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14 pages, 14049 KiB

Open AccessArticle

Fabrication of Nitrogen Based Magnetic Conjugated Microporous Polymer for Efficient Extraction of Neonicotinoids in Water Samples

by Zhenzhen Xia, Xinghua Teng, Yuqi Cheng, Yujie Huang, Liwen Zheng, Lei Ji and Leilei Wang

Molecules 2024, 29(10), 2189; https://doi.org/10.3390/molecules29102189 - 8 May 2024

Viewed by 128

Abstract

Facile and sensitive methods for detecting neonicotinoids (NEOs) in aquatic environments are crucial because they are found in extremely low concentrations in complex matrices. Herein, nitrogen-based magnetic conjugated microporous polymers (Fe₃O₄@N-CMP) with quaternary ammonium groups were synthesized for efficient [...] Read more.

Facile and sensitive methods for detecting neonicotinoids (NEOs) in aquatic environments are crucial because they are found in extremely low concentrations in complex matrices. Herein, nitrogen-based magnetic conjugated microporous polymers (Fe₃O₄@N-CMP) with quaternary ammonium groups were synthesized for efficient magnetic solid-phase extraction (MSPE) of NEOs from tap water, rainwater, and lake water. Fe₃O₄@N-CMP possessed a suitable specific surface area, extended π-conjugated system, and numerous cationic groups. These properties endow Fe₃O₄@N-CMP with superior extraction efficiency toward NEOs. The excellent adsorption capacity of Fe₃O₄@N-CMP toward NEOs was attributed to its π–π stacking, Lewis acid–base, and electrostatic interactions. The proposed MSPE-HPLC-DAD approach based on Fe₃O₄@N-CMP exhibited a wide linear range (0.1–200 µg/L), low detection limits (0.3–0.5 µg/L), satisfactory precision, and acceptable reproducibility under optimal conditions. In addition, the established method was effectively utilized for the analysis of NEOs in tap water, rainwater, and lake water. Excellent recoveries of NEOs at three spiked levels were in the range of 70.4 to 122.7%, with RSDs less than 10%. This study provides a reliable pretreatment method for monitoring NEOs in environmental water samples. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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30 pages, 13773 KiB

Open AccessArticle

Influence of Hydrothermal Modification on Adsorptive Performance of Clay Minerals for Malachite Green

by Enwen Wang, Teng Huang, Qian Wu, Lanchun Huang, Desong Kong and Hai Wang

Molecules 2024, 29(9), 1974; https://doi.org/10.3390/molecules29091974 - 25 Apr 2024

Viewed by 263

Abstract

Artificially modified adsorbing materials mainly aim to remedy the disadvantages of natural materials as much as possible. Using clay materials such as rectorite, sodium bentonite and metakaolinite (solid waste material) as base materials, hydrothermally modified and unmodified materials were compared. CM-HT and CM [...] Read more.

Artificially modified adsorbing materials mainly aim to remedy the disadvantages of natural materials as much as possible. Using clay materials such as rectorite, sodium bentonite and metakaolinite (solid waste material) as base materials, hydrothermally modified and unmodified materials were compared. CM-HT and CM (adsorbing materials) were prepared and used to adsorb and purify wastewater containing malachite green (MG) dye, and the two materials were characterized through methods such as BET, FT-IR, SEM and XRD. Results: (1) The optimal conditions for hydrothermal modification of CM-HT were a temperature of 150 °C, a time of 2 h, and a liquid/solid ratio 1:20. (2) Hydrothermal modification greatly increased the adsorptive effect. The measured maximum adsorption capacity of CM-HT for MG reached 290.45 mg/g (56.92% higher than that of CM). The theoretical maximum capacity was 625.15 mg/g (186.15% higher than that of CM). (3) Because Al-OH and Si-O-Al groups were reserved in unmodified clay mineral adsorbing materials with good adsorbing activity, after hydrothermal modification, the crystal structure of the clay became loosened along the direction of the c axis, and the interlayer space increased to partially exchange interlayer metal cations connected to the bottom oxygen, giving CM-HT higher electronegativity and creating more crystal defects and chemically active adsorbing sites for high-performance adsorption. (4) Chemical adsorption was the primary way by which CM-HT adsorbed cationic dye, while physical adsorption caused by developed pore canal was secondary. The adsorption reaction occurred spontaneously. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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17 pages, 1762 KiB

Open AccessArticle

A Study on the Adsorption of Rhodamine B onto Adsorbents Prepared from Low-Carbon Fossils: Kinetic, Isotherm, and Thermodynamic Analyses

by Aleksandra Bazan-Wozniak, Aleksandra Jędrzejczak, Robert Wolski, Sławomir Kaczmarek, Agnieszka Nosal-Wiercińska, Judyta Cielecka-Piontek, Sultan Yagmur-Kabas and Robert Pietrzak

Molecules 2024, 29(6), 1412; https://doi.org/10.3390/molecules29061412 - 21 Mar 2024

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Abstract

The aim of this study was to obtain a series of activated carbon samples by the chemical activation of low-rank coal. The precursor was impregnated with a NaOH solution. Activated carbons were characterized by determining their textural parameters and content of surface oxygen [...] Read more.

