Nanomaterial-Enabled Environmental Remediation and Removal of Emerging Pollutants

A special issue of Toxics (ISSN 2305-6304). This special issue belongs to the section "Toxicity Reduction and Environmental Remediation".

Deadline for manuscript submissions: closed (31 January 2024) | Viewed by 16030

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Guest Editor
College of Environmental Science and Engineering, Nankai University, Tianjin, China
Interests: environmental chemistry; environmental applications of nanotechnology; interfacial chemistry of organic pollutants; soil pollution remediation; environmental catalysis

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Guest Editor
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China
Interests: environmental photocatalysis; indoor air purification; CO2 capture; CO2 conversion; photocatalysts
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Guest Editor
Department of Civil Engineering, Faculty of Engineering, Naresuan University, Phitsanulok, Thailand
Interests: groundwater and soil remediation; nanomaterials for environmental restoration; nanoscale zerovalent iron; fate and transport of nanoparticles; mine tailing management; site characterization; risk assessment

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Guest Editor
School of Resources and Environmental Engineering, East China University of Science & Technology, Shanghai, China
Interests: fate and removal of emerging contaminants; pharmaceuticals and personal care products; endocrine disrupting chemicals; microplastics; wastewater; landfill leachate
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Environmental pollution has posed a threat to public health and the ecological environment. Fortunately, the rapid development of nanotechnology has opened up new opportunities for more efficient and cost-effective pollution control and environmental remediation. A range of novel nanomaterials have been explored for the enhanced removal of various legacy and emerging pollutants via adsorption, membrane separation, catalytic oxidation/reduction/hydrolysis, and photocatalysis, etc., thereby contributing to global environmental protection and sustainable development.

This Special Issue will focus on recent advances in the nanomaterial-enabled remediation of contaminated environments (e.g., soil, groundwater, surface water, and sediment); the treatment of wastewater, flue gas, and vehicle exhausts; as well as the purification of drinking water and indoor air. Topics include, but are not limited to, the synthesis of novel nanomaterials, such as adsorbents, membranes, (photo)catalysts, oxidants, and/or reducants, as well as their applications for environmental remediation and pollution control, particularly for removing pollutants of emerging concern, such as perfluorinated compounds (PFCs), pharmaceuticals and personal care products (PPCPs), phthalates, organophosphate esters, and micro-/nanoplastics. We encourage an in-depth discussion on the molecular-level mechanisms and quantitative structure—performance relationships underlying enhanced pollutant removal. Authors are invited to submit original research papers, reviews, and short communications on these topics.

Prof. Dr. Chuanjia Jiang
Prof. Dr. Shengwei Liu
Dr. Tanapon Phenrat
Prof. Dr. Qian Sui
Guest Editors

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Keywords

  • nanomaterial
  • environmental remediation
  • wastewater treatment
  • water treatment
  • air purification
  • emerging pollutants
  • adsorption
  • environmental catalysis
  • in situ chemical oxidation
  • advanced oxidation process

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Published Papers (8 papers)

