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11 pages, 3901 KiB

Open AccessArticle

Coupling Removal of P-Chloronitrobenzene and Its Reduction Products by Nano Iron Doped with Ni and FeOOH (nFe/Ni-FeOOH)

by Jing Liang, Zhixue Li, Emmanuella Anang, Hong Liu and Xianyuan Fan

Materials 2022, 15(5), 1928; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15051928 - 04 Mar 2022

Cited by 2 | Viewed by 1322

The removal of chlorinated pollutants from water by nanoparticles is a hot topic in the field of environmental engineering. In this work, a novel technique that includes the coupling effect of n-Fe/Ni and its transformation products (FeOOH) on the removal of p-chloronitrobenzene (p-CNB) [...] Read more.

The removal of chlorinated pollutants from water by nanoparticles is a hot topic in the field of environmental engineering. In this work, a novel technique that includes the coupling effect of n-Fe/Ni and its transformation products (FeOOH) on the removal of p-chloronitrobenzene (p-CNB) and its reduction products, p-chloroaniline (p-CAN) and aniline (AN), were investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed to characterize the nano-iron before and after the reaction. The results show that Fe⁰ is mainly oxidized into lath-like lepidocrocite (γ-FeOOH) and needle-like goethite (α-FeOOH) after 8 h of reaction. The coupling removal process and the mechanism are as follows: Fe⁰ provides electrons to reduce p-CNB to p-CAN and then dechlorinates p-CAN to AN under the catalysis of Ni. Meanwhile, Fe⁰ is oxidized to FeOOH by the dissolved oxygen and H₂O. AN is then adsorbed by FeOOH. Finally, p-CNB, p-CAN, and AN were completely removed from the water. In the pH range between 3 and 7, p-CAN can be completely dechlorinated by n-Fe/Ni within 20 min, while AN can be nearly 100% adsorbed by FeOOH within 36 h. When the temperature ranges from 15 °C to 35 °C, the dechlorination rate of p-CAN and the removal rate of AN are less affected by temperature. This study provides guidance on the thorough remediation of water bodies polluted by chlorinated organics. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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16 pages, 4579 KiB

Open AccessArticle

Adsorption of Copper (II) from Aqueous Solutions with Alginate/Clay Hybrid Materials

by Maria Râpă, Anca Andreea Ţurcanu, Ecaterina Matei, Andra Mihaela Predescu, Mircea Cristian Pantilimon, George Coman and Cristian Predescu

Materials 2021, 14(23), 7187; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14237187 - 25 Nov 2021

Cited by 11 | Viewed by 1750

Abstract

Massive amounts of industrial and agricultural water around the world are polluted by various types of contaminants that harm the environment and affect human health. Alginic acid is a very versatile green polymer used for heavy metal adsorption due to its availability, biocompatibility, [...] Read more.

Massive amounts of industrial and agricultural water around the world are polluted by various types of contaminants that harm the environment and affect human health. Alginic acid is a very versatile green polymer used for heavy metal adsorption due to its availability, biocompatibility, low cost, and non-toxic characteristics. The aim of this paper was to prepare new low-cost hybrid composite beads using sodium alginate with treated montmorillonite and kaolin for the adsorption of copper (Cu) cations. Modified and unmodified clays were investigated by studying their morphology and elemental composition, functional groups, and mean particle size and particle size distribution. The characterization of alginate/clay hybrid composite beads was carried out by evaluating surface morphology (by scanning electron microscopy, SEM), crystallinity (by X-ray diffraction, XRD), and point of zero charge (pH_pzc)(Zeta Potential Analyzer). Batch adsorption experiments of alginate/clay hybrid composite beads investigated the effect of metal concentration in the range of 1–4 mg L⁻¹ on Cu(II) removal, adsorption kinetic for maximum 240 min, and Langmuir and Freundlich adsorption isotherms by using atomic absorption spectrometry. The pseudo-second-order kinetic model best fitted the adsorption for alginate/montmorillonite beads (R² = 0.994), while the diffusion process was predominant for montmorillonite/kaolin beads (R² = 0.985). The alginate/clay hybrid materials best fitted the Langmuir isotherm model. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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16 pages, 9640 KiB

