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Nanomaterials for the Environmental Remediation of Water and Soil

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Nanomaterials and Nanotechnology".

Deadline for manuscript submissions: closed (10 July 2023) | Viewed by 24013

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Special Issue Editors

Dr. Roberta G. Toro

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Guest Editor

Institute for the Study of Nanostructured Materials, National Research Council, Rome, Italy
Interests: nanomaterials; photocatalysis; metal oxide nanoparticles stabilized by organic molecules and natural polymers for wastewater treatment application; thin films; metal–organic chemical vapor deposition
Special Issues, Collections and Topics in MDPI journals

Dr. Daniela Caschera

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Guest Editor

Istituto per lo Studio dei Materiali Nanostrutturati, ISMN-CNR, via Salaria km 29,300, 00015 Monterotondo Scalo, Rome, Italy
Interests: hybrid organic–inorganic nanocomposites; surface treatments; plasma technologies; smart textiles; environmental remediation; circular economy
Special Issues, Collections and Topics in MDPI journals

Dr. Abeer M. Adel

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Guest Editor

National Research Center, 33 El-Bohouth St. (Former El-Tahrir St.), P.O. 12622, Dokki, Giza, Egypt
Interests: biopolymer; sustainable functional biopolymers; material science; recycling; pulp and paper industry; packaging; composites and nanomaterials

Special Issue Information

Dear Colleagues

“Extract, produce, consume, and reproduce”: this is the new economic model to pursue that replaces the concept of waste with that of resource, aiming to reduce the consumption of raw materials and increasing efficiency in the use of materials toward the maximization of reuse and recycling. Treating waste with waste is an efficient environmental protection method since it produces a positive outcome through the simultaneous treatment of multiple wastes. In particular, with the advancement of industrial, agricultural, and urban activities, the levels of groundwater and soil pollution have increased enormously in the last few decades. In this regard, the application of nanotechnology for the remediation of contaminants has shown promising results. Nanomaterials in the form of catalysts, chemical oxidants, and adsorbents guarantee the rapid detection and consequent detoxification of various contaminants such as pharmaceuticals, pesticides, drugs, aromatic heterocycles, volatile organic compounds, heavy metals, and inorganic ions from water, air, and contaminated land sites. This proposed Special Issue will focus on prospects and challenges in nanoremediation and environmental clean-ups. This Special Issue welcomes contributions from all researchers working on the possibility to use waste-derived precursors for preparing nanomaterials for environmental remediation of water and soil.

Some topics of interest covered by this Special Issue include but are not limited to:

Sustainability in agro-based bioeconomy;
Green technology and natural resources;
Fabrication of nanoparticles and nanobiocomposites;
Carbon nanoparticles;
Industrial, electric/electronic, and plastic waste for environmental clean-ups;
Groundwater remediation and desalination for drinking and reuse;
Decontamination of mining or wastes sites.

In this regard, we would be very pleased if you would agree to contribute either an original research paper, a communication, or a focus review to this special issue.

Dr. Roberta G. Toro
Dr. Daniela Caschera
Dr. Abeer M. Adel
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. Materials 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 2600 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

agromaterials
carbon nanoparticles
nano-biocomposite
polluted water
absorption
zeolite
VOC removal
photocatalysis
soil remediation
layered double hydroxide

Published Papers (14 papers)

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Research

16 pages, 4409 KiB

Open AccessArticle

Removal of Cesium and Strontium Ions from Aqueous Solutions by Thermally Treated Natural Zeolite

by Marin Șenilă, Emilia Neag, Claudiu Tănăselia and Lacrimioara Șenilă

Materials 2023, 16(8), 2965; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16082965 - 07 Apr 2023

