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Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ

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A special issue of Toxics (ISSN 2305-6304). This special issue belongs to the section "Toxicity Reduction and Environmental Remediation".

Deadline for manuscript submissions: closed (15 April 2024) | Viewed by 7248

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Special Issue Editors

Prof. Dr. Yuezhou Wei

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Guest Editor

1. School of Nuclear Science and Technology, University of South China, Hengyang, China
2. School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Interests: adsorption materials development; radionuclides separation; heavy metals removal; radioactive wastes management; wastewater treatment; radiochemistry; electrochemistry
Special Issues, Collections and Topics in MDPI journals

Dr. Yan Wu

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Guest Editor

School of Nuclear Science and Engineering, Shanghai Jiao Tong University, Shanghai, China
Interests: porous materials; zeolites; inorganic materials; adsorption; separation science and technology; radiochemistry; waste treatment and disposal
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Dr. Xinpeng Wang

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Guest Editor

Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials, School of Resources, Environment and Materials, Guangxi University, Nanning 530004, China
Interests: adsorption materials; porous materials; radionuclides separation; separation science and technology; waste treatment and disposal
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the rapid increase in the global population and economy over the past few decades, diverse pollutants, such as heavy metals, radionuclides, and organic/inorganic/biological toxicants originating from various industries and human activities, have posed serious threats to human health and the environment. As a main technology of pollutant removal from wastewater, contaminated liquid, and soil, the adsorption method has attracted significant attention among researchers. In recent years, many novel adsorption materials such as highly porous adsorbents, multifunctional hybrid materials, biomass sorbents, nano-structural materials, and COF/MOF materials were developed and applied the elimination of toxic pollutants. Undoubtedly, these new adsorbents and adsorption methods will play an important role in pollutant removal and environment remediation.

This Special Issue will highlight the latest advances in studies on novel adsorbents and adsorption method for pollutants removal. Topics may include, but are not limited to, the synthesis and characterization of novel adsorption materials; mechanistic, thermodynamic, and kinetic approaches of adsorption; the separation, concentration, and removal of pollutants including heavy metals, radionuclides, and various toxicants; and the application of adsorption methods in the pollutant removal process. Authors are invited to submit original research papers, reviews, and short communications.

Prof. Dr. Yuezhou Wei
Dr. Yan Wu
Dr. Xinpeng Wang
Guest Editors

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. Toxics is an international peer-reviewed open access monthly 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 2600 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

fate
transport
environment
in-situ remediation
cross-media transport
critical zone
inundation and drainage
biogeochemistry

Published Papers (7 papers)

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Research

14 pages, 1514 KiB

Open AccessArticle

Application of β-Cyclodextrin Adsorbents in the Removal of Mixed Per- and Polyfluoroalkyl Substances

by Elham Abaie, Manish Kumar, Naveen Kumar, Yilang Sun, Jennifer Guelfo, Yuexiao Shen and Danny Reible

Toxics 2024, 12(4), 264; https://doi.org/10.3390/toxics12040264 - 31 Mar 2024

Viewed by 675

Abstract

The extensive use of per- and polyfluoroalkyl substances (PFASs) in industrial consumer products has led to groundwater contamination, raising concerns for human health and the environment. These persistent chemicals exist in different forms with varying properties, which makes their removal challenging. In this study, we assessed the effectiveness of three different β-cyclodextrin (β-CD) adsorbents at removing a mixture of PFASs, including anionic, neutral, and zwitterionic compounds, at neutral pH. We calculated linear partition coefficient (K_d) values to quantify the adsorption affinity of each PFAS. β-CD polymers crosslinked with hexamethylene diisocyanate (β-CD-HDI) and epichlorohydrin (β-CD-EPI) displayed some adsorption of PFASs. Benzyl chloride β-CD (β-CD-Cl), an adsorbent that had not been previously reported, was also synthesized and tested for PFAS adsorption. β-CD-Cl exhibited higher PFAS adsorption than β-CD-HDI and β-CD-EPI, with log K_d values ranging from 1.9 L·g⁻¹ to 3.3 L·g⁻¹. β-CD-Cl displayed no affinity for zwitterionic compounds, as opposed to β-CD-HDI and β-CD-EPI, which removed N-dimethyl ammonio propyl perfluorohexane sulfonamide (AmPr-FHxSA). A comparison between K_d values and the log K_ow of PFAS confirmed the significant role of hydrophobic interactions in thee adsorption mechanism. This effect was stronger in β-CD-Cl, compared to β-CD-HDI and β-CD-EPI. While no effect of PFAS charge was observed in β-CD-Cl, some influence of charge was observed in β-CD-HDI and β-CD-EPI, with less negative compounds being more adsorbed. The adsorption of PFASs by β-CD-Cl was similar in magnitude to that of other adsorbents proposed in literature. However, it offers the advantage of not containing fluorine, unlike many commonly proposed adsorbents. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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16 pages, 6735 KiB

