Nanomaterials

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3 pages, 185 KiB

Open AccessEditorial

Nanomaterials and Nanotechnology in Wastewater Treatment

by George Z. Kyzas and Athanasios C. Mitropoulos

Nanomaterials 2021, 11(6), 1539; https://doi.org/10.3390/nano11061539 - 10 Jun 2021

Cited by 12 | Viewed by 3057

Abstract

The rapidly increasing population, depleting water resources, and climate change resulting in prolonged droughts and floods have rendered drinking water as a competitive resource in many parts of the world [...] Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

Research

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15 pages, 4017 KiB

Open AccessArticle

Evaluation of Fe-Mg Binary Oxide for As (III) Adsorption—Synthesis, Characterization and Kinetic Modelling

by Saif Ullah Khan, Rumman Zaidi, Feroz Shaik, Izharul Haq Farooqi, Ameer Azam, Hatem Abuhimd and Faheem Ahmed

Nanomaterials 2021, 11(3), 805; https://doi.org/10.3390/nano11030805 - 21 Mar 2021

Cited by 16 | Viewed by 2743

Abstract

Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO₃·9H₂O and MgNO [...] Read more.

Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO₃·9H₂O and MgNO₃·6H₂O in a proportion of molar concentration 1:1 and was later evaluated in removing As (III) from contaminated waters. Characterization of the prepared nanomaterial was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX) and ultraviolet–visible spectrophotometry (UV-VIS). Experimental studies on batch scale were carried out, examining the effect of varying initial concentrations of metal, adsorbent dosage, application time and initial pH on removal efficiency. Arsenic removal increased on increasing adsorbent dosage (0.1–1 g/L) but trend reversed on increasing initial arsenic concentration attaining q_max of 263.20 mg/g. Adsorption was quite efficient in pH range 4–8. Freundlich fitted better for adsorption isotherm along with following Pseudo-2nd order kinetics. The reusability and effect of co-existing ions on arsenic adsorption, namely SO₄²⁻, CO₃²⁻ and PO₄³⁻ were also explored with reusability in 1st and 2nd cycles attained adsorptive removal up to 77% and 64% respectively. The prepared nano-adsorbent showed promising results in terms of high arsenic uptake (q_max of 263.20 mg/g) along with facile and cost-effective synthesis. Thus, the co-precipitation technique used in this work is a simple one step procedure without any use of any precursor as compared to most of the other procedures used for synthesis. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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25 pages, 5295 KiB

Open AccessArticle

Methionine-Functionalized Graphene Oxide/Sodium Alginate Bio-Polymer Nanocomposite Hydrogel Beads: Synthesis, Isotherm and Kinetic Studies for an Adsorptive Removal of Fluoroquinolone Antibiotics

by Sushma Yadav, Anupama Asthana, Ajaya Kumar Singh, Rupa Chakraborty, S. Sree Vidya, Ambrish Singh and Sónia A. C. Carabineiro

Nanomaterials 2021, 11(3), 568; https://doi.org/10.3390/nano11030568 - 25 Feb 2021

Cited by 50 | Viewed by 4026

Abstract

In spite of the growing demand for new antibiotics, in the recent years, the occurrence of fluoroquinolone antibiotics (as a curative agent for urinary tract disorders and respiratory problems) in wastewater have drawn immense attention. Traces of antibiotic left-overs are present in the [...] Read more.

In spite of the growing demand for new antibiotics, in the recent years, the occurrence of fluoroquinolone antibiotics (as a curative agent for urinary tract disorders and respiratory problems) in wastewater have drawn immense attention. Traces of antibiotic left-overs are present in the water system, causing noxious impact on human health and ecological environments, being a global concern. Our present work aims at tackling the major challenge of toxicity caused by antibiotics. This study deals with the efficient adsorption of two commonly used fluoroquinolone (FQ) antibiotics, i.e., Ofloxacin (OFX) and Moxifloxacin (MOX) on spherical hydrogel beads generated from methionine‒functionalized graphene oxide/ sodium alginate polymer (abbreviated Met-GO/SA) from aqueous solutions. The composition, morphology and crystal phase of prepared adsorbents were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM) and thermogravimetric analysis/differential thermogravimetry (TGA/DTG). Batch adsorption tests are followed to optimize the conditions required for adsorption process. Both functionalized and non-functionalized adsorbents were compared to understand the influence of several experimental parameters, such as, the solution pH, contact time, adsorbent dosage, temperature and initial concentration of OFX and MOX on adsorption. The obtained results indicated that the functionalized adsorbent (Met-GO/SA) showed a better adsorption efficiency when compared to non-functionalized (GO/SA) adsorbent. Further, the Langmuir isotherm was validated as the best fitting model to describe adsorption equilibrium and pseudo second-order-kinetic model fitted well for both types of adsorbate. The maximum adsorption capacities of Met-GO/SA were 4.11 mg/g for MOX and 3.43 mg/g for OFX. Thermodynamic parameters, i.e., ∆G°, ∆H° and ∆S° were also calculated. It was shown that the overall adsorption process was thermodynamically favorable, spontaneous and exothermic in nature. The adsorbents were successfully regenerated up to four cycles with 0.005 M NaCl solutions. Overall, our work showed that the novel Met-GO/SA nanocomposite could better contribute to the removal of MOX and OFX from the liquid media. The gel beads prepared have adequate features, such as simple handling, eco-friendliness and easy recovery. Hence, polymer gel beads are promising candidates as adsorbents for large-scale water remediation. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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21 pages, 7350 KiB