Cited by 8 | Viewed by 1415

Abstract

The radionuclides of cesium (Cs) and strontium (Sr) are dangerous products of nuclear fission that can be accidentally released into wastewater. In the present work, the capacity of thermally treated natural zeolite (NZ) from Macicasu (Romania) to remove Cs⁺ and Sr²⁺ ions from aqueous solutions in batch mode was investigated by contacting different zeolite quantities (0.5, 1, and 2 g) of 0.5–1.25 mm (NZ1) and 0.1–0.5 mm (NZ2) particle size fractions with 50 mL working solutions of Cs⁺ and Sr²⁺ (10, 50, and 100 mg L⁻¹ initial concentrations) for 180 min. The concentration of Cs in the aqueous solutions was determined by inductively coupled plasma mass spectrometry (ICP-MS), whereas the Sr concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The removal efficiency of Cs⁺ varied between 62.8 and 99.3%, whereas Sr²⁺ ranged between 51.3 and 94.5%, depending on the initial concentrations, the contact time, the amount, and particle size of the adsorbent material. The sorption of Cs⁺ and Sr²⁺ was analyzed using the nonlinear form of Langmuir and Freundlich isotherm models and pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. The results indicated that the sorption kinetics of Cs⁺ and Sr²⁺ on thermally treated natural zeolite was described by the PSO kinetic model. Chemisorption dominates the retention of both Cs⁺ and Sr²⁺ by strong coordinate bonds with an aluminosilicate zeolite skeleton. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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18 pages, 5281 KiB

Open AccessArticle

Modified Silica Nanoparticles from Rice Husk Supported on Polylactic Acid as Adsorptive Membranes for Dye Removal

by João Otávio Donizette Malafatti, Francine Aline Tavares, Tainara Ramos Neves, Bruno Cano Mascarenhas, Simone Quaranta and Elaine Cristina Paris

Materials 2023, 16(6), 2429; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16062429 - 18 Mar 2023

Cited by 1 | Viewed by 1580

Abstract

Industrial effluents and wastewater treatment have been a mainstay of environmental preservation and remediation for the last decade. Silica nanoparticles (SiO₂) obtained from rice husk (RH) are an alternative to producing low-cost adsorbent and agriculture waste recovery. One adsorption challenge is facilitating the adsorbate separation and reuse cycle from aqueous medium. Thus, the present work employs SiO₂ supported on polylactic acid (PLA) nanofibers obtained by the electrospinning method for Rhodamine B (RhB) dye adsorption. The silica surface was modified with trimethylsilyl chloride (TMCS) to increase affinity towards organic compounds. As a result, the silanized surface of the silica from rice husk (RHSil) promoted an increase in dye adsorption attributed to the hydrophobic properties. The PLA fibers containing 40% SiO₂ (w w⁻¹) showed about 85–95% capacity adsorption. The pseudo-first-order kinetic model was demonstrated to be the best model for PLA:SiO₂ RHSil nanocomposites, exhibiting a 1.2956 mg g⁻¹ adsorption capacity and 0.01404 min⁻¹ kinetic constant (k₁) value. In the reuse assay, PLA:SiO₂ membranes preserved their adsorption activity after three consecutive adsorption cycles, with a value superior to 60%. Therefore, PLA:SiO₂ nanocomposites from agricultural waste are an alternative to “low-cost/low-end” treatments and can be used in traditional treatment systems to improve dye removal from contaminated waters. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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18 pages, 2685 KiB

Open AccessArticle

Molecular Sieve, Halloysite, Sepiolite and Expanded Clay as a Tool in Reducing the Content of Trace Elements in Helianthus annuus L. on Copper-Contaminated Soil

by Mirosław Wyszkowski, Jadwiga Wyszkowska, Natalia Kordala and Magdalena Zaborowska

Materials 2023, 16(5), 1827; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16051827 - 23 Feb 2023

Cited by 1 | Viewed by 1255

Abstract

The aim of this study was to determine the effect of copper soil contamination on the trace element content of sunflower aerial parts and in roots. Another aim was to assess whether the introduction of selected neutralizing substances (molecular sieve, halloysite, sepiolite and expanded clay) into the soil could reduce the impact of copper on the chemical composition of sunflower plants. Copper soil contamination with 150 mg Cu²⁺ kg⁻¹ of soil and 10 g of each adsorbent per kg of soil were used. Soil contamination with copper caused a significant increase in the content of this element in the aerial parts (by 37%) and roots (by 144%) of sunflower. Enriching the soil with the mineral substances reduced the amount of copper in the aerial parts of sunflower. Halloysite had the greatest effect (35%), while expanded clay had the smallest effect (10%). An opposite relationship was found in the roots of this plant. In copper-contaminated objects, a decrease in the content of cadmium and iron and an increase in the concentrations of nickel, lead and cobalt in the aerial parts and roots of sunflower were observed. The applied materials reduced the content of the remaining trace elements more strongly in the aerial organs than in the roots of sunflower. Molecular sieve had the greatest reducing effect on the content of trace elements in sunflower aerial organs, followed by sepiolite, while expanded clay had the least impact. The molecular sieve also reduced the content of iron, nickel, cadmium, chromium, zinc and, especially, manganese, whereas sepiolite reduced the content of zinc, iron, cobalt, manganese and chromium in sunflower aerial parts. Molecular sieve contributed to a slight increase in the content of cobalt, while sepiolite had the same effect on the content of nickel, lead and cadmium in the aerial parts of sunflower. All materials decreased the content of chromium in sunflower roots, molecular sieve—zinc, halloysite—manganese, and sepiolite—manganese and nickel. The materials used in the experiment, especially the molecular sieve and to a lesser extent sepiolite, can be used effectively to reduce the content of copper and some other trace elements, particularly in the aerial parts of sunflower. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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15 pages, 3553 KiB

