Editorial

3 pages, 206 KiB

Open AccessEditorial

Nanostructured Materials and Advanced Processes for Application in Water Purification

by Christos A. Aggelopoulos

Nanomaterials 2023, 13(4), 654; https://doi.org/10.3390/nano13040654 - 07 Feb 2023

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Water pollution is a major environmental problem that has a significant impact on human and animal health and the ecosystem [...] Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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21 pages, 4114 KiB

Open AccessArticle

Mechanisms of Individual and Simultaneous Adsorption of Antibiotics and Dyes onto Halloysite Nanoclay and Regeneration of Saturated Adsorbent via Cold Plasma Bubbling

by Stefania Giannoulia, Irene-Eva Triantaphyllidou, Athanasia G. Tekerlekopoulou and Christos A. Aggelopoulos

Nanomaterials 2023, 13(2), 341; https://doi.org/10.3390/nano13020341 - 13 Jan 2023

Cited by 8 | Viewed by 1879

Abstract

Halloysite nanoclay (HNC) was examined as an adsorbent for the individual and simultaneous removal of antibiotic enrofloxacin (ENRO) and methylene blue (MB) from aqueous solutions, alongside its regeneration via cold atmospheric plasma (CAP) bubbling. Initially, batch kinetics and isotherm studies were carried out, [...] Read more.

Halloysite nanoclay (HNC) was examined as an adsorbent for the individual and simultaneous removal of antibiotic enrofloxacin (ENRO) and methylene blue (MB) from aqueous solutions, alongside its regeneration via cold atmospheric plasma (CAP) bubbling. Initially, batch kinetics and isotherm studies were carried out, while the effect of several parameters was evaluated. Both ENRO and MB adsorption onto HNC was better described by Langmuir model, with its maximum adsorption capacity being 34.80 and 27.66 mg/g, respectively. A Pseudo-second order model fitted the experimental data satisfactorily, suggesting chemisorption (through electrostatic interactions) as the prevailing adsorption mechanism, whereas adsorption was also controlled by film diffusion. In the binary system, the presence of MB seemed to act antagonistically to the adsorption of ENRO. The saturated adsorbent was regenerated inside a CAP microbubble reactor and its adsorption capacity was re-tested by applying new adsorption cycles. CAP bubbling was able to efficiently regenerate saturated HNC with low energy requirements (16.67 Wh/g-adsorbent) in contrast to Fenton oxidation. Most importantly, the enhanced adsorption capacity of the CAP-regenerated HNC (compared to raw HNC), when applied in new adsorption cycles, indicated its activation during the regeneration process. The present study provides a green, sustainable and highly effective alternative for water remediation where pharmaceutical and dyes co-exist. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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14 pages, 6706 KiB

Open AccessArticle

Rapid Synthesis Method of Ag₃PO₄ as Reusable Photocatalytically Active Semiconductor

by Zsejke-Réka Tóth, Diána Debreczeni, Tamás Gyulavári, István Székely, Milica Todea, Gábor Kovács, Monica Focșan, Klara Magyari, Lucian Baia, Zsolt Pap and Klara Hernadi

Nanomaterials 2023, 13(1), 89; https://doi.org/10.3390/nano13010089 - 24 Dec 2022

Cited by 5 | Viewed by 1853

Abstract

The widespread use of Ag₃PO₄ is not surprising when considering its higher photostability compared to other silver-based materials. The present work deals with the facile precipitation method of silver phosphate. The effects of four different phosphate sources (H₃PO [...] Read more.

The widespread use of Ag₃PO₄ is not surprising when considering its higher photostability compared to other silver-based materials. The present work deals with the facile precipitation method of silver phosphate. The effects of four different phosphate sources (H₃PO₄, NaH₂PO₄, Na₂HPO₄, Na₃PO₄·12 H₂O) and two different initial concentrations (0.1 M and 0.2 M) were investigated. As the basicity of different phosphate sources influences the purity of Ag₃PO₄, different products were obtained. Using H₃PO₄ did not lead to the formation of Ag₃PO₄, while applying NaH₂PO₄ resulted in Ag₃PO₄ and a low amount of pyrophosphate. The morphological and structural properties of the obtained samples were studied by X-ray diffractometry, diffuse reflectance spectroscopy, scanning electron microscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy. The photocatalytic activity of the materials and the corresponding reaction kinetics were evaluated by the degradation of methyl orange (MO) under visible light. Their stability was investigated by reusability tests, photoluminescence measurements, and the recharacterization after degradation. The effect of as-deposited Ag nanoparticles was also highlighted on the photostability and the reusability of Ag₃PO₄. Although the deposited Ag nanoparticles suppressed the formation of holes and reduced the degradation of methyl orange, they did not reduce the performance of the photocatalyst. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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16 pages, 4171 KiB

