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Advanced Nanocomposite Materials for Water and Wastewater Treatment

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A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Environmental Nanoscience and Nanotechnology".

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 21381

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Special Issue Editors

Prof. Dr. Ming-lai Fu

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Guest Editor

Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen 361020, China
Interests: novel environmental nanomaterials; wastewater treatment; MOFs based materials; nano-bimetallic catalyst; layered sorbent materials; bimetallic hydroxide sorbent nanomaterials; recycle solid waste; solar distillation

Dr. Lazhar Labiadh

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Guest Editor

Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen 361020, China
Interests: wastewater treatment; advanced oxidation process (AOPs); adsorption; desalination; piezophotocatalysis

Prof. Dr. Baoling Yuan

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Guest Editor

Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China
Interests: water and wastewater treatment; disinfection; nutrient recovery; metallic catalyst; advanced oxidation process (AOPs); adsorption

Special Issue Information

Dear Colleagues,

Nowadays, access to safe drinking water is one of the greatest challenges and future of humanity. The World Health Organization (WHO) considers that 80% of diseases that affect the population world are directly linked to water. Population growth leads to an increase in water needs. In order to preserve the quality of our environment as well as public health, regulations for the treatment of pollutants are constantly evolving towards increasingly stringent standards. The issue of organic or mineral pollutants, including “micropollutants” present in trace amounts, is now emerging as a major issue in wastewater treatment urban or industrial and in the production of drinking water. Techniques aimed at the degradation of pollutants by biologically or by chemical oxidation show their limits because they are often confronted with species poorly biodegradable or refractory to chemical oxidants (O₃, Cl₂, etc.) and can induce secondary reactions or parasites. Other techniques aim to remove pollutants from the aqueous phase by transferring them to another phase. This is the case of adsorption on activated carbon or other support, precipitation (coagulation, flocculation, sedimentation), or reverse osmosis. Advanced nanocomposite materials are currently the most widely used materials in these types of processes; these nanostructures materials are effective for photocatalytic degradation of dyes, color removal, adsorption of heavy metals, organic and inorganic wastes and membranes for wastewater purification. These materials are cost-effective, easy to handle and highly stable materials.

In this special issue, we are pleased to invite you to submit a novel research on advanced nanocomposite materials. Priority will be given to new materials preparation and novel wastewater treatment process including the toxicity’s degree of the target pollutants. In this current special issue, review and original articles are welcome.

Research areas may include (but not limited to) the following:

Advanced nanocomposite materials;
Wastewater treatment;
Porous materials;
Adsorption of organic and inorganic pollutants;
Preparation of new materials, such as MOFs, for water purification purpose;
Photothermal materials for water distillation.

Prof. Dr. Minglai Fu
Dr. Lazhar Labiadh
Prof. Dr. Baoling Yuan
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 2900 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

adsorption
nanomaterials
water pollution
mixed oxides
graphene-based nanocomposites
nanocomposites membranes
environmental remediation
polymer-based nanocomposites
photothermal materials

Published Papers (12 papers)

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15 pages, 3475 KiB

Open AccessFeature PaperArticle

Insights into the Photoelectrocatalytic Behavior of gCN-Based Anode Materials Supported on Ni Foams

by Serge Benedoue, Mattia Benedet, Alberto Gasparotto, Nicolas Gauquelin, Andrey Orekhov, Johan Verbeeck, Roberta Seraglia, Gioele Pagot, Gian Andrea Rizzi, Vincenzo Balzano, Luca Gavioli, Vito Di Noto, Davide Barreca and Chiara Maccato

Nanomaterials 2023, 13(6), 1035; https://doi.org/10.3390/nano13061035 - 13 Mar 2023