Open AccessFeature PaperArticle

CO₂/CH₄ and He/N₂ Separation Properties and Water Permeability Valuation of Mixed Matrix MWCNTs-Based Cellulose Acetate Flat Sheet Membranes: A Study of the Optimization of the Filler Material Dispersion Method

by Tobias Esser, Tobias Wolf, Tim Schubert, Jan Benra, Stefan Forero, George Maistros, Stéphan Barbe, George V. Theodorakopoulos, Dionysios S. Karousos, Andreas A. Sapalidis and Evangelos P. Favvas

Nanomaterials 2021, 11(2), 280; https://doi.org/10.3390/nano11020280 - 22 Jan 2021

Cited by 9 | Viewed by 2952

Abstract

The main scope of this work is to develop nano-carbon-based mixed matrix cellulose acetate membranes (MMMs) for the potential use in both gas and liquid separation processes. For this purpose, a variety of mixed matrix membranes, consisting of cellulose acetate (CA) polymer and [...] Read more.

The main scope of this work is to develop nano-carbon-based mixed matrix cellulose acetate membranes (MMMs) for the potential use in both gas and liquid separation processes. For this purpose, a variety of mixed matrix membranes, consisting of cellulose acetate (CA) polymer and carbon nanotubes as additive material were prepared, characterized, and tested. Multi-walled carbon nanotubes (MWCNTs) were used as filler material and diacetone alcohol (DAA) as solvent. The first main objective towards highly efficient composite membranes was the proper preparation of agglomerate-free MWCNTs dispersions. Rotor-stator system (RS) and ultrasonic sonotrode (USS) were used to achieve the nanofillers’ dispersion. In addition, the first results of the application of the three-roll mill (TRM) technology in the filler dispersion achieved were promising. The filler material, MWCNTs, was characterized by scanning electron microscopy (SEM) and liquid nitrogen (LN₂) adsorption-desorption isotherms at 77 K. The derivatives CA-based mixed matrix membranes were characterized by tensile strength and water contact angle measurements, impedance spectroscopy, gas permeability/selectivity measurements, and water permeability tests. The studied membranes provide remarkable water permeation properties, 12–109 L/m²/h/bar, and also good separation factors of carbon dioxide and helium separations. Specifically, a separation factor of 87 for 10% He/N₂ feed concentration and a selectivity value of 55.4 for 10% CO₂/CH₄ feed concentration were achieved. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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12 pages, 4386 KiB

Open AccessArticle

Adsorption Kinetics of Arsenic (V) on Nanoscale Zero-Valent Iron Supported by Activated Carbon

by Huijie Zhu, Mingyan Shi, Xiuji Zhang, Bo Liu and Dahu Yao

Nanomaterials 2020, 10(9), 1791; https://doi.org/10.3390/nano10091791 - 9 Sep 2020

Cited by 17 | Viewed by 2754

Abstract

The presence of arsenic (As) in drinking water is of serious concern due to its negative impact on human health. This work reports on the kinetics of nanoscale zero-valent iron (Fe⁰) supported by activated carbon (NZVI/AC) for the removal of As [...] Read more.

The presence of arsenic (As) in drinking water is of serious concern due to its negative impact on human health. This work reports on the kinetics of nanoscale zero-valent iron (Fe⁰) supported by activated carbon (NZVI/AC) for the removal of As (V) species from aqueous solutions. To better understand the factors affecting this process, we investigated the effects of various experimental parameters including initial As (V) concentration, adsorbent dosage, pH, temperature, and coexisting ions on the adsorption kinetics using a batch-adsorption method. The optimum conditions for As (V) removal by NZVI/AC were found to be: 318 K, pH 3.5, an adsorbent dosage of 1.5 g/L, and an equilibrium time of 72 h. A greater mass of NZVI/AC, lower concentration of As (V) and lower pH positively promoted adsorption kinetics. The presence of phosphate (

{PO}_{4}^{3 -}

) and silicate (

{SiO}_{4}^{2 -}

) markedly inhibited As (V) removal kinetics. However, in the presence of 4.5 g/L NZVI/AC, ≥99.9% of As (V) was removed from raw groundwater. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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19 pages, 7223 KiB

Open AccessArticle

Improved Removal Capacity and Equilibrium Time of Maghemite Nanoparticles Growth in Zeolite Type 5A for Pb(II) Adsorption

by Juan A. Ramos-Guivar, Katterine Taipe, Miguel Angelo Schettino, Jr., Eloi Silva, Marco Antonio Morales Torres, Edson Caetano Passamani and Fred Jochen Litterst

Nanomaterials 2020, 10(9), 1668; https://doi.org/10.3390/nano10091668 - 26 Aug 2020

Cited by 33 | Viewed by 3331

Abstract

Novel magnetic zeolite type 5A nanocomposites were synthesized by the co-precipitation method and applied to lead removal from aqueous ambient. Maghemite nanoparticles were mixed with zeolite and, by controlling its content, transmission electron microscopy results gave sizes of 5 to 15 nm and [...] Read more.