The aim of this study was to obtain a series of activated carbon samples by the chemical activation of low-rank coal. The precursor was impregnated with a NaOH solution. Activated carbons were characterized by determining their textural parameters and content of surface oxygen functional groups and by using an elemental analysis. The carbons were tested as potential adsorbents for the removal of liquid pollutants represented by rhodamine B. The effectiveness of rhodamine B removal from water solutions depended on the initial concentration of the dye, the mass of rhodamine B, and the pH and temperature of the reaction. The isotherm examination followed the Langmuir isotherm model. The maximum adsorption capacity of the rhodamine B was 119 mg/g. The kinetic investigation favored the pseudo-second-order model, indicating a chemisorption mechanism. The thermodynamic assessment indicated spontaneous and endothermic adsorption, with decreased randomness at the solid–liquid interface. The experiment revealed that a 0.1 M HCl solution was the most effective regenerative agent. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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18 pages, 1575 KiB

Open AccessArticle

Enhanced Sorption Performance of Natural Zeolites Modified with pH-Fractionated Humic Acids for the Removal of Methylene Blue from Water

by Stefano Salvestrini, Jean Debord and Jean-Claude Bollinger

Molecules 2023, 28(20), 7083; https://doi.org/10.3390/molecules28207083 - 14 Oct 2023

Cited by 1 | Viewed by 770

Abstract

This work explores the effect of humic acids (HA) fractionation on the sorption ability of a natural zeolite (NYT)—HA adduct. HA were extracted from compost, fractionated via the pH fractionation method, and characterized via UV-Vis spectroscopy and gel permeation chromatography. The HA samples [...] Read more.

This work explores the effect of humic acids (HA) fractionation on the sorption ability of a natural zeolite (NYT)—HA adduct. HA were extracted from compost, fractionated via the pH fractionation method, and characterized via UV-Vis spectroscopy and gel permeation chromatography. The HA samples were immobilized onto NYT via thermal treatment. The resulting adducts (NYT-HA) were tested for their ability to remove methylene blue (MB) from an aqueous solution. It was found that the sorption performance of NYT-HA strongly depends on the chemical characteristics of humic acids. Sorption capacity increased with the molecular weight and hydrophobicity degree of the HA fractions. Hydrophobic and π–π interactions are likely the primary mechanisms by which MB interacts with HA. The sorption kinetic data conform to the pseudo-second-order model. The Freundlich isotherm model adequately described the sorption equilibrium and revealed that the uptake of MB onto NYT-HA is endothermic in nature. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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15 pages, 1087 KiB

Open AccessArticle

Identification of the Contamination Sources by PCBs Using Multivariate Analyses: The Case Study of the Annaba Bay (Algeria) Basin

by Soumeya Khaled-Khodja, Hassen Cheraitia, Karima Rouibah, Hana Ferkous, Gaël Durand, Semia Cherif, Gamal A. El-Hiti, Krishna Kumar Yadav, Alessandro Erto and Yacine Benguerba

Molecules 2023, 28(19), 6841; https://doi.org/10.3390/molecules28196841 - 28 Sep 2023

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Abstract

Persistent Organic Pollutants (POPs), particularly the indicator polychlorinated biphenyls (PCBs), were first quantified in water and sediments of two wadis, Boujemaâ and Seybouse, as well as in the effluents from a fertilizer and phytosanitary production industrial plant (Fertial). Since these contaminated discharges end [...] Read more.