Cited by 6 | Viewed by 1795

Abstract

Graphitic carbon nitride (gCN) is a promising n-type semiconductor widely investigated for photo-assisted water splitting, but less studied for the (photo)electrochemical degradation of aqueous organic pollutants. In these fields, attractive perspectives for advancements are offered by a proper engineering of the material properties, e.g., by depositing gCN onto conductive and porous scaffolds, tailoring its nanoscale morphology, and functionalizing it with suitable cocatalysts. The present study reports on a simple and easily controllable synthesis of gCN flakes on Ni foam substrates by electrophoretic deposition (EPD), and on their eventual decoration with Co-based cocatalysts [CoO, CoFe₂O₄, cobalt phosphate (CoPi)] via radio frequency (RF)-sputtering or electrodeposition. After examining the influence of processing conditions on the material characteristics, the developed systems are comparatively investigated as (photo)anodes for water splitting and photoelectrocatalysts for the degradation of a recalcitrant water pollutant [potassium hydrogen phthalate (KHP)]. The obtained results highlight that while gCN decoration with Co-based cocatalysts boosts water splitting performances, bare gCN as such is more efficient in KHP abatement, due to the occurrence of a different reaction mechanism. The related insights, provided by a multi-technique characterization, may provide valuable guidelines for the implementation of active nanomaterials in environmental remediation and sustainable solar-to-chemical energy conversion. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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19 pages, 4761 KiB

Open AccessArticle

Preparation and Characterization of PVDF–TiO₂ Mixed-Matrix Membrane with PVP and PEG as Pore-Forming Agents for BSA Rejection

by Rianyza Gayatri, Ahmad Noor Syimir Fizal, Erna Yuliwati, Md Sohrab Hossain, Juhana Jaafar, Muzafar Zulkifli, Wirach Taweepreda and Ahmad Naim Ahmad Yahaya

Nanomaterials 2023, 13(6), 1023; https://doi.org/10.3390/nano13061023 - 12 Mar 2023

Cited by 10 | Viewed by 2004

Abstract

Polymeric membranes offer straightforward modification methods that make industry scaling affordable and easy; however, these materials are hydrophobic, prone to fouling, and vulnerable to extreme operating conditions. Various attempts were made in this study to fix the challenges in using polymeric membranes and create mixed-matrix membrane (MMMs) with improved properties and hydrophilicity by adding titanium dioxide (TiO₂) and pore-forming agents to hydrophobic polyvinylidene fluoride (PVDF). The PVDF mixed-matrix ultrafiltration membranes in this study were made using the non-solvent phase inversion approach which is a simple and effective method for increasing the hydrophilic nature of membranes. Polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) as pore-forming chemicals were created. Pure water flux, BSA flux, and BSA rejection were calculated to evaluate the mixed-matrix membrane’s efficiency. Bovine serum albumin (BSA) solution was employed in this study to examine the protein rejection ability. Increases in hydrophilicity, viscosity, and flux in pure water and BSA solution were achieved using PVP and PEG additives. The PVDF membrane’s hydrophilicity was raised with the addition of TiO₂, showing an increased contact angle to 71°. The results show that the PVDF–PVP–TiO₂ membrane achieved its optimum water flux of 97 L/(m²h) while the PVDF–PEG–TiO₂ membrane rejected BSA at a rate greater than 97%. The findings demonstrate that use of a support or additive improved filtration performance compared to a pristine polymeric membrane by increasing its hydrophilicity. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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14 pages, 4780 KiB

Open AccessArticle

Photocatalytic Activity of MoS₂ Nanoflower-Modified CaTiO₃ Composites for Degradation of RhB under Visible Light

by Minghan Luo, Jiaxing Xu, Wenjie Xu, Yu Zheng, Gongde Wu and Taeseop Jeong

Nanomaterials 2023, 13(4), 636; https://doi.org/10.3390/nano13040636 - 06 Feb 2023

