs were observed as a promising agent for microbial resistance and water remediation.

Adaptive Critic Control Design With Knowledge Transfer for Wastewater Treatment Applications

The wastewater treatment process (WWTP) is of great significance to environmental protection. To improve the efficiency of the WWTP, it is crucial to ensure that the dissolved oxygen (DO) concentration tracks the set value efficiently. Due to the nonlinear and time-varying dynamics of the WWTP, traditional control methods cannot accurately control the DO concentration. To overcome these challenges, this paper proposes an online transferred heuristic dynamic programming (TrHDP) control design by combining transfer learning with adaptive critic design. First, we use the historical sample data to construct a mathematical model of the WWTP and learn the prior knowledge from the model. Then, the online control process of the DO concentration is guided by utilizing the prior knowledge. In order to avoid negative transfer and save computing resources, we design a novel decay function with the truncation mechanism. In addition, we prove the stability of the TrHDP control scheme by constructing a Lyapunov function. Finally, the performance of the TrHDP scheme is verified by the Benchmark Simulation Model No. 1. Compared with other methods, the TrHDP method possesses higher control accuracy for the DO concentration and overcomes the disadvantage of low learning efficiency of general online methods.

Light-Induced Variation of Lithium Coordination Environment in g-C3N4 Nanosheet for Highly Efficient Oxygen Reduction Reactions.

The structure and electronic state of the active center in a single-atom catalyst undergo noticeable changes during a dynamic catalytic process. The metal atom active center is not well demonstrated in a dynamic manner. This study demonstrated that Li metal atoms, serving as active centers, can migrate on a C3N4 monolayer or between C3N4 monolayers when exposed to light irradiation. This migration alters the local coordination environment of Li in the C3N4 nanosheets, leading to a significant enhancement in photocatalytic activity. The photocatalytic H2O2 process could be maintained for 35 h with a 920 mmol/g record-high yield, corresponding to a 0.4% H2O2 concentration, which is far greater than the value (0.1%) of practical application for wastewater treatment. Density functional theory calculations indicated that dynamic Li-coordinated structures contributed to the superhigh photocatalytic activity.

Identification and quantification of electron-generated atomic hydrogen through in-situ electron spin resonance and density functional theory

Electro-generated atomic hydrogen (H*) plays a crucial role in the electrochemical reduction process, serving as the key species that mediates the electrocatalytic hydrogenation reduction of stubborn contaminants in wastewater treatment. However, precisely identifying and quantifying transient atomic H* presents a significant challenge due to its limited lifespan and its existence solely within the boundary layer at the electrode/solution interface. Herein, we developed the electrodeposition of palladium nanoparticles onto carbon cloth and assessed its effectiveness as a cathode for generating and stabilizing atomic H*. The environmental application of atomic H* was validated through the dechlorination of 2, 4-dichlorophenol wastewater and the reduction of antimonite wastewater. Additionally, the identification of atomic H* was verified by electrochemical measurements, high-resolution mass spectra, and density functional theory. Moreover, introducing an excess of a spin trapping agent (5,5-dimethyl-1-pyrroline-N-oxide) and fast in-situ spin trapping facilitated creating favorable conditions for efficient trapping of atomic H* and subsequent electron spin resonance (ESR) spectroscopy quantification analysis. Subsequently, the quantification of atomic H* was achieved by double integration of the ESR signal of spin adduct and comparison with the external standard agent (4-hydroxy-2,2,6,6-tetramethyl-1-piperidine 1-oxyl). This study introduces a novel method for in-situ spin trapping and quantification of atomic H*, facilitating the advancement of electrochemical reduction technology and its application in wastewater treatment.

Confined MOF pyrolysis within mesoporous SiO2 core–shell nanoreactors for superior activity and stability of electro-Fenton catalysts