Open AccessArticle

Synthesis of CuO/GO-DE Catalyst and Its Catalytic Properties and Mechanism on Ciprofloxacin Degradation

by Ting Zhang, Jingjing Zhang, Yinghao Yu, Jinxu Li, Zhifang Zhou and Chunlei Li

Nanomaterials 2022, 12(23), 4305; https://doi.org/10.3390/nano12234305 - 04 Dec 2022

Cited by 2 | Viewed by 1244

Abstract

A new catalyst, copper oxide/graphene oxide–diatomaceous earth (CuO/GO-DE), was prepared by the ultrasonic impregnation method. The optimal conditions for catalyst preparation were explored, and its structure and morphology were characterized by BET, XRD, SEM, TEM, FTIR, Raman and XPS. By taking ciprofloxacin as [...] Read more.

A new catalyst, copper oxide/graphene oxide–diatomaceous earth (CuO/GO-DE), was prepared by the ultrasonic impregnation method. The optimal conditions for catalyst preparation were explored, and its structure and morphology were characterized by BET, XRD, SEM, TEM, FTIR, Raman and XPS. By taking ciprofloxacin as the target pollutant, the performance and reusability of CuO/GO-DE to degrade antibiotic wastewater was evaluated, and the optimal operating conditions were obtained. The main oxidizing substances in the catalytic system under different pH conditions were analyzed, as well as the synergistic catalytic oxidation mechanism. The intermediate products of ciprofloxacin degradation were identified by LC-MS, and the possible degradation process of ciprofloxacin was proposed. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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17 pages, 3866 KiB

Open AccessArticle

Development of Efficient and Recyclable ZnO–CuO/g–C₃N₄ Nanocomposite for Enhanced Adsorption of Arsenic from Wastewater

by Qudrat Ullah Khan, Nabila Begum, Zia Ur Rehman, Afaq Ullah Khan, Kamran Tahir, El Sayed M. Tag El Din, Asma A. Alothman, Mohamed A. Habila, Dahai Liu, Patrizia Bocchetta and Muhammad Sufyan Javed

Nanomaterials 2022, 12(22), 3984; https://doi.org/10.3390/nano12223984 - 12 Nov 2022

Cited by 4 | Viewed by 1420

Abstract

Arsenic (III) is a toxic contaminant in water bodies, especially in drinking water reservoirs, and it is a great challenge to remove it from wastewater. For the successful extraction of arsenic (III), a nanocomposite material (ZnO–CuO/g–C₃N₄) has been synthesized [...] Read more.

Arsenic (III) is a toxic contaminant in water bodies, especially in drinking water reservoirs, and it is a great challenge to remove it from wastewater. For the successful extraction of arsenic (III), a nanocomposite material (ZnO–CuO/g–C₃N₄) has been synthesized by using the solution method. The large surface area and plenty of hydroxyl groups on the nanocomposite surface offer an ideal platform for the adsorption of arsenic (III) from water. Specifically, the reduction process involves a transformation from arsenic (III) to arsenic (V), which is favorable for the attachment to the –OH group. The modified surface and purity of the nanocomposite were characterized by SEM, EDX, XRD, FT–IR, HRTEM, and BET models. Furthermore, the impact of various aspects (temperatures, pH of the medium, the concentration of adsorbing materials) on adsorption capacity has been studied. The prepared sample displays the maximum adsorption capacity of arsenic (III) to be 98% at pH ~ 3 of the medium. Notably, the adsorption mechanism of arsenic species on the surface of ZnO–CuO/g–C₃N₄ nanocomposite at different pH values was explained by surface complexation and structural variations. Moreover, the recycling experiment and reusability of the adsorbent indicate that a synthesized nanocomposite has much better adsorption efficiency than other adsorbents. It is concluded that the ZnO–CuO/g–C₃N₄ nanocomposite can be a potential candidate for the enhanced removal of arsenic from water reservoirs. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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26 pages, 26945 KiB

Open AccessArticle

Preparation and Characterization of an Electrospun Whey Protein/Polycaprolactone Nanofiber Membrane for Chromium Removal from Water

by Laura Cristina Ramírez-Rodríguez, María Ximena Quintanilla-Carvajal, Didilia Ileana Mendoza-Castillo, Adrián Bonilla-Petriciolet and Carlos Jiménez-Junca

Nanomaterials 2022, 12(16), 2744; https://doi.org/10.3390/nano12162744 - 10 Aug 2022

Cited by 7 | Viewed by 1814

Abstract

Chromium pollution represents a worldwide concern due to its high toxicity and bioaccumulation in organisms and ecosystems. An interesting material to remove metal ions from water is a whey-protein-based material elaborated by electrospinning, which is an emerging method to produce adsorbent membranes with [...] Read more.

