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19 pages, 5266 KiB

Open AccessArticle

Sulfonated Pentablock Copolymer Membranes and Graphene Oxide Addition for Efficient Removal of Metal Ions from Water

by Simona Filice, Marta Mazurkiewicz-Pawlicka, Artur Malolepszy, Leszek Stobinski, Ryszard Kwiatkowski, Anna Boczkowska, Leon Gradon and Silvia Scalese

Nanomaterials 2020, 10(6), 1157; https://doi.org/10.3390/nano10061157 - 12 Jun 2020

Cited by 18 | Viewed by 3157

Abstract

Nowadays heavy metals are among the higher environmental priority pollutants, therefore, the identification of new, effective, reusable and easy-to-handle adsorbent materials able to remove metal ions from water is highly desired. To this aim, in this work for the first time, sulfonated pentablock [...] Read more.

Nowadays heavy metals are among the higher environmental priority pollutants, therefore, the identification of new, effective, reusable and easy-to-handle adsorbent materials able to remove metal ions from water is highly desired. To this aim, in this work for the first time, sulfonated pentablock copolymer (s-PBC, Nexar™) membranes and s-PBC/graphene oxide (GO) nanocomposite membranes were investigated for the removal of heavy metals from water. Membranes were prepared by drop casting and their chemical, structural and morphological properties were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, dynamic mechanical analysis (DMA) and small-angle X-ray scattering (SAXS). The adsorption abilities and adsorption kinetics of both the polymer and the s-PBC/GO nanocomposite were investigated for the removal of different heavy metal ions (Ni²⁺, Co²⁺, Cr³⁺ and Pb²⁺) from aqueous solutions containing the corresponding metal salts at different concentrations. The investigated s-PBC membrane shows a good efficiency, due to the presence of sulfonic groups that play a fundamental role in the adsorption process of metal ions. Its performance is further enhanced by embedding a very low amount of GO in the polymer allowing an increase by at least three times of the adsorption efficiencies of the polymer itself. This can be ascribed to the higher porosity, higher roughness and higher lamellar distances introduced by GO in the s-PBC membrane, as evidenced by the SEM and SAXS analysis. Both the polymeric materials showed the best performance in removing Pb²⁺ ions. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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14 pages, 3798 KiB

Open AccessArticle

Carbon Nanomaterials for Sorption of ⁶⁸Ga for Potential Using in Positron Emission Tomography

by Andrey G. Kazakov, Bogdan L. Garashchenko, Milana K. Ivanova, Sergey E. Vinokurov and Boris F. Myasoedov

Nanomaterials 2020, 10(6), 1090; https://doi.org/10.3390/nano10061090 - 1 Jun 2020

Cited by 9 | Viewed by 2453

Abstract

In present work, carbon nanomaterials (CNMs) are investigated as potential carriers of ⁶⁸Ga, which is widely used in positron emission tomography (PET) in nuclear medicine. Sorption behavior of ⁶⁸Ga was studied onto CNMs of various structures and chemical compositions: nanodiamonds (ND), [...] Read more.

In present work, carbon nanomaterials (CNMs) are investigated as potential carriers of ⁶⁸Ga, which is widely used in positron emission tomography (PET) in nuclear medicine. Sorption behavior of ⁶⁸Ga was studied onto CNMs of various structures and chemical compositions: nanodiamonds (ND), reduced graphite oxide (rGiO) and multi-walled carbon nanotubes (MWCNT), as well as their oxidized (ND–COOH) or reduced (rGiO–H, MWCNT–H) forms. The physicochemical properties of the nanoparticles were determined by high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, dynamic light scattering and potentiometric titration. The content of ⁶⁸Ga in the solutions during the study of sorption was determined by gamma-ray spectrometry. The highest degree of ⁶⁸Ga sorption was observed on ND and ND–COOH samples, and the optimal sorption conditions were determined: an aqueous solution with a pH of 5–7, m/V ratio of 50 μg/mL and a room temperature (25 °C). The ⁶⁸Ga@ND and ⁶⁸Ga@ND–COOH conjugates were found to be stable in a model blood solution—phosphate-buffered saline with a pH of 7.3, containing 40 g/L of bovine serum albumin: ⁶⁸Ga desorption from these samples in 90 minutes was no more than 20% at 25 °C and up to 30% at 37 °C. Such a quantity of desorbed ⁶⁸Ga does not harm the body and does not interfere with the PET imaging process. Thus, ND and ND–COOH are promising CNMs for using as carriers of ⁶⁸Ga for PET diagnostics. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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13 pages, 3630 KiB

