Materials

Research

14 pages, 4016 KiB

Open AccessArticle

Thermally Modified Palygorskite Usage as Adsorbent in Fixed-Bed Reactor for High Concentration NH₄⁺-N Removal and Further Application as N—Fertilizer in Hydroponic Cultivation

by Christina Vasiliki Lazaratou, Stylianos Dimitrios Panagopoulos, Dimitrios V. Vayenas, Dionisios Panagiotaras and Dimitrios Papoulis

Materials 2022, 15(19), 6541; https://doi.org/10.3390/ma15196541 - 21 Sep 2022

Cited by 2 | Viewed by 1596

Abstract

Palygorskite sample (Pal) underwent thermal treatment at 400 °C (T-Pal) to be used as adsorbent for the removal of 200 mg NH₄⁺-N/L from artificial solution. After thermal treatment, the sample was characterized via X-ray diffraction (XRD) and scanning electron microscopy [...] Read more.

Palygorskite sample (Pal) underwent thermal treatment at 400 °C (T-Pal) to be used as adsorbent for the removal of 200 mg NH₄⁺-N/L from artificial solution. After thermal treatment, the sample was characterized via X-ray diffraction (XRD) and scanning electron microscopy (SEM). For NH₄⁺-N removal, T-Pal was added as a bed matrix in fixed-bed reactor experiments and the effect of flow rate was determined. It was indicated that with the flow rate increase from 10 mL/min to 50 mL/min, fewer liters of the solution were purified, rendering a longer residual time of interactions, which is optimal for NH₄⁺-N removal from T-Pal. The maximum removed amount was calculated at 978 mg NH₄⁺-N (q_total), suggesting T-Pal is a promising ammonium adsorbent. The data of kinetic experiments were applied to Clark, Yoon–Nelson, and Thomas kinetic models, with Clark having the best fit, highlighting a heterogenous adsorption. At the end of kinetic experiments, T-Pal applied in hydroponic cultivations and presented a sufficient release rate, which was found utilizable for saturated T-Pal usage as N fertilizer that satisfactory results were deemed concerning lettuces characteristics and growth. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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14 pages, 6696 KiB

Open AccessArticle

Facile Approach to the Fabrication of Highly Selective CuCl-Impregnated θ-Al₂O₃ Adsorbent for Enhanced CO Performance

by Cheonwoo Jeong, Joonwoo Kim, Joon Hyun Baik, Sadanand Pandey and Dong Jun Koh

Materials 2022, 15(18), 6356; https://doi.org/10.3390/ma15186356 - 13 Sep 2022

Cited by 5 | Viewed by 1661

Abstract

We have developed a facile and sustainable method to produce a novel θ-Al₂O₃-supported CuCl adsorbent through impregnation methods using CuCl₂ as the precursor. In an easy two-step process, θ-Al₂O₃ was impregnated with a [...] Read more.

We have developed a facile and sustainable method to produce a novel θ-Al₂O₃-supported CuCl adsorbent through impregnation methods using CuCl₂ as the precursor. In an easy two-step process, θ-Al₂O₃ was impregnated with a known concentration of CuCl₂ solutions, and the precursor was calcined to prepare CuCl oversupport. The developed novel θ-Al₂O₃-supported CuCl adsorbent was compared with an adsorbent prepared through the conventional method using CuCl salt. The adsorbents were characterized via X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and temperature-programmed reduction (H₂-TPR). Overall, the adsorbent indicates a high CO adsorption capacity, high CO/CO₂ and CO/N₂ selectivity, and remarkable reusability performance. This process is operated at ambient temperature, which minimizes operation costs in CO separation processes. In addition, these results indicate that the systematic evaluation of alumina-supported CuCl adsorbent can provide significant insight for designing a realistic PSA process for selective CO separation processes. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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13 pages, 1501 KiB

Open AccessArticle

Efficient Removal of Nonylphenol Contamination from Water Using Optimized Magnesium Silicate

by Xu Yan, Qicai Zhang, Qinxiong Rao, Shanshan Chen, Xianli Wang, Wei Song, Lin Cheng, Shuhui Guan and Weiguo Song

Materials 2022, 15(13), 4445; https://doi.org/10.3390/ma15134445 - 24 Jun 2022

Cited by 4 | Viewed by 1532

Abstract

Nonylphenol (NP) is considered to be an environmentally toxic, endocrine-disrupting chemical that affects humans and ecosystems. Adsorption is one of the most promising approaches for the removal of nonylphenol contamination from water. Herein, in order to design an adsorbent with high adsorption capacity, [...] Read more.