Cited by 4 | Viewed by 1486

Abstract

Nanoflower-like MoS₂ deposited on the surface of rectangular CaTiO₃(CTO) was designed and synthesized via a simple template-free strategy. Through SEM, TEM, and other characterization methods, the MoS₂ nanoflowers were confirmed to be well deposited on the surface of CTO. LED was used as the visible light source, and rhodamine B (RhB) in an aqueous solution was used as the model pollutant to assess the photodegradation activity of the samples. The results showed that the MoS₂/CaTiO₃(MCTO) composite significantly improved the photocatalytic degradation of rhodamine B (RhB) in water, compared with a single CTO, and with the MCTO-2 composite photocatalysts, 97% degradation of RhB was achieved in 180 min, and its photocatalytic activity was about 5.17 times higher than that of the bare CTO. The main reasons for enhancing photocatalytic performance are the strong interaction between the nanoflower-like MoS₂ and rectangular CTO, which can lead to the effective separation of electron transfer and photoexcited electron–hole pairs in MCTO composites. This work provides a new notion for researching an effective method of recycling catalytic materials. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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9 pages, 2326 KiB

Open AccessArticle

Cobalt-Phosphate (Co-Pi)-Modified WO₃ Photoanodes for Performance-Enhanced Photoelectrochemical Wastewater Degradation

by Jiakun Zhang, Weixu Sun, Xin Ding, Kai Xia, Tao Liu and Xiaodong Zhang

Nanomaterials 2023, 13(3), 526; https://doi.org/10.3390/nano13030526 - 28 Jan 2023

Viewed by 1298

Abstract

Photocatalytic technology, with features of wide applicability, mild reaction conditions and sunlight availability, satisfies the requirements of “green chemistry”. As the star photoanode material for photoelectrochemical catalysis, WO₃ has a suitable band gap of 2.8 eV and a strong oxidation capacity, as well as displaying great potential in organic wastewater degradation. However, its performance is usually hindered by competition with water oxidation to generate peroxides, rapid charge complexation caused by surface defect sites, and so on. Herein, WO₃ films modified with cobalt–phosphate (Co-Pi/WO₃) film were prepared and involved in photocatalytic organic wastewater degradation. A degradation rate constant of 0.63311 h⁻¹ was obtained for Co-Pi/WO₃, which was much higher than that of WO₃, 10.23 times that of direct photocatalysis (DP) and 23.99 times that of electrocatalysis (EC). After three cycles of degradation, the film can maintain a relatively good level of stability and a degradation efficiency of 93.79%. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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17 pages, 5193 KiB

Open AccessArticle

Fluorometric Sensing and Detection of p-Nitroaniline by Mixed Metal (Zn, Ni) Tungstate Nanocomposite

by Fahad A. Alharthi, Hend Khalid Aldubeikl, Hamdah S. Alanazi, Wedyan Saud Al-Nafaei and Imran Hasan

Nanomaterials 2023, 13(2), 362; https://doi.org/10.3390/nano13020362 - 16 Jan 2023

Cited by 1 | Viewed by 1768

Abstract

Aromatic amines are important chemical intermediates that hold an irreplaceable significance for synthesizing many chemical products. However, they may react with substances excreted from human bodies to generate blood poisoning, skin eczema, and dermatitis disease and even induce cancer-causing high risks to human health and the environment. Metal tungstates have been proven to be highly efficient materials for developing various toxic gases or chemical detection sensor systems. However, the major factors of the sensors, such as sensitivity, selectivity, stability, response, and recovery times, still need to be optimized for practical technological applications. In this work, Ni-doped ZnWO₄ mixed metal tungstate nanocomposite material was synthesized by the hydrothermal method and explored as a sensor for the fluorometric determination of p-nitroaniline (p-NA). Transmission electron microscopy (TEM) was used for the elucidation of the optimized particle diameter. Scanning electron microscopy (SEM) was employed to observe the surface morphological changes in the material during the solid-state reactions. The vibration modes of as-prepared samples were analyzed using Fourier-transform infrared spectroscopy (FTIR). The chemical bonding and oxidation states of individual elements involved in material synthesis were observed using X-ray photoelectron spectroscopy (XPS). The PL activities of the metal tungstate nanoparticles were investigated for the sensing of p-nitroaniline (p-NA). The obtained results demonstrated that ZnNiWO₄ was more effective in sensing p-NA than the other precursors were by using the quenching effect. The material showed remarkably high sensitivity towards p-NA in a concentration range of 25–1000 μM, and the limit of detection (LOD) value was found to be 1.93 × 10⁻⁸ M for ZnWO₄, 2.17 × 10⁻⁸ M for NiWO₄, and 2.98 × 10⁻⁸ M for ZnNiWO₄, respectively. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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12 pages, 7895 KiB