Open AccessArticle

Towards Microorganism-Based Biofuel Cells: The Viability of Saccharomyces cerevisiae Modified by Multiwalled Carbon Nanotubes

by Ingrida Bruzaite, Juste Rozene, Inga Morkvenaite-Vilkonciene and Arunas Ramanavicius

Nanomaterials 2020, 10(5), 954; https://doi.org/10.3390/nano10050954 - 17 May 2020

Cited by 25 | Viewed by 3478

Abstract

This research aimed to evaluate the toxic effect of multi-walled carbon nanotubes (MW-CNTs) on yeast cells in order to apply MW-CNTs for possible improvement of the efficiency of microbial biofuel cells. The SEM and XRD analysis suggested that here used MW-CNTs are in [...] Read more.

This research aimed to evaluate the toxic effect of multi-walled carbon nanotubes (MW-CNTs) on yeast cells in order to apply MW-CNTs for possible improvement of the efficiency of microbial biofuel cells. The SEM and XRD analysis suggested that here used MW-CNTs are in the range of 10–25 nm in diameter and their structure was confirmed by Raman spectroscopy. In this study, we evaluated the viability of the yeast Saccharomyces cerevisiae cells, affected by MW-CNTs, by cell count, culture optical density and atomic force microscopy. The yeast cells were exposed towards MW-CNTs (of 2, 50, 100 μg/mL concentrations in water-based solution) for 24 h. A mathematical model was applied for the evaluation of relative growth and relative death rates of yeast cells. We calculated that both of the rates are two times higher in the case if yeasts were treated by 50, 100 μg/mL of MW-CNTs containing solution, comparing to that treated by 0 and 2 μg/mL c of MW-CNTs containing solution. It was determined that the MW-CNTs have some observable effect upon the incubation of the yeast cells. The viability of yeast has decreased together with MW-CNTs concentration only after 5 h of the treatment. Therefore, we predict that the MW-CNTs can be applied for the modification of yeast cells in order to improve electrical charge transfer through the yeast cell membrane and/or the cell wall. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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19 pages, 3339 KiB

Open AccessArticle

Eco-Friendly Sustainable Fluorescent Carbon Dots for the Adsorption of Heavy Metal Ions in Aqueous Environment

by Musa Yahaya Pudza, Zurina Zainal Abidin, Suraya Abdul Rashid, Faizah Md Yasin, A. S. M. Noor and Mohammed A. Issa

Nanomaterials 2020, 10(2), 315; https://doi.org/10.3390/nano10020315 - 12 Feb 2020

Cited by 120 | Viewed by 9596

Abstract

The materials and substances required for sustainable water treatment by adsorption technique, are still being researched widely by distinguished classes of researchers. Thus, the need to synthesize substances that can effectively clean up pollutants from the environment cannot be overemphasized. So far, materials [...] Read more.

The materials and substances required for sustainable water treatment by adsorption technique, are still being researched widely by distinguished classes of researchers. Thus, the need to synthesize substances that can effectively clean up pollutants from the environment cannot be overemphasized. So far, materials in bulk forms that are rich in carbon, such as biochar and varieties of activated carbon have been used for various adsorptive purposes. The use of bulk materials for such purposes are not efficient due to minimal surface areas available for adsorption. This study explores the adsorption task at nano dimension using carbon dots (CDs) from tapioca. The properties of carbon structure and its influence on the adsorptive efficacy of carbon nanoparticles were investigated by energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HrTEM), and atomic force microscopy (AFM). The results implied carbon present in CDs are good adsorbents for effective adsorption of heavy metal ions (lead) with removal efficiency of 80.6% in aqueous environment. The adsorption process as explored by both Langmuir and Freundlich isotherms have proven favorability of the adsorption process. Langmuir form two and three have correlation coefficients R² at 0.9922 and 0.9912, respectively. The Freundlich isotherm confirms CDs as having defined surface heterogeneity and the exponential distribution of active sites. The adsorption of lead unto CDs obeyed the second order kinetic model with coefficient of determination, R² of 0.9668 and 0.9996 at an initial lead concentration of 20 mg/L and 100 mg/L, respectively. The findings validated the efficiency of CDs derived from tapioca as an excellent material for further utilization in the environmental fields of wastewater pollution detection and clean up, bio-imaging, and chemical sensing applications. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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13 pages, 2895 KiB