Nonylphenol (NP) is considered to be an environmentally toxic, endocrine-disrupting chemical that affects humans and ecosystems. Adsorption is one of the most promising approaches for the removal of nonylphenol contamination from water. Herein, in order to design an adsorbent with high adsorption capacity, magnesium silicate with different Mg/Si ratios was successfully synthesized by a sol–gel method at 60 °C. Magnesium silicate with a Mg/Si ratio of 1:6 was found to possess the best adsorption performance, with maximum 4−NP sorption 30.84 mg/g under 25 °C and 0.2 g/L adsorbent dose. The adsorption was negatively affected by increasing adsorbent dose and temperature. The kinetics and isotherm of 4−NP adsorption by Mg/Si were well described by the pseudo−second−order and Sips model, respectively, and behavior was proven to be physisorption−enhanced by a chemical effect. Detailed characterization by XRD, BET, and SEM confirmed that the magnesium silicate possesses an amorphous, mesoporous structure. The study will contribute to the applicability of cheap magnesium silicate for removal of NP contamination in water. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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24 pages, 3658 KiB

Open AccessFeature PaperArticle

Adsorption of Sodium Diclofenac in Functionalized Palygoskite Clays

by Matheus Urtiga Sousa, Alisson Mendes Rodrigues, Maria Eduarda Barbosa Araujo, Romualdo Rodrigues Menezes, Gelmires Araújo Neves and Hélio Lucena Lira

Materials 2022, 15(8), 2708; https://doi.org/10.3390/ma15082708 - 7 Apr 2022

Cited by 9 | Viewed by 2343

Abstract

The effects of acid and organo-functionalizations on the surface of Brazilian palygorskite clay was investigated, evaluating its potential in the adsorptive capacity of the drug sodium diclofenac present in wastewaters. The modifications on the clay structure were investigated by X-ray diffraction, X-ray fluorescence, [...] Read more.

The effects of acid and organo-functionalizations on the surface of Brazilian palygorskite clay was investigated, evaluating its potential in the adsorptive capacity of the drug sodium diclofenac present in wastewaters. The modifications on the clay structure were investigated by X-ray diffraction, X-ray fluorescence, thermogravimetric, differential thermal analysis, Fourier transform infrared spectroscopy, surface area by N₂ adsorption (77.5 K) and Zeta potential. The experimental design was carried out to find the best conditions for the adsorption tests, in which concentration, mass and pH were significant. In the kinetic study, the pseudo-second-order model better described the adsorption process for acid and organo-functionalized samples. Such results indicate that the adsorption behavior probably occurs due to the phenomenon of chemisorption. Regarding the adsorption isotherms, the Langmuir model was the one that best adjusted both the experimental data of acid and the organo-functionalized samples, whose maximum adsorption capacity were 179.88 and 253.34 mg/g, respectively. This model also indicates that the sodium diclofenac is adsorbed to monolayers homogeneously through chemisorption. In general, the studied clays proved to be suitable adsorbents for the removal of sodium diclofenac. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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16 pages, 3053 KiB

Open AccessArticle

Solvent-Impregnated Sorbents for Tantalum from Niobium Separation Using a Fixed-Bed Column

by Magdalena Turkowska, Krzysztof Karoń, Andrzej Milewski and Agata Jakóbik-Kolon

Materials 2022, 15(4), 1513; https://doi.org/10.3390/ma15041513 - 17 Feb 2022

Cited by 2 | Viewed by 1904

Abstract

Reactor-grade niobium steel is used as a construction material for nuclear reactors. In this case, the presence of tantalum, which is characterized by a 20 times higher active cross section for capturing thermal neutrons than the cross section of niobium (¹⁸¹Ta: [...] Read more.

