Special Issue "Nanoscale Materials for Water Purification and Catalysis"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Energy and Catalysis".

Deadline for manuscript submissions: closed (1 December 2022) | Viewed by 13107

Special Issue Editors

Dr. Michael Arkas
E-Mail Website
Guest Editor
Demokritos National Centre for Scientific Research, Institute of Nanoscience and Nanotechnology, Athens, Greece
Interests: liquid crystals; catalysis; water purification; dendritic polymers; dendrimers; hyperbranched polymers; silica hydrogels-xerogels
Prof. Dr. Ioannis Pashalidis
E-Mail Website
Guest Editor
Department of Agriculture, University of Ioannina, UoI Kostakii Campus, 47100 Arta, Greece
Interests: (radio)toxic inorganic species; bioactive chelating ligands; natural organic matter; metal oxides; mineral surfaces; lanthanides; actinides; humic acids; biomass by-products; pollutant monitoring on ground and sea waters; water purification; plant fibres
Special Issues, Collections and Topics in MDPI journals
Dr. Dimitrios A. Giannakoudakis
E-Mail Website
Guest Editor
Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
Interests: physicochemical, structural, optical, and surface chemistry features of nanostructured materials; photocatalysis; mechanochemistry; ultrasound; sonophotochemistry; interfacial phenomena in catalysis; detoxification of toxic vapors; biomass valorization; selective oxidation processes; adsorptive air and water remediation; materials chemistry; MOFs and metal oxides nanocomposites; activated carbons; graphite/graphite oxide; graphitic carbon nitride polymer; semiconductor nanocatalysts; carbon quantum dots

Special Issue Information

Dear Colleagues,

The interdisciplinary character of nanotechnology has empowered diverse scientific partnerships aiming to discover solutions to major contemporary problems. As water resources continue to be polluted, the need to conceive novel improved antipollution methods is becoming increasingly critical. In parallel, advanced nanoscale materials with far-reaching potential have been developed in order to promote the catalytic and photocatalytic degradation of pollutants as well as chemical reactions such as advanced oxidation processes (AOPs). The concept of employing nanomaterials is not new; existing in a variety of forms including nanospheres, nanomembranes, nanotubes, and nanofibers, they exhibit unique separation and catalytic properties and constitute solutions that prevail compared with their conventional counterparts. Particular emphasis has been placed on the assembly of composite systems combining organic compounds, metals, ceramics, and carbon nanomaterials. They can combine high surface areas permitting optimum adsorption and catalytical performance with high stability and recyclability. Their superior mechanical and chemical characteristics render them ideal alternatives for optimized performance efficiency, cost-effectiveness, and ease of preparation. In this Special Issue, recent trends will be introduced in a comprehensive presentation of the methods adopted for their synthesis, the broad spectrum of applications, and future developments.

The aim of this Special Issue, entitled “Nanoscale Materials for Water Purification and Catalysis”, is to present a collection of original and innovative papers (original research articles, short communications, and reviews) describing recent trends and developments in the synthesis and physicochemical characterization of nanomaterials or nanocomposites for adsorptive and/or (photo)catalytic environmental remediation applications.

Dr. Michael Arkas
Prof. Dr. Ioannis Pashalidis
Dr. Dimitrios A. Giannakoudakis
Prof. Dr. Ioannis Anastopoulos
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Nanomaterials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • nanotubes
  • membranes
  • nanoparticles
  • nanofibers
  • nanospheres
  • photocatalysis
  • electrocatalysis
  • pollutant adsorption
  • separation
  • composite materials
  • organic–inorganic hybrid
  • ceramic materials
  • filtration
  • metal nanoparticles
  • quantum dots
  • synthesis methods
  • theoretical studies
  • water and wastewater treatment

Published Papers (10 papers)