Open AccessArticle

Graphene Oxide with Controlled Content of Oxygen Groups as a Filler for Polymer Composites Used for Infrared Radiation Shielding

by Marta Mazurkiewicz-Pawlicka, Maksymilian Nowak, Artur Malolepszy, Andrzej Witowski, Dariusz Wasik, Yi Hu and Leszek Stobinski

Nanomaterials 2020, 10(1), 32; https://doi.org/10.3390/nano10010032 - 21 Dec 2019

Cited by 38 | Viewed by 4681

Abstract

Infrared (IR) shielding materials are commonly used for different applications, such as smart windows or optical filters. Infrared radiation is responsible for about 50% of the energy coming from the sun. During a hot summer or cold winter a lot of energy is [...] Read more.

Infrared (IR) shielding materials are commonly used for different applications, such as smart windows or optical filters. Infrared radiation is responsible for about 50% of the energy coming from the sun. During a hot summer or cold winter a lot of energy is needed to keep the optimal temperature inside buildings and means of transport. To reduce the heat transmission and save energy IR shielding materials can be used as coatings made of polymer composites. Graphene oxide (GO) and its reduced forms have interesting IR absorption properties and might be used as a filler in a polymer matrix for IR shielding applications. Graphene oxide can be reduced by different methods. Depending on the reduction method reduced graphene oxide (rGO) with a different content of oxygen can be obtained exhibiting different properties. In this work we propose new polymer nanocomposites with poly(vinyl alcohol) as the matrix and 0.1 wt.% addition of graphene materials with different oxygen content to be used for IR shielding applications. The results show that the properties of the graphene filler strongly influence the infrared shielding properties of the obtained nanocomposites. The best IR shielding properties were obtained for the composites where rGO with the lowest oxygen content was used. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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16 pages, 5415 KiB

Open AccessArticle

Dewetted Gold Nanostructures onto Exfoliated Graphene Paper as High Efficient Glucose Sensor

by Antonino Scandurra, Francesco Ruffino, Maria Censabella, Antonio Terrasi and Maria Grazia Grimaldi

Nanomaterials 2019, 9(12), 1794; https://doi.org/10.3390/nano9121794 - 16 Dec 2019

Cited by 12 | Viewed by 3745

Abstract

Non-enzymatic electrochemical glucose sensing was obtained by gold nanostructures on graphene paper, produced by laser or thermal dewetting of 1.6 and 8 nm-thick Au layers, respectively. Nanosecond laser annealing produces spherical nanoparticles (AuNPs) through the molten-phase dewetting of the gold layer and simultaneous [...] Read more.

Non-enzymatic electrochemical glucose sensing was obtained by gold nanostructures on graphene paper, produced by laser or thermal dewetting of 1.6 and 8 nm-thick Au layers, respectively. Nanosecond laser annealing produces spherical nanoparticles (AuNPs) through the molten-phase dewetting of the gold layer and simultaneous exfoliation of the graphene paper. The resulting composite electrodes were characterized by X-ray photoelectron spectroscopy, cyclic voltammetry, scanning electron microscopy, micro Raman spectroscopy and Rutherford back-scattering spectrometry. Laser dewetted electrode presents graphene nanoplatelets covered by spherical AuNPs. The sizes of AuNPs are in the range of 10–150 nm. A chemical shift in the XPS Au4f core-level of 0.25–0.3 eV suggests the occurrence of AuNPs oxidation, which are characterized by high stability under the electrochemical test. Thermal dewetting leads to electrodes characterized by faceted not oxidized gold structures. Glucose was detected in alkali media at potential of 0.15–0.17 V vs. saturated calomel electrode (SCE), in the concentration range of 2.5μM−30 mM, exploiting the peak corresponding to the oxidation of two electrons. Sensitivity of 1240 µA mM⁻¹ cm⁻², detection limit of 2.5 μM and quantifications limit of 20 μM were obtained with 8 nm gold equivalent thickness. The analytical performances are very promising and comparable to the actual state of art concerning gold based electrodes. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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10 pages, 2519 KiB

Open AccessArticle

Chitosan-Derived Porous Activated Carbon for the Removal of the Chemical Warfare Agent Simulant Dimethyl Methylphosphonate

by Hyejin Yu, Ye Rim Son, Hyeonji Yoo, Hyun Gil Cha, Hangil Lee and Hyun Sung Kim

Nanomaterials 2019, 9(12), 1703; https://doi.org/10.3390/nano9121703 - 28 Nov 2019

Cited by 23 | Viewed by 4103

Abstract

Methods for the rapid removal of chemical warfare agents are of critical importance. In this work, a porous activated carbon material (C-PAC) was prepared from chitosan flakes via single-step potassium carbonate (K₂CO₃) activation for the prompt adsorption of dimethyl [...] Read more.