Open AccessArticle

Adsorption and Desorption Behavior and Mechanism of Ruthenium in Nitrite–Nitric Acid System

by Cong Li, Chao Xie, Tianjiao Jiang, Lifeng Chen, Shunyan Ning, Caiwu Luo, Qi Zheng, Ji Wang and Yuezhou Wei

Toxics 2024, 12(3), 181; https://doi.org/10.3390/toxics12030181 - 27 Feb 2024

Viewed by 949

Abstract

Ruthenium is required to separate from high-level liquid waste (HLLW) because Ru is a valuable resource and is negatively influential on the vitrification process of HLLW. However, the separation of Ru is very challenging due to its complicated complexation properties. In this study, the adsorption and desorption characteristics of ruthenium on a synthesized SiPyR-N3 (weak-base anion exchange resin with pyridine functional groups) composite were investigated in nitric acid and nitrite–nitric acid systems, respectively, and the adsorption mechanism was explored. The experimental results showed that SiPyR-N3 has a significantly better adsorption effect on Ru in the nitrite–nitric acid system than in the nitric acid system, with an increase in the adsorption capacity of approximately three times. The maximum adsorption capacity of Ru is 45.6 mg/g in the nitrite–nitric acid system. The SiPyR-N3 possesses good adsorption selectivity (SF_{Ru/other metal ions} is around 100) in 0.1 M NO₂⁻–0.1 M HNO₃ solution. The adsorption processes of Ru in the two different systems are fitted with the pseudo-second-order kinetic model and Langmuir model for uptake kinetics and adsorption isotherms, respectively. The results obtained from the FT-IR, XPS, and UV absorption spectrometry indicate that NO₂⁻ was involved in the adsorption process either as a complexing species with the metal ions or as free NO₂⁻ from the solution. A 0.1 M HNO₃ + 1 M thiourea mixed solution shows effective desorption performance, and the desorption efficiency can reach 92% at 328 K. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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19 pages, 3941 KiB

Open AccessArticle

Efficient Removal of Hazardous P-Nitroaniline from Wastewater by Using Surface-Activated and Modified Multiwalled Carbon Nanotubes with Mesostructure

