Application In Removal Of Pollutants Research Articles

Fabrication of eco-friendly nanocellulose-chitosan-calcium phosphate ternary nanocomposite for wastewater remediation

Nanocomposites have emerged as promising materials for pollutant removal due to their unique properties. However, conventional synthesis methods often involve toxic solvents or expensive materials. In this study, we present a novel ternary nanocomposite synthesized via a simple, cost-effective vacuum filtration method. The composite consists of calcium phosphate (CaP), biowaste-derived nanocellulose (diameter <50 nm) (NC), and chitosan (CH). The nanocomposite exhibited exceptional pollutant removal capabilities due to the hybrid approach of combining adsorption and size exclusion that widens and accelerates pollutant removal. When tested with synthetic wastewater containing 10 ppm of Ni ions and 10 ppm of Congo red (CR) dye, it achieved impressive removal rates of 98.7% for Ni ions and 100% for CR dye. Moreover, the nanocomposite effectively removed heavy metals such as Cd, Ag, Al, Fe, Hg, Mo, Li, and Se at 100%, and Ba, Be, P, and Zn at 80%, 92%, 87%, and 97%, respectively, from real-world municipal wastewater. Importantly, this green nanocomposite membrane was synthesized without the use of harmful chemicals or complex modifications and operated at a high flux rate of 146 L/m2.h.MPa. Its outstanding performance highlights its potential for sustainable pollutant removal applications.

Novel high-valent copper species-involved photo-Fenton-like process boosted by nitrogen/oxygen dual defects modulation

High-valent metal species generated during peroxymonosulfate (PMS) activation have demonstrated significant potential in wastewater treatment. However, the rapid generation of high-valent metal species, especially high-valent copper (Cu(III)), has been challenging. Moreover, the mechanisms behind Cu(III) generation and its role in the PMS-based Fenton-like process have not been fully understood. Herein, a novel N, O dual defects co-modified 0D/2D hybrid of CuO nanodots (NDs)/g-C3N4 nanosheets was constructed as an integrated photocatalytic platform to efficiently activate PMS, which exhibited excellent catalytic activity and stability towards tetracycline degradation through consecutive generation of surface Cu(III) as the key active species. The N, O dual-defects and strong interfacial coupling of NDs/g-C3N4 markedly increased charge separation and induced electron-rich Cu sites. This led to a continuous and rapid Cu(II)/Cu(I) conversion, further triggering persistent Cu(III) generation through Cu(I)-oxidation with a two-electron transfer. The work provides new insights into exploring the properties of Cu(III) species during PMS activation and offers encouraging guidance for their application in pollutant removal.

Co-Zn nanoparticles on N-doped graphene nanocomposites as bifunctional catalysts for non-enzymatic electrochemical sensor and organic dye degradation

Detection of biomolecules by advanced sensing systems and organic pollutant removal is of immense interest in biomedical and environmental remediation sectors. In this regard, effective glucose detection is dynamic in rapid-diagnosis of related diseases and in addition, removal of organic dyes by suitable adsorbent materials is vital for water treatment. The present work involves the facile fabrication of CoZn-N doped graphene nanocomposites and employed in glucose sensors and dye removal. The synthesized materials were characterized to evaluate the structural, morphological, elemental and surface characterizations such as, X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning DR-UV–vis–spectroscopy, electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM) techniques, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. SEM and TEM images revealed the Co-Zn nano particles (NPs) with respective morphologies within the N doped graphene structure. Electrochemical examinations of CoZn-N doped graphene nanocomposites/GCE sensor demonstrated superior sensitivity for the detection of commercial glucose in NaOH. Moreover, CoZnNG nanocatalyst has been investigated for the dye removal of crystal violet (CV), Rhodamine B (RB), methylene blue (MB) and congo red (CR) in the presence of H2O2. CoZnNG catalyst exhibited a maximum efficiency of 96 % over CV dye degradation in 30 min which is comparatively higher than the removal of MB, CR and RB dyes with 36 %, 41 %, 38 % for 120, 60 and 100 min, respectively. The CoZn-N doped graphene nanocomposites exhibited regeneration, reproducibility, and stability toward dye removal. Such multi-component hybrid N doped graphene could be efficacious for real-time non-enzymatic electrochemical sensor and pollutant removal applications.