Chromium pollution represents a worldwide concern due to its high toxicity and bioaccumulation in organisms and ecosystems. An interesting material to remove metal ions from water is a whey-protein-based material elaborated by electrospinning, which is an emerging method to produce adsorbent membranes with diverse applications. The aim of this study was to prepare an adsorbent membrane of whey protein isolate (WPI) and polycaprolactone (PCL) by electrospinning to remove chromium ions from water. The adsorbent membrane was synthesized by a central composed design denaturing WPI using 2-Mercaptoethanol and mixing it with PCL to produce electrospun nanofibers. The adsorbent membrane was characterized by denaturation, Scanning Electron Microscope, Fourier-Transform Infrared Spectroscopy, Contact Angle, Thermogravimetric Analysis, and X-ray Photoelectron Spectrometry. The adsorption properties of this membrane were assessed in the removal of chromium. The removal performance of the membrane was enhanced by an increase in temperature showing an endothermic adsorption process. The adsorption process of chromium ions onto the nanofiber membrane followed the Sips adsorption isotherm, while the adsorption kinetics followed a pseudo-second kinetics where the maximum adsorption capacity was 31.0 mg/g at 30 °C and pH 2. This work provides a novel method to fabricate a hybrid membrane with amyloid-type fibrils of WPI and PCL, which is a promising adsorbent to remove heavy metal ions from water. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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15 pages, 5372 KiB

Open AccessArticle

Nanostructured Metal Oxide Sensors for Antibiotic Monitoring in Mineral and River Water

by Cátia Magro, Tiago Moura, Joana Dionísio, Paulo A. Ribeiro, Maria Raposo and Susana Sério

Nanomaterials 2022, 12(11), 1858; https://doi.org/10.3390/nano12111858 - 29 May 2022

Cited by 6 | Viewed by 1526

Abstract

Antibiotics represent a class of pharmaceuticals used to treat bacterial infections. However, the ever-growing use of antibiotics in agriculture and human and veterinary medicine has led to great concern regarding the outbreak of microbe strains resistant to antimicrobial drugs. Azithromycin, clarithromycin, and erythromycin [...] Read more.

Antibiotics represent a class of pharmaceuticals used to treat bacterial infections. However, the ever-growing use of antibiotics in agriculture and human and veterinary medicine has led to great concern regarding the outbreak of microbe strains resistant to antimicrobial drugs. Azithromycin, clarithromycin, and erythromycin are macrolides, a group of molecules with a broad spectrum of antibiotic properties, included in the second EU watchlist of emerging pollutants which emphasizes the importance of understanding their occurrence, fate, and monitoring in aquatic environments. Thus, the aim of this study was to develop sensors based on nanostructured thin films deposited on ceramic substrates with gold interdigitated electrodes, to detect azithromycin, clarithromycin, and erythromycin in water matrices (mineral and river water). Impedance spectroscopy was employed as the transducing method for the devices’ electrical signal, producing multivariate datasets which were subsequently analyzed by principal component analysis (PCA). The PCA plots for mineral water demonstrated that ZnO- and TiO₂-based sensors produced by DC magnetron sputtering either with 50% or 100% O₂ in the sputtering chamber, were able to detect the three macrolides in concentrations between 10⁻¹⁵ M and 10⁻⁵ M. In river water, the PCA discrimination presented patterns and trends, between non-doped and doped, and sorting the different concentrations of azithromycin, clarithromycin, and erythromycin. Considering both matrices, by applying the e-tongue concept, sensitivity values of 4.8 ± 0.3, 4.6 ± 0.3, and 4.5 ± 0.3 per decade to azithromycin, clarithromycin, and erythromycin concentration, respectively, were achieved. In all cases, a resolution of 1 × 10⁻¹⁶ M was found near the 10⁻¹⁵ M concentration, the lowest antibiotic concentration measured. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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18 pages, 4656 KiB