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Research

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Article
Evaluation of Photocatalytic Performance of Nano-Sized Sr0.9La0.1TiO3 and Sr0.25Ca0.25Na0.25Pr0.25TiO3 Ceramic Powders for Water Purification
Nanomaterials 2022, 12(23), 4193; https://doi.org/10.3390/nano12234193 - 25 Nov 2022
Viewed by 295
Abstract
Water pollution is a significant issue nowadays. Among the many different technologies for water purification, photocatalysis is a very promising and environment-friendly approach. In this study, the photocatalytic activity of Sr0.9La0.1TiO3 (SLTO) and Sr0.25Ca0.25Na [...] Read more.
Water pollution is a significant issue nowadays. Among the many different technologies for water purification, photocatalysis is a very promising and environment-friendly approach. In this study, the photocatalytic activity of Sr0.9La0.1TiO3 (SLTO) and Sr0.25Ca0.25Na0.25Pr0.25TiO3 (SCNPTO) nano-sized powders were evaluated by degradation of pindolol in water. Pindolol is almost entirely insoluble in water due to its lipophilic properties. The synthesis of the SCNPTO was performed using the reverse co-precipitation method using nitrate precursors, whereas the SLTO was produced by spray pyrolysis (CerPoTech, Trondheim Norway). The phase purity of the synthesized powders was validated by XRD, while HR-SEM revealed particle sizes between 50 and 70 nm. The obtained SLTO and SCNPTO powders were agglomerated but had relatively similar specific surface areas of about 27.6 m2 g−1 and 34.0 m2 g−1, respectively. The energy band gaps of the SCNPTO and SLTO were calculated (DFT) to be about 2.69 eV and 3.05 eV, respectively. The photocatalytic performances of the materials were examined by removing the pindolol from the polluted water under simulated solar irradiation (SSI), UV-LED irradiation, and UV irradiation. Ultra-fast liquid chromatography was used to monitor the kinetics of the pindolol degradation with diode array detection (UFLC–DAD). The SLTO removed 68%, 94%, and 100% of the pindolol after 240 min under SSI, UV-LED, and UV irradiation, respectively. A similar but slightly lower photocatalytic activity was obtained with the SCNPTO under identical conditions, resulting in 65%, 84%, and 93% degradation of the pindolol, respectively. Chemical oxygen demand measurements showed high mineralization of the investigated mixtures under UV-LED and UV irradiation. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Article
Surfactant-Modified CdS/CdCO3 Composite Photocatalyst Morphology Enhances Visible-Light-Driven Cr(VI) Reduction Performance
Nanomaterials 2022, 12(21), 3923; https://doi.org/10.3390/nano12213923 - 07 Nov 2022
Viewed by 451
Abstract
The surfactant modification of catalyst morphology is considered as an effective method to improve photocatalytic performance. In this work, the visible-light-driven composite photocatalyst was obtained by growing CdS nanoparticles in the cubic crystal structure of CdCO3, which, after surfactant modification, led [...] Read more.
The surfactant modification of catalyst morphology is considered as an effective method to improve photocatalytic performance. In this work, the visible-light-driven composite photocatalyst was obtained by growing CdS nanoparticles in the cubic crystal structure of CdCO3, which, after surfactant modification, led to the formation of CdCO3 elliptical spheres. This reasonable composite-structure-modification design effectively increased the specific surface area, fully exposing the catalytic-activity check point. Cd2+ from CdCO3 can enter the CdS crystal structure to generate lattice distortion and form hole traps, which productively promoted the separation and transfer of CdS photogenerated electron-hole pairs. The prepared 5-CdS/CdCO3@SDS exhibited excellent Cr(VI) photocatalytic activity with a reduction efficiency of 86.9% within 30 min, and the reduction rate was 0.0675 min−1, which was 15.57 and 14.46 times that of CdS and CdCO3, respectively. Finally, the main active substances during the reduction process, the photogenerated charge transfer pathways related to heterojunctions and the catalytic mechanism were proposed and analyzed. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Article
Activated Carbon/ZnFe2O4 Nanocomposite Adsorbent for Efficient Removal of Crystal Violet Cationic Dye from Aqueous Solutions
Nanomaterials 2022, 12(18), 3224; https://doi.org/10.3390/nano12183224 - 16 Sep 2022
Viewed by 469
Abstract
