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4 pages, 210 KiB

Open AccessEditorial

Nanomaterials in Water Applications: Adsorbing Materials for Fluoride Removal

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Nanomaterials 2021, 11(7), 1866; https://doi.org/10.3390/nano11071866 - 20 Jul 2021

Cited by 5 | Viewed by 1904

Abstract

Fluoride is an important pollutant in many countries, such as China, India, Australia, the United States, Ethiopia, etc [...] Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

Research

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15 pages, 6684 KiB

Open AccessArticle

Preparation of Three-Dimensional MF/Ti₃C₂T_x/PmPD by Interfacial Polymerization for Efficient Hexavalent Chromium Removal

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Nanomaterials 2022, 12(16), 2838; https://doi.org/10.3390/nano12162838 - 18 Aug 2022

Cited by 1 | Viewed by 1060

Abstract

Heavy metal pollution is a serious threat to human health and the ecological environment, but adsorption technology based on nano adsorbents can effectively treat the crisis. However, due to the nanoscale effect, nano adsorbents have some crucial shortcomings, such as recycling difficulty and [...] Read more.

Heavy metal pollution is a serious threat to human health and the ecological environment, but adsorption technology based on nano adsorbents can effectively treat the crisis. However, due to the nanoscale effect, nano adsorbents have some crucial shortcomings, such as recycling difficulty and the loss of nanoparticles, which seriously limit their application. The feasible assembly of nano adsorbents is an accessible technology in urgent need of a breakthrough. In this study, three-dimensional (3D) adsorbent (MF/Ti₃C₂T_x/PmPD) with excellent performance and favorable recyclability was prepared by interfacial polymerization with melamine foam (MF) as the framework, two-dimensional (2D) titanium carbide (Ti₃C₂T_x) as the bridge and Poly (m-Phenylenediamine) (PmPD) as the active nano component. The morphology, structure, mechanical property of MF/Ti₃C₂T_x/PmPD and reference MF/PmPD were investigated through a scanning electron microscope (SEM), Fourier transformed infrared spectra (FT-IR), Raman scattering spectra and a pressure-stress test, respectively. Owning to the regulation of Ti₃C₂T_x on the morphology and structure of PmPD, MF/Ti₃C₂T_x/PmPD showed excellent adsorption capacity (352.15 mg/g) and favorable cycling performance. R–P and pseudo-second-order kinetics models could well describe the adsorption phenomenon, indicating that the adsorption process involved a composite process of single-layer and multi-layer adsorption and was dominated by chemical adsorption. In this research, the preparation mechanism of MF/Ti₃C₂T_x/PmPD and the adsorption process of Cr(VI) were systematically investigated, which provided a feasible approach for the feasible assembly and application of nano adsorbents in the environmental field. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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8 pages, 1986 KiB

Open AccessCommunication

Natural Halloysite-Templated Synthesis of Highly Graphitic Boron-Doped Hollow Carbon Nanocapsule Webs

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Nanomaterials 2022, 12(14), 2352; https://doi.org/10.3390/nano12142352 - 09 Jul 2022

Cited by 1 | Viewed by 927

Abstract

Hollow carbon nanocapsules have been attracting growing interest due to their fascinating characteristics and extensive potential applications. In this work, a novel natural halloysite-templated synthesis approach for highly graphitic boron-doped hollow carbon nanocapsule webs (B-HCNCWs) using glucose as the carbon source and boric [...] Read more.

Hollow carbon nanocapsules have been attracting growing interest due to their fascinating characteristics and extensive potential applications. In this work, a novel natural halloysite-templated synthesis approach for highly graphitic boron-doped hollow carbon nanocapsule webs (B-HCNCWs) using glucose as the carbon source and boric acid as the heteroatom dopant was first reported. The formation process and physicochemical properties of B-HCNCWs were revealed by SEM, TEM, XRD, Raman, Brunauer–Emmett–Teller (BET), and XPS characterization techniques. The outcomes showed that the as-obtained B-HCNCWs with hollow nanocapsule network architecture had a specific surface area of 263 m² g⁻¹, a pore volume of 0.8 cm³ g⁻¹, a high degree of graphitization (81.4%), graphite-like interplanar spacing (0.3370 nm), and B-containing functional groups (0.77 at%). The density function theory (DFT) calculation demonstrated that the adsorption energies of Li on B-HCNCWs were much higher than that of HCNCWs, which proved that B-doping in a carbon matrix could increase the lithium intercalation capacity. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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9 pages, 2515 KiB