Reactor-grade niobium steel is used as a construction material for nuclear reactors. In this case, the presence of tantalum, which is characterized by a 20 times higher active cross section for capturing thermal neutrons than the cross section of niobium (¹⁸¹Ta: 21.3 barn), cannot exceed 100 ppm. Analytical methods for quality and new separation method development control need very pure niobium matrices—niobium compounds with a low tantalum content, which are crucial for preparing matrix reference solutions or certified reference materials (CRMs). Therefore, in this paper, a new, efficient method for separating trace amounts of Ta(V) from Nb(V) using extraction chromatography with the use of sorbents impregnated with methyl isobutyl ketone MIBK solvent is proposed. Various types of MIBK-impregnated sorbents were used (AG^® 1-X8 Anion Exchange Resin, AMBERLITE™ IRC120 Na Ion Exchange Resin, SERVACEL^® Cellulose Anion Exchangers DEAE 52, active carbons of various grain size, carbonized blackcurrant pomace, carbonized chokeberry pomace, bentonite, and polyurethane foam in lumps). The highest tantalum removal efficiency was determined using active coal-based materials (>97%). The separation effectivity of tantalum from niobium was also determined in dynamic studies using a fixed-bed column with MIBK-impregnated active carbon. Solutions of various Nb:Ta weight ratios (1:1, 100:1, 1000:1) were used. The most impressive result was obtaining 70 mL of high purity niobium solution of tantalum content 0.027 ppm (in relation to Nb) with 88.4% yield of niobium from a solution of Nb:Ta, weight ratio 1000:1 (purge factor equaled 35,000). It proves the presented system to be applicable for preparation of pure niobium compounds with very low contents of tantalum. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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17 pages, 4951 KiB

Open AccessArticle

Fluoride Bio-Sorption Efficiency and Antimicrobial Potency of Macadamia Nut Shells

by Humbelani H. Nekhavhambe, Rabelani Mudzielwana, Mugera W. Gitari, Wasiu B. Ayinde and Oisaemi U. Izevbekhai

Materials 2022, 15(3), 1065; https://doi.org/10.3390/ma15031065 - 29 Jan 2022

Cited by 4 | Viewed by 2547

Abstract

This paper presents the potential application of macadamia nut shells (MNS) in the bio-sorption of fluoride and its antimicrobial potency against common pathogens encountered in surface water resources. The efficiency of MNS in the sorption of fluoride was determined using batch mode experiments, [...] Read more.

This paper presents the potential application of macadamia nut shells (MNS) in the bio-sorption of fluoride and its antimicrobial potency against common pathogens encountered in surface water resources. The efficiency of MNS in the sorption of fluoride was determined using batch mode experiments, while the antimicrobial potency was investigated using the well disc diffusion assay method. The maximum fluoride sorption capacity of 1.26 mg/g was recorded at an initial fluoride concentration of 5 mg/L, adsorbent dosage of 0.5 g/100 mL, contact time of 120 min and initial pH of 6. The adsorption kinetics data were better described with a pseudo second order model, indicating the dominance of the chemisorption mechanisms. The Langmuir adsorption isotherm model described the isotherm data suggesting a monolayered adsorption. The thermodynamic parameters, ∆Gº and ∆Hº, confirmed that F⁻ sorption by MNS is a spontaneous and endothermic process. The bio-sorbent was regenerated for seven continuous cycles when HCl was used as regenerating solution. The antimicrobial studies revealed that MNS has minimal activity towards Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. The MNS showed potentials for application in bio-sorption of fluoride. However, the doping of MNS with metal ions is recommended to enhance its anti-microbial potency. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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18 pages, 4795 KiB

Open AccessArticle

Boron Removal by Sorption on Modified Chitosan Hydrogel Beads

by Joanna Kluczka, Gabriela Dudek, Wojciech Pudło, Alicja Kazek-Kęsik and Roman Turczyn

Materials 2021, 14(19), 5646; https://doi.org/10.3390/ma14195646 - 28 Sep 2021

Cited by 1 | Viewed by 2365

Abstract

An excess concentration of boron in irrigation and drinking water can negatively affect the yield of plants and the human nervous system, respectively. To meet the recommended levels, hybrid biosorbent hydrogel beads based on chitosan and manganese (II-IV) were employed for the removal [...] Read more.