Novel magnetic zeolite type 5A nanocomposites were synthesized by the co-precipitation method and applied to lead removal from aqueous ambient. Maghemite nanoparticles were mixed with zeolite and, by controlling its content, transmission electron microscopy results gave sizes of 5 to 15 nm and selected area electron diffraction patterns confirmed the presence of zeolite. The nanocomposites have high specific surface area with values up to 194 m²/g. Magnetization measurements proved superparamagnetic behavior with saturation values of ~35 emu/gFe. Kinetic adsorption experiments showed removal efficiencies of 99.9% and an enhanced equilibrium time of 5 min. The lead concentrations after adsorption experiments lay under the permissible levels of 10 μg L⁻¹, according to the World Health Organization. The maximum adsorption capacity, estimated by Sips model, was 265 mg L⁻¹ at 300 K. The removal efficiency was significantly improved in the range of pH > 6, as well as in the presence of cation interferents such as Ca(II), Cu(II), and Cd(II). The adsorption mechanism was explained with cation exchange between Pb(II), the zeolite framework, and the protonated maghemite surface. Besides, our system revealed recyclability even after seven regeneration cycles. Thus, our synthesized materials have remarkable adsorption properties for lead water remediation processes. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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19 pages, 2889 KiB

Open AccessArticle

Green Synthesis, Characterization and Application of Natural Product Coated Magnetite Nanoparticles for Wastewater Treatment

by Chanchal Das, Subhadeep Sen, Tejinder Singh, Tanmoy Ghosh, Subha Sankar Paul, Tae Wan Kim, Seob Jeon, Dilip K. Maiti, Jungkyun Im and Goutam Biswas

Nanomaterials 2020, 10(8), 1615; https://doi.org/10.3390/nano10081615 - 18 Aug 2020

Cited by 79 | Viewed by 7328

Abstract

Adsorption of organic pollutants, toxic metal ions, and removal of harmful bacteria can give us clean and pure drinkable water from wastewater resources. Respective magnetite nanoparticles (MNPs) were synthesized using a cheaper and greener way in an open-air environment with the use of [...] Read more.

Adsorption of organic pollutants, toxic metal ions, and removal of harmful bacteria can give us clean and pure drinkable water from wastewater resources. Respective magnetite nanoparticles (MNPs) were synthesized using a cheaper and greener way in an open-air environment with the use of crude latex of Jatropha curcas (JC) and leaf extract of Cinnamomum tamala (CT). Characterization of MNPs had been performed by dynamic light scattering (DLS), Ultraviolet-visible (UV-vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, powdered X-ray diffraction (XRD), and field emission scanning electron microscope (FE-SEM). The size ranges of the synthesized MNPs were observed in between 20–42 nm for JC-Fe₃O₄ and within 26–35 nm for CT-Fe₃O₄ by FE-SEM images. The effect of synthesized magnetic nanoparticles in wastewater treatment (bacterial portion), dye adsorption, toxic metal removal as well as antibacterial, antioxidant, and cytotoxic activities were studied. This purification will lead to an increase in the resources of pure drinking water in the future. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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12 pages, 4058 KiB

Open AccessArticle

Upcycling of Wastewater via Effective Photocatalytic Hydrogen Production Using MnO₂ Nanoparticles—Decorated Activated Carbon Nanoflakes

by Sankar Sekar, Sejoon Lee, Preethi Vijayarengan, Kaliyappan Mohan Kalirajan, Thirumavalavan Santhakumar, Saravanan Sekar and Sutha Sadhasivam

Nanomaterials 2020, 10(8), 1610; https://doi.org/10.3390/nano10081610 - 17 Aug 2020

Cited by 32 | Viewed by 4481

Abstract

In the present work, we demonstrated the upcycling technique of effective wastewater treatment via photocatalytic hydrogen production by using the nanocomposites of manganese oxide-decorated activated carbon (MnO₂-AC). The nanocomposites were sonochemically synthesized in pure water by utilizing MnO₂ nanoparticles and [...] Read more.

In the present work, we demonstrated the upcycling technique of effective wastewater treatment via photocatalytic hydrogen production by using the nanocomposites of manganese oxide-decorated activated carbon (MnO₂-AC). The nanocomposites were sonochemically synthesized in pure water by utilizing MnO₂ nanoparticles and AC nanoflakes that had been prepared through green routes using the extracts of Brassica oleracea and Azadirachta indica, respectively. MnO₂-AC nanocomposites were confirmed to exist in the form of nanopebbles with a high specific surface area of ~109 m²/g. When using the MnO₂-AC nanocomposites as a photocatalyst for the wastewater treatment, they exhibited highly efficient hydrogen production activity. Namely, the high hydrogen production rate (395 mL/h) was achieved when splitting the synthetic sulphide effluent (S²⁻ = 0.2 M) via the photocatalytic reaction by using MnO₂-AC. The results stand for the excellent energy-conversion capability of the MnO₂-AC nanocomposites, particularly, for photocatalytic splitting of hydrogen from sulphide wastewater. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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21 pages, 5909 KiB

Open AccessArticle

Cu/CuO Composite Track-Etched Membranes for Catalytic Decomposition of Nitrophenols and Removal of As(III)

by Anastassiya A. Mashentseva, Murat Barsbay, Maxim V. Zdorovets, Dmitriy A. Zheltov and Olgun Güven

Nanomaterials 2020, 10(8), 1552; https://doi.org/10.3390/nano10081552 - 7 Aug 2020

Cited by 26 | Viewed by 3004

Abstract

One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing [...] Read more.

