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Design and Synthesis of Novel Adsorbents for Pollutant Removal
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Design and Synthesis of Novel Adsorbents for Pollutant Removal

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

Deadline for manuscript submissions: 31 March 2025 | Viewed by 8344

Special Issue Editor

Dr. Inna V. Melnyk

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Guest Editor
Institute of Geotechnics Slovak Academy of Sciences, 45, Watsonova Str., 04001 Kosice, Slovakia
Interests: material characterization; hybrid materials; surface chemistry; sol–gel techniques; adsorption and adsorbents; wastewater treatment; tailored surface creation; nanocomposites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

One of the leading global environmental issues facing humanity today is air and water pollution. The World Health Organization estimates that polluted air is the cause of about 7 million deaths per year, and contaminated water is about 5 million. This explains why the creation of new materials for air and water purification is still relevant.

Adsorption processes and adsorbents themselves represent good alternatives to other methods of pollution removal due to the fact that they only (ad)sorb harmful substances and do not produce by-products; they can be regenerated and their design can be aimed at creating necessary linkers and pore sizes for the selective extraction of certain compounds. Therefore, this Special Issue is devoted to the creation of high-performance adsorbents of different types (natural and synthetic), porosity, and the nature of surface groups, which can be used for specific interactions with pollutants. It would also be interesting to consider silica, zeolites, coal, oxides, resins, etc. Many adsorbents have already been studied and reported; for this reason, preference will be given to materials with selective adsorption, large values of sorption capacity, low cost, the possibility of regeneration, mechanical strength, and ease of use.

Dr. Inna V. Melnyk
Guest Editor

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Keywords

  • wastewater treatment
  • adsorbents
  • sustainable materials
  • adsorption mechanisms
  • surface chemistry
  • selective adsorption

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Published Papers (7 papers)

