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Advanced or Conventional Materials as Sorbent

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A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (31 October 2019) | Viewed by 37837

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Prof. Dr. Ki-Hyun Kim

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Department of Civil and Environmental Engineering, Hanyang University, Seoul 04763, Republic of Korea
Interests: environmental & biomedical monitoring; air quality & environmental engineering; material engineering; coordination polymers; metal-organic frameworks (MOFs)
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Dear Colleagues,

For the separation and/or removal of pollutants in water or air, various approaches have been developed and utilized such as thermal oxidation, photocatalytic conversion, absorption, and adsorption. Amongst such available options, sorption has been widely acknowledged as the most economic, practical, flexible, and efficient methodology. For sorption treatment, numerous materials have been introduced as sorbent materials. Many research efforts have been put to develop diverse novel and/or functional materials including carbon nanotubes, graphene materials, metal organic frameworks, and so on. Although the considerably enhanced performance of those materials is well demonstrated, the use of conventional sorbents (e.g., activated carbon) is still preferred in many circumstances due to their high feasibility in terms of price. In this SI, authors are invited to describe various aspects of sorption-related issues with respect to material chemistry/engineering, environmental/energy fields, and many other fields that employ sorbent materials.

Prof. Dr. Ki-Hyun Kim
Guest Editor

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Keywords

novel/functional materials
adsorption
removal
pollutants
environment
energy

Published Papers (10 papers)

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Research

15 pages, 3066 KiB

Open AccessArticle

Adsorption of Lead and Nickel on to Expanded Graphite Decorated with Manganese Oxide Nanoparticles

by Quoc Cuong Do, Seonmi Choi, Hyojeon Kim and Seoktae Kang

Appl. Sci. 2019, 9(24), 5375; https://doi.org/10.3390/app9245375 - 09 Dec 2019

Cited by 28 | Viewed by 5621

Abstract

In this study, expanded graphite (EG) was decorated with manganese oxide nanoparticles (MONPs) by the hydrothermal method, and the newly formed composite (MONPs-EG) was applied as adsorbent for the removal of heavy metals from aqueous solutions. The comparative and competitive adsorption of Pb²⁺ and Ni²⁺ (0.01–1.00 mM) on MONPs-EG was investigated. Data from isothermal adsorption of single and binary systems suggested that both Pb²⁺ and Ni²⁺ were well described by the Langmuir isotherm, and the maximum adsorption capacities at 298 K were calculated at 0.278 and 0.113 mmol/g for Pb²⁺ and Ni²⁺, respectively. In binary systems, a dramatic decrease in adsorption capacity of Ni²⁺ was observed, while the adsorption capacity of Pb²⁺ was almost stable, indicating the favorable adsorption of Pb²⁺ over Ni²⁺ onto the prepared adsorbent. Kinetics studies of single and binary systems showed that a pseudo-second order model could explain the adsorption processes well. Thermodynamic analysis results demonstrated that the adsorption of these metal ions on the prepared adsorbent is spontaneous and exothermic in nature. The adsorption capacity of MONPs-EG increased significantly in the presence of humic acids. Overall, the results of this study suggest that MONPs-EG can be used effectively as an adsorbent for heavy metals removal from aqueous solutions. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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16 pages, 4559 KiB

Open AccessArticle

Adsorption of Ammonium Nitrogen from Aqueous Solution on Chemically Activated Biochar Prepared from Sorghum Distillers Grain

by Derlin Hsu, Changyi Lu, Tairan Pang, Yuanpeng Wang and Guanhua Wang

Appl. Sci. 2019, 9(23), 5249; https://doi.org/10.3390/app9235249 - 03 Dec 2019

Cited by 33 | Viewed by 4092

Abstract

Chemically activated biochars prepared from sorghum distillers grain using two base activators (NaOH and KOH) were investigated for their adsorption properties with respect to ammonium nitrogen from aqueous solution. Detailed characterizations, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TG), and specific surface area analyses, were carried out to offer a broad evaluation of the prepared biochars. The results showed that the NaOH- and KOH-activated biochars exhibited significantly enhanced adsorption capacity, by 2.93 and 4.74 times, respectively, in comparison with the pristine biochar. Although the NaOH-activated biochar possessed larger specific surface area (132.8 and 117.7 m²/g for the NaOH- and KOH-activated biochars, respectively), the KOH-activated biochar had higher adsorption capacity owing to its much higher content of functional groups. The adsorption kinetics and isotherms of the KOH-activated biochar at different temperatures were further studied. The biochar had a maximum adsorption capacity of 14.34 mg/g at 45 °C, which was satisfactory compared with other biochars prepared using different feedstocks. The adsorption process followed pseudo-second-order kinetics, and chemical adsorption was the rate-controlling step. The equilibrium data were consistent with the Freundlich isotherm, and the thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Consequently, this work demonstrates that chemically activated biochar from sorghum distillers grain is effective for ammonium nitrogen removal. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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16 pages, 3274 KiB