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Research

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14 pages, 5483 KiB  
Article
Complete Photooxidation of Formaldehyde to CO2 via Ni-Dual-Atom Decorated Crystalline Triazine Frameworks: A DFT Study
by Zhao Lu and Zhongliao Wang
Toxics 2024, 12(4), 242; https://doi.org/10.3390/toxics12040242 - 26 Mar 2024
Cited by 1 | Viewed by 953
Abstract
Formaldehyde (CH2O) emerges as a significant air pollutant, necessitating effective strategies for its oxidation to mitigate adverse impacts on human health and the environment. Among various technologies, the photooxidation of CH2O stands out owing to its affordability, safety, and [...] Read more.
Formaldehyde (CH2O) emerges as a significant air pollutant, necessitating effective strategies for its oxidation to mitigate adverse impacts on human health and the environment. Among various technologies, the photooxidation of CH2O stands out owing to its affordability, safety, and effectiveness. Nitrogen-rich crystalline triazine-based organic frameworks (CTFs) exhibit considerable potential in this domain. Nevertheless, the weak and unstable CH2O adsorption hinders the overall oxidation efficiency of CTF. To address this limitation, we incorporate single and dual Ni atoms into nitrogen-rich CTFs by density functional theory (DFT) calculations, resulting in CTF-Ni and CTF-2Ni. This strategic modification significantly enhances the adsorption capability of CH2O. Notably, this synergy between Ni dual atoms activates CH2O by strong chemical adsorption, thereby reducing the energy barrier of CH2O oxidation and achieving the complete oxidation of CH2O to CO2. Moreover, the introduction of dual-atom Ni over CTF ameliorates visible and near-infrared light absorption and facilitates photoexcited charge transfer and separation. Finally, the underlying mechanisms of complete CH2O oxidation over CTF-2Ni are proposed. This work offers novel insights into the rational design of photocatalysts for CH2O oxidation through the integration of Ni dual atoms into CTFs. Full article
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14 pages, 5803 KiB  
Article
Sustainable Development of ZnO Nanostructure Doping with Water Hyacinth-Derived Activated Carbon for Visible-Light Photocatalysis
by Sucheewan Krobthong, Tipawan Rungsawang, Naphatson Khaodara, Napat Kaewtrakulchai, Kanit Manatura, Khewika Sukiam, Donchida Wathinputthiporn, Sawitree Wongrerkdee, Chatdanai Boonruang and Sutthipoj Wongrerkdee
Toxics 2024, 12(3), 165; https://doi.org/10.3390/toxics12030165 - 21 Feb 2024
Cited by 4 | Viewed by 1522
Abstract
Water hyacinth (Wh) is an aquatic weed considered a nuisance in agricultural and fishing activities. Therefore, this study proposed repurposing this plant into activated carbon (AC). First, the ZnO-AC was precipitated and applied as a photocatalyst for degrading methylene blue. The preliminary photocatalytic [...] Read more.
Water hyacinth (Wh) is an aquatic weed considered a nuisance in agricultural and fishing activities. Therefore, this study proposed repurposing this plant into activated carbon (AC). First, the ZnO-AC was precipitated and applied as a photocatalyst for degrading methylene blue. The preliminary photocatalytic test under UV irradiation identified the optimum ZnO-AC photocatalyst to degrade methylene blue (MB). The ZnO-AC photocatalyst recorded the highest degradation rate constant of 11.49 × 10−3 min−1, which was almost two-fold higher than that of ZnO (5.55 × 10−3 min−1). Furthermore, photocatalytic degradation of MB and carbaryl under sunlight irradiation by ZnO-AC demonstrated degradation rate constants of 74.46 × 10−3 min−1 and 8.43 × 10−3 min−1, respectively. To investigate the properties of ZnO-AC, several techniques were performed. ZnO-AC and ZnO exhibited similar results in morphology, crystalline structure, and Raman characteristics. However, ZnO-AC presented smaller pore diameters than those of ZnO, which enlarged pore surface area, and the presence of carbon-related groups implied the presence of AC on ZnO-AC surfaces. This can be attributed to the presence of AC on the ZnO surface, increasing the capture of surrounding toxic molecules and elevating the reaction density. This mechanism is attributed to promoting the degradation of toxic molecules. Therefore, using Wh as a carbon source for the transformation of AC can alternatively solve the problems of aquatic weed management and carbon storage strategies, and the application of AC in ZnO-AC photocatalysts can enhance photocatalysis. Full article
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18 pages, 3406 KiB  
Article
Facilitated Adsorption of Mercury(II) and Chromium(VI) Ions over Functionalized Carbon Nanotubes
by Gururaj M. Neelgund, Erica A. Jimenez, Ram L. Ray and Mahaveer D. Kurkuri
Toxics 2023, 11(6), 545; https://doi.org/10.3390/toxics11060545 - 20 Jun 2023
Cited by 1 | Viewed by 1553
Abstract
By considering the importance of water and its purity, herein, a powerful adsorbent has been developed for the adsorption of two toxic contaminants that commonly exist in water, viz., divalent mercury and hexavalent chromium. The efficient adsorbent, CNTs–PLA–Pd, was prepared by covalent grafting [...] Read more.
By considering the importance of water and its purity, herein, a powerful adsorbent has been developed for the adsorption of two toxic contaminants that commonly exist in water, viz., divalent mercury and hexavalent chromium. The efficient adsorbent, CNTs–PLA–Pd, was prepared by covalent grafting polylactic acid to carbon nanotubes and subsequent deposition of palladium nanoparticles. The CNTs–PLA–Pd could adsorb Hg(II), and Cr(VI) entirely exists in water. The adsorption rate for Hg(II) and Cr(VI) was rapid at initial stage, followed by gradual decrease, and attained the equilibrium. The Hg(II) and Cr(VI) adsorption was perceived within 50 min and 80 min, respectively with CNTs–PLA–Pd,. Further, experimental data for Hg(II) and Cr(VI) adsorption was analyzed, and kinetic parameters were estimated using pseudo–first and second–order models. The adsorption process of Hg(II) and Cr(VI) followed the pseudo–second–order kinetics, and the rate–limiting step in the adsorption was chemisorption. The Weber−Morris intraparticle pore diffusion model revealed that the Hg(II) and Cr(VI) adsorption over CNTs–PLA–Pd occurs through multiple phases. The experimental equilibrium parameters for the Hg(II) and Cr(VI) adsorption were estimated by Langmuir, Freundlich, and Temkin isotherms models. All three models were well suited and demonstrated that Hg(II) and Cr(VI) adsorption over CNTs–PLA–Pd transpires through monolayer molecular covering and chemisorption. Full article
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12 pages, 4781 KiB  
Article
Comparison of ZnO Nanoparticles Prepared by Precipitation and Combustion for UV and Sunlight-Driven Photocatalytic Degradation of Methylene Blue
by Sucheewan Krobthong, Tipawan Rungsawang and Sutthipoj Wongrerkdee
Toxics 2023, 11(3), 266; https://doi.org/10.3390/toxics11030266 - 14 Mar 2023
Cited by 19 | Viewed by 2349 | Correction
Abstract