Open AccessArticle

Synthesis and Characterization of Ag/ZnO Nanoparticles for Bacteria Disinfection in Water

by Julia de O. Primo, Dienifer F. Horsth, Jamille de S. Correa, Arkaprava Das, Carla Bittencourt, Polona Umek, Ana Guilherme Buzanich, Martin Radtke, Kirill V. Yusenko, Cristina Zanette and Fauze J. Anaissi

Nanomaterials 2022, 12(10), 1764; https://doi.org/10.3390/nano12101764 - 22 May 2022

Cited by 19 | Viewed by 2853

Abstract

In this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial [...] Read more.

In this study, two green synthesis routes were used for the synthesis of Ag/ZnO nanoparticles, using cassava starch as a simple and low-cost effective fuel and Aloe vera as a reducing and stabilizing agent. The Ag/ZnO nanoparticles were characterized and used for bacterial disinfection of lake water contaminated with Escherichia coli (E. coli). Characterization indicated the formation of a face-centered cubic structure of metallic silver nanoparticles with no insertion of Ag into the ZnO hexagonal wurtzite structure. Physicochemical and bacteriological analyses described in “Standard Methods for the Examination of Water and Wastewater” were used to evaluate the efficiency of the treatment. In comparison to pure ZnO, the synthesized Ag/ZnO nanoparticles showed high efficiencies against Escherichia coli (E. coli) and general coliforms present in the lake water. These pathogens were absent after treatment using Ag/ZnO nanoparticles. The results indicate that Ag/ZnO nanoparticles synthesized via green chemistry are a promising candidate for the treatment of wastewaters contaminated by bacteria, due to their facile preparation, low-cost synthesis, and disinfection efficiency. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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19 pages, 3973 KiB

Open AccessArticle

Treatment of Wastewater, Phenols and Dyes Using Novel Magnetic Torus Microreactors and Laccase Immobilized on Magnetite Nanoparticles

by Paula Andrea Peñaranda, Mabel Juliana Noguera, Sergio Leonardo Florez, Johana Husserl, Nancy Ornelas-Soto, Juan C. Cruz and Johann F. Osma

Nanomaterials 2022, 12(10), 1688; https://doi.org/10.3390/nano12101688 - 15 May 2022

Cited by 9 | Viewed by 2685

Abstract

In this work, the design, manufacture, and testing of three different magnetic microreactors based on torus geometries (i.e., one-loop, two-horizontal-loop, and two-vertical-loop) is explored to increase the enzyme-based transformation of dyes by laccase bio-nanocomposites, improve the particle suspension, and promote the interaction of [...] Read more.

In this work, the design, manufacture, and testing of three different magnetic microreactors based on torus geometries (i.e., one-loop, two-horizontal-loop, and two-vertical-loop) is explored to increase the enzyme-based transformation of dyes by laccase bio-nanocomposites, improve the particle suspension, and promote the interaction of reagents. The laccase enzyme was covalently immobilized on amino-terminated silanized magnetite nanoparticles (laccase-magnetite). The optimal configuration for the torus microreactor and the applied magnetic field was evaluated in silico with the aid of the CFD and particle tracing modules of Comsol Multiphysics^®. Eriochrome Black T (EBt) dye was tested as a biotransformation model at three different concentrations, i.e., 5 mg/L, 10 mg/L, and 20 mg/L. Phenol oxidation/removal was evaluated on artificial wastewater and real wastewater. The optimal catalytic performance of the bionanocomposite was achieved in the range of pH 4 to 4.5. A parabolic movement on the particles along the microchannels was induced by the magnetic field, which led to breaking the stability of the laminar flow and improving the mixing processes. Based on the simulation and experiments conducted with the three geometries, the two-vertical-loop microreactor demonstrated a better performance mainly due to larger dead zones and a longer residence time. Additionally, the overall dye removal efficiencies for this microreactor and the laccase-magnetite bionanocomposite were 98.05%, 93.87%, and 92.74% for the three evaluated concentrations. The maximum phenol oxidation with the laccase-magnetite treatment at low concentration for the artificial wastewater was 79.89%, while its phenol removal efficiency for a large volume of real wastewater was 17.86%. Treatments with real wastewater were carried out with a larger volume, equivalent to 200 biotransformation (oxidation) operating cycles of those carried out with dyes or phenol. Taken together, our results indicate that the novel microreactors introduced here have the potential to process wastewaters rich in contaminant dyes in continuous mode with efficiencies that are attractive for a potential large-scale operation. In this regard, future work will focus on finding the requirements for scaling-up the processes and evaluating the involved environmental impact indexes, economic performance, and different device geometries and processing schemes. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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21 pages, 7543 KiB

