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Adsorbents in Treatment of Pollutants
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Adsorbents in Treatment of Pollutants

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: 15 June 2024 | Viewed by 9077

Special Issue Editor

Prof. Dr. Wei Wang

E-Mail Website
Guest Editor
1. College of Mathematics and Physics, Beijing University of Chemical Technology, Beijing 100029, China
2. Beijing Key Laboratory of Environmentally Harmful Chemical Analysis, Beijing University of Chemical Technology, Beijing 100029, China
Interests: adsorbents; catalysis; microwave absorption; low-dimensional materials; magnetic nanomaterials

Special Issue Information

Dear Colleagues,

Water pollution has been a serious and widespread environmental problem for decades. Owing to low degradability, high toxicity, and easy dispersibility, pollutants in the water bring serious problems of environmental pollution, cause severe health problems for human beings, and lead to the destruction of aquatic ecosystems. Thus, the highly efficient removal of toxic pollutants in the water environment is becoming particularly urgent. To date, various physical, chemical, and biological approaches have been adopted to address water pollutants, including adsorption, photocatalysis, filtration, anion exchange, chemical flocculation, and biodegradation. Among all the technologies, adsorption has attracted much more attention in the removal of pollutants due to its good economic efficiency, high performance, and environmental friendliness. Correspondingly, the design and preparation of high-performance adsorbents appears to be particularly critical.

The main objective of this Special Issue is to highlight the recent advances in the development and design of new adsorbents with superior adsorption ability for the removal of the various pollutants in the environment, which may involve new preparation methods, material designs, characterization techniques, analyses of the adsorption mechanisms and the adsorption capacity of various pollutants.

Prof. Dr. Wei Wang
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • adsorbents
  • pollutants
  • water treatment
  • adsorption mechanism
  • synthesis
  • charaterization
  • adsorption kinetics
  • adsorption thermodynamics

Published Papers (8 papers)