Open AccessArticle

Capacitive Desalination and Disinfection of Water Using UiO-66 Metal–Organic Framework/Bamboo Carbon with Chitosan

by Cuihui Cao, Xiaofeng Wu, Yuming Zheng, Lizhen Zhang and Yunfa Chen

Nanomaterials 2022, 12(21), 3901; https://doi.org/10.3390/nano12213901 - 04 Nov 2022

Cited by 3 | Viewed by 1557

Abstract

The zirconium-based metal–organic framework (MOF) (UiO-66)/bamboo carbon (BC) composite with chitosan was prepared using hydrothermal and impregnation methods and used for capacitive desalination (CDI) and disinfection of water. The results showed that these composites had fast ion exchange and charge transfer properties. During the CDI process, these composites’ electrodes exhibited good cycle stability, electrosorption capacity (4.25 mg/g) and excellent bactericidal effect. These carbon-based composites electrodes’ bactericidal rate for Escherichia coli could reach 99.99% within 20 minutes; therefore, they had good performance and were a good choice for high-performance deionization applications. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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26 pages, 3358 KiB

Open AccessArticle

Fe³⁺/Mn²⁺ (Oxy)Hydroxide Nanoparticles Loaded onto Muscovite/Zeolite Composites (Powder, Pellets and Monoliths): Phosphate Carriers from Urban Wastewater to Soil

by Diana Guaya, Luz Maza, Adriana Angamarca, Eda Mendoza, Luis García, César Valderrama and José Luis Cortina

Nanomaterials 2022, 12(21), 3848; https://doi.org/10.3390/nano12213848 - 31 Oct 2022

Cited by 1 | Viewed by 1154

Abstract

The development of an efficient adsorbent is required in tertiary wastewater treatment stages to reduce the phosphate–phosphorous content within regulatory levels (1 mg L⁻¹ total phosphorous). In this study, a natural muscovite was used for the preparation of muscovite/zeolite composites and the incorporation of Fe³⁺/Mn²⁺ (oxy)hydroxide nanoparticles for the recovery of phosphate from synthetic wastewater. The raw muscovite MC and the obtained muscovite/sodalite composite LMC were used in the powder form for the phosphate adsorption in batch mode. A muscovite/analcime composite was obtained in the pellets PLMCT₃ and monolith SLMCT₂ forms for the evaluation in fixed-bed mode for continuous operation. The effect of pH, equilibrium and kinetic parameters on phosphate adsorption and its further reuse in sorption–desorption cycles were determined. The characterization of the adsorbents determined the Fe³⁺ and Mn²⁺ incorporation into the muscovite/zeolite composite’s structure followed the occupancy of the extra-framework octahedral and in the framework tetrahedral sites, precipitation and inner sphere complexation. The adsorbents used in this study (MC, LMC, PLMCT₃ and SLMCT₂) were effective for the phosphate recovery without pH adjustment requirements for real treated wastewater. Physical (e.g., electrostatic attraction) and chemical (complexation reactions) adsorption occurred between the protonated Fe³⁺/Mn²⁺ (oxy)hydroxy groups and phosphate anions. Higher ratios of adsorption capacities were obtained by powder materials (MC and LMC) than the pellets and monoliths forms (PLMCT₃ and SLMCT₂). The equilibrium adsorption of phosphate was reached within 30 min for powder forms (MC and LMC) and 150 min for pellets and monoliths forms (PLMCT₃ and SLMCT₂); because the phosphate adsorption was governed by the diffusion through the internal pores. The adsorbents used in this study can be applied for phosphate recovery from wastewater treatment plants in batch or fixed-bed mode with limited reusability. However, they have the edge of environmentally friendly final disposal being promissory materials for soil amendment applications. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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25 pages, 2898 KiB

