Special Issue "Novel Inorganic Adsorbents for Environmental Purification"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Porous Materials".

Deadline for manuscript submissions: 20 May 2022.

Special Issue Editors

Dr. Agnieszka Gładysz-Płaska
E-Mail Website
Guest Editor
Maria Curie-Sklodowska University in Lublin, Lublin, Poland
Interests: clay minerals; zeolites; adsorption; uranium; toxic ions
Dr. Ewa Skwarek
E-Mail Website
Guest Editor
Department of Radiochemistry and Environmental Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, University of Marie Skłodowska-Curie, Lublin, Poland
Interests: hydroxyapatite; metal oxide; composites; physicochemical properties
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue, entitled 'New inorganic Adsorbents for Environmental Purification', is devoted to the characteristics and synthesis of inorganic materials such as metal oxides, hydroxyapatite, mesoporous silica, zeolites, clays, and hybrid materials with their application in the adsorption of cations and anions, intended mainly for solving environmental problems. The publication must include innovative synthesis strategies to obtain low-cost materials or transplant functionality to improve their adsorption capacity and selectivity. Papers including reviews and scientific research results are acceptable. The main subject of interest of many scientific and industrial centers is the preparation of new, modern, and technologically advanced materials that are at the same time low cost, readily available, and effective in operation, while also minimizing the process times. Inorganic compounds, their modification, and composites are one of the most important groups in this area. The release of heavy metals and other pollutants into water and soil as a result of human agricultural and industrial activities can pose a serious threat to the environment and human health. There are many processes for the removal of dissolved heavy metal ions. Recently the emphasis has been put on the use of cheaper alternative materials as potential sorbents for heavy metal removal. Hydroxyapatite, clay, oxides, and their derivatives and composites can be a good choice.

Dr. Agnieszka Gładysz-Płaska
Dr. Ewa Skwarek
Guest Editors

Manuscript Submission Information

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Keywords

  • clay minerals
  • zeolites
  • hydroxyapatite
  • metal oxides
  • composites

Published Papers (11 papers)