Open AccessCommunication

Metal–Organic-Framework-Derived Ball-Flower-like Porous Co₃O₄/Fe₂O₃ Heterostructure with Enhanced Visible-Light-Driven Photocatalytic Activity

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Nanomaterials 2022, 12(6), 904; https://doi.org/10.3390/nano12060904 - 09 Mar 2022

Cited by 17 | Viewed by 2198

Abstract

A porous ball-flower-like Co₃O₄/Fe₂O₃ heterostructural photocatalyst was synthesized via a facile metal–organic-framework-templated method, and showed an excellent degradation performance in the model molecule rhodamine B under visible light irradiation. This enhanced photocatalytic activity can be attributed [...] Read more.

A porous ball-flower-like Co₃O₄/Fe₂O₃ heterostructural photocatalyst was synthesized via a facile metal–organic-framework-templated method, and showed an excellent degradation performance in the model molecule rhodamine B under visible light irradiation. This enhanced photocatalytic activity can be attributed to abundant photo-generated holes and hydroxyl radicals, and the combined effects involving a porous structure, strong visible-light absorption, and improved interfacial charge separation. It is notable that the ecotoxicity of the treated reaction solution was also evaluated, confirming that an as-synthesized Co₃O₄/Fe₂O₃ catalyst could afford the sunlight-driven long-term recyclable degradation of dye-contaminated wastewater into non-toxic and colorless wastewater. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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11 pages, 2386 KiB

Open AccessArticle

Facile Preparation of Oxygen-Vacancy-Engineered MoO_x Nanostructures for Photoreversible Switching Systems

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Nanomaterials 2021, 11(12), 3192; https://doi.org/10.3390/nano11123192 - 25 Nov 2021

Cited by 3 | Viewed by 1317

Abstract

Photochromic materials have attracted increasing attention. Here, we report a novel photo-reversible color switching system based on oxygen-vacancy-engineered MoO_x nanostructures with water/N-methyl-2-pyrrolidone (NMP) as solvents. In this work, the system rapidly changed from colorless to blue under UV irradiation (360–400 nm) and [...] Read more.

Photochromic materials have attracted increasing attention. Here, we report a novel photo-reversible color switching system based on oxygen-vacancy-engineered MoO_x nanostructures with water/N-methyl-2-pyrrolidone (NMP) as solvents. In this work, the system rapidly changed from colorless to blue under UV irradiation (360–400 nm) and slowly recovered its colorless state under visible light irradiation. The obtained oxygen vacancy-engineered MoO_x nanostructures exhibited good repeatability, chemical stability, and cycling stability. Upon UV light irradiation, H⁺ was intercalated into layered MoO_x nanostructures and the Mo⁶⁺ concentration in the H_xMoO_x decreased, while the Mo⁵⁺ concentration increased and increased oxygen vacancies changed the color to blue. Then, it recovered its original color slowly without UV light irradiation. What is more, the system was highly sensitive to UV light even on cloudy days. Compared with other reported photochromic materials, the system in this study has the advantage of facile preparation and provides new insights for the development of photochromic materials without dyes. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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13 pages, 4063 KiB

Open AccessArticle

Studies on Kinetics, Isotherms, Thermodynamics and Adsorption Mechanism of Methylene Blue by N and S Co-Doped Porous Carbon Spheres

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Nanomaterials 2021, 11(7), 1819; https://doi.org/10.3390/nano11071819 - 13 Jul 2021

Cited by 7 | Viewed by 1620

Abstract

Heteroatom-doped carbon is widely used in the fields of adsorbents, electrode materials and catalysts due to its excellent physicochemical properties. N and S co-doped porous carbon spheres (N,S-PCSs) were synthesized using glucose and L-cysteine as carbon and heteroatom sources using a combined hydrothermal [...] Read more.