Open AccessArticle

Sustainable Synthesis of Cadmium Sulfide, with Applicability in Photocatalysis, Hydrogen Production, and as an Antibacterial Agent, Using Two Mechanochemical Protocols

by Zhandos Shalabayev, Matej Baláž, Natalya Khan, Yelmira Nurlan, Adrian Augustyniak, Nina Daneu, Batukhan Tatykayev, Erika Dutková, Gairat Burashev, Mariano Casas-Luna, Róbert Džunda, Radovan Bureš, Ladislav Čelko, Aleksandr Ilin and Mukhambetkali Burkitbayev

Nanomaterials 2022, 12(8), 1250; https://doi.org/10.3390/nano12081250 - 07 Apr 2022

Cited by 13 | Viewed by 2794

Abstract

CdS nanoparticles were successfully synthesized using cadmium acetate and sodium sulfide as Cd and S precursors, respectively. The effect of using sodium thiosulfate as an additional sulfur precursor was also investigated (combined milling). The samples were characterized by XRD, Raman spectroscopy, XPS, UV-Vis [...] Read more.

CdS nanoparticles were successfully synthesized using cadmium acetate and sodium sulfide as Cd and S precursors, respectively. The effect of using sodium thiosulfate as an additional sulfur precursor was also investigated (combined milling). The samples were characterized by XRD, Raman spectroscopy, XPS, UV-Vis spectroscopy, PL spectroscopy, DLS, and TEM. Photocatalytic activities of both CdS samples were compared. The photocatalytic activity of CdS, which is produced by combined milling, was superior to that of CdS, and was obtained by an acetate route in the degradation of Orange II under visible light irradiation. Better results for CdS prepared using a combined approach were also evidenced in photocatalytic experiments on hydrogen generation. The antibacterial potential of mechanochemically prepared CdS nanocrystals was also tested on reference strains of E. coli and S. aureus. Susceptibility tests included a 24-h toxicity test, a disk diffusion assay, and respiration monitoring. Bacterial growth was not completely inhibited by the presence of neither nanomaterial in the growth environment. However, the experiments have confirmed that the nanoparticles have some capability to inhibit bacterial growth during the logarithmic growth phase, with a more substantial effect coming from CdS nanoparticles prepared in the absence of sodium thiosulfate. The present research demonstrated the solvent-free, facile, and sustainable character of mechanochemical synthesis to produce semiconductor nanocrystals with multidisciplinary application. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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18 pages, 4147 KiB

Open AccessArticle

Preparation of Amino-Functionalized Mesoporous SBA-15 Nanoparticles and the Improved Adsorption of Tannic Acid in Wastewater

by Tzong-Horng Liou, Guan-Wei Chen and Shang Yang

Nanomaterials 2022, 12(5), 791; https://doi.org/10.3390/nano12050791 - 26 Feb 2022

Cited by 12 | Viewed by 3283

Abstract

Ordered mesoporous Santa Barbara amorphous (SBA-15) materials have high surface areas and are widely used in adsorption, separation, filtration, and heterogeneous catalytic processes. However, SBA-15 surfaces contain hydroxyl groups that are unsuited to the adsorption of organic pollutants; thus, SBA-15 must be chemically [...] Read more.

Ordered mesoporous Santa Barbara amorphous (SBA-15) materials have high surface areas and are widely used in adsorption, separation, filtration, and heterogeneous catalytic processes. However, SBA-15 surfaces contain hydroxyl groups that are unsuited to the adsorption of organic pollutants; thus, SBA-15 must be chemically modified to promote its adsorption activity. In this study, amino-functionalized nanoporous SBA-15 was fabricated by employing sodium silicate as a precursor. The structural characteristics of the prepared composites were examined using thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, field-emission scanning electron microscopy, transmission electron microscopy, and surface area analysis. The prepared SBA-15 had a large pore size (6.46–7.60 nm), large pore volume (1.037–1.105 cm³/g), and high surface area (546–766 m²/g). Functionalization caused a reduction in the SBA-15 pore volume and surface area, whereas amino groups that promoted an interaction between adsorbates and solids facilitated solute adsorption. The adsorption of tannic acid (TA) onto amino-modified silica composites (SBA-15 and 3-aminopropyltriethoxysilane (SBA-15/APTES) and SBA-15 and pentaethylenehexamine (SBA-15/PEHA)) was studied. Their adsorption capacities were affected by solution temperature, solution pH, agitation speed, adsorbent dosage, and initial TA concentration. The maximum adsorption capacities for SBA-15/APTES and SBA-15/PEHA were 485.18 and 413.33 mg/g, respectively, with SBA-15/APTES exhibiting ultrafast removal of TA (98.61% removal rate at 15 min). In addition, this study explored the thermodynamics, adsorption isotherms, and kinetics. A comparison of two types of amino-functionalized SBA-15 was used for the first time to adsorb TA, which providing valuable information on TA adsorption on high adsorption capacity materials in water media. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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16 pages, 3223 KiB