Methods for the rapid removal of chemical warfare agents are of critical importance. In this work, a porous activated carbon material (C-PAC) was prepared from chitosan flakes via single-step potassium carbonate (K₂CO₃) activation for the prompt adsorption of dimethyl methylphosphonate (DMMP). C-PAC samples were prepared using different carbonization temperatures (350, 550, and 750 °C) at a constant K₂CO₃/chitosan ratio (1:2) and using different activator ratios (K₂CO₃/chitosan ratios of 1:0.5, 1:1, 1:2, and 1:3) at 750 °C. Furthermore, we evaluated the effect of preparation conditions on the adsorption capacities of the various C-PAC materials for DMMP under ambient conditions (25 °C). Notably, for the C-PAC material prepared at 750 °C using a K₂CO₃/chitosan ratio of 1:2, the DMMP adsorption was saturated at approximately 412 mg·g⁻¹ carbon after 48 h. The good performance of this material makes it a potential candidate for use in remedial applications or protective gear. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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23 pages, 4979 KiB

Open AccessArticle

Facile Synthesis of Nitrogen-Doped Carbon Dots from Lignocellulosic Waste

by Mohammed Abdullah Issa, Zurina Z. Abidin, Shafreeza Sobri, Suraya Rashid, Mohd Adzir Mahdi, Nor Azowa Ibrahim and Musa Y. Pudza

Nanomaterials 2019, 9(10), 1500; https://doi.org/10.3390/nano9101500 - 22 Oct 2019

Cited by 70 | Viewed by 7492

Abstract

The current research mainly focuses on transforming low-quality waste into value-added nanomaterials and investigating various ways of utilising them. The hydrothermal preparation of highly fluorescent N-doped carbon dots (N–CDs) was obtained from the carboxymethylcellulose (CMC) of oil palm empty fruit bunches and linear-structured [...] Read more.

The current research mainly focuses on transforming low-quality waste into value-added nanomaterials and investigating various ways of utilising them. The hydrothermal preparation of highly fluorescent N-doped carbon dots (N–CDs) was obtained from the carboxymethylcellulose (CMC) of oil palm empty fruit bunches and linear-structured polyethyleneimines (LPEI). Transmission electron microscopy (TEM) analysis showed that the obtained N–CDs had an average size of 3.4 nm. The N–CDs were monodispersed in aqueous solution and were strongly fluorescent under the irradiation of ultra-violet light. A detailed description of the morphology and shape was established using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was shown that LPEI were successfully tuned the fluorescence (PL) properties of CDs in both the intrinsic and surface electronic structures, and enhanced the quantum yield (QY) up to 44%. The obtained N–CDs exhibited remarkable PL stability, long lifetime and pH-dependence behaviour, with the excitation/emission maxima of 350/465.5 nm. Impressively, PL enhancement and blue-shifted emission could be seen with the dilution of the original N–CDs solution. The obtained N–CDs were further applied as fluorescent probe for the identification of Cu²⁺ in aqueous media. The mechanism could be attributed to the particularly high thermodynamic affinity of Cu²⁺ for the N-chelate groups over the surface of N–CDs and the fast metal-to-ligand binding kinetics. The linear relationship between the relative quenching rate and the concentration of Cu²⁺ were applied between 1–30 µM, with a detection limit of 0.93 µM. The fluorescent probe was successfully applied for the detection of Cu²⁺ in real water. Moreover, a solid-state film of N–CDs was prepared in the presence of poly (vinyl alcohol) (PVA) polymer and found to be stable even after 72-h of continuous irradiation to UV-lamp. In contrast to the aqueous N–CDs, the composite film showed only an excitation independent property, with enhanced PL QY of around 47%. Due to the strong and stable emission nature of N–CDs in both aqueous and solid conditions, the obtained N–CDs are ideal for reducing the overall preparation costs and applying them for various biological and environmental applications in the future. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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12 pages, 2893 KiB