Construction of TiO2@Cu2O-CuS heterostructures integrating RGO for enhanced full-spectrum photocatalytic degradation of organic pollutants

This study presents the development and optimization of TiO2@Cu2O-CuS heterostructures, enhanced with reduced graphene oxide (RGO), for efficient photocatalytic degradation of organic pollutants, focusing on imidacloprid. Two configurations, TiO2/RGO/Cu2O-CuS and Cu2O-CuS/RGO/TiO2, are explored to highlight the impact of material layering on photocatalytic efficiency. The strategic integration of RGO optimizes charge transfer, crucial for photocatalysis. Comprehensive characterization techniques, such as X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Raman spectroscopy, and Nitrogen adsorption-desorption isotherms, provide insights into the crystalline structure, morphology, surface chemistry, and textural properties of the heterostructures. The TiO2/RGO/Cu2O-CuS configuration significantly outperforms its counterpart in photocatalytic activity under full-spectrum (UV–VIS–IR) illumination, due to improved charge carrier dynamics and synergistic interactions between the composite materials. Remarkably, the TiO2/RGO/Cu2O-CuS assembly achieved over 95 % degradation of imidacloprid under simulated solar irradiation, marking a breakthrough in solar spectrum utilization for photocatalysis and exhibits promising recyclability, maintaining its high photocatalytic efficiency even after multiple degradation cycles, highlighting its potential for sustainable pollutant removal applications. Additionally, this configuration demonstrates a twofold increase in degradation efficiency compared to separate UV and VIS irradiations, emphasizing its rapid pollutant removal capability. This research underscores the critical role of material layer sequencing in developing high-efficiency photocatalytic systems and marks a significant advancement in environmental remediation technologies that harness renewable energy sources.

Performance and oxidation mechanism of VUV photo–Fenton in simultaneous removal of Ni-EDTA and hypophosphite: decomplexation, low-valent phosphorous oxidation and DFT calculation

The photo–Fenton process offers a promising alternative for the oxidation of complex heavy metals. However, the potential influence of coexisting substrates may be overlooked. The •OH radicals generated in the photo–Fenton process ensure superior oxidation ability. In this study, we used a vacuum ultraviolet (VUV) light-assisted photo–Fenton (VPF) process to explore its performance in the synergistic oxidation of Ni-ethylenediaminetetraacetic acid (EDTA) and coexisting hypophosphite, typical pollutants in electroless nickel plating (ENP) wastewater. Based on electron spin resonance (ESR) and DMSO-probing results, •OH was the predominant reactive oxygen species, and VPF possessed the highest •OH concentration compared to other photochemical processes under identical conditions (pH, Fe, H2O2). Enhanced •OH generation in VPF was attributed to various photochemical reactions, including photo–Fenton, UV/H2O2, and VUV/H2O. Consequently, VPF exhibited efficient Ni-EDTA decomplexation and hypophosphite oxidation. Notably, the evolution and rate-limiting steps during hypophosphite oxidation were demonstrated by experimental results and density functional theory calculations. Hypophosphite was initially oxidized to phosphite, which subsequently oxidized to phosphate. The oxidation of phosphite could be considered the rate-limiting step as it exhibits higher energy barriers than hypophosphite oxidation. Adequate •OH generation in the VPF process could overcome this energy barrier, indicating its potential for application in pollutant removal and resource recovery from ENP wastewater.

Application of ceria materials modified by oxygen vacancies: In photocatalytic process

Cerium-based materials are widely used in various applications such as photocatalytic environmental remediation, CO2 photoreduction and photocatalytic hydrogen production due to their unique optical properties and special oxygen vacancy formation mechanisms. The special external electronic structure of cerium (4f15d16s2f15d16s2), the highly electronic 4f orbital, promotes the formation of oxygen vacancies through Ce4+/Ce3+ conversion, thereby improving the optical properties of the catalyst. Consequently, the application of cerium-based materials in the field of photocatalysis has been of great interest to researchers. In this paper, we briefly review the synthesis of cerium-based photocatalysts and their applications in pollutant removal, CO2 reduction, and hydrogen production, as well as their promising applications.