Open AccessArticle

Adsorptive Removal of Azithromycin Antibiotic from Aqueous Solution by Azolla Filiculoides-Based Activated Porous Carbon

by Davoud Balarak, Amir Hossein Mahvi, Saeideh Shahbaksh, Md A. Wahab and Ahmed Abdala

Nanomaterials 2021, 11(12), 3281; https://doi.org/10.3390/nano11123281 - 03 Dec 2021

Cited by 37 | Viewed by 2888

Abstract

Due to the shortage of freshwater availability, reclaimed water has become an important source of irrigation water. Nevertheless, emergent contaminants such as antibiotics in reclaimed water can cause potential health risks because antibiotics are nonbiodegradable. In this paper, we report the adsorptive removal [...] Read more.

Due to the shortage of freshwater availability, reclaimed water has become an important source of irrigation water. Nevertheless, emergent contaminants such as antibiotics in reclaimed water can cause potential health risks because antibiotics are nonbiodegradable. In this paper, we report the adsorptive removal of azithromycin (AZM) antibiotics using activated porous carbon prepared from Azolla filiculoides (AF) (AFAC). The influence of the adsorption process variables, such as temperature, pH, time, and adsorbent dosage, is investigated and described. The prepared AFAC is very effective in removing AZM with 87% and 98% removal after the treatment of 75 min, at 303 and 333 K, respectively. The Langmuir, Temkin, Freundlich, and Dubinin–Radushkevich isotherm models were used to analyze the adsorption results. The Freundlich isotherm was best to describe the adsorption isotherm. The adsorption process follows second-order pseudo kinetics. The adsorption was endothermic (ΔH°= 32.25 kJ/mol) and spontaneous (ΔS° = 0.128 kJ/mol·K). Increasing the temperature from 273 to 333 K makes the process more spontaneous (ΔG° = −2.38 and −8.72 KJ/mol). The lower mean square energy of 0.07 to 0.845 kJ/mol confirms the process’ physical nature. The results indicate that AFAC can be a potential low-cost adsorbent of AZM from aqueous solutions. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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15 pages, 3145 KiB

Open AccessArticle

Synergetic Effect of Organic Flocculant and Montmorillonite Clay on the Removal of Nano-CuO by Coagulation-Flocculation-Sedimentation Process

by Rizwan Khan, Muhammad Ali Inam, Kang-Hoon Lee, Abdul Sami Channa, Mukhtiar Ali Mallah, Young-Min Wie and Mahmood Nabi Abbasi

Nanomaterials 2021, 11(10), 2753; https://doi.org/10.3390/nano11102753 - 17 Oct 2021

Cited by 3 | Viewed by 2112

Abstract

The widespread usage of nano-copper oxide particles (nano-CuO) in several industrial products and applications raises concerns about their release into water bodies. Thus, their elimination from drinking water is essential to reduce the risk to human health. This work investigated the removal of [...] Read more.