ZnO nanoparticles (NPs) were comparatively synthesized via precipitation and combustion techniques. The ZnO NPs synthesized via precipitation and combustion exhibited similar polycrystalline hexagonal wurtzite structures. The large crystal sizes of ZnO NPs were obtained from the ZnO precipitation in comparison with those from [...] Read more.
ZnO nanoparticles (NPs) were comparatively synthesized via precipitation and combustion techniques. The ZnO NPs synthesized via precipitation and combustion exhibited similar polycrystalline hexagonal wurtzite structures. The large crystal sizes of ZnO NPs were obtained from the ZnO precipitation in comparison with those from the ZnO combustion, while the particle sizes were in the same range. The functional analysis implied that the ZnO structures had surface defects. Moreover, absorbance measurement showed the same absorbance range in ultraviolet light. In the photocatalytic degradation of methylene blue, ZnO precipitation exhibited higher degradation performance than ZnO combustion. This was attributed to the larger crystal sizes of ZnO NPs, which provided an enduring carrier movement at semiconductor surfaces and reduced electron-hole recombination. Thus, the crystallinity of ZnO NPs can be considered an important factor in photocatalytic activity. Furthermore, precipitation is an interesting synthesizing method for preparing ZnO NPs with large crystal sizes. Full article
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16 pages, 5551 KiB  
Article
Zinc Removal from Water via EDTA-Modified Mesoporous SBA-16 and SBA-15
by Zeinab Ezzeddine, Isabelle Batonneau-Gener and Yannick Pouilloux
Toxics 2023, 11(3), 205; https://doi.org/10.3390/toxics11030205 - 23 Feb 2023
Cited by 4 | Viewed by 2103
Abstract
The removal of zinc ions from water was investigated using two types of ordered mesoporous silica (SBA-15 and SBA-16). Both materials were functionalized with APTES (3-aminopropyltriethoxy-silane) and EDTA (ethylenediaminetetraacetic acid) through post grafting methods. The modified adsorbents were characterized by scanning electron microscopy [...] Read more.
The removal of zinc ions from water was investigated using two types of ordered mesoporous silica (SBA-15 and SBA-16). Both materials were functionalized with APTES (3-aminopropyltriethoxy-silane) and EDTA (ethylenediaminetetraacetic acid) through post grafting methods. The modified adsorbents were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen (N2) adsorption–desorption analysis, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis. The ordered structure of the adsorbents was conserved after modification. SBA-16 was found to be more efficient than SBA-15 owing to its structural characteristics. Different experimental conditions were examined (pH, contact time, and initial zinc concentration). The kinetic adsorption data followed the pseudo-second-order model indicating favorable adsorption conditions. The intra-particle diffusion model plot represented a two-stage adsorption process. The maximum adsorption capacities were calculated by the Langmuir model. The adsorbent can be regenerated and reused several times without a significant decline in adsorption efficiency. Full article
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13 pages, 3490 KiB  
Article
Recyclable Carbon Cloth-Supported ZnO@Ag3PO4 Core–Shell Structure for Photocatalytic Degradation of Organic Dye
by Yuan Yi, Qifang Guan, Wenguang Wang, Siyuan Jian, Hengchao Li, Liangpeng Wu, Haiyan Zhang and Chuanjia Jiang
Toxics 2023, 11(1), 70; https://doi.org/10.3390/toxics11010070 - 11 Jan 2023
Cited by 16 | Viewed by 2242
Abstract
The extensive use of organic dyes in industry has caused serious environmental problems, and photocatalysis is a potential solution to water pollution by organic dyes. The practical application of powdery photocatalysts is usually limited by the rapid recombination of charge carriers and difficulty [...] Read more.
The extensive use of organic dyes in industry has caused serious environmental problems, and photocatalysis is a potential solution to water pollution by organic dyes. The practical application of powdery photocatalysts is usually limited by the rapid recombination of charge carriers and difficulty in recycling. In this study, recyclable carbon cloth-supported ZnO@Ag3PO4 composite with a core–shell structure was successfully prepared by solvothermal treatment and subsequent impregnation–deposition. The as-prepared carbon cloth-supported ZnO@Ag3PO4 composite showed an improved photocatalytic activity and stability for the degradation of rhodamine B (RhB), a model organic dye, under visible light irradiation. The decomposition ratio of RhB reached 87.1% after exposure to visible light for 100 min, corresponding to a reaction rate constant that was 4.8 and 15.9 times that of carbon cloth-supported Ag3PO4 or ZnO alone. The enhanced performance of the composite can be attributed to the effectively inhibited recombination of photoinduced electron–hole pairs by the S-scheme heterojunction. The carbon fibers further promoted the transfer of charges. Moreover, the carbon cloth-supported ZnO@Ag3PO4 can be easily separated from the solution and repeatedly used, demonstrating a fair recyclability and potential in practical applications. Full article
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12 pages, 4345 KiB  
Article
Enhanced Photocatalytic Degradation of Methylene Blue Using Ti-Doped ZnO Nanoparticles Synthesized by Rapid Combustion
by Sutthipoj Wongrerkdee, Sawitree Wongrerkdee, Chatdanai Boonruang and Supphadate Sujinnapram
Toxics 2023, 11(1), 33; https://doi.org/10.3390/toxics11010033 - 29 Dec 2022
Cited by 16 | Viewed by 2366
Abstract
ZnO and Ti-doped ZnO (Ti-ZnO) nanoparticles were synthesized using rapid combustion. The morphology of ZnO and Ti-ZnO featured nanoparticles within cluster-like structures. The ZnO and Ti-ZnO structures exhibited similar hexagonal wurtzite structures and crystal sizes. This behavior occurred because Zn2+ sites of [...] Read more.
ZnO and Ti-doped ZnO (Ti-ZnO) nanoparticles were synthesized using rapid combustion. The morphology of ZnO and Ti-ZnO featured nanoparticles within cluster-like structures. The ZnO and Ti-ZnO structures exhibited similar hexagonal wurtzite structures and crystal sizes. This behavior occurred because Zn2+ sites of the ZnO lattice were substituted by Ti4+ ions. The chemical structure characterization implied the major vibration of the ZnO structure. The physisorption analysis showed similar mesoporous and non-rigid aggregation structures for ZnO and Ti-ZnO using N2 adsorption–desorption. However, Ti-ZnO demonstrated a specific surface area two times higher than that of ZnO. This was a major factor in improving the photocatalytic degradation of methylene blue (MB). The photocatalytic degradation analysis showed a kinetic degradation rate constant of 2.54 × 10−3 min−1 for Ti-ZnO, which was almost 80% higher than that of ZnO (1.40 × 10−3 min−1). The transformation mechanism of MB molecules into other products, including carbon dioxide, aldehyde, and sulfate ions, was also examined. Full article
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Review