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Research

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19 pages, 5807 KiB  
Article
Significant Differences in the Effects of Nitrogen Doping on Pristine Biochar and Graphene-like Biochar for the Adsorption of Tetracycline
by Lingling Rong, Ligui Wu, Tiao Zhang, Cui Hu, Haihui Tang, Hongcheng Pan and Xiaoming Zou
Molecules 2024, 29(1), 173; https://doi.org/10.3390/molecules29010173 - 27 Dec 2023
Cited by 1 | Viewed by 887
Abstract
To improve the adsorption efficiency of pollutants by biochar, preparing graphene-like biochar (GBC) or nitrogen-doped biochar are two commonly used methods. However, the difference in the nitrogen doping (N-doping) effects upon the adsorption of pollutants by pristine biochar (PBC) and GBC, as well [...] Read more.
To improve the adsorption efficiency of pollutants by biochar, preparing graphene-like biochar (GBC) or nitrogen-doped biochar are two commonly used methods. However, the difference in the nitrogen doping (N-doping) effects upon the adsorption of pollutants by pristine biochar (PBC) and GBC, as well as the underlying mechanisms, are still unclear. Take the tetracycline (TC) as an example, the present study analyzed the characteristics of the adsorption of TCs on biochars (PBC, GBC, N-PBC, N-GBC), and significant differences in the effects of N-doping on the adsorption of TCs by PBC and GBC were consistently observed at different solution properties. Specifically, N-doping had varied effects on the adsorption performance of PBC, whereas it uniformly improved the adsorption performance of GBC. To interpret the phenomenon, the N-doping upon the adsorption was revealed by the QSAR model, which indicated that the pore filling (VM) and the interactions between TCs with biochars (Ead-v) were found to be the most important two factors. Furthermore, the density functional theory (DFT) results demonstrated that N-doping slightly affects biochar’s chemical reactivity. The van der Waals (vdWs) and electrostatic interactions are the main forces for TCs-biochars interactions. Moreover, N-doping mostly strengthened the electrostatic interactions of TCs-biochars, but the vdWs interactions of most samples remained largely unaffected. Overall, the revealed mechanism of N-doping on TCs adsorption by biochars will enhance our knowledge of antibiotic pollution remediation. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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18 pages, 6141 KiB  
Article
Construction of Ketoenamine-Based Covalent Organic Frameworks with Electron-Rich Sites for Efficient and Rapid Removal of Iodine from Solution
by Qi Tao, Xiao Zhang, Liping Jing, Lu Sun and Peipei Dang
Molecules 2023, 28(24), 8151; https://doi.org/10.3390/molecules28248151 - 18 Dec 2023
Viewed by 991
Abstract
Porous covalent organic frameworks (COFs) have been widely used for the efficient removal of iodine from solution due to their abundance of electron-rich sites. In this study, two kinds of ketoenamine-based COFs, TpBD-(OMe)2 and TpBD-Me2, are successfully synthesized via Schiff [...] Read more.
Porous covalent organic frameworks (COFs) have been widely used for the efficient removal of iodine from solution due to their abundance of electron-rich sites. In this study, two kinds of ketoenamine-based COFs, TpBD-(OMe)2 and TpBD-Me2, are successfully synthesized via Schiff base reaction under solvothermal conditions using 1, 3, 5-triformylphoroglucinol as aldehyde monomer, o-tolidine and o-dianisidine as amino monomers. The ability of TpBD-(OMe)2 and TpBD-Me2 to adsorb iodine in cyclohexane or aqueous solutions has been quantitatively analyzed and interpreted in terms of adsorption sites. TpBD-Me2 possesses two adsorption sites, -NH- and -C=O, and exhibits an adsorption capacity of 681.67 mg/g in cyclohexane, with an initial adsorption rate of 0.6 g/mol/min with respect to COF unit cell. The adsorption capacity of TpBD-(OMe)2 can be as high as 728.77 mg/g, and the initial adsorption rate of TpBD-(OMe)2 can reach 1.2 g/mol/min in the presence of oxygen atoms between the methyl group and the benzene ring. Compared with TpBD-Me2, the higher adsorption capacity and adsorption rate of TpBD-(OMe)2 towards iodine are not only reflected in organic solvents, but also in aqueous solutions. It is proven through X-ray photoelectron spectroscopy and Raman spectroscopy that iodine exists in the form of I2, I3−, and I5− within TpBD-(OMe)2 and TpBD-Me2 after adsorption. This work not only expands the application of COFs in the field of iodine adsorption, but also provides research ideas and important an experimental basis for the optimization of iodine adsorption sites. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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14 pages, 2356 KiB  
Article
A Carboxyl Group-Functionalized Ionic Liquid Hybrid Adsorbent for Solid-Phase Extraction and Determination of Trace Diclofenac Sodium in Milk Samples
by Hongrui Yang, Chen Wang, Wenjuan Zhu, Pingning Jin, Fei Li and Jing Fan
Molecules 2023, 28(17), 6216; https://doi.org/10.3390/molecules28176216 - 24 Aug 2023
Cited by 1 | Viewed by 745
Abstract
A simple and efficient sample pretreatment technology is very important for the accurate determination of trace drug residues in foods to ensure food safety. Herein, we report a new carboxyl group-functionalized ionic liquid hybrid solid- phase adsorbent (PS-IL-COOH) for the highly efficient extraction [...] Read more.
A simple and efficient sample pretreatment technology is very important for the accurate determination of trace drug residues in foods to ensure food safety. Herein, we report a new carboxyl group-functionalized ionic liquid hybrid solid- phase adsorbent (PS-IL-COOH) for the highly efficient extraction and quantitative determination of diclofenac sodium (DS) residue in milk samples. It was found that the adsorption efficiency of PS-IL-COOH for the ppb level of DS was greater than 93.0%, the adsorption capacity was 934.1 mg/g, and the enrichment factor was 620.0, which surpass most of the previously reported values for DS adsorbents. The high concentration of salts did not interfere with the adsorption of DS. Importantly, the recovery of DS was above 90% after 16 adsorption–-regeneration cycles. The synergistic effect of the multiple interactions was found to be the main factor for the high efficiency of DS adsorption. The proposed method was applied to the extraction and detection of DS in milk samples, with the relative recovery ranging from 88.2 to 103.0%. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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13 pages, 5788 KiB  
Article
Electron-Rich Triazine-Conjugated Microporous Polymers for the Removal of Dyes from Wastewater
by Bao-Ning Li, Xing-Long Zhang, Xiao-Hui Bai, Zhen-Jie Liang, Jian Li and Xiao-Yong Fan
Molecules 2023, 28(12), 4785; https://doi.org/10.3390/molecules28124785 - 15 Jun 2023
Cited by 1 | Viewed by 1051
Abstract
Conjugated microporous polymers (CMP) as porous functional materials have received considerable attention due to their unique structures and fascinating properties for the adsorption and degradation of dyes. Herein, a triazine-conjugated microporous polymer material with rich N-donors at the skeleton itself was successfully synthesized [...] Read more.
