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Editorial

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2 pages, 173 KiB

Open AccessEditorial

Foreword to the Special Issue on Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects

by Stefano Salvestrini

Appl. Sci. 2023, 13(1), 242; https://doi.org/10.3390/app13010242 - 25 Dec 2022

Viewed by 1121

Abstract

Although new technologies are continuously proposed for water pollutant removal, sorption is still a very effective process used today for this purpose, largely due to its relatively low cost, tunability, and ease of use [...] Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

Research

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14 pages, 2675 KiB

Open AccessArticle

Preparation and Physicochemical Properties of Tannin-Immobilized Membrane Adsorbent

by Wei Luo, Huiting Lin, Zhihao Wu, Jingteng Chen, Ruiyang Chi, Xiaoxia Ye and Jie Chen

Appl. Sci. 2021, 11(20), 9684; https://doi.org/10.3390/app11209684 - 17 Oct 2021

Cited by 3 | Viewed by 2049

Abstract

Plant tannins have the ability to form stable complexes with metal ions, while microporous membranes have low pressure drop and high flux characteristics. Combining these two materials, a new type of tannin-immobilized membrane (M-TAN) adsorption material has been developed. The PA-BWT, PVDF-BWT, CELL [...] Read more.

Plant tannins have the ability to form stable complexes with metal ions, while microporous membranes have low pressure drop and high flux characteristics. Combining these two materials, a new type of tannin-immobilized membrane (M-TAN) adsorption material has been developed. The PA-BWT, PVDF-BWT, CELL -BWT, and PA-AA-BWT were prepared using different types of microporous membranes as substrates, which maintained the porous structure of the membranes and had the characteristics of high flux and fast filtration rate. The surface contact angle and pure water flux analysis showed that the introduction of tannin with multi-phenolic hydroxyl groups increased the hydrophilicity and water flux of the M-TANs. The adsorption performance shows that the adsorption capacity of four kinds of M-TANs for UO₂²⁺ is in the order of PA-BWT > PA-AA-BWT > PVDF-BWT > CELL-BWT, and PA-BWT has the largest adsorption capacity of 0.398 mmol g⁻¹. In addition, the adsorption isothermal and kinetic data of PA-BWT were well fitted by the Langmuir equation and the Elovich model, respectively. The negative values of ΔG for UO₂²⁺ adsorption on PA-BWT indicated that adsorption is a spontaneous and favorable process. These facts indicate that PA-BWT can be used as a low-cost adsorbent for effective removal of UO₂²⁺ from aqueous solutions. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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22 pages, 3883 KiB

Open AccessArticle

Cationic and Anionic Dye Adsorption on a Natural Clayey Composite

by Carmen Omaira Márquez, Víctor Julio García, Jefferson Raúl Guaypatin, Francisco Fernández-Martínez and Anita Cecilia Ríos

Appl. Sci. 2021, 11(11), 5127; https://doi.org/10.3390/app11115127 - 31 May 2021

Cited by 15 | Viewed by 3343

Abstract

One of the main challenges for environmental sciences today is the effective treatment of dye-laden industrial effluents. This work aimed to study the potential of an untreated (natural occurring clayey composite) red clay (RC) for the adsorption of a cationic dye Basic Navy [...] Read more.

One of the main challenges for environmental sciences today is the effective treatment of dye-laden industrial effluents. This work aimed to study the potential of an untreated (natural occurring clayey composite) red clay (RC) for the adsorption of a cationic dye Basic Navy Blue 2RN (CNB) and anionic dye Drimaren Yellow CL-2R (ADY). We evaluated the effect of pH, dye concentration, and adsorbent concentration on the removal effectiveness to study the absorption process. Also, we studied the adsorption process by analyzing the feasibility of several known adsorption isotherms and kinetic models. The results show that at a pH of less than 4, the CNB and ADY removal percentages were 97% and 96%, respectively. At a pH greater than 8, the CNB and ADY removals were 75% and 25%, respectively. The CNB adsorption happened by chemisorption of a monolayer on iron-containing particles (IPs). In congtrast, the ADY adsorption occurred by monolayer physisorption on kaolinite particles (KPs) and Na, K-rich Laumontite particles (LPs). The Langmuir isotherm model fits very well with CNB experimental data. The Temkin model shows the best fit between the isotherm function and the ADY dye-adsorption data. The pseudo-second-order kinetic model fits the CNB and ADY dye-adsorption data on RC particles. The heterogeneous composition of naturally occurring clay favors different adsorption mechanisms and opens an avenue for the separation process’s engineering. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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12 pages, 772 KiB