The aim of this study was to investigate the potential advantage of ZnFe2O4-incorporated activated carbon (ZFAC), fabricated via a simple wet homogenization, on the removal of cationic dye crystal violet (CV) from its aqueous solutions. The as-prepared ZFAC nanocomposite [...] Read more.
The aim of this study was to investigate the potential advantage of ZnFe2O4-incorporated activated carbon (ZFAC), fabricated via a simple wet homogenization, on the removal of cationic dye crystal violet (CV) from its aqueous solutions. The as-prepared ZFAC nanocomposite was characterized using Fourier transform infrared (FTIR), X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscope (SEM), thermogravimetric analysis (TGA), and ultraviolet–visible (UV–Vis). Batch adsorption operating conditions such as the pH (3–11), CV concentration (25–200 ppm), ZFAC dose (10–50 mg), temperature (23–45 °C), and contact time were evaluated. The results indicate pH-dependent uptake (optimum at pH 7.2) increased with temperature and CV concentration increase and decreased as adsorbent dose increased. Modeling of experimental data revealed better fit to the Langmuir than Freundlich and Temkin isotherms, with maximum monolayer capacities (Qm) of 208.29, 234.03, and 246.19 mg/g at 23, 35, and 45 °C, respectively. Kinetic studies suggest pseudo-second order; however, the intra-particle diffusion model indicates a rate-limiting step controlled by film diffusion mechanism. Based on the thermodynamic parameters, the sorption is spontaneous (−ΔG°), endothermic (+ΔH°), and random process (+ΔS°), and their values support the physical adsorption mechanism. In addition to the ease of preparation, the results confirm the potential of ZFAC as a purifier for dye removal from polluted water. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Article
Ni-Doped Ordered Nanoporous Carbon Prepared from Chestnut Wood Tannins for the Removal and Photocatalytic Degradation of Methylene Blue
Nanomaterials 2022, 12(10), 1625; https://doi.org/10.3390/nano12101625 - 10 May 2022
Viewed by 819
Abstract
In this work, Ni-doped ordered nanoporous carbon was prepared by a simple and green one-pot solvent evaporation induced self-assembly process, where chestnut wood tannins were used as a precursor, Pluronic® F-127 as a soft template, and Ni2+ as a crosslinking agent [...] Read more.
In this work, Ni-doped ordered nanoporous carbon was prepared by a simple and green one-pot solvent evaporation induced self-assembly process, where chestnut wood tannins were used as a precursor, Pluronic® F-127 as a soft template, and Ni2+ as a crosslinking agent and catalytic component. The prepared carbon exhibited a 2D hexagonally ordered nanorod array mesoporous structure with an average pore diameter of ~5 nm. Nickel was found to be present on the surface of nanoporous carbon in the form of nickel oxide, nickel hydroxide, and metallic nickel. Nickel nanoparticles, with an average size of 13.1 nm, were well dispersed on the carbon surface. The synthesized carbon was then tested for the removal of methylene blue under different conditions. It was found that the amount of methylene blue removed increased with increasing pH and concentration of carbon but decreased with increasing concentration of methylene blue. Furthermore, photocatalytic tests carried out under visible light illumination showed that purple light had the greatest effect on the methylene blue adsorption/degradation, with the maximum percent degradation achieved at ~4 h illumination time, and that the percent degradation at lower concentrations of methylene blue was much higher than that at higher concentrations. The adsorption/degradation process exhibited pseudo second-order kinetics and strong initial adsorption, and the prepared carbon showed high magnetic properties and good recyclability. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Article
Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism
Nanomaterials 2022, 12(4), 678; https://doi.org/10.3390/nano12040678 - 18 Feb 2022
Cited by 12 | Viewed by 914
Abstract
In this study, ferric-loaded magnetic burley tobacco stem biochar (MBTS) was synthesized via pyrolysis to improve the removal of Cr(VI). The results showed that MBTS had an adsorption capacity of 54.92 mg Cr(VI)/g, which was about 14 times higher than raw burley tobacco [...] Read more.