One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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17 pages, 5462 KiB

Open AccessArticle

Synthesis and Characterization of Amorphous Iron Oxide Nanoparticles by the Sonochemical Method and Their Application for the Remediation of Heavy Metals from Wastewater

by Virendra Kumar Yadav, Daoud Ali, Samreen Heena Khan, Govindhan Gnanamoorthy, Nisha Choudhary, Krishna Kumar Yadav, Van Nam Thai, Seik Altaf Hussain and Salim Manhrdas

Nanomaterials 2020, 10(8), 1551; https://doi.org/10.3390/nano10081551 - 7 Aug 2020

Cited by 106 | Viewed by 8332

Abstract

Nanoparticles have gained huge attention in the last decade due to their applications in electronics, medicine, and environmental clean-up. Iron oxide nanoparticles (IONPs) are widely used for the wastewater treatment due to their recyclable nature and easy manipulation by an external magnetic field. [...] Read more.

Nanoparticles have gained huge attention in the last decade due to their applications in electronics, medicine, and environmental clean-up. Iron oxide nanoparticles (IONPs) are widely used for the wastewater treatment due to their recyclable nature and easy manipulation by an external magnetic field. Here, in the present research work, iron oxide nanoparticles were synthesized by the sonochemical method by using precursors of ferrous sulfate and ferric chloride at 70 °C for one hour in an ultrasonicator. The synthesized iron oxide nanoparticles were characterized by diffraction light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), electron diffraction spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The FTIR analysis exhibits characteristic absorption bands of IONPs at 400–800 cm⁻¹, while the Raman spectra showed three characteristic bands at 273, 675, and 1379 cm⁻¹ for the synthesized IONPs. The XRD data revealed three major intensity peaks at two theta, 33°, 35°, and 64° which indicated the presence of maghemite and magnetite phase. The size of the spherical shaped IONPs was varying from 9–70 nm with an average size of 38.9 nm while the size of cuboidal shaped particle size was in microns. The purity of the synthesized IONPs was confirmed by the EDS attached to the FESEM, which clearly show sharp peaks for Fe and O, while the magnetic behavior of the IONPs was confirmed by the VSM measurement and the magnetization was 2.43 emu/g. The batch adsorption study of lead (Pb) and chromium (Cr) from 20% fly ash aqueous solutions was carried out by using 0.6 mg/100 mL IONPs, which exhibited maximum removal efficiency i.e., 97.96% and 82.8% for Pb²⁺ and Cr ions, respectively. The fly ash are being used in making cements, tiles, bricks, bio fertilizers etc., where the presence of fly ash is undesired property which has to be either removed or will be brought up to the value of acceptable level in the fly ash. Therefore, the synthesized IONPs, can be applied in the elimination of heavy metals and other undesired elements from fly ash with a short period of time. Moreover, the IONPs that have been used as a nanoadsorbent can be recovered from the reaction mixture by applying an external magnetic field that can be recycled and reused. Therefore, this study can be effective in all the fly ash-based industries for elimination of the undesired elements, while recyclability and reusable nature of IONPs will make the whole adsorption or elimination process much economical. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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17 pages, 5441 KiB

Open AccessArticle

Aerobic Oil-Phase Cyclic Magnetic Adsorption to Synthesize 1D Fe₂O₃@TiO₂ Nanotube Composites for Enhanced Visible-Light Photocatalytic Degradation

by Qingqing Tao, Xin Huang, Jingtao Bi, Rongli Wei, Chuang Xie, Yongzhu Zhou, Lu Yu, Hongxun Hao and Jingkang Wang

Nanomaterials 2020, 10(7), 1345; https://doi.org/10.3390/nano10071345 - 9 Jul 2020

Cited by 18 | Viewed by 2720

Abstract

In this work, Fe₂O₃@TiO₂ nanostructures with staggered band alignment were newly designed by an aerobic oil-phase cyclic magnetic adsorption method. XRD and TEM analyses were performed to verify the uniform deposition of Fe₂O₃ nanoparticles on [...] Read more.