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Research

Jump to: Review

Article
Enhanced Defluoridation of Water Using Zirconium—Coated Pumice in Fixed-Bed Adsorption Columns
Materials 2021, 14(20), 6145; https://doi.org/10.3390/ma14206145 - 16 Oct 2021
Viewed by 266
Abstract
Millions of people across the globe suffer from health issues related to high fluoride levels in drinking water. The purpose of this study was to test modified pumice as an adsorbent for the purification of fluoride-containing waters. The adsorption of fluoride onto zirconium-coated [...] Read more.
Millions of people across the globe suffer from health issues related to high fluoride levels in drinking water. The purpose of this study was to test modified pumice as an adsorbent for the purification of fluoride-containing waters. The adsorption of fluoride onto zirconium-coated pumice (Zr–Pu) adsorbent was examined in fixed-bed adsorption columns. The coating of zirconium on the surface of VPum was revealed by X-ray diffractometer (XRD), Inductively coupled plasma-optical emission spectroscopy (ICP-EOS), and X-ray fluorescence (XRF) techniques. The degree of surface modification with the enhanced porosity of Zr–Pu was evident from the recorded scanning electron microscope (SEM) micrographs. The Brunauer-Emmett-Teller (BET) analysis confirmed the enhancement of the specific surface area of VPum after modification. The Fourier transform infrared (FTIR) examinations of VPum and Zr–Pu before and after adsorption did not reveal any significant spectrum changes. The pH drift method showed that VPum and Zr–Pu have positive charges at pHPZC lower than 7.3 and 6.5, respectively. Zr–Pu yielded a higher adsorption capacity of 225 mg/kg (2.05 times the adsorption capacity of VPum: 110 mg/kg), at pH = 2 and volumetric flow rate (QO) of 1.25 mL/min. Breakthrough time increases with decreasing pH and flow rate. The experimental adsorption data was well-matched by the Thomas and Adams-Bohart models with correlation coefficients (R2) of ≥ 0.980 (Zr–Pu) and ≥ 0.897 (VPum), confirming that both models are suitable tools to design fixed-bed column systems using volcanic rock materials. Overall, coating pumice with zirconium improved the defluoridation capacity of pumice; hence, a Zr–Pu-packed fixed-bed can be applied for defluoridation of excess fluoride from groundwater. However, additional investigations on, for instance, the influences of competing ions are advisable to draw explicit conclusions. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Preparation and Characterization of Physicochemical Properties of Spruce Cone Biochars Activated by CO2
Materials 2021, 14(14), 3859; https://doi.org/10.3390/ma14143859 - 10 Jul 2021
Cited by 1 | Viewed by 470
Abstract
In this study the pyrolysis of Norway spruce cones, a lignocellulosic biomass was made. The biochar product was obtained by means of the physical activation method. CO2 was used as the activating gas. The surface properties of biochars were characterized by the [...] Read more.
In this study the pyrolysis of Norway spruce cones, a lignocellulosic biomass was made. The biochar product was obtained by means of the physical activation method. CO2 was used as the activating gas. The surface properties of biochars were characterized by the nitrogen adsorption/desorption isotherms, scanning electron microscopy (SEM/EDS), X-ray fluorescence energy dispersion spectroscopy (ED-XRF), thermal analysis (TGA/DTA), infrared spectroscopy (ATR FT-IR), Raman spectroscopy and the Boehm’s titration method as well as the point of zero charge (pHpzc). The adsorption capacity and the possibility of ammonia desorption (TPD) were also examined. It has been shown that spruce cones can be successfully used as a cheap precursor of well-developed surface biochars, characterized by a large pore volume and good sorption properties. All obtained activated biochars exhibit a largely microporous structure and an acidic character surface. The investigated activated materials have the specific surface areas from 112 to 1181 m2 g−1. The maximum NH3 adsorption capacity of the activated biochar was determined to be 5.18 mg g−1 (88.22 mmol g−1) at 0 °C. These results indicate the applicability of spruce cones as a cheap precursor for the sustainable production of the cost-effective and environmentally friendly biochar adsorbent. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Adsorption of the Tartrate Ions in the Hydroxyapatite/Aqueous Solution of NaCl System
Materials 2021, 14(11), 3039; https://doi.org/10.3390/ma14113039 - 03 Jun 2021
Viewed by 550
Abstract
The research on the interaction of tartrate ions with the surface of hydroskyapatite was presented, including the measurements of the kinetics of tartrate ion adsorption and tartrate ion adsorption as a function of pH. The adsorption of tartrate ions was calculated from the [...] Read more.
The research on the interaction of tartrate ions with the surface of hydroskyapatite was presented, including the measurements of the kinetics of tartrate ion adsorption and tartrate ion adsorption as a function of pH. The adsorption of tartrate ions was calculated from the loss of tartrate concentration in the solution as measured by a radioisotope method using C-14 labeled tartaric acid. In order to explain the mechanism of interaction of tartrate ions with hydroxyapatite, supplementary measurements were carried out, i.e., potentiometric measurements of the balance of released/consumed ions in the hydroxyapatite/electrolyte solution system, zeta potential measurements, FTIR spectrophotometric measurements and the hydroxyapatite crystal structure and particle size distribution were characterized. It was found that the adsorption of tartrate ions occurs as a result of the exchange of these ions with hydroxyl, phosphate and carbonate ions. Replacing the ions with the abovementioned tartrate ions leads to the appearance of a negative charge on the surface of the hydroxapatite. On the basis of XRD study and particle size distribution, a decrease in the size of crystallites and the diameter of hydroxyapatite particles in contact with a solution of 0.001 mol/dm3 of tartaric acid was found. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Uptake of Radionuclides 60Co, 137Cs, and 90Sr with α-Fe2O3 and Fe3O4 Particles from Aqueous Environment
Materials 2021, 14(11), 2899; https://doi.org/10.3390/ma14112899 - 28 May 2021
Viewed by 539
Abstract