Open AccessArticle

The Diffusion Role in Adsorption of Hexavalent Chromium on Solid Olive Mill Waste

by Gennaro Bufalo, Francesca Di Nezza, Marco Perna, Stefano Salvestrini and Luigi Ambrosone

Appl. Sci. 2021, 11(7), 3096; https://doi.org/10.3390/app11073096 - 31 Mar 2021

Cited by 3 | Viewed by 1367

Abstract

The removal of Cr(VI) ions from aqueous solutions with wet pomace treated with laponite was investigated. A direct comparison with untreated biomass revealed an increase in both the rate of adsorption and the amount adsorbed. A cooperative interaction between the laponite platelets and [...] Read more.

The removal of Cr(VI) ions from aqueous solutions with wet pomace treated with laponite was investigated. A direct comparison with untreated biomass revealed an increase in both the rate of adsorption and the amount adsorbed. A cooperative interaction between the laponite platelets and biomass surface making more adsorption sites accessible was suggested. In this process, a key role is played by intraparticle diffusion. The experimental results indicate that intraparticle diffusion plays an important role in the adsorption process. A simple diffusion-binding model is presented to discuss the experimental results. The diffusion lifetime is linearly related to the adsorbent mass. The model combined with experimental results allowed us to estimate the average free path of a Cr(VI) molecule. Particularly, it was obtained that, in 1 dm

^{3}

of solution, the diffusion path increased by nearly 1 cm per gram of adsorbent. However, this did not imply that the amount of Cr(VI) removed decreased because the total number of adsorption sites also increased. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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19 pages, 12104 KiB

Open AccessArticle

Sorption of Organic Electrolytes and Surfactants from Natural Waters by Heterogeneous Membranes

by Irina Bejanidze, Oleksandr Petrov, Volodymyr Pohrebennyk, Tina Kharebava, Nunu Nakashidze, Nato Didmanidze, Nazi Davitadze and Anton Petrov

Appl. Sci. 2020, 10(20), 7383; https://doi.org/10.3390/app10207383 - 21 Oct 2020

Cited by 4 | Viewed by 2276

Abstract

The widespread use of surfactants increasingly requires the development and application of reliable methods for the demineralization of wastewaters, preventing environmental pollution. One of the most reliable and effective methods of demineralization of wastewaters is the electrodialysis method. Studying the behavior of large [...] Read more.

The widespread use of surfactants increasingly requires the development and application of reliable methods for the demineralization of wastewaters, preventing environmental pollution. One of the most reliable and effective methods of demineralization of wastewaters is the electrodialysis method. Studying the behavior of large organic ions in the membrane is important for modeling cell membranes and purification of medicinal and biological preparations. The sorption characteristics of the MA-40 and MK-40 ion-exchange membranes in solutions of simple and organic electrolytes, and in a solution of the surfactant were investigated. It was found that the sorption of organic ions by membranes is mainly of an ion-exchange nature. The moisture content and elasticity of the membranes decreases in solutions of organic electrolytes, during the sorption of which the membrane becomes brittle. A study showed that in the solutions of organic electrolytes, the MA-40 membrane retains high electrochemical activity, while the MK-40 in a solution of the surfactant completely loses it. From the data obtained in this work, it is shown that organic ions do not present a hazard when water is desalted by electrodialysis, whereas sorption of surfactant ions leads to membrane poisoning. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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20 pages, 2228 KiB

Open AccessFeature PaperArticle

Zeolite-Rich Composite Materials for Environmental Remediation: Arsenic Removal from Water

by Bruno de Gennaro, Paolo Aprea, Barbara Liguori, Barbara Galzerano, Antonio Peluso and Domenico Caputo

Appl. Sci. 2020, 10(19), 6939; https://doi.org/10.3390/app10196939 - 3 Oct 2020

Cited by 26 | Viewed by 3553

Abstract

Natural zeolites are used as adsorbents in purification processes due to their cation-exchange ability and molecular sieve properties. Surface modified natural zeolites (SMNZs), produced by attaching cationic organic surfactants to the external surface, can simultaneously act as ionic exchangers and organic molecule adsorbents. [...] Read more.