In this study, ferric-loaded magnetic burley tobacco stem biochar (MBTS) was synthesized via pyrolysis to improve the removal of Cr(VI). The results showed that MBTS had an adsorption capacity of 54.92 mg Cr(VI)/g, which was about 14 times higher than raw burley tobacco stem biochar (i.e., 3.84 mg/g). According to the findings obtained, a three-step mechanism of Cr(VI) removal by MBTS was further put forward, i.e., (1) Cr(VI) exchanged with hydroxyl groups on MBTS, (2) the reduction in Cr(VI) to Cr(III) mediated by oxygen-containing groups, and (3) the chelation of produced Cr(III) with the amino groups on MBTS. FTIR spectra further revealed that C-N, C-H, and C=C groups played an important role in Cr(VI) removal. Furthermore, the adsorption equilibrium and kinetics of Cr(VI) on MBTS could better be described by the Langmuir equation and pseudo-second-order rate equation. This study clearly demonstrated that ferric-loaded biochar derived from burley tobacco stems could serve as a cost-effective magnetic adsorbent for the high-efficiency removal of soluble Cr(VI) from wastewater. Tobacco stem-adsorbed Cr(VI) realized a green path for treating waste by waste. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Article
N-Doped Biochar as a New Metal-Free Activator of Peroxymonosulfate for Singlet Oxygen-Dominated Catalytic Degradation of Acid Orange 7
Nanomaterials 2021, 11(9), 2288; https://doi.org/10.3390/nano11092288 - 02 Sep 2021
Cited by 9 | Viewed by 1897
Abstract
In this paper, using rice straw as a raw material and urea as a nitrogen precursor, a composite catalyst (a nitrogen-doped rice straw biochar at the pyrolysis temperature of 800 °C, recorded as NRSBC800) was synthesized by one-step pyrolysis. NRSBC800 was then characterized [...] Read more.
In this paper, using rice straw as a raw material and urea as a nitrogen precursor, a composite catalyst (a nitrogen-doped rice straw biochar at the pyrolysis temperature of 800 °C, recorded as NRSBC800) was synthesized by one-step pyrolysis. NRSBC800 was then characterized using XPS, BET, TEM and other technologies, and its catalytic performance as an activator for permonosulfate (PMS) to degrade acid orange 7 (AO7) was studied. The results show that the introduction of N-doping significantly improved the catalytic performance of NRSBC800. The NRSBC800/PMS oxidation system could fully degrade AO7 within 30 min, with the reaction rate constant (2.1 × 10 −1 min−1) being 38 times that of RSBC800 (5.5 × 10−3 min−1). Moreover, NRSBC800 not only had better catalytic performance than traditional metal oxides (Co3O4 and Fe3O4) and carbon nanomaterial (CNT) but also received less impact from environmental water factors (such as anions and humic acids) during the catalytic degradation process. In addition, a quenching test and electron paramagnetic resonance (EPR) research both indicated that AO7 degradation relied mainly on non-free radical oxidation (primarily singlet oxygen (1O2)). A recycling experiment further demonstrated NRSBC800’s high stability after recycling three times. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Article
Improving the Performance of ZnS Photocatalyst in Degrading Organic Pollutants by Constructing Composites with Ag2O
Nanomaterials 2021, 11(6), 1451; https://doi.org/10.3390/nano11061451 - 30 May 2021
Cited by 8 | Viewed by 1640
Abstract
ZnS is a promising photocatalyst in water purification, whereas its low photon efficiency and poor visible-light response restrict its application. Constructing composites may help solve these problems. In this work, Ag2O was introduced to ZnS for the first time based on [...] Read more.
ZnS is a promising photocatalyst in water purification, whereas its low photon efficiency and poor visible-light response restrict its application. Constructing composites may help solve these problems. In this work, Ag2O was introduced to ZnS for the first time based on their energy band characteristics to form a novel ZnS/Ag2O composite photocatalyst. In the model reaction of degrading methylene blue, the as-designed catalyst exhibited high catalytic activity among a series of ZnS-based composite photocatalysts under similar conditions. The catalytic rate constant was up to 0.138 min−1, which is 27.4- and 15.6-times higher than those of ZnS and Ag2O. This composite degraded 92.4% methylene blue in 50 min, while the ratios were 31.9% and 68.8% for ZnS and Ag2O. Catalytic mechanism study based on photoluminescence and radical-scavenging experiments revealed that the enhanced photocatalytic activity was attributed to the composite structure of ZnS/Ag2O. The structure not only facilitated the separation and transmission of photogenerated carriers but also extended the light response range of the catalyst. The as-designed ZnS/Ag2O composite is promising in degrading organic pollutants in water. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Review