Open AccessEditor’s ChoiceArticle

Novel Adsorbent Based on Banana Peel Waste for Removal of Heavy Metal Ions from Synthetic Solutions

by Mihai Negroiu, Anca Andreea Țurcanu, Ecaterina Matei, Maria Râpă, Cristina Ileana Covaliu, Andra Mihaela Predescu, Cristian Mircea Pantilimon, George Coman and Cristian Predescu

Materials 2021, 14(14), 3946; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14143946 - 14 Jul 2021

Cited by 21 | Viewed by 3369

Abstract

Due to its valuable compounds, food waste has been gaining attention in different applications, such as life quality and environment. Combined with circular economy requirements, a valorization method for waste, especially banana waste, was to convert them into adsorbents with advanced properties. The [...] Read more.

Due to its valuable compounds, food waste has been gaining attention in different applications, such as life quality and environment. Combined with circular economy requirements, a valorization method for waste, especially banana waste, was to convert them into adsorbents with advanced properties. The banana waste, after thermal treatment, was used with high removal performances (100%) for the removal of heavy metals, such as Cr, Cu, Pb, and Zn, but their small particle size makes them very hard to recover and reuse. For this reason, a biopolymeric matrix was used to incorporate the banana waste. The matrix was chosen for its remarkable properties, such as low cost, biodegradability, low carbon footprint, and reduced environmental impact. In this research, different types of materials (simple banana peel ash BPA and combined with biopolymeric matrix, ALG–BPA, CS–BPA) were prepared, characterized, and tested. The materials were characterized by means of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), optical microscopy (OM), scanning electron microscopy (SEM), and tested for the removal of metal ions from synthetic solutions using atomic absorption spectroscopy (AAS). The ALG–BPA material proved to be the most efficient in the removal of heavy metal ions from synthetic solution, reaching even 100% metal removal for Cr, Fe, Pb, and Zn, while the CS-based materials were the least efficient, presenting the best values for Cr and Fe ions with a removal efficiency of 34.14% and 28.38%, respectively. By adding BPA to CS, the adsorption properties of the material were slightly improved, but also only for Cr and Fe ions, to 37.09% and 57.78%. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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11 pages, 809 KiB

Open AccessArticle

Magnetite Oxide Nanomaterial Used for Lead Ions Removal from Industrial Wastewater

by Oana Stoian, Cristina Ileana Covaliu, Gigel Paraschiv, Gina-Alina Catrina (Traistaru), Mihai Niță-Lazăr, Ecaterina Matei, Sorin Ștefan Biriş and Paula Tudor

Materials 2021, 14(11), 2831; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14112831 - 25 May 2021

Cited by 18 | Viewed by 2109

Abstract

The aim of this article is to present a nonconventional method for the efficient removal of lead ions from industrial wastewater. For this purpose, magnetite nanomaterial was used, which was very easily separated from the wastewater at the end of the treatment due [...] Read more.

The aim of this article is to present a nonconventional method for the efficient removal of lead ions from industrial wastewater. For this purpose, magnetite nanomaterial was used, which was very easily separated from the wastewater at the end of the treatment due to its magnetic properties. Currently, nanotechnology is an efficient and inexpensive manner that is being researched for wastewater treatment. Additionally, iron oxide nanoparticles are widely used to remove heavy metal ions from water due to their special properties. The experimental results detailed in this article show the influence of pH and contact time on the process of adsorption of lead ions from wastewater. The magnetite nanomaterial had its maximum efficiency of speed when the wastewater had pH 6. At a lower pH, the highest treatment efficiency was over 85%, and the required contact time has doubled. When the pH increases above 6, the precipitation process occurs. Langmuir and Freundlich models were used to describe the adsorption process. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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16 pages, 5301 KiB

Open AccessArticle

An Innovative Method of Converting Ferrous Mill Scale Wastes into Superparamagnetic Nanoadsorbents for Water Decontamination

by Andra Mihaela Predescu, Ecaterina Matei, Andrei Constantin Berbecaru, Maria Râpă, Mirela Gabriela Sohaciu, Cristian Predescu and Ruxandra Vidu

Materials 2021, 14(10), 2539; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14102539 - 13 May 2021

Cited by 9 | Viewed by 1991

Abstract

The need to recycle and develop nanomaterials from waste, and use them in environmental applications has become increasingly imperative in recent decades. A new method to convert the mill scale, a waste of the steel industry that contains large quantity of iron and [...] Read more.