Open AccessArticle

Effect of Mn²⁺/Zn²⁺/Fe³⁺ Oxy(Hydroxide) Nanoparticles Doping onto Mg-Al-LDH on the Phosphate Removal Capacity from Simulated Wastewater

by Diana Guaya, Hernán Cobos, César Valderrama and José Luis Cortina

Nanomaterials 2022, 12(20), 3680; https://doi.org/10.3390/nano12203680 - 20 Oct 2022

Cited by 7 | Viewed by 1634

Abstract

A parent Mg-Al-LDH was upgraded in its adsorption properties due to the incorporation of tri-metal species oxy(hydroxide) nanoparticles obtaining Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH composite for the phosphate recovery from simulated urban treated wastewater. The physicochemical properties of the synthesized Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH make promising for real application without being environmentally harmful. The performance of Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH composite was evaluated through batch adsorption assays. The support of iron, manganese, and zinc (oxy)hydroxide nanoparticles onto the parent Mg-Al-LDH structure was performed by precipitation, isomorphic substitution, and complexation reactions. The main improvement of the Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH composite was the highest phosphate adsorption capacity (82.3 mg∙g⁻¹) in comparison to the parent Mg-Al-LDH (65.3 mg∙g⁻¹), in a broad range of concentrations and the effective phosphate adsorption at neutral pH (7.5) near to the real wastewater effluents conditions in comparison to the conventional limitations of other adsorbents. The effectiveness of Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH composite was higher than the conventional metal LDHs materials synthesized in a single co-precipitation step. The phosphate adsorption onto Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH composite was described to be governed by both physical and chemical interactions. The support of Mn²⁺/Zn²⁺/Fe³⁺ oxy(hydroxide) nanoparticles over the parent Mg-Al-LDH was a determinant for the improvement of the phosphate adsorption that was governed by complexation, hydrogen bonding, precipitation, and anion exchange. The intra-particular diffusion also described well the phosphate adsorption onto the Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH composite. Three specific stages of adsorption were determined during the phosphate immobilization with an initial fast rate, followed by the diffusion through the internal pores and the final equilibrium stage, reaching 80% of removal and the equilibrium within 1 h. The Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH was strongly selective towards phosphate adsorption in presence of competing ions reducing the adsorption capacity at 20%. The Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH has limited reusability, only 51% of the adsorbed phosphate could be recovered in the second cycle of the adsorption-desorption process. Around 14% of phosphate was loosely-bond to Mn²⁺/Zn²⁺/Fe³⁺/Mg-Al-LDH which brings the opportunity to be a new source of phosphorus. The use of eluted concentrates and the final disposal of the exhausted adsorbent for soil amendment applications can be an integral nutrient system (P, Mn, Zn, Fe) for agriculture purposes. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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19 pages, 3961 KiB

Open AccessArticle

Fabrication of Ternary Nanoparticles for Catalytic Ozonation to Treat Parabens: Mechanisms, Efficiency, and Effects on Ceratophyllum demersum L. and Eker Leiomyoma Tumor-3 Cells

by Apiladda Pattanateeradetch, Chainarong Sakulthaew, Athaphon Angkaew, Samak Sutjarit, Thapanee Poompoung, Yao-Tung Lin, Clifford E. Harris, Steve Comfort and Chanat Chokejaroenrat

Nanomaterials 2022, 12(20), 3573; https://doi.org/10.3390/nano12203573 - 12 Oct 2022