Persistent Organic Pollutants (POPs), particularly the indicator polychlorinated biphenyls (PCBs), were first quantified in water and sediments of two wadis, Boujemaâ and Seybouse, as well as in the effluents from a fertilizer and phytosanitary production industrial plant (Fertial). Since these contaminated discharges end in Annaba Bay (Algeria) in the Mediterranean Sea, with a significant level of contamination, all the potential sources should be identified. In this work, this task is conducted by a multivariate analysis. Liquid–liquid extraction and gas chromatography/mass spectrometry (GC–MS) methods were applied to quantify seven PCB congeners, usually taken as indicators of contamination. The sum of the PCB concentrations in the sediments ranged from 1 to 6.4 μg/kg dw (dry weight) and up to 0.027 μg/L in waters. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used for the multivariate analysis, indicating that the main sources of PCB emissions in the bay are urban/domestic and agricultural/industrial. The outfalls that mostly contribute to the pollution of the gulf are the Boujemaâ wadi, followed by the Seybouse wadi, and finally by the Fertial cluster and more precisely the annex basin of the plant. Although referring to a specific site of local importance, the work aims to present a procedure and a methodological analysis that can be potentially applicable to further case studies all over the world. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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14 pages, 4808 KiB

Open AccessArticle

Removal of Hexamethyldisiloxane via a Novel Hydrophobic (3–Aminopropyl)Trimethoxysilane-Modified Activated Porous Carbon

by Siqi Lv, Yingrun Wang, Yanhui Zheng and Zichuan Ma

Molecules 2023, 28(18), 6493; https://doi.org/10.3390/molecules28186493 - 7 Sep 2023

Viewed by 943

Abstract

Volatile methyl siloxanes (VMS) must be removed because the formation of silica in the combustion process seriously affects the resource utilization of biogas. Herein, a series of APTMS ((3–aminopropyl)trimethoxysilane)-modified activated porous carbon (APC) adsorbents (named APTMS@APC) were prepared for VMS efficient removal. The [...] Read more.

Volatile methyl siloxanes (VMS) must be removed because the formation of silica in the combustion process seriously affects the resource utilization of biogas. Herein, a series of APTMS ((3–aminopropyl)trimethoxysilane)-modified activated porous carbon (APC) adsorbents (named APTMS@APC) were prepared for VMS efficient removal. The as-prepared adsorbents were characterized using SEM, FTIR, Raman, X-ray diffraction analyses, and N₂ adsorption/desorption. The results showed that the surface modification with APTMS enhanced the hydrophobicity of APC with the water contact angle increasing from 74.3° (hydrophilic) to 127.1° (hydrophobic), and meanwhile improved its texture properties with the S_BET increasing from 981 to 1274 m² g⁻¹. The maximum breakthrough adsorption capacity of APTMS@APC for hexamethyldisiloxane (L2, model pollutant) was 360.1 mg g⁻¹. Effects of an inlet L2 concentration (31.04–83.82 mg L⁻¹) and a bed temperature (0–50 °C) on the removal of L2 were investigated. Meanwhile, after five adsorption–desorption cycles, the APTMS@APC demonstrated a superior cycling performance. This indicated that the hydrophobic APTMS@APC has a great significance to remove VMS. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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20 pages, 4503 KiB

Open AccessArticle

Experimental and Theoretical Estimations of Atrazine’s Adsorption in Mangosteen-Peel-Derived Nanoporous Carbons

by Juan Matos, Claudia P. Amézquita-Marroquín, Johan D. Lozano, Jhon Zapata-Rivera, Liliana Giraldo, Po S. Poon and Juan C. Moreno-Piraján

Molecules 2023, 28(13), 5268; https://doi.org/10.3390/molecules28135268 - 7 Jul 2023

Viewed by 942

Abstract

Nanoporous carbons were prepared via chemical and physical activation from mangosteen-peel-derived chars. The removal of atrazine was studied due to the bifunctionality of the N groups. Pseudo-first-order, pseudo-second-order, and intraparticle pore diffusion kinetic models were analyzed. Adsorption isotherms were also analyzed according to [...] Read more.

Nanoporous carbons were prepared via chemical and physical activation from mangosteen-peel-derived chars. The removal of atrazine was studied due to the bifunctionality of the N groups. Pseudo-first-order, pseudo-second-order, and intraparticle pore diffusion kinetic models were analyzed. Adsorption isotherms were also analyzed according to the Langmuir and Freundlich models. The obtained results were compared against two commercially activated carbons with comparable surface chemistry and porosimetry. The highest uptake was found for carbons with higher content of basic surface groups. The role of the oxygen-containing groups in the removal of atrazine was estimated experimentally using the surface density. The results were compared with the adsorption energy of atrazine theoretically estimated on pristine and functionalized graphene with different oxygen groups using periodic DFT methods. The energy of adsorption followed the same trend observed experimentally, namely the more basic the pH, the more favored the adsorption of atrazine. Micropores played an important role in the uptake of atrazine at low concentrations, but the presence of mesoporous was also required to inhibit the pore mass diffusion limitations. The present work contributes to the understanding of the interactions between triazine-based pollutants and the surface functional groups on nanoporous carbons in the liquid–solid interface. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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17 pages, 3190 KiB