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Research

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18 pages, 8812 KiB  
Article
Gold(III) Ions Sorption on Amberlite XAD-16 Impregnated with TBP After Leaching Smart Card Chips
by Karolina Zinkowska, Zbigniew Hubicki and Grzegorz Wójcik
Molecules 2025, 30(1), 151; https://doi.org/10.3390/molecules30010151 - 2 Jan 2025
Viewed by 485
Abstract
Owing to the intensive development of electrical and electronic equipment, there is an increasing demand for precious metals, which are often used for its production. Due to their scarce supply, it is important to recover them from secondary sources. A promising way to [...] Read more.
Owing to the intensive development of electrical and electronic equipment, there is an increasing demand for precious metals, which are often used for its production. Due to their scarce supply, it is important to recover them from secondary sources. A promising way to recover precious metals are impregnated resins. In this research, Amberlite XAD-16 was impregnated with TBP at the weight ratios of 1:2 and 1:3 using the ‘warm impregnation’ method. Studies were carried out on the sorption of Au(III), Pd(II), Pt(IV), and Rh(III) ions from the model chloride solutions as well as the real solution formed after leaching the smart card chips. Only Au(III) ions were efficiently sorbed on the prepared impregnated sorbents. The best results were obtained at 6 M HCl and the sorbent mass: 0.1 g/25 mL. The maximum sorption capacity for the impregnated sorbents was: 147.91 mg/g (ratio 1:2) and 149.66 mg/g (ratio 1:3). Recovery of Au(III) ions from the real leaching solution was: 97.36% and 97.77%, respectively. The Langmuir isotherm was the best-fit model for the experimental results. Thermodynamic studies proved that the investigated sorption process is spontaneous and exothermic. The desorption process can be easily carried out with 1 M HCl/1 M TU. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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21 pages, 26975 KiB  
Article
Recovery of Nd3+ and Dy3+ from E-Waste Using Adsorbents from Spent Tyre Rubbers: Batch and Column Dynamic Assays
by Miguel Nogueira, Inês Matos, Maria Bernardo, Filomena Pinto, Isabel Fonseca and Nuno Lapa
Molecules 2025, 30(1), 92; https://doi.org/10.3390/molecules30010092 - 29 Dec 2024
Viewed by 618
Abstract
This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO2 activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. [...] Read more.
This paper investigates the use of spent tyre rubber as a precursor for synthesising adsorbents to recover rare earth elements. Through pyrolysis and CO2 activation, tyre rubber is converted into porous carbonaceous materials with surface properties suited for rare earth element adsorption. The study also examines the efficiency of leaching rare earth elements from NdFeB magnets using optimised acid leaching methods, providing insights into recovery processes. The adsorption capacity of the materials was assessed through batch adsorption assays targeting neodymium (Nd3⁺) and dysprosium (Dy3⁺) ions. Results highlight the superior performance of activated carbon derived from tyre rubber following CO2 activation, with the best-performing adsorbent achieving maximum uptake capacities of 24.7 mg·g⁻1 for Nd3⁺ and 34.4 mg·g⁻1 for Dy3⁺. Column studies revealed efficient adsorption of Nd3⁺ and Dy3⁺ from synthetic and real magnet leachates with a maximum uptake capacity of 1.36 mg·g⁻1 for Nd3⁺ in real leachates and breakthrough times of 25 min. Bi-component assays showed no adverse effects when both ions were present, supporting their potential for simultaneous recovery. Furthermore, the adsorbents effectively recovered rare earth elements from e-waste magnet leachates, demonstrating practical applicability. This research underscores the potential of tyre rubber-derived adsorbents to enhance sustainability in critical raw material supply chains. By repurposing waste tyre rubber, these materials offer a sustainable solution for rare earth recovery, addressing resource scarcity while aligning with circular economy principles by diverting waste from landfills and creating value-added products. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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18 pages, 6305 KiB  
Article
Advanced Photodegradation of Azo Dye Methyl Orange Using H2O2-Activated Fe3O4@SiO2@ZnO Composite under UV Treatment
by Oksana Makota, Erika Dutková, Jaroslav Briančin, Jozef Bednarcik, Maksym Lisnichuk, Iryna Yevchuk and Inna Melnyk
Molecules 2024, 29(6), 1190; https://doi.org/10.3390/molecules29061190 - 7 Mar 2024
Cited by 7 | Viewed by 1698
Abstract
The Fe3O4@SiO2@ZnO composite was synthesized via the simultaneous deposition of SiO2 and ZnO onto pre-prepared Fe3O4 nanoparticles. Physicochemical methods (TEM, EDXS, XRD, SEM, FTIR, PL, zeta potential measurements, and low-temperature nitrogen adsorption/desorption) revealed [...] Read more.
The Fe3O4@SiO2@ZnO composite was synthesized via the simultaneous deposition of SiO2 and ZnO onto pre-prepared Fe3O4 nanoparticles. Physicochemical methods (TEM, EDXS, XRD, SEM, FTIR, PL, zeta potential measurements, and low-temperature nitrogen adsorption/desorption) revealed that the simultaneous deposition onto magnetite surfaces, up to 18 nm in size, results in the formation of an amorphous shell composed of a mixture of zinc and silicon oxides. This composite underwent modification to form Fe3O4@SiO2@ZnO*, achieved by activation with H2O2. The modified composite retained its structural integrity, but its surface groups underwent significant changes, exhibiting pronounced catalytic activity in the photodegradation of methyl orange under UV irradiation. It was capable of degrading 96% of this azo dye in 240 min, compared to the initial Fe3O4@SiO2@ZnO composite, which could remove only 11% under identical conditions. Fe3O4@SiO2@ZnO* demonstrated robust stability after three cycles of use in dye photodegradation. Furthermore, Fe3O4@SiO2@ZnO* exhibited decreased PL intensity, indicating an enhanced efficiency in electron-hole pair separation and a reduced recombination rate in the modified composite. The activation process diminishes the electron-hole (e−)/(h+) recombination and generates the potent oxidizing species, hydroxyl radicals (OH˙), on the photocatalyst surface, thereby playing a crucial role in the enhanced photodegradation efficiency of methyl orange with Fe3O4@SiO2@ZnO*. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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20 pages, 2498 KiB  
Article
Aminated Rapeseed Husks (Brassica napus) as an Effective Sorbent for Removing Anionic Dyes from Aqueous Solutions