Open AccessArticle

Investigation of ZnO-decorated CNTs for UV Light Detection Applications

by Stefano Boscarino, Simona Filice, Antonella Sciuto, Sebania Libertino, Mario Scuderi, Clelia Galati and Silvia Scalese

Nanomaterials 2019, 9(8), 1099; https://doi.org/10.3390/nano9081099 - 31 Jul 2019

Cited by 29 | Viewed by 4502

Abstract

Multi-walled carbon nanotubes (CNTs) decorated with zinc oxide nanoparticles (ZnO NPs) were prepared in isopropanol solution by a simple, room-temperature process and characterized from structural, morphological, electronic, and optical points of view. A strong interaction between ZnO and CNTs is fully confirmed by [...] Read more.

Multi-walled carbon nanotubes (CNTs) decorated with zinc oxide nanoparticles (ZnO NPs) were prepared in isopropanol solution by a simple, room-temperature process and characterized from structural, morphological, electronic, and optical points of view. A strong interaction between ZnO and CNTs is fully confirmed by all the characterization techniques. ZnO-CNTs nanocomposites, with different weight ratios, were deposited as a dense layer between two electrodes, in order to investigate the electrical behaviour. In particular, the electrical response of the nanocomposite layers to UV light irradiation was recorded for a fixed voltage: As the device is exposed to the UV lamp, a sharp current drop takes place and then an increase is observed as the irradiation is stopped. The effect can be explained by adsorption and desorption phenomena taking place on the ZnO nanoparticle surface under irradiation and by charge transfer between ZnO and CNTs, thanks to the strong interaction between the two nanomaterials. The nanocomposite material shows good sensitivity and fast response to UV irradiation. Room temperature and low-cost processes used for the device preparation combined with room temperature and low voltage operational conditions make this methodology very promising for large scale UV detectors applications. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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23 pages, 9060 KiB

Open AccessArticle

Preparation, Characterization and Adsorption Potential of Grainy Halloysite-CNT Composites for Anthracene Removal from Aqueous Solution

by Gabriela Kamińska, Mariusz Dudziak, Edyta Kudlek and Jolanta Bohdziewicz

Nanomaterials 2019, 9(6), 890; https://doi.org/10.3390/nano9060890 - 17 Jun 2019

Cited by 23 | Viewed by 4211

Abstract

Grainy Hal-CNT composites were prepared from powder halloysite nanoclay (Hal) and carbon nanotubes (CNTs). The effect of the amount and type of CNTs, as well as calcination temperature on morphology and properties of Hal-CNT composites and their adsorption capacity of anthracene (ANT), were [...] Read more.

Grainy Hal-CNT composites were prepared from powder halloysite nanoclay (Hal) and carbon nanotubes (CNTs). The effect of the amount and type of CNTs, as well as calcination temperature on morphology and properties of Hal-CNT composites and their adsorption capacity of anthracene (ANT), were studied. The surface topography of granules was heterogenous, with cracks and channels created during granulation of powder clay and CNTs. In FTIR, spectra were exhibited only in the bands arising from halloysite, due to its dominance in the granules. The increase in the heating temperature to 550 °C resulted in mesoporosity/macroporosity of the granules, the lowest specific surface area (SSA) and poorest adsorption potential. Overall, SSA of all Hal-CNT composites were higher than raw Hal, and by itself, heated halloysite. The larger amount of CNTs enhanced adsorption kinetics due to the more external adsorption sites. The equilibrium was established with the contact time of approximately 30 min for the sample Hal-SWCNT 85:15, while the samples with loading 96:4, it was 60–90 min. Adsorption isotherms for ANT showed L1 type, which is representative for the sorbents with limited adsorption capacity. The Langmuir model described the adsorption process, suggesting a monolayer covering. The sample Hal-SWCNT 85:15 exhibited the highest adsorption capacity of ANT, due to its highest SSA and microporous character. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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11 pages, 1776 KiB

Open AccessArticle

Electrochemical Detection of Ultratrace Lead Ion through Attaching and Detaching DNA Aptamer from Electrochemically Reduced Graphene Oxide Electrode

by Su Hwan Yu, Chang-Seuk Lee and Tae Hyun Kim

Nanomaterials 2019, 9(6), 817; https://doi.org/10.3390/nano9060817 - 30 May 2019

Cited by 34 | Viewed by 4509

Abstract

This paper describes a simple strategy for the ultratrace level detection of Pb²⁺ ion based on G-quadruplex DNA and an electrochemically reduced graphene oxide (ERGO) electrode. First, ERGO was formed on a glassy carbon electrode (GCE) by the reduction of graphene oxide [...] Read more.