Open AccessArticle

Eco-Friendly Polysaccharide-Based Synthesis of Nanostructured MgO: Application in the Removal of Cu²⁺ in Wastewater

by Nayara Balaba, Dienifer F. L. Horsth, Jamille de S. Correa, Julia de O. Primo, Silvia Jaerger, Helton J. Alves, Carla Bittencourt and Fauze J. Anaissi

Materials 2023, 16(2), 693; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16020693 - 10 Jan 2023

Cited by 1 | Viewed by 1573

Abstract

The present study described three synthesis routes using different natural polysaccharides as low-cost non-toxic fuels and complexing agents for obtaining MgO. Cassava starch, Aloe vera leaves (mainly acemannan) gel, and citric pectin powder were mixed with magnesium nitrate salt and calcined at 750 °C for 2 h. The samples were named according to the polysaccharide: cassava starch (MgO-St), citrus pectin (MgO-CP), and Aloe vera (MgO-Av). X-ray diffraction identified the formation of a monophasic periclase structure (FCC type) for the three samples. The N₂ adsorption/desorption isotherms (B.E.T. method) showed an important difference in textural properties, with a higher pore volume (V_max = 89.76 cc/g) and higher surface area (SA = 43.93 m²/g) obtained for MgO-St, followed by MgO-CP (V_max = 11.01 cc/g; SA = 7.01 m²/g) and MgO-Av (V_max = 6.44 cc/g; SA = 6.63 m²/g). These data were consistent with the porous appearance observed in SEM images. Porous solids are interesting as adsorbents for removing metallic and molecular ions from wastewater. The removal of copper ions from water was evaluated, and the experimental data at equilibrium were adjusted according to the Freundlich, Langmuir, and Temkin isotherms. According to the Langmuir model, the maximum adsorption capacity (q_max) was 6331.117, 5831.244, and 6726.623 mg·g⁻¹ for the adsorbents MgO-St, MgO-Av, and MgO-CP, respectively. The results of the adsorption isotherms indicated that the synthesized magnesium oxides could be used to decrease the amount of Cu²⁺ ions in wastewater. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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14 pages, 3367 KiB

Open AccessArticle

Kinetics and Thermodynamics of Adsorption for Aromatic Hydrocarbon Model Systems via a Coagulation Process with a Ferric Sulfate–Lime Softening System

by Deysi J. Venegas-García and Lee D. Wilson

Materials 2023, 16(2), 655; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16020655 - 10 Jan 2023

Cited by 3 | Viewed by 1254

Abstract

The adsorption mechanisms for model hydrocarbons, 4-nitrophenol (PNP), and naphthalene were studied in a coagulation-based process using a ferric sulfate–lime softening system. Kinetic and thermodynamic adsorption parameters for this system were obtained under variable ionic strength and temperature. An in situ method was used to investigate kinetic adsorption profiles for PNP and naphthalene, where a pseudo-first order kinetic model adequately described the process. Thermodynamic parameters for the coagulation of PNP and naphthalene reveal an endothermic and spontaneous process. River water was compared against lab water samples at optimized conditions, where the results reveal that ions in the river water decrease the removal efficiency (RE; %) for PNP (RE = 28 to 20.3%) and naphthalene (RE = 89.0 to 80.2%). An aluminum sulfate (alum) coagulant was compared against the ferric system. The removal of PNP with alum decreased from RE = 20.5% in lab water and to RE = 16.8% in river water. Naphthalene removal decreased from RE = 89.0% with ferric sulfate to RE = 83.2% with alum in lab water and from RE = 80.2% for the ferric system to RE = 75.1% for alum in river water. Optical microscopy and dynamic light scattering of isolated flocs corroborated the role of ions in river water, according to variable RE and floc size distribution. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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15 pages, 1582 KiB