An excess concentration of boron in irrigation and drinking water can negatively affect the yield of plants and the human nervous system, respectively. To meet the recommended levels, hybrid biosorbent hydrogel beads based on chitosan and manganese (II-IV) were employed for the removal of boron from aqueous media. The results showed that the biosorbent effectively removed boric acid from the aqueous medium at neutral pH over a sorption time of 2 h and the liquid/hydrogel ratio of 20 mL/g, achieving a maximum sorption capacity near 190 mg/g. The modeling of the sorption equilibrium data indicated that the Freundlich isotherm equation gave the best fit out of the isotherm models examined. A pseudo-second-order model was found to best describe the sorption kinetics. The favorable attachment of manganese to the chitosan structure enabled the sorption of boron and was confirmed by FTIR, RS, XRD, SEM and ICP-OES methods. Boron desorption from the spent biosorbent was successfully achieved in three cycles using a NaOH solution. In general, the results of this research indicate that this method is one of the possibilities for improving water quality and may contribute to reducing pollution of the aquatic environment. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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16 pages, 4380 KiB

Open AccessArticle

Studies on the Mechanism of Cu(II) Ion Sorption on Purolite S 940 and Purolite S 950

by Weronika Sofińska-Chmiel, Dorota Kołodyńska, Agnieszka Adamczuk, Aleksander Świetlicki, Marta Goliszek and Radosław Smagieł

Materials 2021, 14(11), 2915; https://doi.org/10.3390/ma14112915 - 28 May 2021

Cited by 5 | Viewed by 2414

Abstract

The aim of the presented research was to investigate the mechanism of sorption of Cu(II) ions on the commercially available Purolite S 940 and Purolite S 950 chelating ion exchangers with the aminophosphonic functional groups. In order to understand better the sorption mechanism, [...] Read more.

The aim of the presented research was to investigate the mechanism of sorption of Cu(II) ions on the commercially available Purolite S 940 and Purolite S 950 chelating ion exchangers with the aminophosphonic functional groups. In order to understand better the sorption mechanism, the beads were cut with an ultramicrotome before and after the Cu(II) ion sorption process. The cut beads were examined by scanning electron microscopy (SEM) with an EDX detector. The performed linear profiles of the elemental composition allowed us to examine the depth with which the sorbed metal penetrates into. For further investigations concerning the mechanism of the sorption process, the Fourier transform infrared spectroscopy (FTIR) analysis using the attenuated total reflectance (ATR) technique and the X-ray photoelectron spectroscopy (XPS) methods have been used. The comparison of FTIR and XPS spectra before and after the sorption of Cu(II) ions showed that free electron pairs from nitrogen and oxygen in the aminophosphonic functional groups participate in the process of copper ion sorption. In addition, the microscopic studies suggested that the process of ion exchange between Na(I) ions and sorbed Cu(II) ions takes place on the Purolite S 940 and Purolite S 950. This study concerning the in-depth understanding the of Cu(II) sorption mechanism, using modern analytical tools and research methods could be very useful for its further modifications leading to the improvement of the process efficiency. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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14 pages, 1323 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Cocoa Beans Shell Powder as a Bioadsorbent of Congo Red Dye Aqueous Solutions

by Gabriela Rodríguez-Arellano, Juan Barajas-Fernández, Ricardo García-Alamilla, Laura Mercedes Lagunes-Gálvez, Antonio Hilario Lara-Rivera and Pedro García-Alamilla

Materials 2021, 14(11), 2763; https://doi.org/10.3390/ma14112763 - 23 May 2021

Cited by 23 | Viewed by 3047

Abstract

The use of synthetic dyes in the textile, leather, and paper industries is a source of groundwater pollution around the world. There are different methods for the treatment of wastewater that has been contaminated with dyes, among which adsorption with agro-industrial wastes is [...] Read more.

The use of synthetic dyes in the textile, leather, and paper industries is a source of groundwater pollution around the world. There are different methods for the treatment of wastewater that has been contaminated with dyes, among which adsorption with agro-industrial wastes is gaining relevance. In the present study, the adsorption capacity of cocoa bean shell powder was evaluated when it was used as a bioadsorbent for Congo red dye in an aqueous medium. A 2⁴ central factorial design with central and axial points was proposed to determine the adsorption capacity. The factors that were studied were the adsorbent (0.06–0.15 g), Congo red (40–120 mg L⁻¹), pH (3–11), and time (4–36 h). The bioadsorbent was characterized through scanning electron microscopy and Fourier-transform infrared spectroscopy. The effects of the factors on the adsorption capacity for Congo red using cocoa bean shell were nonlinear, and they were modeled with a second-order polynomial (p < 0.05) and with an R² of 0.84. The bioadsorbent obtained a maximum adsorption of 89.96% in runs. The process of optimization by using the surface response allowed the maximization of the adsorption, and the validation showed that 95.79% adsorption of the dye was obtained. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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16 pages, 3845 KiB