Insights into kinetics, thermodynamics, and mechanisms of chemically activated sunflower stem biochar for removal of phenol and bisphenol-A from wastewater

This study synthesized a highly efficient KOH-treated sunflower stem activated carbon (KOH-SSAC) using a two-step pyrolysis process and chemical activation using KOH. The resulting material exhibited exceptional properties, such as a high specific surface area (452 m2/g) and excellent adsorption capacities for phenol (333.03 mg/g) and bisphenol A (BPA) (365.81 mg/g). The adsorption process was spontaneous and exothermic, benefiting from the synergistic effects of hydrogen bonding, electrostatic attraction, and stacking interactions. Comparative analysis also showed that KOH-SSAC performed approximately twice as well as sunflower stem biochar (SSB), indicating its potential for water treatment and pollutant removal applications. The study suggests the exploration of optimization strategies to further enhance the efficiency of KOH-SSAC in large-scale scenarios. These findings contribute to the development of improved materials for efficient water treatment and pollution control.

Efficient catalytic activity of NiO and CeO2 films in benzoic acid removal using ozone.

This research focuses on the synthesis of NiO and CeO2 thin films using spray pyrolysis for the removal of benzoic acid using ozone as an oxidant. The results indicate that the addition of CeO2 films significantly enhances the mineralization of benzoic acid, achieving a rate of over 80% as the CeO2 films react with ozone to produce strong oxidant species, such as hydroxyl radicals, superoxide radicals, and singlet oxygen as demonstrated by the presence of quenchers in the reaction system. The difference in catalytic activity between NiO and CeO2 films was analyzed via XPS technique; specifically, hydroxyl oxygen groups in the CeO2 film were greater in number than those in the NiO film, thus benefitting catalytic oxidation as these species are considered active oxidation sites. The effects of nozzle-substrate distances and deposition time during the synthesis of the films on benzoic acid removal efficiency were also explored. Based on XRD characterization, it was established that the NiO and CeO2 films were polycrystalline with a cubic structure. NiO spherical nanoparticles were well-distributed on the substrate surface, while some pin holes and overgrown clusters were observed in the CeO2 films according to the SEM results. The stability of the CeO2 films after five consecutive cycles confirms their reusability. The retrieval of films is easy because it does not require additional separation methods, unlike the catalyst in powder form. The obtained results indicate that the CeO2 films have potential application in pollutant removal from water through catalytic ozonation.

Poly(PEI‐catechol‐tetraethylenepentamine) was prepared by “one‐pot method” for removing Reactive Red 195

AbstractWastewater containing dyes is frequently discharged by industrial processes and needs separation and recycling. To solve this problem, it is important to research and develop environmentally friendly, efficient adsorbent materials for pollutant separation and recovery. In this study, a poly(PEI‐catechol‐tetraethylenepentamine) (PPCT) adsorbent was synthesized using a simple catecholamine reaction. This adsorbent exhibited high adsorption capacity and excellent removal efficiency for Reactive Red 195 (RR‐195) in wastewater. The material was characterized using SEM, FT‐IR, TGA, EA, and XPS. Its performance was optimized by varying the type of polyethyleneimine and the amount added during the preparation process. The effects of temperature, pH, contact time, and salt concentration on the adsorption were systematically investigated. Additionally, the experimental data showed consistency with both the Langmuir and pseudo‐second‐order kinetic models, simultaneously. The maximum adsorption capacity can reach 1754 mg g−1 at 303 K, with a retention rate of 86.6% after two cycles. The removal rate exceeds 98% at a concentration of 400 mg g−1 or lower. Additionally, the protonated amine group in PPCT carries a positive charge under acidic conditions, enabling selective adsorption of the anionic dye RR‐195. Consequently, PPCT exhibits an excellent adsorption effect on RR‐195 and holds promising applications in pollutant removal.