In this work, Fe₂O₃@TiO₂ nanostructures with staggered band alignment were newly designed by an aerobic oil-phase cyclic magnetic adsorption method. XRD and TEM analyses were performed to verify the uniform deposition of Fe₂O₃ nanoparticles on the nanotube inner walls of TiO₂. The steady-state degradation experiments exhibited that 1FeTi possessed the most superior performance, which might be ascribable to the satisfying dark adsorption capacity, efficient photocatalytic activity, ease of magnetic separation, and economic efficiency. These results indicated that the deposition of Fe₂O₃ into TiO₂ nanotubes significantly enhanced the activity of Fe₂O₃, which was mainly ascribed to the Fe₂O₃-induced formation of staggered iron oxides@TiO₂ band alignment and thus efficient separation of h⁺ and e⁻. Furthermore, the PL intensity and lifetime of the decay curve were considered as key criterions for the activity’s evaluation. Finally, the leaching tests and regeneration experiments were also performed, which illustrated the inhibited photodissolution compared with TiO₂/Fe₃O₄ and stable cycling ability, enabling 1FeTi to be a promising magnetic material for photocatalytic water remediation. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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26 pages, 6526 KiB

Open AccessArticle

Acid Dye Removal from Aqueous Solution by Using Neodymium(III) Oxide Nanoadsorbents

by Shahin Ahmadi, Leili Mohammadi, Abbas Rahdar, Somayeh Rahdar, Ramin Dehghani, Chinenye Adaobi Igwegbe and George Z. Kyzas

Nanomaterials 2020, 10(3), 556; https://doi.org/10.3390/nano10030556 - 19 Mar 2020

Cited by 81 | Viewed by 4496

Abstract

In the current work, neodymium oxide (Nd₂O₃) nanoparticles were synthesized and characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The major aim/investigation of this research was to fit/model and optimize the [...] Read more.

In the current work, neodymium oxide (Nd₂O₃) nanoparticles were synthesized and characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The major aim/investigation of this research was to fit/model and optimize the removal of Acid Blue 92 (AB92) dye from synthetic effluents (aqueous solutions) using the adsorption process based on neodymium oxide (Nd₂O₃) nanoparticles. To optimize the adsorption conditions, central composite design (CCD) based on response surface methodology (RSM) was applied. The effects of pH (3–9), adsorbent dosage (0.1–1 g/L), initial concentration of AB92 (100–300 mg/L), and contact time (10–100 min) on the adsorption process were investigated. Apart from equilibrium and kinetic experiments, thermodynamic evaluation of the adsorption process was also undertaken. The adsorption process was found to have the best fitting to Langmuir isotherm model and pseudo-second-order kinetic equation. Also, the process was found to be spontaneous and favorable with increased temperature. The optimal conditions found were: pH = 3.15, AB92 concentration equal to 138.5 mg/L, dosage of nanoadsorbent equal to 0.83 g/L, and 50 min as contact time, which resulted in 90.70% AB92 removal. High values for the coefficient of determination, R² (0.9596) and adjusted R² (0.9220) indicated that the removal of AB92 dye using adsorption can be explained and modeled by RSM. The Fisher’s F-value (25.4683) denotes that the developed model was significant for AB92 adsorption at a 95% confidence level. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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14 pages, 3511 KiB

Open AccessArticle

Almond Shell-Derived, Biochar-Supported, Nano-Zero-Valent Iron Composite for Aqueous Hexavalent Chromium Removal: Performance and Mechanisms

by Yaorong Shu, Bin Ji, Baihui Cui, Yuting Shi, Jian Wang, Mian Hu, Siyi Luo and Dabin Guo

Nanomaterials 2020, 10(2), 198; https://doi.org/10.3390/nano10020198 - 23 Jan 2020

Cited by 52 | Viewed by 3652

Abstract

Nano-zero-valent iron biochar derived from almond shell (nZVI-ASBC) was used for hexavalent chromium (CR) removal. Experiments showed that pH was the main factor (p < 0.01) that affected the experimental results. At a dosage of 10 mg·L⁻¹ and pH of 2–6, [...] Read more.

Nano-zero-valent iron biochar derived from almond shell (nZVI-ASBC) was used for hexavalent chromium (CR) removal. Experiments showed that pH was the main factor (p < 0.01) that affected the experimental results. At a dosage of 10 mg·L⁻¹ and pH of 2–6, in the first 60 min, nZVI-ASBC exhibited a removal efficiency of 99.8%, which was approximately 20% higher than the removal yield at pH 7–11. Fourier transform infrared spectroscopy results indicated N-H was the main functional group that influenced the chemisorption process. The pseudo second-order dynamics and Langmuir isotherm models proved to be the most suitable. Thermodynamic studies showed that the reaction was exothermic and spontaneous at low temperatures (T < 317 K). Various interaction mechanisms, including adsorption and reduction, were adopted for the removal of Cr(VI) using the nZVI-ASBC composite. The findings showed that the BC-modified nZVI prepared with almond shell exerts a good effect and could be used for the removal of Cr(VI). Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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25 pages, 4084 KiB

Open AccessArticle

In Situ Copolymerized Polyacrylamide Cellulose Supported Fe₃O₄ Magnetic Nanocomposites for Adsorptive Removal of Pb(II): Artificial Neural Network Modeling and Experimental Studies

by Imran Hasan, Rais Ahmad Khan, Walaa Alharbi, Khadijah H. Alharbi and Ali Alsalme

Nanomaterials 2019, 9(12), 1687; https://doi.org/10.3390/nano9121687 - 25 Nov 2019

Cited by 19 | Viewed by 3974

Abstract

The inimical effects associated with heavy metals are serious concerns, particularly with respect to global health-related issues, because of their non-ecological characteristics and high toxicity. Current research in this area is focused on the synthesis of poly(acrylamide) grafted Cell@Fe₃O₄ nanocomposites [...] Read more.