by Tzong-Horng Liou and Jyun-Jie Huang

Toxics 2024, 12(1), 88; https://doi.org/10.3390/toxics12010088 - 19 Jan 2024

Viewed by 823

Abstract

P-nitroaniline (PNA) is an aniline compound with high toxicity and can cause serious harm to aquatic animals and plants. Multiwalled carbon nanotubes (MWCNTs) are a multifunctional carbon-based material that can be applied in energy storage and biochemistry applications and semiconductors as well as for various environmental purposes. In the present study, MWCNTs (CO₂–MWCNTs and KOH–MWCNTs) were obtained through CO₂ and KOH activation. ACID–MWCNTs were obtained through surface treatment with an H₂SO₄–HNO₃ mixture. Herein, we report, for the first time, the various MWCNTs that were employed as nanoadsorbents to remove PNA from aqueous solution. The MWCNTs had nanowire-like features and different tube lengths. The nanotubular structures were not destroyed after being activated. The KOH–MWCNTs, CO₂–MWCNTs, and ACID–MWCNTs had surface areas of 487, 484, and 80 m²/g, respectively, and pore volumes of 1.432, 1.321, and 0.871 cm³/g, respectively. The activated MWCNTs contained C–O functional groups, which facilitate PNA adsorption. To determine the maximum adsorption capacity of the MWCNTs, the influences of several adsorption factors—contact time, solution pH, stirring speed, and amount of adsorbent—on PNA adsorption were investigated. The KOH–MWCNTs had the highest adsorption capacity, followed by the CO₂–MWCNTs, pristine MWCNTs, and ACID–MWCNTs. The KOH–MWCNTs exhibited rapid PNA adsorption (>85% within the first 5 min) and high adsorption capacity (171.3 mg/g). Adsorption isotherms and kinetics models were employed to investigate the adsorption mechanism. The results of reutilization experiments revealed that the MWCNTs retained high adsorption capacity after five cycles. The surface-activated and modified MWCNTs synthesized in this study can effectively remove hazardous pollutants from wastewater and may have additional uses. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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17 pages, 1686 KiB

Open AccessArticle

Some Unmodified Household Adsorbents for the Adsorption of Benzalkonium Chloride—A Kinetic and Thermodynamic Case Study for Commercially Available Paper

by Enikő Bitay and Alexandra Csavdari

Toxics 2023, 11(12), 950; https://doi.org/10.3390/toxics11120950 - 21 Nov 2023

Viewed by 1157

Abstract

The extensive use of biocide surfactant benzalkonium chloride (BAC) during the SARS-CoV-2 pandemic has led to the buildup of this hazardous chemical in waste, surface and groundwater. e The study aims to elucidate whether various low-cost household materials are suitable, in their unmodified and untreated form, to effectively adsorb BAC from its aqueous solutions.. Additionally, if a proper adsorbent is identified, a description of the kinetics and thermodynamics of the process is also targeted. From among the five tested materials, a commercially available white household paper towel was chosen to best satisfy the criteria of low price, large availability, and standardization degree, as well as high adsorption capacity within a fairly short time window needed until equilibrium. Batch experiments were carried out with a commercial mixture of BAC-12 and BAC-14 within a temperature range of 18-45 degrees Celsius, and a 25-100 mg/g BAC/adsorbent initial mass ratio range, respectively. The overall process follows a pseudo-second-order kinetic law, with an apparent activation energy of 73.35 KJ/mole. Both the Langmuir and the Redlich–Peterson isotherms describe the equilibrium data at 298 K well, with a Gibbs free energy of −20.64 KJ/mole. These findings are in agreement with previous reports and suggest a hybrid but chemisorption-dominated process. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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19 pages, 5267 KiB

Open AccessArticle

Study on Dynamic Column Behavior and Complexation Mechanism of DBS-Modified Crown Ether-Based Silica to ⁹⁰Sr

by Yan Wu, Hongji Sang, Jiawei Zheng, Lejin Xu, Tong Liu and Yuezhou Wei

Toxics 2023, 11(11), 919; https://doi.org/10.3390/toxics11110919 - 10 Nov 2023

Viewed by 927

Abstract

A crown ether-loaded hybrid adsorbent suitable for the separation and enrichment of strontium from high-level liquid waste was synthesized. 4′,4′(5″)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its modifiers dodecyl benzenesulfonic acid (DBS) and 1-dodecanol were impregnated into silica-based polymer support. The hybrid adsorbent exhibited excellent Sr(II) selectivity ability, and effective chromatographic separation and recovery of Sr(II) from simulated high-level liquid waste could be achieved with a (DtBuCH18C6 + DBS + dodec)/SiO₂-P packed column. The recovery rate of Sr(II) calculated based on the mass balance was approximately 99% and over 80% for the other coexisting metal ions. An appropriate increase in the concentration of Na-DTPA eluent was favorable to improve the efficiency of the elution process because of the increased complexation capacity of [DTPA]⁵⁻ to Sr(II). The developed theoretical model can simulate the dynamic breakthrough curves of the material on the basis of short column data, thereby predicting the scale-up column of the practical operation. Density functional theory calculation was used to explore the action mechanism of DBS modifiers on the Sr(II) complexation process of crown ether groups. Two Sr(II) complexation isomeric models of DtBuCH18C6 were established, and the calculation results revealed a similar complexation ability. DtBuCH18C6 could form a stable Sr(II) complexation structure with DBS coordination, which further indicated that DBS could be a ligand to promote the Sr(II) adsorption ability of crown ether materials. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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13 pages, 7021 KiB