Open AccessArticle

Adsorption and Desorption Mechanisms of Rare Earth Elements (REEs) by Layered Double Hydroxide (LDH) Modified with Chelating Agents

by Shuang Zhang, Naoki Kano, Kenji Mishima and Hirokazu Okawa

Appl. Sci. 2019, 9(22), 4805; https://doi.org/10.3390/app9224805 - 10 Nov 2019

Cited by 25 | Viewed by 3510

Abstract

In order to obtain the adsorption mechanism and adsorption structures of Rare Earth Elements (REEs) ions adsorbed onto layered double hydroxides (LDH), the adsorption performance of LDH and ethylenediaminetetraacetic acid (EDTA) intercalated LDH for REEs was investigated by batch experiments and regeneration studies. In addition to adsorption capacity, the partition coefficient (PC) was also evaluated to assess their true performance metrics. The adsorption capacity of LDH increases from 24.9 μg·g⁻¹ to 145 μg·g⁻¹ for Eu, and from 20.8 μg·g⁻¹ to 124 μg·g⁻¹ for La by intercalating EDTA in this work; and PC increases from 45.5 μg·g⁻¹·uM⁻¹ to 834 μg·g⁻¹·uM⁻¹ for Eu, and from 33.6 μg·g⁻¹·μM⁻¹ to 405 μg·g⁻¹·μM⁻¹ for La. Comparison of the data indicates that the adsorption affinity of EDTA-intercalated LDH is better than that of precursor LDH no matter whether the concept of adsorption capacity or that of the PC was used. The prepared adsorbent was characterized by XRD, SEM-EDS and FT-IR techniques. Moreover, quantum chemistry calculations were also performed using the GAUSSIAN09 program package. In this calculation, the molecular locally stable state structures were optimized by density functional theory (DFT). Both the quantum chemistry calculations and the experimental data showed that REEs ions adsorbed by EDTA-intercalated LDH are more stable than those adsorbed by precursor LDH. Furthermore, the calculation results of adsorption and desorption rates show that adsorption rates are larger for Eu(III) than for La(III), which agrees with the experimental result that Eu(III) has a higher adsorption ability under the same conditions. The LDHs synthesized in this work have a high affinity for removing REEs ions. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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16 pages, 4475 KiB

Open AccessArticle

Assessment of an MnCe-GAC Treatment Process for Tetramethylammonium-Contaminated Wastewater from Optoelectronic Industries

by Da Tian Chang, Daeryong Park, Jun-Jie Zhu and Huan-Jung Fan

Appl. Sci. 2019, 9(21), 4578; https://doi.org/10.3390/app9214578 - 28 Oct 2019

Cited by 5 | Viewed by 4564

Abstract

Nitrogen-containing wastewater is an important issue in optoelectronic and semiconductor industries. Wastewater containing nitrogen compounds such as ammonium, monoethanolamine (MEA), and tetramethylammonium hydroxide (TMAH) must be properly treated due to concerns about health and environmental effects. MnCe-GAC (granular activated carbon) processes were developed in this study for the treatment of TMAH-contaminated wastewater in high-tech industries. The MnCe-GAC processes could effectively remove ammonium, MEA, and TMAH from aqueous solutions. The removal efficiencies of ammonium and MEA by these processes were better than observed for TMAH. Parameters affecting TMAH removal such as type of process, type of wastewater (synthetic or real), pH, salts, and t-butanol were investigated. In general, removal efficiencies of TMAH by various processes were in the following order: MnCe-GAC/O₃/H₂O₂ > MnCe-GAC/O₃ > MnCe-GAC/H₂O₂ > MnCe-GAC > GAC. The negative effect of sulfate and nitrate on pollutant removal might be due to the salting-out effect. Based on t-butanol experiments, the main degradation mechanisms of TMAH by the MnCe-GAC/O₃/H₂O₂ process likely involved hydroxyl radicals. The process proposed in this study could be an effective alternative method for the treatment of high-tech industrial wastewater to meet the new TMAH discharge limit. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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17 pages, 2228 KiB

Open AccessArticle

Sorption of Pb(II) from Aqueous Solutions by Acid-Modified Clinoptilolite-Rich Tuffs with Different Si/Al Ratios

by Mohamed Abatal, Atl V. Córdova Quiroz, María T. Olguín, América R. Vázquez-Olmos, Joel Vargas, Francisco Anguebes-Franseschi and German Giácoman-Vallejos