The inimical effects associated with heavy metals are serious concerns, particularly with respect to global health-related issues, because of their non-ecological characteristics and high toxicity. Current research in this area is focused on the synthesis of poly(acrylamide) grafted Cell@Fe₃O₄ nanocomposites via oxidative free radical copolymerization of the acrylamide monomer and its application for the removal of Pb(II). The hybrid material was analyzed using different analytical techniques, including thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. The efficacious impact of variable parameters, including contact time, pH, material dose, initial Pb(II) concentration, and the temperature, was investigated and optimized using both batch and artificial neural networks (ANN). Surface digestion of metal ions is exceedingly pH-dependent, and higher adsorption efficiencies and adsorption capacities of Pb(II) were acquired at a pH value of 5. The acquired equilibrium data were analyzed using different isotherm models, including Langmuir, Freundlich, Temkin, and Redlich–Peterson models. In this investigation, the best performance was obtained using the Langmuir model. The maximum adsorption capacity of the material investigated via monolayer formation was determined to be 314.47 mg g⁻¹ at 323 K, 239.74 mg g⁻¹ at 313 K, and 100.79 mg g⁻¹ at 303 K. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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12 pages, 6425 KiB

Open AccessArticle

Silver Quantum Dot Decorated 2D-SnO₂ Nanoflakes for Photocatalytic Degradation of the Water Pollutant Rhodamine B

by Nadavala Siva Kumar, Mohammad Asif, T. Ranjeth Kumar Reddy, Gnanendra Shanmugam and Abdelhamid Ajbar

Nanomaterials 2019, 9(11), 1536; https://doi.org/10.3390/nano9111536 - 30 Oct 2019

Cited by 11 | Viewed by 4381

Abstract

Decoration of 2D semiconductor structures with heterogeneous metal quantum dots has attracted considerable attention due to advanced optical, electrical, and catalytic properties that result from the large surface-to-volume ratio associated with these structures. Herein, we report on silver quantum dot decorated 2D SnO [...] Read more.

Decoration of 2D semiconductor structures with heterogeneous metal quantum dots has attracted considerable attention due to advanced optical, electrical, and catalytic properties that result from the large surface-to-volume ratio associated with these structures. Herein, we report on silver quantum dot decorated 2D SnO₂ nanoflakes for the photocatalytic abatement of water effluents, the synthesis of which was achieved through a straightforward and mild hydrothermal procedure. The photocatalysts were systematically investigated using UV–Vis, XRD, electron microscopy (SEM, HR-TEM), EDX, XPS and FTIR. The photocatalytic activity of the nanostructures was evaluated for the abatement of water pollutant rhodamine B (RhB), under light irradiation. The mild hydrothermal synthesis (100 °C) proved highly efficient for the production of large scale Ag quantum dot (QD)/SnO₂ nanoflakes for a novel photocatalytic application. The decoration of SnO₂ with Ag QDs significantly enhances the synergetic charge transfer, which diminishes the photo-induced electron-hole reunion. Moreover, the plasmonic effect from Ag QDs and 2D-SnO₂ structures acts as an electron tank to collect the photo-induced electrons, generating a Schottky barrier between the SnO₂ structures and quantum dots. Overall, this resulted in a facile and efficient degradation of RhB, with a rate double that of pristine SnO₂. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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23 pages, 9667 KiB

Open AccessArticle

Removal of Mercury (II) by EDTA-Functionalized Magnetic CoFe₂O₄@SiO₂ Nanomaterial with Core-Shell Structure

by Kai Xia, Yongfu Guo, Qijun Shao, Qu Zan and Renbi Bai

Nanomaterials 2019, 9(11), 1532; https://doi.org/10.3390/nano9111532 - 29 Oct 2019

Cited by 55 | Viewed by 5070

Abstract

In order to reduce the difficulty and risk of operation, decrease the preparation time and improve the adsorption performance of magnetic nano-silicon adsorbent with core-shell structure, a carboxylated CoFe₂O₄@SiO₂ was prepared by EDTA-functionalized method using a safe, mild [...] Read more.

In order to reduce the difficulty and risk of operation, decrease the preparation time and improve the adsorption performance of magnetic nano-silicon adsorbent with core-shell structure, a carboxylated CoFe₂O₄@SiO₂ was prepared by EDTA-functionalized method using a safe, mild and simple hydrothermal method. The results show that the prepared material of CoFe₂O₄@SiO₂-EDTA has a maximum adsorption capacity of 103.3 mg/g for mercury ions (Hg(II)) at pH = 7. The adsorption process of Hg(II) is a chemical reaction involving chelation and single-layer adsorption, and follows the pseudo-second-order kinetic and Langmuir adsorption isotherm models. Moreover, the removal of Hg(II) is a spontaneous and exothermic reaction. The material characterization, before and after adsorption, shows that CoFe₂O₄@SiO₂-EDTA has excellent recyclability, hydrothermal stability and fully biodegradable properties. To summarize, it is a potential adsorption material for removing heavy metals from aqueous solutions in practical applications. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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17 pages, 5420 KiB