Open AccessArticle

Preparation and Density Functional Theory Studies of Aluminosilicate-Based Ceramic Solidified Products for Sr Immobilization

by Yan Wu, Hongji Sang, Jiawei Zheng, Shuyi Yang, Zhengcheng Gu, Hao Wu and Yuezhou Wei

Toxics 2023, 11(10), 850; https://doi.org/10.3390/toxics11100850 - 11 Oct 2023

Cited by 1 | Viewed by 1077

Abstract

Strontium is a common radionuclide in radioactive waste, and its release into the environment can cause enormous damage to the ecosystem environment. In this study, the natural mineral allophane was selected as the substrate to prepare solidified ceramic products by cold pressing/sintering to solve the problem of the final disposal of radioactive strontium. Ceramic solidified products with various crystal structures were successfully prepared, and the microscopic morphology and energy-dispersive spectroscopy images of the samples showed a uniform distribution of Sr in the solidified products. Sr₂Al₂SiO₇ and SrAl₂Si₂O₈, which can stably solidify strontium, were formed in the solidified products, and the structural characteristics and stability of the above-mentioned substances were analyzed from the perspective of quantum chemical calculations using density functional theory. The calculation results showed that the overall deformation resistance of Sr₂Al₂SiO₇ was higher than that of SrAl₂Si₂O₈. Considering the isomorphic substitution effect of CaO impurities, we inferred that a mixed-crystalline structure of Ca_2−xSr_xAl₂SiO₇ may be present in the solidified products. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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19 pages, 4228 KiB

Open AccessArticle

Arsenic Removal Using Unconventional Material with Iron Content: Batch Adsorption and Column Study

by Cosmin Vancea, Georgiana Mladin, Mihaela Ciopec, Adina Negrea, Narcis Duteanu, Petru Negrea, Giannin Mosoarca and Catalin Ianasi

Toxics 2023, 11(10), 849; https://doi.org/10.3390/toxics11100849 - 10 Oct 2023

Cited by 2 | Viewed by 1083

Abstract

The remediation of arsenic contamination in potable water is an important and urgent concern, necessitating immediate attention. With this objective in mind, the present study investigated arsenic removal from water using batch adsorption and fixed-bed column techniques. The material employed in this study was a waste product derived from the treatment of groundwater water for potable purposes, having a substantial iron composition. The material’s properties were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FT-IR). The point of zero charge (pH_PZC) was measured, and the pore size and specific surface area were determined using the BET method. Under static conditions, kinetic, thermodynamic, and equilibrium studies were carried out to explore the influencing factors on the adsorption process, namely the pH, contact time, temperature, and initial arsenic concentration in the solution. It was found that the adsorption process is spontaneous, endothermic, and of a physical nature. In the batch adsorption studies, the maximum removal percentage was 80.4% after 90 min, and in a dynamic regime in the fixed-bed column, the efficiency was 99.99% at a sludge:sand = 1:1 ratio for 380 min for a volume of water with arsenic of ~3000 mL. The kinetics of the adsorption process conformed to a pseudo-second-order model. In terms of the equilibrium studies, the Sips model yielded the most accurate representation of the data, revealing a maximum equilibrium capacity of 70.1 mg As(V)/g sludge. For the dynamic regime, the experimental data were fitted using the Bohart–Adams, Thomas, and Clark models, in order to establish the mechanism of the process. Additionally, desorption studies were conducted, serving as an essential step in validating the practical applicability of the adsorption process, specifically in relation to the reutilization of the adsorbent material. Full article

(This article belongs to the Special Issue Novel Adsorbents and Adsorption Methods for Pollutants Removal Ⅱ)

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