Appl. Sci. 2019, 9(12), 2415; https://doi.org/10.3390/app9122415 - 13 Jun 2019

Cited by 21 | Viewed by 3159

Abstract

The removal of Pb(II) from aqueous solutions by acid-modified clinoptilolite-rich tuff was investigated in this work. Clinoptilolite-rich tuff samples were treated using H₂SO₄ at different concentrations. Prior to and following acid treatment, the samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). The pH of the point of zero charge (pH_PZC) was also determined as part of this characterization. Batch studies were studied to investigate Pb(II) removal as a function of contact time, initial Pb(II) concentration, adsorbent dosage, and solution pH. The results of the XRD and SEM techniques showed that clinoptilolite is the main mineral of the non- and acid-treated natural zeolite samples. However, EDS analysis indicated that the Si/Al ratio increases as the exchangeable ions decrease with increasing acid concentrations. The optimum conditions for Pb(II) removal for samples with 4.37 ≤ Si/Al ≤ 7.9 were found to be as follows: Contact time of 60–360 min, pH: 6–8, and adsorbent dose of 6 mg g⁻¹; whereas for acid-modified clinoptilolite-rich tuffs with 9.01 ≤ Si/Al ≤ 9.52, these conditions were as follows: Contact time of 1440 min, pH: 8–10, and adsorbent dose of 10 mg g⁻¹. The experimental data were analyzed by kinetic and isotherms models. The results showed that the sorption of Pb(II) on samples with Si/Al ratios of 4.37, 5.31, and 7.91 were in agreement with the pseudo-second order and Langmuir isotherm with q_m = 48.54, 37.04, and 14.99 mg g⁻¹, respectively, while the kinetic data and isotherm for samples with 9.01 ≤ Si/Al ≤ 9.52 were found to fit the pseudo-first order and Freundlich model. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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19 pages, 3893 KiB

Open AccessArticle

Kinetics and Thermodynamics of Efficient Phosphorus Removal by a Composite Fiber

by Yan Liu and Xiao Hu

Appl. Sci. 2019, 9(11), 2220; https://doi.org/10.3390/app9112220 - 30 May 2019

Cited by 22 | Viewed by 2959

Abstract

In the current study, we investigated the kinetics and thermodynamics of phosphorus removal by zeolite/steel slag/fly ash/basalt (ZSFB) composite fiber. Kinetic analysis indicated that the adsorption of phosphorus is best fitted with the pseudo-second-order model. The maximum adsorption capacity of the fiber calculated by the Langmuir model was found to be 4.18 mg/g and the partition coefficient was 1.49 mg/g/µM. Thermodynamics results revealed that the Gibbs free energy ΔG⁰ of the composite fiber was negative, indicating that the adsorption is a spontaneous process; the standard enthalpy of reaction ΔH⁰ was positive, indicating that the adsorption is endothermic. Adsorption under different influencing factors and desorption experiments were conducted to investigate the phosphorus removal characteristics of ZSFB composite fiber. Dynamic adsorption and the phosphorus removal experiment were also conducted in a fixed-bed reactor to study factors affecting the time of breakthrough. Results indicate that the performance of ZSFB composite fiber was not relatively outstanding compared with nanomaterials and magnetic composites. However, its performance has already met the class A demands of “discharge standard of pollutants for municipal wastewater treatment plant” (GB18918-2002) which means it can be applied to remove phosphorus from real wastewater in a cost-effective way with low-priced raw materials. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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15 pages, 3011 KiB

Open AccessArticle

Sustainable Removal of Cr(VI) by Lime Peel and Pineapple Core Wastes

by Emilio Rosales, Silvia Escudero, Marta Pazos and Mª Angeles Sanromán

Appl. Sci. 2019, 9(10), 1967; https://doi.org/10.3390/app9101967 - 14 May 2019

Cited by 18 | Viewed by 3142

Abstract

The search for efficient and environmentally friendly adsorbents has positioned lignocellulosic materials as attractive and low-cost alternatives instead of synthetic materials. Consequently, the present work investigates the efficacy of untreated lime peel (LM) and pineapple core (PP) as biosorbents for Cr(VI) removal. The maximum adsorption capacities (acquired at 24 h) of these sorbents were 9.20 and 4.99 mg/g, respectively. The use of these sorbents is expected to offer a rapid and efficient solution to treat effluents containing Cr(VI). Pineapple core showed the best biosorption properties and good distribution coefficients (distribution coefficient K_D 8.35–99.20 mL/g) and the optimization of the adsorption was carried out by a response surface methodology using the Box–Behnken design. Thus, the effect of pH, biosorbent dosage, and temperature were assessed during the whole procedure. Three different responses were studied—Cr(VI) removal, Cr biosorption, and distribution coefficient—and the optimal conditions for maximizing the responses were identified by numerical optimization applying the desirability function. The resulting optimal conditions were: initial solution pH 2.01, biosorbent dosage 30 g/L, and temperature 30.05 °C. Finally, the process scale-up was evaluated by the simulation of the process working with a column of 100 L using the Fixed-bed Adsorption Simulation Tool (FASTv2.1). This research presents the obtained environmental benefits: i) reduction of pineapple waste, ii) Cr(VI) reduction and biosorption, iii) shortest sorption time for Cr, iv) properties that allow the biosorption process on the flow system, and v) low-cost process. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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15 pages, 3472 KiB