This paper describes a simple strategy for the ultratrace level detection of Pb²⁺ ion based on G-quadruplex DNA and an electrochemically reduced graphene oxide (ERGO) electrode. First, ERGO was formed on a glassy carbon electrode (GCE) by the reduction of graphene oxide (GO) using cyclic voltammetry. Subsequently, a methylene blue (MB)-tagged, guanine-rich DNA aptamer (Apt) was attached to the surface of ERGO via π-π interaction, leading to the Apt-modified ERGO electrode. The presence of Pb²⁺ could generate the folding of Apt to a G-quadruplex structure. The formation of G-quadruplex resulted in detaching the Apt from the ERGO/GCE, leading to a change in redox current of the MB tag. Electrochemical measurements showed the proposed sensor had an exceptional sensitivity for Pb²⁺ with a linear range from 10⁻¹⁵ to 10⁻⁹ M and a detection limit of 0.51 fM. The sensor also exhibited high selectivity for Pb²⁺, as well as many other advantages, such as stability, reproducibility, regeneration, as well as simple fabrication and operation processes. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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15 pages, 2579 KiB

Open AccessArticle

Preparation of N-Doped Carbon Nanosheets from Sewage Sludge for Adsorption Studies of Cr(VI) from Aqueous Solution

by Yi Wang, Weinan Zhao, Wanlan Zheng, Shuang Chen and Jinsheng Zhao

Nanomaterials 2019, 9(2), 265; https://doi.org/10.3390/nano9020265 - 15 Feb 2019

Cited by 16 | Viewed by 3406

Abstract

Porous activated carbon with specific morphology and structure are of particular importance for waste water treatment, especially for the adsorption of toxic hexavalent chromium Cr(VI). However, the scalable and cheap production of such absorbents still suffer a grand challenge. Herein, a new type [...] Read more.

Porous activated carbon with specific morphology and structure are of particular importance for waste water treatment, especially for the adsorption of toxic hexavalent chromium Cr(VI). However, the scalable and cheap production of such absorbents still suffer a grand challenge. Herein, a new type of N-doped nanosheet was innovatively prepared from easily available and low-cost sewage sludge via a facile and recyclable KOH activation method. The N-doped porous carbon nanosheets (N-SAC) produced by introduction of KOH and dicyandiamide, which performed favourable features for metal ions adsorption (93.2% for Cr(VI)) due to its high specific surface area, tuneable pore size distributions and good hydrophilicity. Additionally, the capacity also remained high after two cycles of adsorption by thermal regeneration, with 90.8% removal rate. The DFT calculation also approved that the doping of N could optimize the Mulliken charges distribution and improve the HOMO energy and improve the adsorption ability of N-SAC. This original proposal may inspire new possibility of creating porous carbon absorbents in a recyclable method. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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15 pages, 4878 KiB

Open AccessArticle

Biosynthesized Highly Stable Au/C Nanodots: Ideal Probes for the Selective and Sensitive Detection of Hg²⁺ Ions

by Sada Venkateswarlu, Saravanan Govindaraju, Roopkumar Sangubotla, Jongsung Kim, Min-Ho Lee and Kyusik Yun

Nanomaterials 2019, 9(2), 245; https://doi.org/10.3390/nano9020245 - 12 Feb 2019

Cited by 10 | Viewed by 4271

Abstract

The enormous ongoing industrial development has caused serious water pollution which has become a major crisis, particularly in developing countries. Among the various water pollutants, non-biodegradable heavy metal ions are the most prevalent. Thus, trace-level detection of these metal ions using a simple [...] Read more.