Heteroatom-doped carbon is widely used in the fields of adsorbents, electrode materials and catalysts due to its excellent physicochemical properties. N and S co-doped porous carbon spheres (N,S-PCSs) were synthesized using glucose and L-cysteine as carbon and heteroatom sources using a combined hydrothermal and KOH activation process. The physicochemical structures and single-factor methylene blue (MB) adsorption properties of the N,S-PCSs were then studied. The optimized N,S-PCSs-1 possessed a perfect spherical morphology with a 2–8-μm diameter and a large specific area of 1769.41 m² g⁻¹, in which the N and S contents were 2.97 at% and 0.88 at%, respectively. In the single-factor adsorption experiment for MB, the MB adsorption rate increased with an increase in carbon dosage and MB initial concentration, and the adsorption reached equilibrium within 2–3 h. The pseudo-second-order kinetic model could excellently fit the experimental data with a high R² (0.9999). The Langmuir isothermal adsorption equation fitted well with the experimental results with an R² value of 0.9618, and the MB maximum adsorption quantity was 909.10 mg g⁻¹. The adsorption of MB by N,S-PCSs-1 was a spontaneous, endothermic, and random process based on the thermodynamics analyses. The adsorption mechanism mainly involved Van der Waals force adsorption, π-π stacking, hydrogen bonds and Lewis acid–base interactions. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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Review

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25 pages, 2182 KiB

Open AccessReview

Chitosan Nanoparticles as Potential Nano-Sorbent for Removal of Toxic Environmental Pollutants

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Nanomaterials 2023, 13(3), 447; https://doi.org/10.3390/nano13030447 - 21 Jan 2023

Cited by 17 | Viewed by 2351

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Adsorption is the most widely used technique for advanced wastewater treatment. The preparation and application of natural renewable and environmentally friendly materials makes this process easier and more profitable. Chitosan is often used as an effective biomaterial in the adsorption world because of [...] Read more.

Adsorption is the most widely used technique for advanced wastewater treatment. The preparation and application of natural renewable and environmentally friendly materials makes this process easier and more profitable. Chitosan is often used as an effective biomaterial in the adsorption world because of its numerous functional applications. Chitosan is one of the most suitable and functionally flexible adsorbents because it contains hydroxyl (-OH) and amine (-NH₂) groups. The adsorption capacity and selectivity of chitosan can be further improved by introducing additional functions into its basic structure. Owing to its unique surface properties and adsorption ability of chitosan, the development and application of chitosan nanomaterials has gained significant attention. Here, recent research on chitosan nanoparticles is critically reviewed by comparing various methods for their synthesis with particular emphasis on the role of experimental conditions, limitations, and applications in water and wastewater treatment. The recovery of pollutants using magnetic nanoparticles is an important treatment process that has contributed to additional development and sustainable growth. The application of such nanoparticles in the recovery metals, which demonstrates a “close loop technology” in the current scenarios, is also presented in this review. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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22 pages, 3646 KiB

Open AccessReview

Adsorption of Different Pollutants by Using Microplastic with Different Influencing Factors and Mechanisms in Wastewater: A Review

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Nanomaterials 2022, 12(13), 2256; https://doi.org/10.3390/nano12132256 - 30 Jun 2022

Cited by 12 | Viewed by 3161

Abstract

The studies on microplastics are significant in the world. According to the literature, microplastics have greatly specific surface areas, indicating high adsorption capacities for highly toxic pollutants in aquatic and soil environments, and these could be used as adsorbents. The influencing factors of [...] Read more.

The studies on microplastics are significant in the world. According to the literature, microplastics have greatly specific surface areas, indicating high adsorption capacities for highly toxic pollutants in aquatic and soil environments, and these could be used as adsorbents. The influencing factors of microplastic adsorption, classification of microplastics, and adsorption mechanisms using microplastics for adsorbing organic, inorganic, and mixed pollutants are summarized in the paper. Furthermore, the influence of pH, temperature, functional groups, aging, and other factors related to the adsorption performances of plastics are discussed in detail. We found that microplastics have greater advantages in efficient adsorption performance and cost-effectiveness. In this paper, the adsorptions of pollutants by microplastics and their performance is proposed, which provides significant guidance for future research in this field. Full article

(This article belongs to the Special Issue Nanomaterials in Water Applications)

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