Highly efficient removal of Aflatoxin B1 employing a flower-like covalent organic framework-based fiber membrane

Mycotoxin pollutants removal using adsorbents has been studied extensively in recent years, although the development of low-cost, recyclable, and highly efficient adsorbents remains a challenge to date. Covalent Organic Frameworks (COFs) represent a novel kind of porous crystalline material, which have been applied widely. In this work, a flower-like COF fiber membrane (PAN@COF FM) for adsorbing Aflatoxin B1 was fabricated using a simple approach. The COF was grown on the surface of polyacrylonitrile (PAN) skeleton using the in situ growth method. Then, the AFB1 adsorption performance of the prepared membrane and the underlying adsorption mechanism were studied. The results revealed that the activated PAN@COF FM reached adsorption equilibrium within 30 min. The used membranes were regenerated by washing with an alkaline solution and then tested for adsorption efficiency again. The PAN@COF FM could adsorb above 98% Aflatoxin B1 after 10 cycles, indicating its good reusability. The well adsorption performance of the membrane was attributed to the π-π stacking, hydrogen bonding, and hydrophobic interactions between PAN@COF FM and Aflatoxin B1. In summary, the as-prepared PAN@COF FM possesses the advantage of high reusability and good adsorption performance, and has the promising application in pollutant removal.

Outstanding adsorption capacity of iron oxide synthesized with extract of açaí berry residue: kinetic, isotherm, and thermodynamic study for dye removal.

Contamination of water by toxic dyes is a serious environmental problem. Adsorbents prepared by an environmentally safe route have stood out for application in pollutant removal. Herein, iron oxide-based nanomaterial composed of Fe(III)-OOH and Fe(II/III) bound to proanthocyanidins, with particles in the order of 20 nm, was prepared by green synthesis assisted by extract of açaí (Euterpe oleracea Mart.) berry seeds from an agro-industrial residue. The nanomaterial was applied in the adsorption of cationic dyes. Screening tests were carried out for methylene blue (MB), resulting in an outstanding maximum adsorption capacity of 531.8 mg g-1 at 343 K, pH 10, 180 min. The kinetics followed a pseudo-second-order model and the isotherm of Fritz-Schülnder provided the best fit. Thermodynamic data show an endothermic process with entropy increase, typical of chemisorption. The proposed mechanism is based on the multilayer formation over a heterogeneous adsorbent surface, with chemical and electrostatic interactions of MB with the iron oxide nanoparticles and with the proanthocyanidins. The high adsorption efficiency was attributed to the network formed by the polymeric proanthocyanidins that entangled and protected the iron oxide nanoparticles, which allowed the reuse of the nanomaterial for seven cycles without loss of adsorption efficiency.

Synthesis of recyclable SERS platform based on magnetic Fe3O4/mTiO2/Ag composites for photodegradation and identification of organic pollutants in different water samples

In this study, we coatedmagnetic Fe3O4 nanospheres with a crystalline mesoporous TiO2 (mTiO2) layer with photocatalytic activity, followed by the deposition of Ag nanoparticles as an outer layer through in-situ reduction of AgNO3 to obtain multifunctional Fe3O4/mTiO2/Ag core-shell-shell structured composites. By adjusting the amount of AgNO3, we were able to precisely control the size and coverage of the Ag nanoparticles. To evaluate the surface-enhanced Raman spectroscopy (SERS) activity of the Fe3O4/mTiO2/Ag composites, we employed 4-mercaptobenzoic acid (4-MBA) as a model Raman reporter. The limit of detection (LOD) of 4-MBA was down to 10−10 M. Moreover, for practical applications, we successfully detected methylene blue (MB) in different water samples, such as tap water and industrial wastewater, and both of systems presented an ultralow LOD of 10−9 M. Notably, a strong linear relationship (R2 ≥ 0.95) between the SERS intensities and the logarithmic concentration of MB was observed, highlighting the excellent quantitative sensing capabilities of these substrates. The Fe3O4/mTiO2/Ag composites also exhibited remarkable signal reproducibility and exceptional stability during storage. Additionally, these composites demonstrated promising photocatalytic property. In five consecutive cycles, we were able to efficiently detect MB by utilizing the composites' photocatalytic removal ability under UV irradiation, which was facilitated by simple magnetic separation. These findings hold significant importance for environmental safety and pollutant removal applications.