Cited by 3 | Viewed by 1518

Abstract

The use of parabens in personal care products can result in their leakage into water bodies, especially in public swimming pools with insufficient water treatment. We found that ferrite-based nanomaterials could catalytically enhance ozone efficiency through the production of reactive oxygen species. Our objective was to develop a catalytic ozonation system using ternary nanocomposites that could minimize the ozone supply while ensuring the treated water was acceptable for disposal into the environment. A ternary CuFe₂O₄/CuO/Fe₂O₃ nanocomposite (CF) delivered excellent degradation performance in catalytic ozonation systems for butylparaben (BP). By calcining with melamine, we obtained the CF/g-C₃N₄ (CFM) nanocomposite, which had excellent magnetic separation properties with slightly lower degradation efficiency than CF, due to possible self-agglomeration that reduced its electron capture ability. The presence of other constituent ions in synthetic wastewater and actual discharge water resulted in varying degradation rates due to the formation of secondary active radicals. ¹O₂ and ^•O₂⁻ were the main dominant reactive species for BP degradation, which originated from the O₃ adsorption that occurs on the CF≡Cu^(I)–OH and CF≡Fe^(III)–OH surface, and from the reaction with ^•OH from indirect ozonation. Up to 50% of O₃-treated water resulted in >80% ELT3 cell viability, the presence of well-adhered cells, and no effect on the young tip of Ceratophyllum demersum L. Overall, our results demonstrated that both materials could be potential catalysts for ozonation because of their excellent degrading performance and, consequently, their non-toxic by-products. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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14 pages, 4235 KiB

Open AccessArticle

Magnetic TiO₂/CoFe₂O₄ Photocatalysts for Degradation of Organic Dyes and Pharmaceuticals without Oxidants

by Islam Ibrahim, George V. Belessiotis, Ahmed Mourtada Elseman, Mohamed Mokhtar Mohamed, Yatao Ren, Tarek M. Salama and Mahmoud Basseem I. Mohamed

Nanomaterials 2022, 12(19), 3290; https://doi.org/10.3390/nano12193290 - 21 Sep 2022

Cited by 22 | Viewed by 2327

Abstract

In the current study, CoFe₂O₄ and TiO₂ nanoparticles were primarily made using the sol-gel method, and subsequently, the hybrid magnetic composites of TiO₂ loaded with CoFe₂O₄ (5–15 percent w/w) were made using a hydrothermal procedure. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) were all used to thoroughly characterize the materials. Additionally, the zero-charge point (ZCP) determination, the examination of the pore structure by nitrogen adsorption, and an evaluation of magnetic properties were performed. Six organic dye pollutants were selected to evaluate the performance of the synthesized nanocomposites toward photocatalytic degradation, including methylene blue (MB), methyl orange (MO), crystal violet (CV), acridine orange (AO), rhodamine B (RhB), and rhodamine 6G (R-6G). Photodegradation of tetracycline (TL), a model pharmaceutical pollutant, was also studied under UV and visible light. The composites exhibited a high degradation performance in all cases without using any oxidants. The photocatalytic degradation of tetracycline revealed that the CoFe₂O₄/TiO₂ (5% w/w) composite exhibited a higher photocatalytic activity than either pure TiO₂ or CoFe₂O₄, and thus attained 75.31% and 50.4% degradation efficiency under UV and visible light, respectively. Trapping experiments were conducted to investigate the photodegradation mechanism, which revealed that holes and super oxide radicals were the most active species in the photodegradation process. Finally, due to the inherent magnetic attributes of the composites, their easy removal from the treated solution via a simple magnet became possible. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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20 pages, 5155 KiB

Open AccessArticle

Adsorption of Methylene Blue from Aqueous Solution Using Gelatin-Based Carboxylic Acid-Functionalized Carbon Nanotubes@Metal–Organic Framework Composite Beads

by Yang Zhang, Yanhui Li, Mingzhen Wang, Bing Chen, Yaohui Sun, Kewei Chen, Qiujv Du, Xinxin Pi and Yuqi Wang