Open AccessArticle

Utilization of Bioflocculants from Flaxseed Gum and Fenugreek Gum for the Removal of Arsenicals from Water

by Deysi J. Venegas-García and Lee D. Wilson

Materials 2022, 15(23), 8691; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15238691 - 06 Dec 2022

Cited by 5 | Viewed by 1789

Abstract

Mucilage-based flocculants are an alternative to synthetic flocculants and their use in sustainable water treatment relates to their non-toxic and biodegradable nature. Mucilage extracted from flaxseed (FSG) and fenugreek seed (FGG) was evaluated as natural flocculants in a coagulation–flocculation (CF) process for arsenic removal, and were compared against a commercial xanthan gum (XG). Mucilage materials were characterized by spectroscopy (FT-IR, ¹³C NMR), point-of-zero charge (pH_pzc) and thermogravimetric analysis (TGA). Box–Behnken design (BBD) with response surface methodology (RSM) was used to determine optimal conditions for arsenic removal for the CF process for three independent variables: coagulant dosage, flocculant dosage and settling time. Two anionic systems were tested: S1, roxarsone (organic arsenate 50 mg L⁻¹) at pH 7 and S2 inorganic arsenate (inorganic arsenate 50 mg L⁻¹) at pH 7.5. Variable arsenic removal (RE, %) was achieved: 92.0 (S1-FSG), 92.3 (S1-FGG), 92.8 (S1-XG), 77.0 (S2-FSG), 69.6 (S2-FGG) and 70.6 (S2-XG) based on the BBD optimization. An in situ kinetic method was used to investigate arsenic removal, where the pseudo-first-order model accounts for the kinetic process. The FSG and FGG materials offer a sustainable alternative for the controlled removal of arsenic in water using a facile CF treatment process with good efficiency, as compared with a commercial xanthan gum. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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16 pages, 1156 KiB

Open AccessEditor’s ChoiceArticle

Effects of Functionalized Materials and Bacterial Metabolites on Quality Indicators in Composts

by Krzysztof Gondek, Piotr Micek, Monika Mierzwa-Hersztek, Jerzy Kowal, Krzysztof Andres, Katarzyna Szczurowska, Marcin Lis and Krzysztof Smoroń

Materials 2022, 15(23), 8564; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15238564 - 01 Dec 2022

Cited by 1 | Viewed by 1312

Abstract

The addition of functionalized materials (biochar, zeolite, and diatomite) and lyophilized metabolic products of Pseudomonas sp. and Bacillus subtilis to composted biomass may bring many technological and environmental benefits. In this study, we verify the effects of biochar, zeolite Na-P1 (Na₆Si₁₀Al₆O₃₂·12 H₂O), diatomite (SiO_{2_}nH₂O), and bacterial metabolites on the composting of biomass prepared from poultry litter, corn straw, grass, leonardite, and brown coal. The experimental design included the following treatments: C—biomass without the addition of functionalized materials and bacterial metabolites, CB—biomass with the addition of biochar, CBM—biomass with the addition of biochar and bacterial metabolites, CZ—biomass with the addition of zeolite, CZM—biomass with the addition of zeolite and bacterial metabolites, CD—biomass with the addition of diatomite, and CDM—biomass with the addition of diatomite and bacterial metabolites. Composts were analyzed for enzymatic and respiratory activities, mobility of heavy metals, and the presence of parasites. The results of this study revealed that, among the analyzed functionalized materials, the addition of diatomite to the composted biomass (CD and CDM) resulted in the most effective immobilization of Cd, Zn, Pb, and Cu. Zinc immobilization factors (IFHM) for diatomite-amended composts averaged 30%. For copper, each functionalized material was found to enhance mobilization of the element in bioavailable forms; similar observations were made for lead, except for the compost to which biochar and bacterial metabolites were added (CBM). The determined values of biochemical indicators proved the different effects of the applied functionalized materials and bacterial metabolites on the microbial communities colonizing individual composts. The dehydrogenase activity (DhA) was lower in all combinations as compared with the control, indicating an intensification of the rate of processes in the studied composts. The highest basal respiration (BR) and substrate-induced respiration (SIR) activities were determined in composts with the addition of bacterial metabolites (CBM, CZM, and CDM). The addition of functionalized materials completely inactivated Eimeria sp. in all combinations. In the case of Capillaria sp., complete inactivation was recorded for the combination with zeolite as well as biochar and diatomite without bacterial metabolites (CB, CZ, and CD). Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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15 pages, 4271 KiB