The widespread usage of nano-copper oxide particles (nano-CuO) in several industrial products and applications raises concerns about their release into water bodies. Thus, their elimination from drinking water is essential to reduce the risk to human health. This work investigated the removal of nano-CuO from pure water and montmorillonite clay (MC) suspensions using poly aluminum ferric chloride (PAFC) as well as cationic polyacrylamide (PAM) by the coagulation-flocculation-sedimentation (C/F/S) process. Moreover, the PAFC and PAFC/PAM flocculation performance for various nano-CuO particles concentrations, dosages, pH, settling times and stirring speeds were also investigated. The findings showed that the removal of nano-CuO and turbidity in MC suspension were higher as compared to pure water. Moreover, the combined effect of PAFC/PAM on the elimination of nano-CuO and turbidity was also substantially better than the individual use of PAFC or PAM. The efficient removal of CuO was observed in the solution containing higher mass concentration in the order (10 mg/L > 2.5 mg/L > 1 mg/L) with an increased coagulant dose. The improved removal performance of nano-CuO was observed in a pH range of 7–11 under various water matrices. The C/F/S conditions of nano-CuO were further optimized by the Box–Behnken statistical experiment design and response surface methodology. The PAFC/PAM dose resulted in the maximum removal of nano-CuO (10 mg/L) in both pure water (>97%) and MC suspension (>99%). The results of particle monitoring and Fourier transform infrared of composite flocs revealed that the main removal mechanism of nano-CuO may be the combined effect of neutralization, complexation as well as adsorption. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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13 pages, 2423 KiB

Open AccessArticle

Efficiency of Wood-Dust of Dalbergia sisoo as Low-Cost Adsorbent for Rhodamine-B Dye Removal

by Dibyashree Shrestha

Nanomaterials 2021, 11(9), 2217; https://doi.org/10.3390/nano11092217 - 28 Aug 2021

Cited by 18 | Viewed by 2032

Abstract

Wood-dust of Dalbergia sisoo (Sisau) derived activated carbon (AC) was successfully tested as an adsorbent material for the removal of rhodamine B dye from an aqueous solution. The AC was prepared in a laboratory by the carbonization of wood powder of Dalbergia sisoo [...] Read more.

Wood-dust of Dalbergia sisoo (Sisau) derived activated carbon (AC) was successfully tested as an adsorbent material for the removal of rhodamine B dye from an aqueous solution. The AC was prepared in a laboratory by the carbonization of wood powder of Dalbergia sisoo at 400 °C in an inert atmosphere of N₂, which was chemically activated with H₃PO₄. Several instrumental techniques have been employed to characterize the as-prepared AC (Db-s). Thermogravimetric analysis (TGA)/differential scanning colorimetry (DSC) confirmed that 400 °C was an appropriate temperature for the carbonization of raw wood powder. The FTIR spectra clearly confirmed the presence of oxygenated functional groups such as hydroxyl (–OH), aldehyde/ketone (–CHO/C=O) and ether (C–O–C) at its surface. The XRD pattern showed the amorphous structure of carbon having the 002 and 100 planes, whereas the Raman spectra clearly displayed G and D bands that further confirmed the amorphous nature of carbon. The SEM images displayed the high porosity, and the BET analysis revealed a high surface area of 1376 m² g⁻¹, a pore volume of 1.2 cm³ g⁻¹, and a pore size of 4.06 nm with the coexistence of micropores and mesopores. The adsorption of dyes was performed by varying the dye concentration, pH, time, and the sample dose. The maximum percent of RhB dye removal by AC (Db-s) was 98.4% at an aqueous solution of 20 ppm, pH 8.5, an adsorbent dose of 0.03 g, and a time of 5 min. This study proved to be successful in addressing the local problem of wastewater pollution of garment and textile industrial effluents using locally available agro-waste of Dalbergia sisoo. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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17 pages, 6221 KiB

Open AccessArticle

Cinnamomum tamala Leaf Extract Stabilized Zinc Oxide Nanoparticles: A Promising Photocatalyst for Methylene Blue Degradation

by Sajina Narath, Supin Karonnan Koroth, Sarojini Sharath Shankar, Bini George, Vasundhara Mutta, Stanisław Wacławek, Miroslav Černík, Vinod Vellora Thekkae Padil and Rajender S. Varma

Nanomaterials 2021, 11(6), 1558; https://doi.org/10.3390/nano11061558 - 13 Jun 2021

Cited by 40 | Viewed by 4398

Abstract

A facile green synthetic method is proposed for the synthesis of zinc oxide nanoparticles (ZnO NPs) using the bio-template Cinnamomum tamala (C. tamala) leaves extract. The morphological, functional, and structural characterization of synthesized ZnO NPs were studied by adopting different techniques [...] Read more.