In the paper, investigation results of the uptake efficiency of radionuclides 60Co, 90Sr, and 137Cs dissolved in water onto iron oxides α-Fe2O3 and Fe3O4 are presented. It was found that sorption efficiency increased for [...] Read more.
In the paper, investigation results of the uptake efficiency of radionuclides 60Co, 90Sr, and 137Cs dissolved in water onto iron oxides α-Fe2O3 and Fe3O4 are presented. It was found that sorption efficiency increased for higher pH values. Independent of the oxide nature, the uptake characteristics are the best toward 60Co and the worst toward 137Cs, forming the row as follows: 60Co > 90Sr > 137Cs. The highest sorption ability at pH 9 was found for magnetite Fe3O4, which was 93%, 73%, and 26% toward 60Co, 90Sr, and 137Cs, respectively, while the respective percentages for hematite α-Fe2O3 were 85%, 41%, and 18%. It was assumed that the main sorption mechanism was ion exchange. That may explain some decrease of the sorption efficiency in drinking water due to the interfering presence of magnesium and calcium cations. The obtained results indicated the feasibility of the tested sorbents and their merits, especially in terms of relatively high uptake coefficients, low costs, availability, and lack of toxicity. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Adsorptive Removal of Phosphate from Aqueous Solutions Using Low-Cost Volcanic Rocks: Kinetics and Equilibrium Approaches
Materials 2021, 14(5), 1312; https://doi.org/10.3390/ma14051312 - 09 Mar 2021
Cited by 4 | Viewed by 745
Abstract
The contamination of surface and groundwater with phosphate originating from industrial and household wastewater remains a serious environmental issue in low-income countries. Herein, phosphate removal from aqueous solutions was studied using low-cost volcanic rocks such as pumice (VPum) and scoria (VSco), obtained from [...] Read more.
The contamination of surface and groundwater with phosphate originating from industrial and household wastewater remains a serious environmental issue in low-income countries. Herein, phosphate removal from aqueous solutions was studied using low-cost volcanic rocks such as pumice (VPum) and scoria (VSco), obtained from the Ethiopian Great Rift Valley. Batch adsorption experiments were conducted using phosphate solutions with concentrations of 0.5 to 25 mg·L−1 to examine the adsorption kinetic as well as equilibrium conditions. The experimental adsorption data were tested by employing various equilibrium adsorption models, and the Freundlich and Dubinin-Radushkevich (D-R) isotherms best depicted the observations. The maximum phosphate adsorption capacities of VPum and VSco were calculated and found to be 294 mg·kg−1 and 169 mg·kg−1, respectively. A pseudo-second-order kinetic model best described the experimental data with a coefficient of correlation of R2 > 0.99 for both VPum and VSco; however, VPum showed a slightly better selectivity for phosphate removal than VSco. The presence of competitive anions markedly reduced the removal efficiency of phosphate from the aqueous solution. The adsorptive removal of phosphate was affected by competitive anions in the order: HCO3 >F > SO4−2 > NO3 > Cl for VPum and HCO3 > F > Cl > SO4−2 > NO3 for VSco. The results indicate that the readily available volcanic rocks have a good adsorptive capacity for phosphate and shall be considered in future studies as test materials for phosphate removal from water in technical-scale experiments. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Interactions between Active Ingredient Ranitidine and Clay Mineral Excipients in Pharmaceutical Formulations
Materials 2020, 13(23), 5558; https://doi.org/10.3390/ma13235558 - 06 Dec 2020
Cited by 1 | Viewed by 563
Abstract
Excipients play an important role in pharmaceutical formulations. Many clay minerals, because of their large specific surface area and inert behaviour in reactions with active ingredients, are commonly used as excipients. In this study, the uptake of ranitidine (RT), the active ingredient of [...] Read more.
Excipients play an important role in pharmaceutical formulations. Many clay minerals, because of their large specific surface area and inert behaviour in reactions with active ingredients, are commonly used as excipients. In this study, the uptake of ranitidine (RT), the active ingredient of Zantac, on and released from palygorskite (Pal), kaolinite (Kao), and talc was evaluated under different physicochemical conditions. The results showed that the uptake of RT on these minerals was limited to the external surface areas only. Cation exchange and electrostatic interactions were responsible for the RT uptake on Pal and Kao, resulting in a monolayer sorption. In contrast, multilayer RT uptake was found on the talc surfaces. Under different desorbing conditions, significant amounts of sorbed RT remained on the solid surface after 5 h of desorption. The results suggest that the sorptive interactions between the active ingredients and the excipients may not be neglected in pharmaceutical formulations, should these minerals be used as additives and/or excipients. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Effect of Pressure and Temperature on CO2/CH4 Competitive Adsorption on Kaolinite by Monte Carlo Simulations
Materials 2020, 13(12), 2851; https://doi.org/10.3390/ma13122851 - 25 Jun 2020
Viewed by 668
Abstract
The adsorption of CO2 and CO2/CH4 mixtures on kaolinite was calculated by grand canonical Monte Carlo (GCMC) simulations with different temperatures (283.15, 293.15, and 313.15 K) up to 40 MPa. The simulation results show that the adsorption amount of [...] Read more.
The adsorption of CO2 and CO2/CH4 mixtures on kaolinite was calculated by grand canonical Monte Carlo (GCMC) simulations with different temperatures (283.15, 293.15, and 313.15 K) up to 40 MPa. The simulation results show that the adsorption amount of CO2 followed the Langmuir model and decreased with an increasing temperature. The excess adsorption of CO2 increased with an increasing pressure until the pressure reached 3 MPa and then decreased at different temperatures. The S C O 2 / C H 4 decreased logarithmically with increasing pressure, and the S C O 2 / C H 4 was lower with a higher temperature at the same pressure. The interaction energy between CO2 and kaolinite was much higher than that between CH4 and kaolinite at the same pressure. The interaction energy between the adsorbent and adsorbate was dominant, and that between CO2 and CO2 and between CH4 and CH4 accounted for less than 20% of the total interaction energy. The isothermal adsorption heat of CO2 was higher than that of CH4, indicating that the affinity of kaolinite to CO2 was higher than that of CH4. The strong adsorption sites of carbon dioxide on kaolinite were hydrogen, oxygen, and silicon atoms, respectively. CO2 was not only physically adsorbed on kaolinite, but also exhibited chemical adsorption. In gas-bearing reservoirs, a CO2 injection to displace CH4 and enhance CO2 sequestration and enhanced gas recovery (CS-EGR) should be implemented at a low temperature. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Removal of Barium from Solution by Natural and Iron(III) Oxide-Modified Allophane, Beidellite and Zeolite Adsorbents