Frontispiece: In situ H2O2 Generation and Corresponding Pollutant Removal Applications: A Review

This review starts from the perspective of three methods for in situ H2O2 generation (photocatalysis, electrocatalysis and chemical activation), makes a detailed summary and analysis of the related three types of reaction mechanisms, catalyst design principles and organic pollutant removal applications, and clarifies the possible development direction of pollutant removal through in situ H2O2 generation in the future. For more information, see the Review by M. Xing et al. (DOI: 10.1002/chem.202203921)

In situ H2 O2 Generation and Corresponding Pollutant Removal Applications: A Review.

Catalytic hydrogen peroxide (H2 O2 ) generation from oxygen and water enables a sustainable environment to operate in an effective and green energy-to-chemical conversion way, which has attracted increasing interest in the fields of energy production and environment treatment. In light of this, tremendous progresses and developments have been made during the past decades in catalytic H2 O2 production for pollutant removal from three perspectives including photocatalysis, electrocatalysis or chemical activation. Herein, we critically review the state-of-the-art developments over various procedures of H2 O2 generation and its further application, with the existence of photocatalysts, electrocatalysts, and catalysts, respectively. Benefiting from extensively experimental and theoretical investigations, the performance and stability of H2 O2 generation and its utilization can be maneuvered by devising catalytic platform based on numerous catalysts with predominant electronic, chemical and physical properties, which endow the catalysts with efficient electrons transportation, abundant active sites, and sufficient oxygen adsorption for H2 O2 generation. Furthermore, this review also discusses the formation mechanism of H2 O2 by 2e-ORR and 2e-WOR, as well as its functional process of activating and removing pollutants, and summarizes the design principles of various catalysts by focusing on the formation of H2 O2 . We finally highlight the specific challenges and prospects related to the utilization of catalysts and envision the possible future development trends in the fields of pollutant removal.

Construction of Z-Scheme Ag2MoO4/ZnWO4 Heterojunctions for Photocatalytically Removing Pollutants.

Facilitation of the photocarrier separation is a crucial strategy for developing highly efficient photocatalysts in eliminating environmental pollutants. Herein we have developed a new kind of Ag2MoO4/ZnWO4 (AMO/ZWO) composite photocatalysts with a Z-scheme mechanism by anchoring AMO nanoparticles onto ZWO nanorods. Multiple characterization methodologies and density functional theory (DFT) calculations were employed to study the performances of the AMO/ZWO heterojunctions as well as the underlying photocatalytic mechanism. Simulated-sunlight-driven photodegradation experiments for removing methylene blue (MB) demonstrates that the 8%AMO/ZWO heterojunction can photocatalytically remove 99.8% of MB within 60 min, and the reaction rate constant is obtained as 0.10199 min-1, which is enhanced by 6.8 (or 4.9) times when compared with that of pure ZWO (or AMO). On the base of the experimental results and DFT calculations, the enhanced photocatalytic mechanism of the AMO/ZWO heterojunctions was revealed to be the efficient separation of photocarriers via a Z-scheme transfer process. In addition, photodegradion of various organic pollutants over 8%AMO/ZWO was further compared and aimed at incorporating it into industrial application in pollutant removal.

Highly-efficient and recyclable Bi2O2CO3 adsorbent achieved by surfactant modification and its application in pollutant removal

Herein we have developed a highly efficient and recyclable Bi2O2CO3 (BOC) adsorbent by introducing different surfactants during the hydrothermal synthesis of BOC nanostructures. It is demonstrated that the CTAB modified BOC sample (termed as BOC-CTAB) exhibits the highest adsorption performance for removing organic pollutants and Cr(VI) ions. More interestingly, the developed BOC adsorbent can be easily regenerated via a simple photodegradation process and exhibits excellent reusability. The adsorption kinetics, isotherms and thermodynamics of methyl orange (MO) and Cr(VI) onto the BOC-CTAB adsorbent were systematically investigated. The effect of adsorbent dosage, MO concentration and temperature on the adsorption of MO onto BOC-CTAB was predicted by response surface methodology (RSM). Moreover, the adsorption performance of BOC-CTAB towards various organic pollutants at different acidic-alkaline environments was further compared; among them, the strongest adsorption is observed for congo red (CR) with qe(pH 2) = 962 mg g−1.