Open AccessArticle

Effect of Oxygen Plasma Pre-Treatment on the Surface Properties of Si-Modified Cotton Membranes for Oil/Water Separations

by Leila Ghorbani, Daniela Caschera and Babak Shokri

Materials 2022, 15(23), 8551; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15238551 - 30 Nov 2022

Cited by 1 | Viewed by 1157

Abstract

Hydrophobic and oleophilic Si-based cotton fabrics have recently gained a lot of attention in oil/water separation due to their high efficiency. In this study, we present the effect of O₂ plasma pre-treatment on the final properties of two Si-based cotton membranes obtained from dip coating and plasma polymerization, using polydimethylsiloxane (PDMS) as starting polymeric precursor. The structural characterizations indicate the presence of Si bond on both the modified cotton surfaces, with an increase of the carbon bond, assuring the success in surface modification. On the other hand, employing O₂ plasma strongly changes the cotton morphology, inducing specific roughness and affecting the hydrophobicity durability and separation efficiency. In particular, the wettability has been retained after 20 laundry tests at 40 °C and 80 °C, and, for separation efficiency, even after 30 cycles, an improvement in the range of 10–15%, both at room temperature and at 90 °C can be observed. These results clearly demonstrate that O₂ plasma pre-treatment, an eco-friendly, non-toxic, solvent-free, and one-step method for inducing specific functionalities on surfaces, is very effective in enhancing the oil/water separation properties for Si-based cotton membranes, especially in combination with plasma polymerization procedure for Si-based deposition. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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14 pages, 1185 KiB

Open AccessArticle

Lithium Accumulation in Salvinia natans Free-Floating Aquatic Plant

by Anamaria Iulia Török, Ana Moldovan, Eniko Kovacs, Oana Cadar, Anca Becze, Erika Andrea Levei and Emilia Neag

Materials 2022, 15(20), 7243; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207243 - 17 Oct 2022

Cited by 2 | Viewed by 1500

Abstract

The new context of the intensive use of lithium-based batteries led to increased production of Li and Li-containing wastes. All these activities are potential sources of environmental pollution with Li. However, the negative impact of Li on ecosystems, its specific role in the plants’ development, uptake mechanism, and response to the induced stress are not fully understood. In this sense, the Li uptake and changes induced by Li exposure in the major and trace element contents, photosynthetic pigments, antioxidant activity, and elemental composition of Salvinia natans were also investigated. The results showed that Salvinia natans grown in Li-enriched nutrient solutions accumulated much higher Li contents than those grown in spring waters with a low Li content. However, the Li bioaccumulation factor in Salvinia natans grown in Li-enriched nutrient solutions was lower (13.3–29.5) than in spring waters (13.0–42.2). The plants exposed to high Li contents showed a decrease in their K and photosynthetic pigments content, while their total antioxidant activity did not change substantially. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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14 pages, 2654 KiB

Open AccessArticle

Mechanical Performance of Fly Ash Based Geopolymer (FAG) as Road Base Stabilizer

by Liyana Ahmad Sofri, Mohd Mustafa Al Bakri Abdullah, Andrei Victor Sandu, Thanongsak Imjai, Petrica Vizureanu, Mohd Rosli Mohd Hasan, Mohammad Almadani, Ikmal Hakem Ab Aziz and Farahiyah Abdul Rahman

Materials 2022, 15(20), 7242; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207242 - 17 Oct 2022