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20 pages, 2271 KiB  
Review
Selective Adsorption of Hazardous Substances from Wastewater by Hierarchical Oxide Composites: A Review
by Wenjun Tu and Weiquan Cai
Toxics 2024, 12(7), 447; https://doi.org/10.3390/toxics12070447 - 21 Jun 2024
Viewed by 648
Abstract
Large volumes of wastewater containing toxic contaminants (e.g., heavy metal ions, organic dyes, etc.) are produced from industrial processes including electroplating, mining, petroleum exploitation, metal smelting, etc., and proper treatment prior to their discharge is mandatory in order to alleviate the impacts on [...] Read more.
Large volumes of wastewater containing toxic contaminants (e.g., heavy metal ions, organic dyes, etc.) are produced from industrial processes including electroplating, mining, petroleum exploitation, metal smelting, etc., and proper treatment prior to their discharge is mandatory in order to alleviate the impacts on aquatic ecosystems. Adsorption is one of the most effective and practical methods for removing toxic substances from wastewater due to its simplicity, flexibility, and economics. Recently, hierarchical oxide composites with diverse morphologies at the micro/nanometer scale, and the combination advantages of oxides and composite components have been received wide concern in the field of adsorption due to their multi-level structures, easy functionalization characteristic resulting in their large transport passages, high surface areas, full exposure of active sites, and good stability. This review summarizes the recent progress on their typical preparation methods, mainly including the hydrothermal/solvothermal method, coprecipitation method, template method, polymerization method, etc., in the field of selective adsorption and competitive adsorption of hazardous substances from wastewater. Their formation processes and different selective adsorption mechanisms, mainly including molecular/ion imprinting technology, surface charge effect, hard-soft acid-base theory, synergistic effect, and special functionalization, were critically reviewed. The key to hierarchical oxide composites research in the future is the development of facile, repeatable, efficient, and scale preparation methods and their dynamic adsorption with excellent cyclic regeneration adsorption performance instead of static adsorption for actual wastewater. This review is beneficial to broaden a new horizon for rational design and preparation of hierarchical oxide materials with selective adsorption of hazardous substances for wastewater treatment. Full article
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