Despite the high density and uniform distribution of active sites in metal–organic frameworks (MOFs) and their derivatives, the relatively low stability in water still limits their utilization in heterogeneous catalysis. Herein, the confinement of pyrolyzed MIL-88B(Fe) derivatives within mesoporous SiO2 allowed fabricating core–shell nanoreactors (Fe/C@mSiO2) that served as heterogeneous electro-Fenton (HEF) catalysts for the first time, revealing an excellent performance. The as-prepared catalysts were featured by high specific surface area and dense active sites. During service as core–shell nanoreactors, they behaved as a dual function adsorbent-catalyst, exhibiting superior catalytic activity and recyclability as compared to HEF catalysts without shell. Using 0.2 g/L of catalyst, the complete removal of bisphenol A at pH 6.2 and 100 mA was achieved at 120 min, with extremely low iron leaching of 0.11 mg/L. The rigid mSiO2 shell not only protected the iron active sites from leaching, but it also provided porous and permeable channels for efficient mass transport. The unique core–shell architecture concentrates the catalytic sites and reactants within a confined space, promoting the fast degradation of bisphenol A. Furthermore, the defect-rich carbon substrate and the high dispersibility of iron-rich sites favor a fast electron transfer. The efficient treatment of several organic micropollutants in consecutive trials corroborated the high activity and stability of the Fe/C@mSiO2. This work contributes to the rational design of HEF catalysts, aiming at consolidating their practical application in advanced wastewater treatment.

Efficient photocatalytic degradation of textile dye pollutants using thermally exfoliated graphitic carbon nitride (TE–g–C3N4)

Graphitic carbon nitride (g–C3N4), an organic photocatalyst was reported to have beneficial properties to be used in wastewater treatment applications. However, g–C3N4, in its bulk form was found to have poor photocatalytic degradation efficiency due to its inherent limitations such as poor specific surface area and fast electron–hole pair recombination rate. In this study, we have tuned the physiochemical properties of bulk g–C3N4 by direct thermal exfoliation (TE–g–C3N4) and examined their photocatalytic degradation efficiency against abundant textile dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB). The degradation efficiencies for MB, MO, and RhB dyes are 92 ± 0.18%, 93 ± 0.31%, and 95 ± 0.4% respectively in 60 min of UV light irradiation. The degradation efficiency increased with an increase in the exfoliation temperature. The prepared catalysts were characterized using FTIR, XRD, FE-SEM, EDAX, BET, and UV-DRS. In BET analysis, TE–g–C3N4 samples showed improved surface area (48.20 m2/g) when compared to the bulk g–C3N4 (5.03 m2/g). Further, the TE–g–C3N4 had 2.98 times higher adsorption efficiency than the bulk ones. The free radicals scavenging studies revealed that the superoxide radicals played an important role in the photodegradation for dyes, when compared to the hydroxyl radical (.OH) and the photo-induced holes (h+), Photoluminescence (PL) emission and electrochemical impedance spectroscopy (EIS) spectra of TE–g–C3N4 indicated a lowered electron–hole pairs’ recombination rate and an increased photo-induced charge transfer respectively. Further, the TE–g–C3N4 were found to have excellent stability for up to 5 cycles with only a minor decrease in the activity from 92% to 86.2%. These findings proved that TE–g–C3N4 was an excellent photocatalyst for the removal and degradation of textile dyes from wastewater.

Mesoporous Magnetic/Polymer Hybrid Nanoabsorbent for Rapid and Efficient Removal of Heavy Metal Ions from Wastewater.

As an advanced water purification technology, magnetic nanoabsorbents are highly attractive for their sustainability, robustness, and energy efficiency. However, magnetic responsiveness and high adsorptive capacity are irreconcilable during the design and synthesis of a high-performance magnetic nanoabsorbent. Here, we address this issue by designing a kind of mesoporous magnetic polymer hybrid microspheres, where functional polymers such as polyrhodanine and polypyrrole were attached to the pore walls in the interior of mesoporous Fe3O4 microspheres through in situ polymerization. Due to the integrated large saturation magnetic moment, porous structure, and dense polymer layer, the mesoporous magnetic polymer hybrid microspheres demonstrated fast magnetic responsiveness, excellent recycling performance, and high adsorption capacities toward Pb(II) ions (189 mg g-1) for polyrhodanine and Cr(VI) ions (199 mg g-1) for polypyrrole. Furthermore, their potential application in wastewater treatment was verified by a self-made magnetic separation column, where the designed magnetic nanoabsorbent exhibits significant advantages including rapid separation of heavy metal ions and high outflow. This study provided a promising magnetic polymer hybrid nanoabsorbent for realizing efficient removal of heavy metal ions from wastewater.

Biopolymeric Nanocomposites for Wastewater Remediation: An Overview on Recent Progress and Challenges.