Cited by 8 | Viewed by 1636

Abstract

This study examines the strength development of fly ash-based geopolymer (FAG) as a stabilizer for road base material for pavement construction. In the last decade, there has been a rapid development of conventionally treated bases, such as cement-treated bases. However, a major problem with this kind of application is the shrinkage cracking in cement-treated bases that may result in the reflection cracks on the asphalt pavement surface. This study explores the effects of FAG on base layer properties using mechanistic laboratory evaluation and its practicability in pavement base layers. The investigated properties are flexural strength (FS), unconfined compressive strength (UCS), shrinkage, and resilient modulus (RM), as well as indirect tensile strength (ITS). The findings showed that the mechanical properties of the mixture enhanced when FAG was added to 80–85% of crushed aggregate, with the UCS being shown to be a crucial quality parameter. The effectiveness of FAG base material can have an impact on the flexible pavements’ overall performance since the base course stiffness directly depends on the base material properties. As a stabilizing agent for flexible pavement applications, the FAG-stabilized base appeared promising, predicated on test outcomes. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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28 pages, 4444 KiB

Open AccessArticle

Equilibrium and Kinetic Modeling of Crystal Violet Dye Adsorption by a Marine Diatom, Skeletonema costatum

by Mohamed Ashour, Ahmed E. Alprol, Mohamed Khedawy, Khamael M. Abualnaja and Abdallah Tageldein Mansour

Materials 2022, 15(18), 6375; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15186375 - 14 Sep 2022

Cited by 14 | Viewed by 1671

Abstract

Significant efforts have been made to improve adsorbents capable of eliminating pollutants from aqueous solutions, making it simple and quick to separate from the treated solution. In the current study, the removal of Crystal Violet Dye (CVD) from an aqueous synthetic solution onto a marine diatom alga, Skeletonema costatum, was investigated. Different experiments were conducted as a function of different pH, contact time, adsorbent dosage, temperature, and initial CVD concentration. The highest adsorption efficiency (98%) was obtained at 0.4 g of S. costatum, pH 3, and a contact time of 120 min, at 25 °C. Furthermore, Fourier-transform infrared spectroscopy (FTIR) results display that binding of CVD on S. costatum may occur by electrostatic and complexation reactions. Moreover, the Brunauer–Emmett–Teller surface area analysis (BET) obtained was 87.17 m² g⁻¹, which, in addition to a scanning electron microscope (SEM), reveals large pores that could enhance the uptake of large molecules. However, the equilibrium adsorption models were conducted by Halsey, Langmuir, Freundlich, Henderson, and Tempkin isotherm. In addition, multilayer adsorption isotherm best described the uptake of CVD onto S. costatum. The maximum monolayer adsorption capacity (q_max) was 6.410 mg g⁻¹. Moreover, thermodynamic parameters of the adsorption studies suggested that the uptake of CVD onto S. costatum was endothermic and spontaneous. The pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetic equations were applied to model the adsorption kinetic data. It was seen that the kinetics of the adsorption may be described using pseudo-second-order kinetic equations. Finally, the present work concluded that the marine diatom alga S. costatum is suitable as a natural material for the adsorption of CVD. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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16 pages, 3608 KiB

Open AccessEditor’s ChoiceArticle

A Facile One-Pot Approach to the Fabrication of Nanocellulose–Titanium Dioxide Nanocomposites with Promising Photocatalytic and Antimicrobial Activity

by Roberta G. Toro, Abeer M. Adel, Tilde de Caro, Bruno Brunetti, Mona T. Al-Shemy and Daniela Caschera

Materials 2022, 15(16), 5789; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15165789 - 22 Aug 2022

Cited by 9 | Viewed by 1733

Abstract

The combination of cellulosic materials and metal oxide semiconductors can provide composites with superior functional properties compared to cellulose. By using nanocellulose derived from agricultural waste, we propose a one-pot and environmentally friendly approach to the synthesis of nanocellulose–TiO₂ (NC–TiO₂) nanocomposites with peculiar photocatalytic activity and antibacterial effects. The as-prepared NC–TiO₂ composites were fully characterized by different techniques, such as X-ray diffraction (XRD), μ-Raman, Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The results showed that well crystalline anatase TiO₂ nanoparticles of about 5–6 nm were obtained. The photocatalytic activity in particular was evaluated by using methyl orange (MO) solution as a target pollutant at different pH values. It was found that all the tested NC–TiO₂ nanocomposites showed stable photocatalytic activity, even after consecutive photocatalytic runs. In addition, NCT nanocomposites with higher TiO₂ content showed degradation efficiency of almost 99% towards MO after 180 min of UV illumination. Finally, NC–TiO₂ nanocomposites also showed intriguing antimicrobial properties, demonstrating to be effective against Gram-positive (Staphylococcus aureus, Bacillus subtilis) with 20–25 mm of inhibition zone and Gram-negative bacteria (Escherichia coli, Pseudomonas aeuroginosa) with 21–24 mm of inhibition zone, and fungi (Candida albicans) with 9–10 mm of inhibition zone. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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25 pages, 6638 KiB