by Tomasz Jóźwiak and Urszula Filipkowska
Molecules 2024, 29(4), 843; https://doi.org/10.3390/molecules29040843 - 14 Feb 2024
Cited by 3 | Viewed by 1081
Abstract
The study investigated the effect of modifying rapeseed husks with ammonia and epichlorohydrin on their sorption capacity against anionic reactive dyes: Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84). Its scope included sorbents characterization (FTIR, pHPZC), determination of pH influence [...] Read more.
The study investigated the effect of modifying rapeseed husks with ammonia and epichlorohydrin on their sorption capacity against anionic reactive dyes: Reactive Black 5 (RB5) and Reactive Yellow 84 (RY84). Its scope included sorbents characterization (FTIR, pHPZC), determination of pH influence on the sorption effectiveness of dyes, the adsorption kinetics of dyes, as well as the maximum sorption capacity. The study proved that the reaction of rapeseed husk biomass with ammonia can lead to its amination, namely to the introduction of amine functional groups into the material’s structure. The sorption effectiveness of RB5 and RY84 on the tested sorbents was the highest in the pH range of 2–3. The dye sorption kinetics was well described by the pseudo-second-order model. The sorption equilibrium time ranged from 90 to 180 min, and depended on the initial concentration of dyes and the number of amino groups on the sorbent’s surface. The most efficient of the sorbents tested were rapeseed husks pre-activated with epichlorohydrin and then aminated with ammonia. Their sorption capacity determined for RB5 and RY84 was 135.83 mg/g and 114.23 mg/g, respectively, which was 794% and 737% higher than that of the non-modified husks. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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17 pages, 2852 KiB  
Article
Optimization of Pt(II) and Pt(IV) Adsorption from a Water Solution on Biochar Originating from Honeycomb Biomass
by Kinga Morlo, Rafał Olchowski and Ryszard Dobrowolski
Molecules 2024, 29(2), 547; https://doi.org/10.3390/molecules29020547 - 22 Jan 2024
Cited by 1 | Viewed by 1507
Abstract
Novel CO2- and H3PO4-modified biochars were successfully synthesized from raw honeycomb biomass. They were characterized via several instrumental techniques. The optimal Pt(II) and Pt(IV) adsorption onto the studied biochars was reached for the initial pH of 1.5 [...] Read more.
Novel CO2- and H3PO4-modified biochars were successfully synthesized from raw honeycomb biomass. They were characterized via several instrumental techniques. The optimal Pt(II) and Pt(IV) adsorption onto the studied biochars was reached for the initial pH of 1.5 and a contact time of 5 min (Pt(II)) and 24–48 h (Pt(IV)). The highest static adsorption capacities for Pt(II) and Pt(IV) were obtained for the H3PO4-modified biochar: 47 mg g−1 and 35 mg g−1, respectively. The Freundlich model described the Pt(II) adsorption isotherms onto both materials and the Pt(IV) adsorption isotherm onto the CO2-activated material, and the Langmuir model was the best fitted to the Pt(IV) adsorption isotherm onto the H3PO4-activated biochar. The best medium for the quantitative desorption of the Pt form from the H3PO4-modified biochar was 1 mol L−1 thiourea in 1 mol L−1 HCl. The adsorption mechanism of both the studied ions onto the synthesized H3PO4-modified biochar was complex and should be further investigated. The H3PO4-modified biochar was successfully applied for the first time for Pt(IV) removal from a spent automotive catalyst leaching solution. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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20 pages, 4944 KiB  
Article
Ecofriendly Synthesis of Magnetic Composites Loaded on Rice Husks for Acid Blue 25 Decontamination: Adsorption Kinetics, Thermodynamics, and Isotherms
by Fozia Batool, Samia Kanwal, Hafsa Kanwal, Sobia Noreen, Mohamed S. Hodhod, Muhammad Mustaqeem, Gulnaz Sharif, Hafiza Komal Naeem, Javeria Zahid and Abdel-Rhman Z. Gaafar
Molecules 2023, 28(20), 7124; https://doi.org/10.3390/molecules28207124 - 17 Oct 2023
Cited by 5 | Viewed by 1341
Abstract
Addressing the growing need for methods for ecofriendly dye removal from aqueous media, this study explores the potential of rice husks coated with iron oxide (Fe2O3@RH composites) for efficient Acid Blue 25 decontamination. The adsorption potential of Acid Blue [...] Read more.
Addressing the growing need for methods for ecofriendly dye removal from aqueous media, this study explores the potential of rice husks coated with iron oxide (Fe2O3@RH composites) for efficient Acid Blue 25 decontamination. The adsorption potential of Acid Blue 25 is analyzed using raw rice husks and Fe2O3 nanoparticles in the literature, but their enhanced removal capacity by means of Fe2O3@RH composites is reported for the first time in this study. Fe2O3@RH composites were analyzed by using analytical techniques such as TGA, SEM, FTIR, BET, and the point of zero charge (pH(PZC)). The Acid Blue 25 adsorption experiment using Fe2O3@RH composites showed maximum adsorption at an initial concentration of Acid Blue 25 of 80 ppm, a contact time of 50 min, a temperature of 313 K, 0.25 g of Fe2O3@RH composites, and a pH of 2. The maximum percentage removal of Acid Blue 25 was found to be 91%. Various linear and nonlinear kinetic and isothermal models were used in this study to emphasize the importance and necessity of the adsorption process. Adsorption isotherms such as the Freundlich, Temkin, Langmuir, and Dubinin–Radushkevich (D–R) models were applied. The results showed that all the isotherms were best fitted on the data, except the linear form of the D–R isotherm. Adsorption kinetics such as the intraparticle kinetic model, the Elovich kinetic model, and the pseudo-first-order and pseudo-second-order models were applied. All the kinetic models were found to be best fitted on the data, except the PSO model (types II, III, and IV). Thermodynamic parameters such as ΔG° (KJ/mol), ΔH° (KJ/mol), and ΔS° (J/K*mol) were studied, and the reaction was found to be exothermic in nature with an increase in the entropy of the system, which supported the adsorption phenomenon. The current study contributes to a comprehensive understanding of the adsorption process and its underlying mechanisms through characterization, the optimization of the conditions, and the application of various models. The findings of the present study suggest practical applications of this method in wastewater treatment and environmental remediation. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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Review