Essential for human development, water is increasingly polluted by diverse anthropogenic activities, containing contaminants like organic dyes, acids, antibiotics, inorganic salts, and heavy metals. Conventional methods fall short, prompting the exploration of advanced, cost-effective remediation. Recent research focuses on sustainable adsorption, with nano-modifications enhancing adsorbent efficacy against persistent waterborne pollutants. This review delves into recent advancements (2020-2023) in sustainable biopolymeric nanocomposites, spotlighting the applications of biopolymers like chitosan in wastewater remediation, particularly as adsorbents and filtration membranes along with their mechanism. The advantages and drawbacks of various biopolymers have also been discussed along with their modification in synthesizing biopolymeric nanocomposites by combining the benefits of biodegradable polymers and nanomaterials for enhanced physiochemical and mechanical properties for their application in wastewater treatment. The important functions of biopolymeric nanocomposites by adsorbing, removing, and selectively targeting contaminants, contributing to the purification and sustainable management of water resources, have also been elaborated on. Furthermore, it outlines the reusability and current challenges for the further exploration of biopolymers in this burgeoning field for environmental applications.

Phenol degradation and Sb(V) adsorption by superparamagnetic CTAB-modified iron calcium composite

The heavy metal ions and organic dyes in textile wastewater treatment pose a significant environmental burden and are challenging to effectively manage. A magnetic cationic surfactant hexadecyltrimethylammonium bromide (CTAB), modified iron-calcium composite (referred to as CIC), was prepared using a straightforward method from iron-calcium composites as raw materials. The simultaneous catalytic degradation and adsorption efficiency of phenol and Sb(V) from textile wastewater were evaluated using this material. The results indicate that under conditions of pH 5.0 and a duration of 180 min, both phenol and Sb(V) removal rates exceed 90%. Characterization and experimental findings reveal that CIC possesses magnetic properties, facilitating easy separation, and offers a large surface area, ensuring abundant adsorption sites and stability. Additionally, CIC can assist in the enhanced degradation of phenol by H2O2. Pseudo-second-order kinetics describe the adsorption of Sb(V) by CIC, while oxidative kinetics explain the degradation of phenol. The primary removal mechanisms involve the oxidation and degradation of phenol through the generation of hydroxyl radicals by H2O2 and the formation of Fe-O-Sb complexes between Sb(V) and the iron sites on CIC, as well as the precipitation of Ca-O-Sb compounds between Sb(V) and the calcium sites on CIC. Therefore, the synergistic effect of CIC and H2O2 offers an efficient and environmentally friendly method for the simultaneous removal of Sb(V) and phenol in coupled wastewater, presenting broad prospects for application in wastewater treatment.

Surface Aerophilicity Engineering of Heterogeneous Catalysts for Enhanced Catalytic Ozonation

AbstractHeterogeneous catalysts for catalytic ozonation are elaborately designed with commendable intrinsic activity, while their industrial applications are limited by inadequate mass transfer of ozone (O3). In this work, it is demonstrated that engineering the surface aerophilicity of heterogeneous catalyst enables fast mass transfer of O3 reactant, giving rise to much enhanced catalytic ozonation performance. Taking active 4A zeolite catalyst as an example, the aerophilicity of spherical 4A zeolite can be greatly enhanced by coating polytetrafluoroethylene (PTFE) with low surface energy, and the optimized sample exhibits a 99.5% removal of atrazine (ATZ) within 20 min (corresponding to a k of 0.269 min−1), much better than 4A zeolite without surface aerophilicity engineering (k≈0.156 min−1). The PTFE coating does not change the ozone activation mechanism and degradation pathways for ATZ, further demonstrating that the enhanced ozonation activity is attributed to the enhanced mass transfer process. In addition, the general applicability of this surface aerophilicity and the potential ozonation application for industrial wastewater treatment are both demonstrated.