The need to recycle and develop nanomaterials from waste, and use them in environmental applications has become increasingly imperative in recent decades. A new method to convert the mill scale, a waste of the steel industry that contains large quantity of iron and low impurities into a nanoadsorbent that has the necessary properties to be used for water purification is presented. The mill scale waste was used as raw material for iron oxide nanopowder. A thorough characterization was performed in each stage of the conversion process from the mill scale powder to magnetic nanopowder including XRD (X-ray diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), BET (Brunauer, Emmett and Teller) and magnetization properties. Iron oxide nanoparticles were approximately 5–6 nm with high specific surface area and good magnetic properties. These are the necessary properties that a magnetic nanopowder must have in order to be used as nanoadsorbents in the heavy metal removal from waters. The iron oxide nanoparticles were evaluated as adsorbents for the removal of Cu, Cd and Ni ions. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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17 pages, 57598 KiB

Open AccessEditor’s ChoiceArticle

Synthesis and Characterization of Novel Hybrid Flocculants Based on Potato Starch Copolymers with Hollow Carbon Spheres

by Beata Schmidt, Krzysztof Kowalczyk and Beata Zielinska

Materials 2021, 14(6), 1498; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14061498 - 18 Mar 2021

Cited by 4 | Viewed by 1738

Abstract

Novel carbon nanofiller-based starch-g-polyacrylamide hybrid flocculation materials (St-PAM-CS) were in situ prepared using potato starch (St), acrylamide (AM), and hollow mesoporous carbon spheres (CSs; diameters of 300–400 nm). Structures of different St-PAM-CS systems were characterized by Fourier transform infrared (FTIR) spectroscopy, X-Ray diffraction [...] Read more.

Novel carbon nanofiller-based starch-g-polyacrylamide hybrid flocculation materials (St-PAM-CS) were in situ prepared using potato starch (St), acrylamide (AM), and hollow mesoporous carbon spheres (CSs; diameters of 300–400 nm). Structures of different St-PAM-CS systems were characterized by Fourier transform infrared (FTIR) spectroscopy, X-Ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), laser scanning microscopy (LSM), and particle size analysis. The flocculation tests were evaluated by removing high turbidity kaolin suspension—initial absorbance 1.84. The effect of the St to AM molar ratio, doses, and content of CSs in hybrids on flocculation efficiency were examined. Satisfactory flocculation efficiency was obtained for all hybrids with 1 wt.% of the CS component. The highest reduction of the kaolin suspension absorbance (to 0.06) was observed for a 3 mL dose of the starch hybrid with the highest AM content. Additionally, St-PAM-CS showed a reduction in the sludge volume in time. The hybrids reached better flocculation efficiency in relation to the reference systems without CSs. The proposed flocculation mechanism (considering bridging, patching, and formation of hydrogen bonds) has been confirmed by the recorded results. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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Review

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27 pages, 1243 KiB

Open AccessEditor’s ChoiceReview

Valorization of Agri-Food Wastes as Sustainable Eco-Materials for Wastewater Treatment: Current State and New Perspectives

by Ecaterina Matei, Maria Râpă, Andra Mihaela Predescu, Anca Andreea Țurcanu, Ruxandra Vidu, Cristian Predescu, Constantin Bobirica, Liliana Bobirica and Cristina Orbeci

Materials 2021, 14(16), 4581; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14164581 - 15 Aug 2021

Cited by 23 | Viewed by 3846

Abstract

The paper addresses environmental protection by valorizing an important agri-food waste category, namely fruit and vegetables with focusing on the main characteristics regarding consumption, waste quantities, and ways for valorizing these materials. Thus, vast research was undertaken in order to emphasize the main [...] Read more.