Materials 2020, 13(11), 2582; https://doi.org/10.3390/ma13112582 - 05 Jun 2020
Cited by 7 | Viewed by 796
Abstract
Efficient capture of barium (Ba) from solution is a serious task in environmental protection and remediation. Herein, the capacity and the mechanism of Ba adsorption by natural and iron(III) oxide (FeO) modified allophane (ALO), beidellite (BEI) and zeolite (ZEO) were investigated by considering [...] Read more.
Efficient capture of barium (Ba) from solution is a serious task in environmental protection and remediation. Herein, the capacity and the mechanism of Ba adsorption by natural and iron(III) oxide (FeO) modified allophane (ALO), beidellite (BEI) and zeolite (ZEO) were investigated by considering the effects of contact time, temperature, pH, Ba2+ concentration, adsorbent dosage, the presence of competitive ions and adsorption–desorption cycles (regenerability). Physicochemical and mineralogical properties of the adsorbents were characterized by XRD, FTIR, SEM with EDX and N2 physisorption techniques. The Ba2+ adsorption fitted to a pseudo-first-order reaction kinetics, where equilibrium conditions were reached within <30 min. BEI, ALO and ZEO with(out) FeO-modification yielded removal efficiencies for Ba2+ of up to 99.9%, 97% and 22% at optimum pH (pH 7.5–8.0). Adsorption isotherms fitted to the Langmuir model, which revealed the highest adsorption capacities for BEI and FeO-BEI (44.8 mg/g and 38.6 mg/g at 313 K). Preferential ion uptake followed in the order: Ba2+ > K+ > Ca2+ >> Mg2+ for all adsorbents; however, BEI and FeO-BEI showed the highest selectivity for Ba2+ among all materials tested. Barium removal from solution was governed by physical adsorption besides ion exchange, intercalation, surface complexation and precipitation, depending mainly on the absorbent type and operational conditions. BEI and FeO-BEI showed a high regenerability (>70–80% desorption efficiency after 5 cycles) and could be considered as efficient sorbent materials for wastewater clean-up. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Development of an Adsorbing System Made of DMS-1 Mesh Modified by Amino Groups to Remove Pb(II) Ions from Water
Materials 2020, 13(8), 1914; https://doi.org/10.3390/ma13081914 - 18 Apr 2020
Viewed by 1221
Abstract
Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal [...] Read more.
Water pollution by heavy metals represents several health risks. Conventional technologies employed to eliminate lead ions from residual or drinking water are expensive, therefore an efficient and low-cost technique is required and adsorption processes are a good alternative. In this work, the goal was to determine the adsorption capacity of a Disordered Mesoporous Silica 1 material (DMS-1) functionalized with amino groups, for Pb(II) ions removal. DMS-1 was prepared by sol-gel method and the incorporation of amino groups was performed by ex-situ method. As the source of amine groups, (3-Aminopropyl) triethoxysilane (APTES) was used and three different xNH2/DMS-1 molar ratios (0.2, 0.3, 0.4) were evaluated. In order to evaluate the incorporation of the amino group into the mesopore channels, thermal and structural analysis were made through Thermogravimetric Analysis (TGA), nitrogen adsorption–desorption at 77 K by Specific Brunauer–Emmett–Teller (SBET) method, Fourier Transfer Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS). The higher Pb(II) ions removal was achieved with the 0.3 molar proportion of xNH2/DMS-1 reaching 99.44% efficiency. This result suggests that the functionalized material can be used as an efficient adsorbent for Pb(II) ions from aqueous solution. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Article
Laponites® for the Recovery of 133Cs, 59Co, and 88Sr from Aqueous Solutions and Subsequent Storage: Impact of Grafted Silane Loads
Materials 2020, 13(3), 572; https://doi.org/10.3390/ma13030572 - 25 Jan 2020
Viewed by 768
Abstract
In this study, silylated Laponites® (LAP) were synthetized with various loads of 3-aminopropyltriethoxysilane (APTES) to evaluate their adsorption properties of 133Cs, 59Co, and 88Sr during single-solute and competitive experiments. The increase in the initial load of APTES increased the [...] Read more.
In this study, silylated Laponites® (LAP) were synthetized with various loads of 3-aminopropyltriethoxysilane (APTES) to evaluate their adsorption properties of 133Cs, 59Co, and 88Sr during single-solute and competitive experiments. The increase in the initial load of APTES increased the adsorbed amount of APTES in the resulted grafted clay. The characterization of LAP-APTES exhibited a covalent binding between APTES and LAP and emphasized the adsorption sites of APTES for each tested load. In comparison with raw LAP, LAP-APTES displayed significantly higher adsorption properties of Co2+, Cs+, and Sr2+. The competitive adsorption of these three contaminants provides a deeper understanding of the affinity between adsorbate and adsorbent. Therefore, Co2+ displayed a strong and specific adsorption onto LAP-APTES. Except for Cs+, the adsorption capacity was improved with increasing the load of APTES. Finally, the desorption behavior of the three contaminants was tested in saline solutions. Cs+ and Sr2+ were significantly released especially by inorganic cations displaying the same valence. Conversely, desorption of Co2+ was very low whatever the saline solution. LAP-APTES, therefore, presented suitable adsorption properties for the removal of radionuclides especially for Co2+, making this material suitable to improve the decontamination of radioactive wastewaters. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Review