Modeling optical energy gap of thin film cuprous oxide semiconductor using swarm intelligent computational method

Cuprous oxide (Cu2O) is a p-type metal oxide semiconducting material with potential in photovoltaic and photocatalysis applications due to its excellent absorption capacity in visible region and tunable energy gap. Experimental synthesis and energy gap characterization of thin film cuprous oxide semiconductor with desired dopants and varying experimental conditions for enhanced photocatalytic as well as photovoltaic activities are laborious and consume appreciable precious resources. This work hybridizes particle swarm optimization method with support vector regression algorithm for computing energy gap of thin film cuprous oxide semiconductor using the thickness of thin film and distorted lattice parameter as descriptors. The predictions of swarm-based support vector regression (S-SVR) model are compared with estimates of stepwise regression (SR) model while S-SVR shows superior performance of 39.47 %, 36.20 % and 114.41 % on testing data samples over SR model using root mean square error (RMSE), mean absolute error (MAE) and correlation coefficient (CC), respectively. The developed S-SVR model is characterized with 0.9559 CC, 0.0586 MAE and 0.028 RMSE on the basis of training samples. The developed S-SVR and SR models were further validated using external data samples while the developed S-SVR demonstrates excellent agreement with the measured values. The convincing precision demonstrated by S-SVR model would be of indispensable significance in determining energy gap of cuprous oxide semiconductor (for photocatalytic applications in pollutant removal, solar cell, gas sensors and thin film transistors) with appreciable quickness and reduced cost coupled with experimental difficulty circumvention.

Magnetic Metal Oxide-Based Photocatalysts with Integrated Silver for Water Treatment.

In this review, the most recent advances in the field of magnetic composite photocatalysts with integrated plasmonic silver (Ag) is presented, with an overview of their synthesis techniques, properties and photocatalytic pollutant removal applications. Magnetic attributes combined with plasmonic properties in these composites result in enhancements for light absorption, charge-pair generation-separation-transfer and photocatalytic efficiency with the additional advantage of their facile magnetic separation from water solutions after treatment, neutralizing the issue of silver’s inherent toxicity. A detailed overview of the currently utilized synthesis methods and techniques for the preparation of magnetic silver-integrated composites is presented. Furthermore, an extended critical review of the most recent pollutant removal applications of these composites via green photocatalysis technology is presented. From this survey, the potential of magnetic composites integrated with plasmonic metals is highlighted for light-induced water treatment and purification. Highlights: (1) Perspective of magnetic properties combined with plasmon metal attributes; (2) Overview of recent methods for magnetic silver-integrated composite synthesis; (3) Critical view of recent applications for photocatalytic pollutant removal.

Investigation of the boosted persulfate activation in the degradation of bisphenol A over MOF-derived cerium-doped Fe3O4 clusters with different shapes: the role of coordinatively unsaturated metal sites

A great challenge for the application of metal–organic frameworks (MOFs) as peroxymonosulfate (PMS) activators for environmental applications in pollutant removal is their stability and activity.

Sonication-Induced, Solvent-Selective Gelation of a 1,8-Napthalimide-Conjugated Amide: Structural Insights and Pollutant Removal Applications.

Reported herein is the synthesis, characterization, and dye removal applications of a highly solvent-selective organogel-forming amide, compound 1, which contains a 1,8-naphthalmide moiety, flexible n-hexyl chain, and benzene ring. This compound displayed remarkable solvent selectivity, with gel formation occurring only in the presence of alkylated aromatic solvents. Detailed structural characterization of the gels, combined with notable theoretical insights, is invoked to explain the highly selective gelation properties of compound 1, as is a comparison to non-gel forming structural isomer 2, which contains the same structural elements in a different arrangement. Finally, the ability of the gel derived from compound 1 to act as a reusable material for the efficient removal of cationic organic dyes from contaminated aqueous environments is also reported, with up to 11 repeated uses of the gel still maintaining the ability to effectively remove Rhodamine B.