Open AccessArticle

Enhanced Kinetic Removal of Ciprofloxacin onto Metal-Organic Frameworks by Sonication, Process Optimization and Metal Leaching Study

by Aliakbar Dehghan, Ali Akbar Mohammadi, Mahmood Yousefi, Ali Asghar Najafpoor, Mahmoud Shams and Shahabaldin Rezania

Nanomaterials 2019, 9(10), 1422; https://doi.org/10.3390/nano9101422 - 8 Oct 2019

Cited by 60 | Viewed by 3812

Abstract

Metal-organic frameworks (MOFs) are currently recognized as unique platforms for environmental studies. This study evaluated the potential of nine MOFs from ZIF-8, ZIF-67, and UIO-66 families for the removal of ciprofloxacin (CIP), a toxic, bio-accumulative, and persistent fluoroquinolone antibiotic. ZIF-67-SO₄, with [...] Read more.

Metal-organic frameworks (MOFs) are currently recognized as unique platforms for environmental studies. This study evaluated the potential of nine MOFs from ZIF-8, ZIF-67, and UIO-66 families for the removal of ciprofloxacin (CIP), a toxic, bio-accumulative, and persistent fluoroquinolone antibiotic. ZIF-67-SO₄, with a rhombic crystalline morphology and 1375 m²/g BET surface area, has the highest CIP adsorption efficiency among the studied MOFs. The mathematical sorption model predicted that the highest CIP removal (99.2%) occurs when adsorbent dose, pH, and agitation time are adjusted to 6.82, 832.4 mg/L, and 39.95 min, respectively. Further studies revealed that the CIP adsorbed onto ZIF-67-SO₄ in monolayer (q_max: 2537.5 mg/g) and chemisorption controlled the rate of the process. Mass transfer kinetic coefficients improved significantly by sonication at 35 KHz in comparison with mechanical agitation. Thermodynamic parameters (minus signs of ∆G° [7.8 to 14.2], positive signs of ∆H° (58.9 KJ/mol), and ∆S° (0.23 KJ/mol·K)) demonstrated the spontaneous, endothermic, and chemical sorption of CIP. The level of cobalt leached from ZIF-67-SO₄ structure varied 1.2–4.5 mg/L, depending on pH, mixing time, and agitation type. In conclusion, the excellent adsorption properties of ZIF-67-SO₄ for CIP, made it an outstanding candidate for environmental protection purposes. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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11 pages, 4159 KiB

Open AccessCommunication

Continuous Flow Removal of Anionic Dyes in Water by Chitosan-Functionalized Iron Oxide Nanoparticles Incorporated in a Dextran Gel Column

by Sang Yeob Lee, Ha Eun Shim, Jung Eun Yang, Yong Jun Choi and Jongho Jeon

Nanomaterials 2019, 9(8), 1164; https://doi.org/10.3390/nano9081164 - 14 Aug 2019

Cited by 24 | Viewed by 5269

Abstract

This paper describes a novel chromatographic method for efficient removal of anionic dyes from aqueous solutions. Chitosan-coated Fe₃O₄ nanoparticles can easily be immobilized on a dextran gel column. Single elution of Evans Blue (EB) solution to the nanoadsorbent-incorporated columns provides [...] Read more.

This paper describes a novel chromatographic method for efficient removal of anionic dyes from aqueous solutions. Chitosan-coated Fe₃O₄ nanoparticles can easily be immobilized on a dextran gel column. Single elution of Evans Blue (EB) solution to the nanoadsorbent-incorporated columns provides high removal efficiency with a maximum adsorption capacity of 243.9 mg/g. We also investigated the influence of initial concentration and solution pH on the removal efficiency of EB. The electrostatic interaction between the adsorbent surface and negatively charged sulfate groups on EB molecules promotes the efficient adsorption of dyes. The equilibrium data matched well with the Langmuir isotherm model, which indicated monolayer dye adsorption onto the adsorbent surface. To extend the application of the current method, we performed further adsorption experiments using other anionic dyes of different colors (Cy5.5, Acid Yellow 25, Acid Green 25, and Acid Red 1). All of these molecules can efficiently be captured under continuous flow conditions, with higher removal efficiency obtained with more negatively charged dyes. These findings clearly demonstrate that the present approach is a useful method for the removal of anionic dye contaminants in aqueous media by adsorption. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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12 pages, 7440 KiB

Open AccessArticle

Synthesis of Hierarchical Porous Carbon in Molten Salt and Its Application for Dye Adsorption

by Saisai Li, Haijun Zhang, Shiya Hu, Jie Liu, Qing Zhu and Shaowei Zhang

Nanomaterials 2019, 9(8), 1098; https://doi.org/10.3390/nano9081098 - 31 Jul 2019

Cited by 19 | Viewed by 3765

Abstract

Hierarchical porous carbon was successfully synthesized from glucose in a molten salt at 800 °C for 2 h. It was amorphous and contained numerous oxygen containing functional groups on its surface. The porous carbon with 1.0 wt% Fe(NO₃)₃·9H₂ [...] Read more.