Nanomaterials 2022, 12(15), 2533; https://doi.org/10.3390/nano12152533 - 23 Jul 2022

Cited by 11 | Viewed by 1981

Abstract

A novel gelatin-based functionalized carbon nanotubes@metal–organic framework (F-CNTs@MOF@Gel) adsorbent was prepared by the green and simple method for the adsorption of methylene blue (MB). Cu-BTC (also known as HKUST-1) was selected as the MOF type. F-CNTs@Cu-BTC particles were fixed by gelatin, thus avoiding the secondary pollution of carbon nanomaterial particles to the environment. CNTs were used as the connecting skeleton to make more effective adsorption sites exposed on the surface of the internal pore structure of the adsorbent. In this paper, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), thermogravimetry (TGA) and BET analysis methods were used to characterize the new adsorbent. The effects of time, temperature, pH, dosage and initial concentration on the adsorption process were investigated by batch adsorption experiments. The adsorption mechanism was further analyzed by several commonly used kinetic and isotherm models, and the reliability of several fitting models was evaluated by the Akaike information criterion (AIC), Bayesian information criterion (BIC) and Hannan information criterion (HIC). After five regeneration experiments, the adsorbent still had 61.23% adsorption capacity. In general, the new adsorbent studied in this paper has an optimistic application prospect. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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21 pages, 4456 KiB

Open AccessArticle

LDH-TiO₂ Composite for Selenocyanate (SeCN⁻) Photocatalytic Degradation: Characterization, Treatment Efficiency, Reaction Intermediates and Modeling

by Minaam Hussaini and Muhammad Vohra

Nanomaterials 2022, 12(12), 2035; https://doi.org/10.3390/nano12122035 - 14 Jun 2022

Cited by 5 | Viewed by 1758

Abstract

Selenium as a nutrient has a narrow margin between safe and toxic limits. Hence, wastewater discharges from selenium-containing sources require appropriate treatment that considers health concerns and stringent selenium-related water treatment standards. This work examined the use of a photocatalysis-cum-adsorption system based on a layered double hydroxide coupled with TiO₂ (LDH-TiO₂) to remove aqueous phase selenocyanate (SeCN⁻), which is difficult to treat and requires specific treatment procedures. The synthesized LDH and LDH-TiO₂ composite samples were characterized using the X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetry analysis (TGA) methods. The XRD results for the uncalcined LDH indicated a hydrotalcite mass with a rhombohedral structure, whereas increasing the calcination temperature indicated transition to an amorphous state. FESEM results for the LDH-TiO₂ matrix indicated round titanium dioxide particles and LDH hexagonal layers. The TGA findings for uncalcined LDH showed a gradual decrease in weight up to 250 °C, followed by a short plateau and then a sharp decrease in LDH weight from 320 °C, with a net weight loss around 47%. Based on the characterization and initial selenocyanate adsorption results, the 250 °C calcined LDH-TiO₂ matrix was used for the selenocyanate photocatalysis. A ~100% selenium removal was observed using LDH:TiO₂ at a 1.5:1 w/w ratio with a 2 g/L dose, whereas up to 80% selenium removal was noted for LDH:TiO₂ at a 0.5:1 w/w ratio. The respective difference in the efficiency of selenium treatment was attributed to enhanced LDH-based adsorption sites in the enhanced LDH:TiO₂ w/w ratio. Furthermore, the selenite and selenate that occurred during SeCN⁻ photocatalytic degradation (PCD) were also nearly completely removed via adsorption. An optimization exercise using response surface methodology (RSM) for total selenium removal showed R² values of more than 0.95, with a prediction accuracy of more than 90%. In summary, the present findings show that the use of a photocatalysis-cum-adsorption system based on LDH-TiO₂ is a promising technique to treat industrial wastewater discharges for selenocyanate and also remove the resulting intermediates. Full article

(This article belongs to the Special Issue Advanced Nanocomposite Materials for Water and Wastewater Treatment)

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