Conjugated microporous polymers (CMP) as porous functional materials have received considerable attention due to their unique structures and fascinating properties for the adsorption and degradation of dyes. Herein, a triazine-conjugated microporous polymer material with rich N-donors at the skeleton itself was successfully synthesized via the Sonogashira–Hagihara coupling by a one–pot reaction. These two polymers had Brunauer–Emmett–Teller (BET) surface areas of 322 and 435 m2g−1 for triazine-conjugated microporous polymers (T-CMP) and T-CMP-Me, respectively. Due to the porous effects and the rich N-donor at the framework, it displayed a higher removal efficiency and adsorption performance compared to cationic-type dyes and selectivity properties for (methylene blue) MB+ from a mixture solution of cationic-type dyes. Furthermore, the T-CMP-Me could quickly and drastically separate MB+ and (methyl orange) MO− from the mixed solution within a short time. Their intriguing absorption behaviors are supported by 13C NMR, UV−vis absorption spectroscopy, scanning electron microscopy, and X-ray powder diffraction studies. This work will not only improve the development of porous material varieties, but also demonstrate the adsorption or selectivity of porous materials for dyes from wastewater. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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15 pages, 3504 KiB  
Article
β-CD-Induced Precipitation of Eriochrome Black T Recovered via CTAB-Assisted Foam Fractionation for Adsorption of Trace Cu(II)
by Yunkang Chang, Chengsong Cao, Yuhuan Li, Yitong Yin, Yangjing Liu, Rui Li and Yimin Zhu
Molecules 2023, 28(12), 4619; https://doi.org/10.3390/molecules28124619 - 07 Jun 2023
Cited by 1 | Viewed by 842
Abstract
In order to remove and reuse the ecotoxic dye Eriochrome black T (EBT) from dyeing wastewater, we used a process called cetyltrimethylammonium bromide (CTAB)-assisted foam fractionation. By optimizing this process with response surface methodology, we achieved an enrichment ratio of 110.3 ± 3.8 [...] Read more.
In order to remove and reuse the ecotoxic dye Eriochrome black T (EBT) from dyeing wastewater, we used a process called cetyltrimethylammonium bromide (CTAB)-assisted foam fractionation. By optimizing this process with response surface methodology, we achieved an enrichment ratio of 110.3 ± 3.8 and a recovery rate of 99.1 ± 0.3%. Next, we prepared composite particles by adding β-cyclodextrin (β-CD) to the foamate obtained through foam fractionation. These particles had an average diameter of 80.9 μm, an irregular shape, and a specific surface area of 0.15 m2/g. Using these β-CD-CTAB-EBT particles, we were able to effectively remove trace amounts of Cu2+ ions (4 mg/L) from the wastewater. The adsorption of these ions followed pseudo-second-order kinetics and Langmuir isotherm models, and the maximal adsorption capacities at different temperatures were 141.4 mg/g at 298.15 K, 143.1 mg/g at 308.15 K, and 144.5 mg/g at 318.15 K. Thermodynamic analysis showed that the mechanism of Cu2+ removal via β-CD-CTAB-EBT was spontaneous and endothermic physisorption. Under the optimized conditions, we achieved a removal ratio of 95.3 ± 3.0% for Cu2+ ions, and the adsorption capacity remained at 78.3% after four reuse cycles. Overall, these results demonstrate the potential of β-CD-CTAB-EBT particles for the recovery and reuse of EBT in dyeing wastewater. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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21 pages, 6040 KiB  
Article
Pb(II) Uptake from Polluted Irrigation Water Using Anatase TiO2 Nanoadsorbent
by Miguel A. Vasquez-Caballero, Yamerson Canchanya-Huaman, Angie F. Mayta-Armas, Jemina Pomalaya-Velasco, Noemi-Raquel Checca-Huaman, Yéssica Bendezú-Roca and Juan A. Ramos-Guivar
Molecules 2023, 28(12), 4596; https://doi.org/10.3390/molecules28124596 - 07 Jun 2023
Cited by 1 | Viewed by 1582
Abstract
The adsorption characteristics of titanium dioxide nanoparticles (nano-TiO2) for the removal of Pb(II) from irrigation water were investigated in this work. To accomplish this, several adsorption factors, such as contact time and pH, were tested to assess adsorption efficiencies and mechanisms. [...] Read more.
The adsorption characteristics of titanium dioxide nanoparticles (nano-TiO2) for the removal of Pb(II) from irrigation water were investigated in this work. To accomplish this, several adsorption factors, such as contact time and pH, were tested to assess adsorption efficiencies and mechanisms. Before and after the adsorption experiments, commercial nano-TiO2 was studied using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The outcomes showed that anatase nano-TiO2 was remarkably efficient in cleaning Pb(II) from water, with a removal efficiency of more than 99% after only one hour of contact time at a pH of 6.5. Adsorption isotherms and kinetic adsorption data matched the Langmuir and Sips models quite well, showing that the adsorption process occurred at homogenous sites on the surface of nano-TiO2 by forming a Pb(II) adsorbate monolayer. The XRD and TEM analysis of nano-TiO2 following the adsorption procedure revealed a non-affected single phase (anatase) with crystallite sizes of 9.9 nm and particle sizes of 22.46 nm, respectively. According to the XPS data and analyzed adsorption data, Pb ions accumulated on the surface of nano-TiO2 through a three-step mechanism involving ion exchange and hydrogen bonding mechanisms. Overall, the findings indicate that nano-TiO2 has the potential to be used as an effective and long-lasting mesoporous adsorbent in the treatment and cleaning of Pb(II) from water bodies. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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16 pages, 2892 KiB  
Article
Simple Co-Precipitation of Iron Minerals for the Removal of Phenylarsonic Acid: Insights into the Adsorption Performance and Mechanism
by Lili Wang, Changchao Hu, Ze Yang, Songding Guo, Tingting Zhang and Shangyi Li
Molecules 2023, 28(8), 3448; https://doi.org/10.3390/molecules28083448 - 13 Apr 2023
Viewed by 1388
Abstract
In this study, three kinds of iron minerals, ferrihydrite, hematite, and goethite, were prepared by a simple coprecipitation method for the adsorption and removal of phenylarsonic acid (PAA). The adsorption of PAA was explored, and the influences of ambient temperature, pH, and co-existing [...] Read more.
In this study, three kinds of iron minerals, ferrihydrite, hematite, and goethite, were prepared by a simple coprecipitation method for the adsorption and removal of phenylarsonic acid (PAA). The adsorption of PAA was explored, and the influences of ambient temperature, pH, and co-existing anions on adsorption were evaluated. The experimental results show that rapid adsorption of PAA occurs within 180 min in the presence of iron minerals, and the adsorption process conforms to a pseudo-second-order kinetic model. The isothermal adsorption of PAA by ferrihydrite, goethite, and hematite agrees with the Redlich–Peterson model. The maximum adsorption capacities of PAA are 63.44 mg/g, 19.03 mg/g, and 26.27 mg/g for ferrihydrite, goethite, and hematite, respectively. Environmental factor experiments illustrated that an alkaline environment will significantly inhibit the adsorption of PAA by iron minerals. CO32−, SiO32−, and PO43− in the environment will also significantly reduce the adsorption performance of the three iron minerals. The adsorption mechanism was analyzed by FTIR and XPS, which indicated that ligand exchange between the surface hydroxyl group and the arsine group leads to the formation of an Fe-O-As bond, and electrostatic attraction between the iron minerals and PAA played an important role in the adsorption. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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Review