Jump to: Research

Review
Mineral Materials Coated with and Consisting of MnOx—Characteristics and Application of Filter Media for Groundwater Treatment: A Review
Materials 2020, 13(10), 2232; https://doi.org/10.3390/ma13102232 - 13 May 2020
Cited by 11 | Viewed by 924
Abstract
For groundwater treatment, the technologies involving oxidation on MnOx filter bed are beneficial, common, and effectively used. The presence of MnOx is the mutual feature of filter media, both MnOx-coated mineral materials like quartz sand and gravel, chalcedonite, diatomite, [...] Read more.
For groundwater treatment, the technologies involving oxidation on MnOx filter bed are beneficial, common, and effectively used. The presence of MnOx is the mutual feature of filter media, both MnOx-coated mineral materials like quartz sand and gravel, chalcedonite, diatomite, glauconite, zeolite, or anthracite along with consisting of MnOx manganese ores. This review is based on the analysis of research and review papers, commercial data sheets, and standards. The paper aimed to provide new suggestions and useful information for further investigation of MnOx filter media for groundwater treatment. The presented compilations are based on the characteristics of coatings, methods, and conditions of its obtaining and type of filter media. The relationship between the properties of MnOx amendments and the obtained purification effects as well as the commonly used commercial products, their features, and applications have been discussed. The paper concludes by mentioning about improving catalytic/adsorption properties of non-reactive siliceous media opposed to ion-exchange minerals and about possible significance of birnessite type manganese oxide for water treatment. Research needs related to the assessment of the use MnOx filter media to heavy metals removal from groundwater in field operations and to standardize methodology of testing MnOx filter media for water treatment were identified. Full article
(This article belongs to the Special Issue Novel Inorganic Adsorbents for Environmental Purification)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. 

Author: Dr. hab. Agnieszka Gładysz-Płaska

Affiliation: Maria Curie-Sklodowska University in Lublin, Lublin, Poland

2.
Author:  Dr. Katarzyna Jedynak
Affiliation: Institute of Chemistry, Jan Kochanowski University, 25-406 Kielce, Poland

3.
Author: Dr. Iwona Zawierucha
Affiliation: Institute of Chemistry, Jan Dlugosz University in Czestochowa, 42-200 Czestochowa, Poland

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