Iodide ion-imprinted chitosan beads for highly selective adsorption for nuclear wastewater treatment applications

Iodide ions from radioactive iodine isotopes are common contaminants present in nuclear wastewater from nuclear power plants which are considered hazardous contaminants to be released in water sources even at low concentrations due to their association with metabolic disorders, therefore its removal from the nuclear wastewater effluents is necessary. Chitosan beads are natural and cost-efficient adsorbents that have been used for ion removal from wastewater. However, issues of poor selectivity persist in achieving high-efficiency iodide ion removal. In this study, ion-imprinted chitosan beads (IIC) have been synthesized using the phase-inversion method, IIC beads were modified by cross-linking with epichlorohydrin (IIC-EPI) and modified by cross-linking with epichlorohydrin and silicon dioxide nanoparticles (IIC–SiO2-EPI). Through 4 h of batch adsorption experiments, IIC beads achieved a maximum adsorption capacity (Qe) of 0.65 mmol g−1 and showed more preference for the iodide ions compared to the non-imprinted chitosan beads which achieved a maximum adsorption capacity of 0.27 mmol g−1 at pH 7. While the modified beads IIC-EPI and IIC-SiO2-EPI beads have boosted the adsorption capacities to 0.72 mmol g−1 and 0.91 mmol g−1. Scanning electron microscopic cross-sectional images have shown more pores and cavities than the surface images which agrees with the multilayer heterogeneous diffusion suggested by the Freundlich adsorption isotherm, that the experimental data has fitted. Adsorption kinetic data have fitted the Pseudo-second-order model as well as the Weber and Morris intraparticle model, which suggest an intraparticle pore diffusion adsorption mechanism, with the involvement of the physical electrostatic interactions with the cationic chitosan surface.

Temperature and photosensitive PVDF-g-PNIPAAm/GPE-PDA@ZnO composite membranes with efficient dyes separation capability and light-cleaning function

In this paper, PVDF-g-PNIPAAm/GEP-PDA@ZnO composite membranes that can undergo light-induced structural response and photodegradation to achieve self-cleaning have been designed and applied to the separation and purification of dye wastewater. The membranes were prepared by blending graphene (GPE)-polydopamine (PDA)-coated zinc oxide (ZnO) core–shell particles into the PVDF-g-PNIPAAm matrix with a non-solvent induced phase separation technique. The GPE and ZnO are tightly bonded by highly adhesive PDA to form a “strawberry-like” core–shell structure. GPE absorbs light energy and converts it into heat, resulting in changes in PNIPAAm chain segments to expand the pore size for self-cleaning. While the membrane is warming up, GPE further promotes the activation of active groups on the surface of PDA@ZnO at high temperature, resulting in unique and excellent photothermal catalytic activity. As a result, the membrane achieves both self-cleaning and pollutant degradation, which results in an FRR of 99.6% after light cleaning. Moreover, the GPE-PDA@ZnO nanoparticle-modified PVDF-g-PNIPAAm membranes exhibit excellent cycling stability with a degradation flux recovery rate of more than 97% even after multiple UV cleaning. Thus, PVDF-g-PNIPAAm/GPE-PDA@ZnO composite membranes extend the versatility of PVDF-based membranes and show extraordinary potential for application in wastewater treatment.

Characteristics of annular surface dielectric barrier discharge with microsecond pulse under water-covered condition.

Surface dielectric barrier discharge (SDBD) has wide applications in flow control, wastewater treatment, and biomedicine. The dielectric surface of an SDBD actuator is generally attached to the water droplets during applications. Thus far, only a few studies have been conducted on the effects of water covering the dielectric surface on the discharge characteristics of SDBD. Therefore, the effects of water droplets on the discharge of an SDBD actuator based on a repetitive microsecond pulse power supply were investigated in this study. The results show that a filament micro-discharge channel forms between the light and dark regions at the internal edge of the SDBD high-voltage electrode and develops toward the center of the dielectric surface in the region without water droplet coverage. SDBD in the water-covered region was divided into two stages. This paper compares the electrical characteristics of SDBD with and without water droplet, and explores the electric field distortion effect of water droplet endpoints through 3D simulation.Based on the theories of water droplet polarization and gas discharge, the effects of water droplets on plasma development and surface charge accumulation under water-covered condition were analyzed. The water droplet plays a similar role as a "secondary electrode" during the discharge process.