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15 pages, 1425 KiB  
Review
Effective Removal of Boron from Aqueous Solutions by Inorganic Adsorbents: A Review
by Xiang-Yang Lou, Lucia Yohai, Roberto Boada, Montserrat Resina-Gallego, Dong Han and Manuel Valiente
Molecules 2024, 29(1), 59; https://doi.org/10.3390/molecules29010059 - 21 Dec 2023
Cited by 1 | Viewed by 1127
Abstract
Increasing levels of boron in water exceeding acceptable thresholds have triggered concerns regarding environmental pollution and adverse health effects. In response, significant efforts are being made to develop new adsorbents for the removal of boron from contaminated water. Among the various materials proposed, [...] Read more.
Increasing levels of boron in water exceeding acceptable thresholds have triggered concerns regarding environmental pollution and adverse health effects. In response, significant efforts are being made to develop new adsorbents for the removal of boron from contaminated water. Among the various materials proposed, inorganic adsorbents have emerged as promising materials due to their chemical, thermal, and mechanical stability. This review aims to comprehensively examine recent advances made in the development of inorganic adsorbents for the efficient removal of boron from water. Firstly, the adsorption performance of the most used adsorbents, such as magnesium, iron, aluminum, and individual and mixed oxides, are summarized. Subsequently, diverse functionalization methods aimed at enhancing boron adsorption capacity and selectivity are carefully analyzed. Lastly, challenges and future perspectives in this field are highlighted to guide the development of innovative high-performance adsorbents and adsorption systems, ultimately leading to a reduction in boron pollution. Full article
(This article belongs to the Special Issue Adsorbents in Treatment of Pollutants)
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