Open AccessArticle

Untreated Opuntia ficus indica for the Efficient Adsorption of Ni(II), Pb(II), Cu(II) and Cd(II) Ions from Water

by Marcella Barbera, Serena Indelicato, David Bongiorno, Valentina Censi, Filippo Saiano and Daniela Piazzese

Molecules 2023, 28(9), 3953; https://doi.org/10.3390/molecules28093953 - 8 May 2023

Cited by 2 | Viewed by 1610

Abstract

The raw cladode of Opuntia ficus indica (OFI) was evaluated as a sustainable biosorbent for the removal of heavy metals (Ni, Pb, Cu, and Cd) from aqueous solutions. The functional groups of OFI were identified by employing DRIFT-FTIR and CP-MAS-NMR techniques before and [...] Read more.

The raw cladode of Opuntia ficus indica (OFI) was evaluated as a sustainable biosorbent for the removal of heavy metals (Ni, Pb, Cu, and Cd) from aqueous solutions. The functional groups of OFI were identified by employing DRIFT-FTIR and CP-MAS-NMR techniques before and after contact with the ions in an aqueous media, showing a rearrangement of the biomass structure due to the complexation between the metal and the functional groups. The adsorption process was studied in both single- and multi-component systems under batch conditions at different pHs (4.0, 5.0, and 6.0), different metal concentrations, and different biomass amounts. The results show that the raw OFI had a removal capacity at room temperature of over 80% for all metals studied after only 30 min of contact time, indicating a rapid adsorption process. Biosorption kinetics were successfully fitted by the pseudo-second-order equation, while Freundlich correctly modelled the biosorption data at equilibrium. The results of this work highlight the potential use of the untreated cladode of OFI as an economical and environmentally friendly biosorbent for the removal of heavy metals from the contaminated aqueous solution. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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Review

Jump to: Research

24 pages, 2417 KiB

Open AccessReview

Application of Electrochemical Oxidation for Water and Wastewater Treatment: An Overview

by Mohammad Saleh Najafinejad, Simeone Chianese, Angelo Fenti, Pasquale Iovino and Dino Musmarra

Molecules 2023, 28(10), 4208; https://doi.org/10.3390/molecules28104208 - 20 May 2023

Cited by 11 | Viewed by 3616

Abstract

In recent years, the discharge of various emerging pollutants, chemicals, and dyes in water and wastewater has represented one of the prominent human problems. Since water pollution is directly related to human health, highly resistant and emerging compounds in aquatic environments will pose [...] Read more.

In recent years, the discharge of various emerging pollutants, chemicals, and dyes in water and wastewater has represented one of the prominent human problems. Since water pollution is directly related to human health, highly resistant and emerging compounds in aquatic environments will pose many potential risks to the health of all living beings. Therefore, water pollution is a very acute problem that has constantly increased in recent years with the expansion of various industries. Consequently, choosing efficient and innovative wastewater treatment methods to remove contaminants is crucial. Among advanced oxidation processes, electrochemical oxidation (EO) is the most common and effective method for removing persistent pollutants from municipal and industrial wastewater. However, despite the great progress in using EO to treat real wastewater, there are still many gaps. This is due to the lack of comprehensive information on the operating parameters which affect the process and its operating costs. In this paper, among various scientific articles, the impact of operational parameters on the EO performances, a comparison between different electrochemical reactor configurations, and a report on general mechanisms of electrochemical oxidation of organic pollutants have been reported. Moreover, an evaluation of cost analysis and energy consumption requirements have also been discussed. Finally, the combination process between EO and photocatalysis (PC), called photoelectrocatalysis (PEC), has been discussed and reviewed briefly. This article shows that there is a direct relationship between important operating parameters with the amount of costs and the final removal efficiency of emerging pollutants. Optimal operating conditions can be achieved by paying special attention to reactor design, which can lead to higher efficiency and more efficient treatment. The rapid development of EO for removing emerging pollutants from impacted water and its combination with other green methods can result in more efficient approaches to face the pressing water pollution challenge. PEC proved to be a promising pollutants degradation technology, in which renewable energy sources can be adopted as a primer to perform an environmentally friendly water treatment. Full article

(This article belongs to the Special Issue Chemical Technologies for Environmental Analysis and Pollution Removal)

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