Embedding electronic perpetual motion into single-atom catalysts for persistent Fenton-like reactions

In our quest to leverage the capabilities of the emerging single-atom catalysts (SACs) for wastewater purification, we confronted fundamental challenges related to electron scarcity and instability. Through meticulous theoretical calculations, we identified optimal placements for nitrogen vacancies (Nv) and iron (Fe) single-atom sites, uncovering a dual-site approach that significantly amplified visible-light absorption and charge transfer dynamics. Informed by these computational insights, we cleverly integrated Nv into the catalyst design to boost electron density around iron atoms, yielding a potent and flexible photoactivator for benign peracetic acid. This exceptional catalyst exhibited remarkable stability and effectively degraded various organic contaminants over 20 cycles with self-cleaning properties. Specifically, the Nv sites captured electrons, enabling their swift transfer to adjacent Fe sites under visible light irradiation. This mechanism accelerated the reduction of the formed "peracetic acid-catalyst" intermediate. Theoretical calculations were used to elucidate the synergistic interplay of dual mechanisms, illuminating increased adsorption and activation of reactive molecules. Furthermore, electron reduction pathways on the conduction band were elaborately explored, unveiling the production of reactive species that enhanced photocatalytic processes. A six-flux model and associated parameters were also applied to precisely optimize the photocatalytic process, providing invaluable insights for future photocatalyst design. Overall, this study offers a molecule-level insight into the rational design of robust SACs in a photo-Fenton-like system, with promising implications for wastewater treatment and other high-value applications.

Comprehensive Investigation of Cu2+ Adsorption from Wastewater Using Olive-Waste-Derived Adsorbents: Experimental and Molecular Insights.

This study investigates the efficacy of adsorbents from locally sourced olive waste-encompassing olive skins, leaves, and pits, recovered from the initial centrifugation of olives (OWP)-and a composite with sodium alginate (OWPSA) for the removal of Cu2+ ions from synthetic wastewater. Experimental analyses conducted at room temperature, with an initial Cu2+ concentration of 50 mg/L and a solid/liquid ratio of 1 g/L, showed that the removal efficiencies were approximately 79.54% and 94.54% for OWP and OWPSA, respectively, highlighting the positive impact of alginate on adsorption capacity. Utilizing statistical physics isotherm models, particularly the single-layer model coupled to real gas (SLMRG), allowed us to robustly fit the experimental data, providing insights into the adsorption mechanisms. Thermodynamic parameters affirmed the spontaneity and endothermic nature of the processes. Adsorption kinetics were interpreted effectively using the pseudo-second-order (PSO) model. Molecular modeling investigations, including the conductor-like screening model for real solvents (COSMO-RS), density functional theory (DFT), and atom-in-molecule (AIM) analysis, unveiled intricate molecular interactions among the adsorbent components-cellulose, hemicellulose, lignin, and alginate-and the pollutant Cu2+, confirming their physically interactive nature. These findings emphasize the synergistic application of experimental and theoretical approaches, providing a comprehensive understanding of copper adsorption dynamics at the molecular level. This methodology holds promise for unraveling intricate processes across various adsorbent materials in wastewater treatment applications.

Enhanced heterogeneous electro-Fenton process for degradation of rhodamine B: FeOCl/CF@AB composite cathode with superior efficiency and sustainability

With the growing environmental concerns and increasing demand for clean energy, the synthesis of Stable and efficient heterogeneous Electro-Fenton catalysts gains significant attention in the market. We present a novel FeOCl/CF@AB composite cathode designed for efficient heterogeneous electro-Fenton degradation of rhodamine B. The composite cathode exhibits remarkable catalytic performance, outperforming the raw carbon felt electrode, and achieving significantly higher rhodamine B degradation rates. The incorporation of acetylene black encapsulation provides excellent stability, preserving the FeOCl active sites from corrosion and ensuring sustained catalytic activity even after multiple reuse cycles. The electron penetration mechanism on the FeOCl/CF@AB cathode is elucidated through density functional theory calculations, revealing spontaneous O2 activation and H2O2 generation. Electron transfer between Fe(II) species and the acetylene black shell facilitates these processes. The presence of •OH species supports the degradation of rhodamine B to intermediates and mineralization to CO2 and H2O. Furthermore, LC-MS analysis unveils the detoxification effect of the electro-Fenton process with FeOCl/CF@AB, presenting reduced developmental toxicity of degradation intermediates. Economic cost analysis demonstrates the feasibility and cost-effectiveness of the FeOCl/CF@AB cathode for large-scale wastewater treatment applications. In conclusion, the FeOCl/CF@AB composite cathode showcases stability and efficiency, offering a promising and sustainable electro-Fenton technology for dye wastewater treatment.