Open AccessEditor’s ChoiceArticle

Efficient Removal of Methylene Blue from Aqueous Solutions Using a High Specific Surface Area Porous Carbon Derived from Soybean Dreg

by Zhiwei Ying, Lu Huang, Lili Ji, He Li, Xinqi Liu, Chi Zhang, Jian Zhang and Guofu Yi

Materials 2021, 14(7), 1754; https://doi.org/10.3390/ma14071754 - 2 Apr 2021

Cited by 11 | Viewed by 2487

Abstract

Porous carbon material with high specific surface area was prepared from soybean dreg by a simple and effective two-step method (high temperature pyrolysis and activation). The structural characteristics of the synthesized carbon were evaluated by Brunauer–Emmett–Teller (BET), N₂ adsorption/desorption measurements/techniques, an elemental [...] Read more.

Porous carbon material with high specific surface area was prepared from soybean dreg by a simple and effective two-step method (high temperature pyrolysis and activation). The structural characteristics of the synthesized carbon were evaluated by Brunauer–Emmett–Teller (BET), N₂ adsorption/desorption measurements/techniques, an elemental analyzer (EA), scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), an X-ray diffractometer (XRD), Raman spectroscopy (Raman), a Fourier transform infrared spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS). The specific surface area of SDB-6-K was 2786 m² g⁻¹, the pore volume was 2.316 cm³ g⁻¹, and the average pore size was 3.326 nm. The high specific surface area and effective functional groups of carbon material promoted the adsorption of methylene blue. The maximum adsorption capacity of SDB-6-K to methylene blue was 2636 mg g⁻¹ at 318 K. The adsorption kinetic and isotherm data were most suitable for pseudo-second-order and Langmuir equations. The results showed that the adsorbent had excellent adsorptive ability and had good practical application potential in the field of dye wastewater treatment in the future. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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18 pages, 16588 KiB

Open AccessEditor’s ChoiceArticle

Utilization of Rice Husk Ash in the Preparation of Graphene-Oxide-Based Mesoporous Nanocomposites with Excellent Adsorption Performance

by Tzong-Horng Liou and Yuan Hao Liou

Materials 2021, 14(5), 1214; https://doi.org/10.3390/ma14051214 - 4 Mar 2021

Cited by 26 | Viewed by 3464

Abstract

Rice husk is an agricultural biomass waste. Burning rice husks in an oxygenic atmosphere releases thermal energy and produces ash that is rich in silica. Rice husk ash (RHA) can be used as a sustainable source of silica for producing high-value-added products. In [...] Read more.

Rice husk is an agricultural biomass waste. Burning rice husks in an oxygenic atmosphere releases thermal energy and produces ash that is rich in silica. Rice husk ash (RHA) can be used as a sustainable source of silica for producing high-value-added products. In this study, mesostructural graphene oxide (GO)/SBA-15, a graphene-based hybrid material, was synthesized from RHA. The materials are inspected by Fourier transform infrared spectrometer, Raman spectrometer, field-emission scanning electron microscopy, transmission electron microscopy, surface area analyzer, and X-ray diffraction analyzer. Studies have revealed that GO/SBA-15 possesses various oxygen functional groups that are helpful for dye adsorption. The material consisted of high pore volume of 0.901 cm³/g, wide pores of diameter 11.67 nm, and high surface area of 499 m²/g. Analysis of the methylene blue (MB) adsorption behavior of GO/SBA-15 composites revealed that their adsorption capacity depended on the gelation pH, GO content, adsorbent dosage, and initial dye (MB) concentration. The highest adsorption capacity of GO/SBA-15 was 632.9 mg/g. Furthermore, the adsorption isotherms and kinetics of GO/SBA-15 were investigated. This study demonstrated the great advantage of treated RHA and the potential of this material for use in organic dye adsorption. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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17 pages, 2698 KiB

Open AccessArticle

Efficient Removal of Cu(II), Zn(II), and Cd(II) from Aqueous Solutions by a Mineral-Rich Biochar Derived from a Spent Mushroom (Agaricus bisporus) Substrate

by Guosheng Zhang, Na Liu, Yuan Luo, Haibo Zhang, Long Su, Kokyo Oh and Hongyan Cheng

Materials 2021, 14(1), 35; https://doi.org/10.3390/ma14010035 - 23 Dec 2020

Cited by 21 | Viewed by 2971

Abstract

This study evaluated the novel application of a mineral-rich biochar derived from a spent Agaricus bisporus substrate (SAS). Biochars with various pyrolysis temperatures (350–750 °C) were used to remove Cu(II), Zn(II), and Cd(II) from aqueous solutions. The adsorption characteristics and removal mechanisms of [...] Read more.