The paper addresses environmental protection by valorizing an important agri-food waste category, namely fruit and vegetables with focusing on the main characteristics regarding consumption, waste quantities, and ways for valorizing these materials. Thus, vast research was undertaken in order to emphasize the main commodities and their potential application as adsorbents for organic and inorganic pollutants. The main methods or treatment techniques applied for the valorization of eco-materials as adsorbents were presented and the principal efficiency results were indicated. The advantages and disadvantages of using these eco-materials as adsorbents in wastewater treatment were revealed and future recommendations were established. According to the international statistics, the most purchased and consumed five commodities were studied regarding waste generations as potential conversion into eco-materials with an adsorbent role for water pollutants. Thus, the performances for adsorbents based on fruit wastes (such as citrus, banana, apples, grapes, mango) and vegetable wastes (such as potatoes, tomatoes, cabbage, carrots, cauliflower, and/or broccoli) were studied and highlighted in this research. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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29 pages, 2950 KiB

Open AccessEditor’s ChoiceReview

Polyelectrolyte Multilayers: An Overview on Fabrication, Properties, and Biomedical and Environmental Applications

by Larisa-Maria Petrila, Florin Bucatariu, Marcela Mihai and Carmen Teodosiu

Materials 2021, 14(15), 4152; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14154152 - 26 Jul 2021

Cited by 35 | Viewed by 4083

Abstract

Polyelectrolyte multilayers are versatile materials that are used in a large number of domains, including biomedical and environmental applications. The fabrication of polyelectrolyte multilayers using the layer-by-layer technique is one of the simplest methods to obtain composite functional materials. The properties of the [...] Read more.

Polyelectrolyte multilayers are versatile materials that are used in a large number of domains, including biomedical and environmental applications. The fabrication of polyelectrolyte multilayers using the layer-by-layer technique is one of the simplest methods to obtain composite functional materials. The properties of the final material can be easily tuned by changing the deposition conditions and the used building blocks. This review presents the main characteristics of polyelectrolyte multilayers, the fabrication methods currently used, and the factors influencing the layer-by-layer assembly of polyelectrolytes. The last section of this paper presents some of the most important applications of polyelectrolyte multilayers, with a special focus on biomedical and environmental applications. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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29 pages, 509 KiB

Open AccessReview

Chitosan-Based Nanocomposite Polymeric Membranes for Water Purification—A Review

by Angela Spoială, Cornelia-Ioana Ilie, Denisa Ficai, Anton Ficai and Ecaterina Andronescu

Materials 2021, 14(9), 2091; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14092091 - 21 Apr 2021

Cited by 46 | Viewed by 6059

Abstract

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding [...] Read more.

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding diverse materials used in developing innovative chitosan-based nanocomposite polymeric membranes for water purification. The first part of the review presents a detailed introduction about chitosan, highlighting the fact that is a biocompatible, biodegradable, low-cost, nontoxic biopolymer, having unique structure and interesting properties, and also antibacterial and antioxidant activities, reasons for using it in water treatment applications. To use chitosan-based materials for developing nanocomposite polymeric membranes for wastewater purification applications must enhance their performance by using different materials. In the second part of the review, the performance’s features will be presented as a consequence of adding different nanoparticles, also showing the effect that those nanoparticles could bring on other polymeric membranes. Among these features, pollutant’s retention and enhancing thermo-mechanical properties will be mentioned. The focus of the third section of the review will illustrate chitosan-based nanocomposite as polymeric membranes for water purification. Over the last few years, researchers have demonstrated that adsorbent nanocomposite polymeric membranes are powerful, important, and potential instruments in separation or removal of pollutants, such as heavy metals, dyes, and other toxic compounds presented in water systems. Lastly, we conclude this review with a summary of the most important applications of chitosan-based nanocomposite polymeric membranes and their perspectives in water purification. Full article

(This article belongs to the Special Issue Advanced Eco-Technology and Materials in Water Treatment)

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