The enormous ongoing industrial development has caused serious water pollution which has become a major crisis, particularly in developing countries. Among the various water pollutants, non-biodegradable heavy metal ions are the most prevalent. Thus, trace-level detection of these metal ions using a simple technique is essential. To address this issue, we have developed a fluorescent probe of Au/C nanodots (GCNDs-gold carbon nanodots) using an eco-friendly method based on an extract from waste onion leaves (Allium cepa-red onions). The leaves are rich in many flavonoids, playing a vital role in the formation of GCNDs. Transmission electron microscopy (TEM) and Scanning transmission electron microscopy-Energy-dispersive X-ray spectroscopy (STEM-EDS) elemental mapping clearly indicated that the newly synthesized materials are approximately 2 nm in size. The resulting GCNDs exhibited a strong orange fluorescence with excitation at 380 nm and emission at 610 nm. The GCNDs were applied as a fluorescent probe for the detection of Hg²⁺ ions. They can detect ultra-trace concentrations of Hg²⁺ with a detection limit of 1.3 nM. The X-ray photoelectron spectroscopy results facilitated the identification of a clear detection mechanism. We also used the new probe on a real river water sample. The newly developed sensor is highly stable with a strong fluorescent property and can be used for various applications such as in catalysis and biomedicine. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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16 pages, 3265 KiB

Open AccessArticle

Facile Electrochemical Sensor for Nanomolar Rutin Detection Based on Magnetite Nanoparticles and Reduced Graphene Oxide Decorated Electrode

by Quanguo He, Yiyong Wu, Yaling Tian, Guangli Li, Jun Liu, Peihong Deng and Dongchu Chen

Nanomaterials 2019, 9(1), 115; https://doi.org/10.3390/nano9010115 - 18 Jan 2019

Cited by 115 | Viewed by 8142

Abstract

A new electrochemical sensor for nanomolar rutin detection based on amine-functionalized Fe₃O₄ nanoparticles and electrochemically reduced graphene oxide nanocomposite modified glassy carbon electrode (NH₂-Fe₃O₄ NPs-ErGO/GCE) was fabricated through a simple method, and the X-ray diffraction [...] Read more.

A new electrochemical sensor for nanomolar rutin detection based on amine-functionalized Fe₃O₄ nanoparticles and electrochemically reduced graphene oxide nanocomposite modified glassy carbon electrode (NH₂-Fe₃O₄ NPs-ErGO/GCE) was fabricated through a simple method, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and electrochemical technique were used to characterize the modified electrode. The electrochemical behavior of rutin on the Fe₃O₄ NPs-ErGO/GCE was studied in detail. The electrochemical response of rutin at this modified electrode was remarkably higher than that of the bare GCE or other modified GCE (GO/GCE, Fe₃O₄ NPs-GO/GCE, and ErGO/GCE). Under the optimum determination conditions, Fe₃O₄ NPs-ErGO/GCE provided rutin with a broader detection range of 6.0 nM–0.1 µM; 0.1–8.0 µM and 8.0–80 µM, a minimum detectable concentration of 4.0 nM was obtained after 210 s accumulation. This novel method was applied in determination of rutin in pharmaceutical tablets and urine samples with satisfactory results. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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46 pages, 13783 KiB

Open AccessReview

Review of Polymer Composites with Diverse Nanofillers for Electromagnetic Interference Shielding

by Dimuthu Wanasinghe, Farhad Aslani, Guowei Ma and Daryoush Habibi

Nanomaterials 2020, 10(3), 541; https://doi.org/10.3390/nano10030541 - 17 Mar 2020

Cited by 115 | Viewed by 7774

Abstract

Polymer matrix composites have generated a great deal of attention in recent decades in various fields due to numerous advantages polymer offer. The advancement of technology has led to stringent requirements in shielding materials as more and more electronic devices are known to [...] Read more.

Polymer matrix composites have generated a great deal of attention in recent decades in various fields due to numerous advantages polymer offer. The advancement of technology has led to stringent requirements in shielding materials as more and more electronic devices are known to cause electromagnetic interference (EMI) in other devices. The drive to fabricate alternative materials is generated by the shortcomings of the existing metallic panels. While polymers are more economical, easy to fabricate, and corrosion resistant, they are known to be inherent electrical insulators. Since high electrical conductivity is a sought after property of EMI shielding materials, polymers with fillers to increase their electrical conductivity are commonly investigated for EMI shielding. Recently, composites with nanofillers also have attracted attention due to the superior properties they provide compared to their micro counterparts. In this review polymer composites with various types of fillers have been analysed to assess the EMI shielding properties generated by each. Apart from the properties, the manufacturing processes and morphological properties of composites have been analysed in this review to find the best polymer matrix composites for EMI shielding. Full article

(This article belongs to the Special Issue Carbon-Based Nanostructures and Nanocomposites for Health and Environmental Applications)

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