This study evaluated the novel application of a mineral-rich biochar derived from a spent Agaricus bisporus substrate (SAS). Biochars with various pyrolysis temperatures (350–750 °C) were used to remove Cu(II), Zn(II), and Cd(II) from aqueous solutions. The adsorption characteristics and removal mechanisms of the biochars were investigated. The adsorption kinetics and isotherm data were fitted well by pseudo-second-order and Freundlich models. The Langmuir maximum removal capacity (Q_max) values of Cu(II), Zn(II), and Cd(II) were ordered as SAS750 > SAS350 > SAS550, and the Q_max values of SAS750 were 68.1, 55.2, and 64.8 mg·g⁻¹, respectively. Overall, the removal mechanisms of biochar at a low production temperature (350 °C) to Cu(II), Zn(II), and Cd(II) were mainly via ion exchange (54.0, 56.0, and 43.0%), and at a moderate production temperature (550 °C), removal mechanisms were mainly via coordination with π electrons (38.3, 45.9, and 55.0%), while mineral precipitation (65.2, 44.4, and 76.3%, respectively) was the dominant mechanism at a high produced temperature (750 °C). The variation of the mutual effect of minerals and heavy metals was the predominant factor in the sorption mechanism of mineral precipitation and ion exchange. The results demonstrated that spent Agaricus bisporus substrate biochar is a potential candidate for the efficient removal of heavy metals, which provides a utilization route for spent mushroom substrates. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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19 pages, 4689 KiB

Open AccessArticle

Utilization of Tires Waste-Derived Magnetic-Activated Carbon for the Removal of Hexavalent Chromium from Wastewater

by Waqas Ahmad, Shanif Qaiser, Rahman Ullah, Badrul Mohamed Jan, Michael A. Karakassides, Constantinos E. Salmas, George Kenanakis and Rabia Ikram

Materials 2021, 14(1), 34; https://doi.org/10.3390/ma14010034 - 23 Dec 2020

Cited by 19 | Viewed by 3062

Abstract

The present study focuses on fabrication of magnetic activated carbon (M-AC) using tire waste and its potential investigation for adsorption of Cr (VI) from wastewater. The composite material (M-AC) was synthesized by pyrolysis followed by in situ magnetization method, and characterized by FTIR, [...] Read more.

The present study focuses on fabrication of magnetic activated carbon (M-AC) using tire waste and its potential investigation for adsorption of Cr (VI) from wastewater. The composite material (M-AC) was synthesized by pyrolysis followed by in situ magnetization method, and characterized by FTIR, FESEM, EDX, and XRD analysis. The maximum adsorption of Cr (VI) ion over composite adsorbent was found (~99.5%) to occur at pH 2, sample volume 10 mL, adsorbent dose 100 mg, contact time 30 min. The adsorption process was endothermic, feasible, spontaneous, and was found to follow pseudo second order of the reaction. The Cr ion could be completely desorbed (~99.3%) from the composite adsorbent by using 20 mL of 2 M NaOH solution. The composite adsorbent was regenerated by continuous adsorption and desorption for 5 consecutive cycles by using 10 mL 0.1 M HCl solution. M-AC also performed well in case of tannery wastewater by removing about 97% of Cr (VI). Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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21 pages, 2486 KiB

Open AccessArticle

Modeling and Optimization of Pollutants Removal during Simultaneous Adsorption onto Activated Carbon with Advanced Oxidation in Aqueous Environment

by Lidia Dąbek, Anna Picheta-Oleś, Bartosz Szeląg, Joanna Szulżyk-Cieplak and Grzegorz Łagód

Materials 2020, 13(19), 4220; https://doi.org/10.3390/ma13194220 - 23 Sep 2020

Cited by 9 | Viewed by 2216

Abstract

The paper presents the results of studies on the modeling and optimization of organic pollutant removal from an aqueous solution in the course of simultaneous adsorption onto activated carbons with varied physical characteristics and oxidation using H₂O₂. The methodology [...] Read more.