Natural zeolites are used as adsorbents in purification processes due to their cation-exchange ability and molecular sieve properties. Surface modified natural zeolites (SMNZs), produced by attaching cationic organic surfactants to the external surface, can simultaneously act as ionic exchangers and organic molecule adsorbents. In this paper, SMNZs were produced and investigated as adsorbents for As(V) removal from wastewater: two natural zeolites, clinoptilolite and phillipsite, were modified using HDTMA-Br and HDTMA-Cl as surfactants. The obtained samples were then characterized under static and dynamic conditions. Results showed that As(V) removal follows a pseudo-second order kinetic, with fast adsorption rates: every sample reached 100 % removal in 2 h, while equilibrium data showed a Langmuir-like behavior, with a greater anion uptake by the HDTMA-Br modified SMNZs due to the formation of a compact and complete micellar structure. Finally, fixed-bed tests were performed to characterize the samples under dynamic conditions assessing the effect of severe operating parameters on the dynamic exchange capacity, selectivity and efficiency of the process. The obtained results demonstrate a good ability of the tested materials to adsorb As(V) from wastewater, confirming the effectiveness of the proposed surface modification technique in expanding the possibility of using natural zeolites in these processes. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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Review

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21 pages, 2275 KiB

Open AccessReview

Cr(VI) Sorption from Aqueous Solution: A Review

by Angelo Fenti, Simeone Chianese, Pasquale Iovino, Dino Musmarra and Stefano Salvestrini

Appl. Sci. 2020, 10(18), 6477; https://doi.org/10.3390/app10186477 - 17 Sep 2020

Cited by 43 | Viewed by 4008

Abstract

Hexavalent chromium (Cr(VI)) in water systems is a major hazard for living organisms, including humans. The most popular technology currently used to remove Cr(VI) from polluted water is sorption for its effectiveness, ease of use, low cost and environmental friendliness. The electrostatic interactions [...] Read more.

Hexavalent chromium (Cr(VI)) in water systems is a major hazard for living organisms, including humans. The most popular technology currently used to remove Cr(VI) from polluted water is sorption for its effectiveness, ease of use, low cost and environmental friendliness. The electrostatic interactions between chromium species and the sorbent matrix are the main determinants of Cr(VI) sorption. The pH plays a central role in the process by affecting chromium speciation and the net charge on sorbent surface. In most cases, Cr(VI) sorption is an endothermic process whose kinetics is satisfactorily described by the pseudo second-order model. A critical survey of the recent literature, however, reveals that the thermodynamic and kinetic parameters reported for Cr(VI) sorption are often incorrect and/or erroneously interpreted. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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Other

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7 pages, 503 KiB

Open AccessCommentary

Freundlich Isotherm: An Adsorption Model Complete Framework

by Michael Vigdorowitsch, Alexander Pchelintsev, Liudmila Tsygankova and Elena Tanygina

Appl. Sci. 2021, 11(17), 8078; https://doi.org/10.3390/app11178078 - 31 Aug 2021

Cited by 60 | Viewed by 9526

Abstract

The absolute majority of modern studies dealing with the interpretation of experimental data on the basis of the Freundlich isotherm ignore the fact that the data obtained for regions of low and moderate adsorbate concentration/pressure can be analytically continued within the Freundlich adsorption [...] Read more.

The absolute majority of modern studies dealing with the interpretation of experimental data on the basis of the Freundlich isotherm ignore the fact that the data obtained for regions of low and moderate adsorbate concentration/pressure can be analytically continued within the Freundlich adsorption model to the adsorptive saturation area with coverages tending to 100%. Needless to say, this would give valuable extended information about the corresponding adsorption process. This message proposes a framework to comprehensively analyse experimental data first recognised as complying with the Freundlich adsorption model. An algorithm-driven method is presented which enables one to translate the data obtained in the area of small and moderate the coverages of the area of adsorptive saturation regime. As examples, three sets of experimental data for adsorption of mercury (II) on N-rich porous organic polymers and of protein on carrier nano-Mg(OH)₂ have been processed and presented according to the framework developed. Full article

(This article belongs to the Special Issue Sorption of Environmental Pollutants: Thermodynamic and Kinetic Aspects)

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