Open AccessArticle

Green Synthesis of Zinc Oxide Nanoparticles Using Red Seaweed for the Elimination of Organic Toxic Dye from an Aqueous Solution

by Abdallah Tageldein Mansour, Ahmed E. Alprol, Mohamed Khedawy, Khamael M. Abualnaja, Tarek A. Shalaby, Gamal Rayan, Khaled M. A. Ramadan and Mohamed Ashour

Materials 2022, 15(15), 5169; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15155169 - 26 Jul 2022

Cited by 35 | Viewed by 2741

Abstract

This study aims to produce green zinc oxide nanoparticles (ZnO-NPs) derived from red seaweed (Pterocladia Capillacea) and evaluate their potential to absorb Ismate violet 2R (IV2R) ions from an aqueous solution. UV-vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and a Brunauer–Emmett–Teller surface area analysis (BET) were used to analyze the structural, morphological, and optical features of the synthesized nanoparticles. The change in color of the chemical solution revealed the formation of zinc oxide nanoparticles. The FTIR examination confirmed the synthesis of both Zn and ZnO nanoparticle powder, with a BET surface area of 113.751 m² g⁻¹ and an average pore size of 2.527 nm for the synthesized adsorbent. Furthermore, the maximum removal effectiveness of IV2R was 99% when 0.08 g ZnO-NPs was applied at a pH of 6, a temperature of 55 °C, and a contact time of 120 min. The dye adsorption capacity of the ZnO-NPs was 72.24 mg g⁻¹. The adsorption process was also controlled by the Freundlich adsorption model and pseudo-second-order reaction kinetics. The adsorption of IV2R ions onto the ZnO-NPs could be represented as a nonideal and reversible sorption process of a nonuniform surface, according to Freundlich adsorption isotherms. In addition, the constant values of the model parameters were determined using various nonlinear regression error functions. Moreover, thermodynamic parameters such as entropy change, enthalpy change, and free energy change were investigated; the adsorption process was spontaneous and endothermic. The high capacity of the ZnO-NPs synthesized by red seaweed promotes them as promising substances for applications in water treatment for the removal of IV2R dye from aqueous systems. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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19 pages, 6117 KiB

Open AccessArticle

Synthesis of Mg-Al Hydrotalcite Clay with High Adsorption Capacity

by Zhaoyi Li, Jie Zhang, Chengtun Qu, Ying Tang and Michal Slaný

Materials 2021, 14(23), 7231; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14237231 - 26 Nov 2021

Cited by 14 | Viewed by 2140

Abstract

A novel Mg-Al metal oxide has been successfully synthesized by the calcination of hierarchical porous Mg-Al hydrotalcite clay obtained by using filter paper as a template under hydrothermal conditions. Various characterizations of the obtained nanoscale oxide particles verified the uniform dispersion of Mg-Al metal oxides on the filter paper fiber, which had a size of 2–20 nm and a highest specific surface area (SSA) of 178.84 m²/g. Structural characterization revealed that the as-prepared Mg-Al metal oxides preserved the tubular morphology of the filter paper fibers. Further experiments showed that the as-synthesized Mg-Al metal oxides, present at concentrations of 0.3 g/L, could efficiently remove sulfonated lignite from oilfield wastewater (initial concentration of 200 mg/L) in a neutral environment (pH = 7) at a temperature of 298 K. An investigation of the reaction kinetics found that the adsorption process of sulfonated lignite (SL) on biomorphic Mg-Al metal oxides fits a Langmuir adsorption model and pseudo-second-order rate equation. Thermodynamic calculations propose that the adsorption of sulfonated lignite was spontaneous, endothermic, and a thermodynamically feasible process. Full article

(This article belongs to the Special Issue Nanomaterials for the Environmental Remediation of Water and Soil)

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