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Review
Carbon-Based Nanocatalysts (CnCs) for Biomass Valorization and Hazardous Organics Remediation
Nanomaterials 2022, 12(10), 1679; https://doi.org/10.3390/nano12101679 - 14 May 2022
Cited by 1 | Viewed by 2020
Abstract
The continuous increase of the demand in merchandise and fuels augments the need of modern approaches for the mass-production of renewable chemicals derived from abundant feedstocks, like biomass, as well as for the water and soil remediation pollution resulting from the anthropogenic discharge [...] Read more.
The continuous increase of the demand in merchandise and fuels augments the need of modern approaches for the mass-production of renewable chemicals derived from abundant feedstocks, like biomass, as well as for the water and soil remediation pollution resulting from the anthropogenic discharge of organic compounds. Towards these directions and within the concept of circular (bio)economy, the development of efficient and sustainable catalytic processes is of paramount importance. Within this context, the design of novel catalysts play a key role, with carbon-based nanocatalysts (CnCs) representing one of the most promising class of materials. In this review, a wide range of CnCs utilized for biomass valorization towards valuable chemicals production, and for environmental remediation applications are summarized and discussed. Emphasis is given in particular on the catalytic production of 5-hydroxymethylfurfural (5-HMF) from cellulose or starch-rich food waste, the hydrogenolysis of lignin towards high bio-oil yields enriched predominately in alkyl and oxygenated phenolic monomers, the photocatalytic, sonocatalytic or sonophotocatalytic selective partial oxidation of 5-HMF to 2,5-diformylfuran (DFF) and the decomposition of organic pollutants in aqueous matrixes. The carbonaceous materials were utilized as stand-alone catalysts or as supports of (nano)metals are various types of activated micro/mesoporous carbons, graphene/graphite and the chemically modified counterparts like graphite oxide and reduced graphite oxide, carbon nanotubes, carbon quantum dots, graphitic carbon nitride, and fullerenes. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Review
Catalytic Neutralization of Water Pollutants Mediated by Dendritic Polymers
Nanomaterials 2022, 12(3), 445; https://doi.org/10.3390/nano12030445 - 28 Jan 2022
Cited by 3 | Viewed by 1126
Abstract
Radially polymerized dendritic compounds are nowadays an established polymer category next to their linear, branched, and cross-linked counterparts. Their uncommon tree-like architecture is characterized by adjustable internal cavities and external groups. They are therefore exceptional absorbents and this attainment of high concentrations in [...] Read more.
Radially polymerized dendritic compounds are nowadays an established polymer category next to their linear, branched, and cross-linked counterparts. Their uncommon tree-like architecture is characterized by adjustable internal cavities and external groups. They are therefore exceptional absorbents and this attainment of high concentrations in their interior renders them ideal reaction media. In this framework, they are applied in many environmentally benign implementations. One of the most important among them is water purification through pollutant decomposition. Simple and composite catalysts and photo-catalysts containing dendritic polymers and applied in water remediation will be discussed jointly with some unconventional solutions and prospects. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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Review
Differentiating Nanomaghemite and Nanomagnetite and Discussing Their Importance in Arsenic and Lead Removal from Contaminated Effluents: A Critical Review
Nanomaterials 2021, 11(9), 2310; https://doi.org/10.3390/nano11092310 - 06 Sep 2021
Cited by 19 | Viewed by 1922
Abstract
Arsenic and lead heavy metals are polluting agents still present in water bodies, including surface (lake, river) and underground waters; consequently, the development of new adsorbents is necessary to uptake these metals with high efficiency, quick and clean removal procedures. Magnetic nanoparticles, prepared [...] Read more.
Arsenic and lead heavy metals are polluting agents still present in water bodies, including surface (lake, river) and underground waters; consequently, the development of new adsorbents is necessary to uptake these metals with high efficiency, quick and clean removal procedures. Magnetic nanoparticles, prepared with iron-oxides, are excellent candidates to achieve this goal due to their ecofriendly features, high catalytic response, specific surface area, and pulling magnetic response that favors an easy removal. In particular, nanomagnetite and maghemite are often found as the core and primary materials regarding magnetic nanoadsorbents. However, these phases show interesting distinct physical properties (especially in their surface magnetic properties) but are not often studied regarding correlations between the surface properties and adsorption applications, for instance. Thus, in this review, we summarize the main characteristics of the co-precipitation and thermal decomposition methods used to prepare the nano-iron-oxides, being the co-precipitation method most promising for scaling up processes. We specifically highlight the main differences between both nano-oxide species based on conventional techniques, such as X-ray diffraction, zero and in-field Mössbauer spectroscopy, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and X-ray magnetic circular dichroism, the latter two techniques performed with synchrotron light. Therefore, we classify the most recent magnetic nanoadsorbents found in the literature for arsenic and lead removal, discussing in detail their advantages and limitations based on various physicochemical parameters, such as temperature, competitive and coexisting ion effects, i.e., considering the simultaneous adsorption removal (heavy metal–heavy metal competition and heavy metal–organic removal), initial concentration, magnetic adsorbent dose, adsorption mechanism based on pH and zeta potential, and real water adsorption experiments. We also discuss the regeneration/recycling properties, after-adsorption physicochemical properties, and the cost evaluation of these magnetic nanoadsorbents, which are important issues, but less discussed in the literature. Full article
(This article belongs to the Special Issue Nanoscale Materials for Water Purification and Catalysis)
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