The paper presents the results of studies on the modeling and optimization of organic pollutant removal from an aqueous solution in the course of simultaneous adsorption onto activated carbons with varied physical characteristics and oxidation using H₂O₂. The methodology for determining the models used for predicting the sorption and catalytic parameters in the process was presented. The analysis of the influence of the sorption and catalytic parameters of activated carbons as well as the oxidizer dose on the removal dynamics of organic dyes-phenol red and crystal violet-was carried out based on the designated empirical models. The obtained results confirm the influence of specific surface area (S) of the activated carbon and oxidizer dose on the values of the reaction rate constants related to the removal of pollutants from the solution in a simultaneous process. It was observed that the lower the specific surface area of carbon (S), the greater the influence of the oxidizer on the removal of pollutants from the solution. The proposed model, used for optimization of parameters in a simultaneous process, enables to analyze the effect of selected sorbents as well as the type and dose of the applied oxidizer on the pollutant removal efficiency. The practical application of models will enable to optimize the selection of a sorbent and oxidizer used simultaneously for a given group of pollutants and thus reduce the process costs. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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14 pages, 2650 KiB

Open AccessArticle

Adsorption of Cadmium, Manganese and Lead Ions from Aqueous Solutions Using Spent Coffee Grounds and Biochar Produced by Its Pyrolysis in the Fluidized Bed Reactor

by Jarosław Chwastowski, Dariusz Bradło and Witold Żukowski

Materials 2020, 13(12), 2782; https://doi.org/10.3390/ma13122782 - 20 Jun 2020

Cited by 44 | Viewed by 3807

Abstract

The adsorption process of cadmium ions (Cd), manganese ions (Mn) and lead ions (Pb) onto the spent coffee grounds (SCG) and activated spent coffee grounds (biochar, A-SCG) was investigated. The SCG activation was carried out in the pyrolysis process in a fluidized bed [...] Read more.

The adsorption process of cadmium ions (Cd), manganese ions (Mn) and lead ions (Pb) onto the spent coffee grounds (SCG) and activated spent coffee grounds (biochar, A-SCG) was investigated. The SCG activation was carried out in the pyrolysis process in a fluidized bed reactor. scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) measurements and CHN analysis were used in order to define the differences between biomaterials. In the study the different mass of materials (0.2–0.5 g) and constant heavy metal volume and concentration (20 cm3/100 ppm) were investigated on the adsorption process. In order to describe the sorption parameters the Langmuir, Freundlich and Temkin isotherms were used. The maximum adsorption for biochar reached 22.3 mg/g for Pb ions, 19.6 mg/g for Mn ions and 19.4 mg/g for Cd ions which were noticeably higher than the results obtained for spent coffee grounds which reached 13.6 mg/g for Pb ions, 13.0 mg/g for Mn ions and 11.0 mg/g for Cd ions. Metal ion adsorption on both SCG and A-SCG was best described by the Langmuir model, thus chemisorption was a dominant type of adsorption. Studying the kinetics of the sorption process, one can see that the process is of a chemical nature according to the best fit of the pseudo-second rate order model. The obtained results show that the chosen sorbents can be used for the removal of cadmium, manganese and lead compounds from aqueous solutions with high efficiency. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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22 pages, 3801 KiB

Open AccessFeature PaperArticle

Enhanced Arsenic(V) Removal on an Iron-Based Sorbent Modified by Lanthanum(III)

by Sebastian Dudek and Dorota Kołodyńska

Materials 2020, 13(11), 2553; https://doi.org/10.3390/ma13112553 - 3 Jun 2020

Cited by 12 | Viewed by 3169

Abstract

Modification of a commercial iron oxide ion exchanger (Arsen X^np) was carried out to enhance the removal of arsenic(V) ions. The modification consisted of the adsorption of lanthanum(III) ions on the Arsen X^np surface. After adsorption, the material was dried [...] Read more.