Hierarchical porous carbon was successfully synthesized from glucose in a molten salt at 800 °C for 2 h. It was amorphous and contained numerous oxygen containing functional groups on its surface. The porous carbon with 1.0 wt% Fe(NO₃)₃·9H₂O oxidizing agent showed the highest specific surface area of 1078 m²/g, and the largest pore volume of 0.636 cm³/g, among all of the samples. Raman and TEM results revealed that it had more defects and pores than other as-prepared carbon materials. The adsorption capacities of as-prepared porous carbon for methylene blue (MB) and methyl orange (MO) were 506.8 mg/g and 683.8 mg/g, respectively. The adsorption isotherms fit the Langmuir model and the adsorption kinetics followed the pseudo-second-order kinetic model. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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11 pages, 2628 KiB

Open AccessArticle

Tailoring the Performance of Graphene Aerogels for Oil/Organic Solvent Separation by 1-Step Solvothermal Approach

by Alina Pruna, Alfonso C. Cárcel, Arturo Barjola, Adolfo Benedito and Enrique Giménez

Nanomaterials 2019, 9(8), 1077; https://doi.org/10.3390/nano9081077 - 26 Jul 2019

Cited by 12 | Viewed by 2907

Abstract

Ultra-light eco-friendly graphene oxide (GO)-based aerogels are reported by simple one-step solvothermal self-assembly. The effect of varying parameters such as C/O ratio of GO; reducing agent amount; temperature; and duration on the properties of the aerogels was studied. The structural and vibrational features [...] Read more.

Ultra-light eco-friendly graphene oxide (GO)-based aerogels are reported by simple one-step solvothermal self-assembly. The effect of varying parameters such as C/O ratio of GO; reducing agent amount; temperature; and duration on the properties of the aerogels was studied. The structural and vibrational features and hydrophobic surface properties of the obtained aerogels were obtained by XRD; FTIR; XPS; Raman; SEM; and contact angle measurements. The effect of synthesis conditions on the engine oil and organic solvent absorption properties was assessed. The results indicated that the lower the C/O ratio of GO, the better the absorption properties, with the best performance for oil uptake reaching 86 g g⁻¹. The obtained results indicate the approach based on ice-templating and the tailoring of oxygen content in GO make the resulting aerogels potential candidates for use in oil spill and organic solvent treatments. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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13 pages, 3866 KiB

Open AccessArticle

CoMn₂O₄ Catalyst Prepared Using the Sol-Gel Method for the Activation of Peroxymonosulfate and Degradation of UV Filter 2-Phenylbenzimidazole-5-sulfonic Acid (PBSA)

by Chihao Lin, Dejian Shi, Zhentao Wu, Lingfeng Zhang, Zhicai Zhai, Yingsen Fang, Ping Sun, Ruirui Han, Jiaqiang Wu and Hui Liu

Nanomaterials 2019, 9(5), 774; https://doi.org/10.3390/nano9050774 - 20 May 2019

Cited by 25 | Viewed by 4474

Abstract

In this study, a bimetallic oxide catalyst of cobalt-manganese (CoMn₂O₄) was synthesized using the sol-gel method, and it was then characterized using a variety of techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) [...] Read more.

In this study, a bimetallic oxide catalyst of cobalt-manganese (CoMn₂O₄) was synthesized using the sol-gel method, and it was then characterized using a variety of techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption isotherms. The obtained novel catalyst, i.e., CoMn₂O₄, was then used as an activator of peroxymonosulfate (PMS) for the catalytic degradation of a commonly-used UV filter, 2-phenylbenzimidazole-5-sulfonic acid (PBSA) in water. The effects of various factors (e.g., catalyst dosage, PMS concentration, reaction temperature, and pH) in the process were also evaluated. Chemical scavengers and electron paramagnetic resonance (EPR) tests showed that the ^•OH and SO₄^•− were the main reactive oxygen species. Furthermore, this study showed that CoMn₂O₄ is a promising catalyst for activating PMS to degrade the UV filters. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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Review

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23 pages, 3153 KiB

Open AccessReview

Recent Progress in Heavy Metal Ion Decontamination Based on Metal–Organic Frameworks

by Yajie Chen, Xue Bai and Zhengfang Ye

Nanomaterials 2020, 10(8), 1481; https://doi.org/10.3390/nano10081481 - 29 Jul 2020

Cited by 51 | Viewed by 4943

Abstract

Heavy metals are inorganic pollutants which pose a serious threat to human and environmental safety, and their effective removal is becoming an increasingly urgent issue. Metal–organic frameworks (MOFs) are a novel group of crystalline porous materials, which have proven to be promising adsorbents [...] Read more.

Heavy metals are inorganic pollutants which pose a serious threat to human and environmental safety, and their effective removal is becoming an increasingly urgent issue. Metal–organic frameworks (MOFs) are a novel group of crystalline porous materials, which have proven to be promising adsorbents because of their extremely high surface areas, optimizable pore volumes and pore size distributions. This study is a systematic review of the recent research on the removal of several major heavy metal ions by MOFs. Based on the different structures of MOFs, varying adsorption capacity can be achieved, ranging from tens to thousands of milligrams per gram. Many MOFs have shown a high selectivity for their target metal ions. The corresponding mechanisms involved in capturing metal ions are outlined and finally, the challenges and prospects for their practical application are discussed. Full article

(This article belongs to the Special Issue Nanomaterials and Nanotechnology in Wastewater Treatment)

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