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38 pages, 6908 KiB  
Review
A Concise Review on Porous Adsorbents for Benzene and Other Volatile Organic Compounds
by Jerzy Choma, Barbara Szczęśniak, Adam Kapusta and Mietek Jaroniec
Molecules 2024, 29(23), 5677; https://doi.org/10.3390/molecules29235677 - 30 Nov 2024
Cited by 1 | Viewed by 891
Abstract
Emissions of volatile organic compounds (VOCs) such as benzene, toluene, xylene, styrene, hexane, tetrachloroethylene, acetone, acetaldehyde, formaldehyde, isopropanol, etc., increase dramatically with accelerated industrialization and economic growth. Most VOCs cause serious environmental pollution and threaten human health due to their toxic and carcinogenic [...] Read more.
Emissions of volatile organic compounds (VOCs) such as benzene, toluene, xylene, styrene, hexane, tetrachloroethylene, acetone, acetaldehyde, formaldehyde, isopropanol, etc., increase dramatically with accelerated industrialization and economic growth. Most VOCs cause serious environmental pollution and threaten human health due to their toxic and carcinogenic nature. Adsorption on porous materials is considered one of the most promising technologies for VOC removal due to its cost-effectiveness, operational flexibility, and low energy consumption. This review aims to provide a comprehensive understanding of VOC adsorption on various porous adsorbents and indicate future research directions in this field. It is focused on (i) the molecular characterization of structures, polarity, and boiling points of VOCs, (ii) the adsorption mechanisms and adsorption interactions in the physical, chemical, and competitive adsorption of VOCs on adsorbents, and (iii) the favorable characteristics of materials for VOCs adsorption. Porous adsorbents that would play an important role in the removal of benzene and other VOCs are presented in detail, including carbon-based materials (activated carbons, active carbon fibers, ordered mesoporous carbons, and graphene-based materials), metal-organic frameworks, covalent organic frameworks, zeolites, and siliceous adsorbents. Finally, the challenges and prospects related to the removal of VOCs via adsorption are pointed out. Full article
(This article belongs to the Special Issue Design and Synthesis of Novel Adsorbents for Pollutant Removal)
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