Modification of a commercial iron oxide ion exchanger (Arsen X^np) was carried out to enhance the removal of arsenic(V) ions. The modification consisted of the adsorption of lanthanum(III) ions on the Arsen X^np surface. After adsorption, the material was dried at 313 K to obtain the modified ion exchanger Arsen X^np-La(III). The modification process itself was tested for optimal pH, kinetics, and equilibrium adsorption isotherm study. Accurate sorbent characteristics were made using, among others, SEM, FTIR, and nitrogen adsorption/desorption isotherms. Then, various tests were carried out to compare the adsorption properties of the modified and unmodified material. It turned out that the tested material was able to completely remove arsenic from an aqueous solution with an initial concentration of up to 50 mg/dm³. Without modification, it was not possible to reach the WHO recommended 10 μg/dm³ arsenic limit even at an initial concentration of 25 mg/dm³. Moreover, the maximum sorption capacity increased from 22.37 to 61.97 mg/g after modification (3 times greater than before modification). It is worth noting that the process of removing arsenic on Arsen X^np-La(III) is fast—equilibrium is reached after about 120 min. Under almost neutral conditions, precipitation and adsorption can be the main mechanisms of As(V) removal. After modification, the removal capacity was enhanced by the co-precipitation and adsorption by exchange of the OH– group with arsenic ions. Such La(III) based adsorbent can be successfully applied in wastewater purification and displays superior performance for removing arsenic. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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12 pages, 2874 KiB

Open AccessArticle

Sorption Behaviors of Light Lanthanides(III) (La(III), Ce(III), Pr(III), Nd(III)) and Cr(III) Using Nitrolite

by Grzegorz Wójcik

Materials 2020, 13(10), 2256; https://doi.org/10.3390/ma13102256 - 14 May 2020

Cited by 19 | Viewed by 2186

Abstract

The sorption of light lanthanides(III) (La(III), Ce(III), Pr(III), Nd(III)) and chromium(III) ions from acidic solutions on Nitrolite was studied at varying ions concentrations, pH, contact time and temperatures. The sorption capacity of lanthanides(III) and chromium(III) ions were examined in the ranges 2–9 and [...] Read more.

The sorption of light lanthanides(III) (La(III), Ce(III), Pr(III), Nd(III)) and chromium(III) ions from acidic solutions on Nitrolite was studied at varying ions concentrations, pH, contact time and temperatures. The sorption capacity of lanthanides(III) and chromium(III) ions were examined in the ranges 2–9 and 2–5, respectively. The adsorption capacities of all metals are increase with the increasing pH (up to initial pH 9), despite the potential precipitation of metals at higher pH values. Therefore, an initial pH 9 of lanthanides gives the highest adsorption capacities. The kinetics of sorption chromium(III) and light lanthanides(III) were investigated. The experimental data were analyzed using the pseudo-first-order, pseudo-second-order forms, Elovich, and intra-particle diffusion models. The sorption kinetics of investigated ions was described by pseudo-second-order model the best. The results indicate the endothermic process of Cr(III), La(III), Ce(III), Pr(III) and Nd(III) ions sorption. The sorption capacities of La(III) 4.77 mg/g, Ce(III) 4.45 mg/g, Pr(III) 4.30 mg/g, Nd(III) 4.13 mg/g and Cr(III) 2.39 mg/g were calculated from the Langmiur model, which describes adsorption better than Freundlich and Dubinin–Radushkevich. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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15 pages, 4178 KiB

Open AccessArticle

Hybrid Pectin-Based Sorbents for Cesium Ion Removal

by Joanna Bok-Badura, Agata Jakóbik-Kolon, Alicja Kazek-Kęsik and Krzysztof Karoń

Materials 2020, 13(9), 2160; https://doi.org/10.3390/ma13092160 - 7 May 2020

Cited by 5 | Viewed by 2431

Abstract

In this paper, beads-shaped hybrid sorbents composed of pectin and Prussian blue were prepared. Various ratios of pectin and Prussian blue in hybrid sorbents were tested. Obtained sorbents had high and roughly constant sorption capacity in a broad pH range (4–10), in which [...] Read more.

In this paper, beads-shaped hybrid sorbents composed of pectin and Prussian blue were prepared. Various ratios of pectin and Prussian blue in hybrid sorbents were tested. Obtained sorbents had high and roughly constant sorption capacity in a broad pH range (4–10), in which also the swelling index and stability of sorbents were satisfactory. The preliminary sorption studies proved that almost 100% of cesium removal efficiency may be achieved by using the proper sorbent dose. The sorption capacity of the hybrid sorbent with a 1:1 ratio of pectin to Prussian blue equaled q = 36.5 ± 0.8 mg/g (dose 3 g/L, pH = 6, temp. = 22 ± 1 °C, t = 24 h). The obtained results showed that the prepared hybrid pectin-based sorbents are promising for cesium ions removal. Full article

(This article belongs to the Special Issue Adsorbents and Their Applications)

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