A facile green synthetic method is proposed for the synthesis of zinc oxide nanoparticles (ZnO NPs) using the bio-template Cinnamomum tamala (C. tamala) leaves extract. The morphological, functional, and structural characterization of synthesized ZnO NPs were studied by adopting different techniques such as energy dispersive X-ray analysis (EDX), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Visible spectroscopy, fourier transform infrared (FTIR) spectroscopy, raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The fabricated ZnO NPs exhibit an average size of 35 nm, with a hexagonal nanostructure. Further, the well-characterized ZnO NPs were employed for the photocatalytic degradation of methylene blue (MB) in an aqueous solution. The photocatalytic activity was analyzed by changing the various physicochemical factors such as reaction time, amount of photocatalyst, precursor concentration, and calcination temperature of the ZnO NPs. All the studies suggest that the ZnO synthesized through the green protocol exhibits excellent photocatalytic potency against the dye molecules. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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12 pages, 3681 KiB

Open AccessCommunication

Removal of Radioactive Iodine Using Silver/Iron Oxide Composite Nanoadsorbents

by Mah Rukh Zia, Muhammad Asim Raza, Sang Hyun Park, Naseem Irfan, Rizwan Ahmed, Jung Eun Park, Jongho Jeon and Sajid Mushtaq

Nanomaterials 2021, 11(3), 588; https://doi.org/10.3390/nano11030588 - 26 Feb 2021

Cited by 19 | Viewed by 2903

Abstract

Efficient and cost-effective removal of radioactive iodine (radioiodine) from radioactive contaminated water has become a crucial task, following nuclear power plant disasters. Several materials for removing radioiodine have been reported in the literature. However, most of these materials exhibit some limitations, such as [...] Read more.

Efficient and cost-effective removal of radioactive iodine (radioiodine) from radioactive contaminated water has become a crucial task, following nuclear power plant disasters. Several materials for removing radioiodine have been reported in the literature. However, most of these materials exhibit some limitations, such as high production cost, slow adsorption kinetics, and poor adsorption capacity. Herein, we present silver/iron oxide nanocomposites (Ag/Fe₃O₄) for the efficient and specific removal of iodine anions from contaminated water. The Ag/Fe₃O₄ were synthesized using a modified method and characterized via scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analyses. This adsorbent showed a high adsorption capacity for iodine anions (847 mg/g of the adsorbent) in pure water. Next, Ag/Fe₃O₄ was applied to the removal of radioiodine, and high removal efficiencies were observed in water. In addition, its desalination capacity was retained in the presence of competitive ions and varied pH. After the adsorption process, Ag/Fe₃O₄ was easily removed from the water by applying an external magnetic field. Moreover, the same operation can be repeated several times without a significant decrease in the performance of Ag/Fe₃O₄. Therefore, it is expected that the findings presented in this study will offer a new method for desalinating radioiodine in various aqueous media. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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20 pages, 6033 KiB

Open AccessArticle

Fe₃O₄@C Nanoparticles Synthesized by In Situ Solid-Phase Method for Removal of Methylene Blue

by Hengli Xiang, Genkuan Ren, Yanjun Zhong, Dehua Xu, Zhiye Zhang, Xinlong Wang and Xiushan Yang

Nanomaterials 2021, 11(2), 330; https://doi.org/10.3390/nano11020330 - 27 Jan 2021

Cited by 29 | Viewed by 3528

Abstract

Fe₃O₄@C nanoparticles were prepared by an in situ, solid-phase reaction, without any precursor, using FeSO₄, FeS₂, and PVP K30 as raw materials. The nanoparticles were utilized to decolorize high concentrations methylene blue (MB). The results [...] Read more.

Fe₃O₄@C nanoparticles were prepared by an in situ, solid-phase reaction, without any precursor, using FeSO₄, FeS₂, and PVP K30 as raw materials. The nanoparticles were utilized to decolorize high concentrations methylene blue (MB). The results indicated that the maximum adsorption capacity of the Fe3O4@C nanoparticles was 18.52 mg/g, and that the adsorption process was exothermic. Additionally, by employing H₂O₂ as the initiator of a Fenton-like reaction, the removal efficiency of 100 mg/L MB reached ~99% with Fe₃O₄@C nanoparticles, while that of MB was only ~34% using pure Fe₃O₄ nanoparticles. The mechanism of H₂O₂ activated on the Fe₃O₄@C nanoparticles and the possible degradation pathways of MB are discussed. The Fe₃O₄@C nanoparticles retained high catalytic activity after five usage cycles. This work describes a facile method for producing Fe₃O₄@C nanoparticles with excellent catalytic reactivity, and therefore, represents a promising approach for the industrial production of Fe₃O₄@C nanoparticles for the treatment of high concentrations of dyes in wastewater. Full article

(This article belongs to the Special Issue Nanostructured Materials and Advanced Processes for Application in Water Purification)

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