Open AccessArticle

Hydrothermal Conversion of Red Mud into Magnetic Adsorbent for Effective Adsorption of Zn(II) in Water

by Wenqing Dong, Kun Liang, Yanyi Qin, Huijia Ma, Xuan Zhao, Leilei Zhang, Suiyi Zhu, Yang Yu, Dejun Bian and Jiakuan Yang

Appl. Sci. 2019, 9(8), 1519; https://doi.org/10.3390/app9081519 - 12 Apr 2019

Cited by 16 | Viewed by 3440

Abstract

Red mud, a Fe-rich waste generated from the aluminum industry, was recovered as an adsorbent for wastewater treatment. The separation process of red mud from water after adsorption, including centrifugation and filtration, was complicated. This study demonstrated an alternative option to recycle red mud for preparing magnetic adsorbent via a facile hydrothermal route using ascorbic acid as reductant. Red mud is weakly magnetized and consists of andradite, muscovite, hematite, and cancrinite. After hydrothermal treatment, andradite in red mud was reductively dissolved by ascorbic acid, and transformed into magnetite and morimotoite. With increasing hydrothermal temperature, the dissolution of andradite accelerated, and the crystallite size of magnetite increased. When the hydrothermal temperature reached 200 °C, the prepared adsorbent P-200 showed a desirable saturation magnetization of 4.1 Am²/kg, and could be easily magnetically separated from water after adsorption. The maximum adsorption capacity of P-200 for Zn²⁺ was 89.6 mg/g, which is eight-fold higher than that of the raw red mud. The adsorption of Zn²⁺ by P-200 fitted the Langmuir model, where cation exchange was the main adsorption mechanism. The average distribution coefficient of Zn²⁺ at low ppm level was 16.81 L/g for P-200, higher than those of the red mud (0.3 L/g) and the prepared P-120 (1.48 L/g) and P-270 (5.48 L/g), demonstrating that P-200 had the best adsorption capacity for Zn²⁺ and can be served as a practical adsorbent for real-world applications. To our knowledge, this is the first study to report the conversion of red mud into a magnetic adsorbent under mild conditions. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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19 pages, 6099 KiB

Open AccessArticle

Electroadsorptive Removal of Gaseous Pollutants

by Mattia Pierpaoli, Gabriele Fava and Maria Letizia Ruello

Appl. Sci. 2019, 9(6), 1162; https://doi.org/10.3390/app9061162 - 19 Mar 2019

Cited by 2 | Viewed by 3412

Abstract

Adsorption is a consequence of surface energy distribution, and the existence of electrostatic bonding suggests that the presence of an external electric field may affect adsorbate/adsorbent interactions. Nevertheless, this aspect has been poorly studied in the literature, except under non-thermal plasma or corona discharge conditions. After having demonstrated in our previous work that the adsorption kinetics of gaseous organic compounds can be enhanced by the presence of an external applied electric field, in this study, we focus on the influence of the electric field on adsorbent and adsorptive interactions. By using a commercially available activated carbon cloth, in addition to increasing the adsorbent mass transfer coefficient by virtue of the increasing intensity of the applied electric field, the results suggest that adsorbent morphology is only influenced by the formation of new surface functional groups. Moreover, enhanced adsorption kinetics and capacity may result from the electrohydrodynamic force induced by the movement of charged and neutral particles towards the adsorbent, as confirmed by the reversibility of the process. Such enhancement results in a negligible increase, of about 3%, in adsorption capacity (i.e., from 91 mmol m⁻² Pa⁻¹ for only adsorption to 94 mmol m⁻² Pa⁻¹ in the presence of the applied electric field), but also in a dramatic doubling of adsorption kinetics (i.e., from 0.09 min⁻¹ for only adsorption to 0.19 min⁻¹ in the presence of the applied electric field). In reality, the application of an electric field to an activated carbon cloth leads to faster adsorption kinetics, without substantially altering its adsorption capacity. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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18 pages, 4685 KiB

Open AccessArticle

The Effects of Textural Parameters of Zeolite and Silica Materials on the Protective and Functional Properties of Polymeric Nonwoven Composites

by Agnieszka Brochocka, Aleksandra Nowak, Rafał Panek and Wojciech Franus

Appl. Sci. 2019, 9(3), 515; https://doi.org/10.3390/app9030515 - 02 Feb 2019

Cited by 8 | Viewed by 3214

Abstract

Zeolites are micro- and mesoporous aluminosilicate minerals (both natural and industrially produced) widely used as catalysts and sorbents in domestic and commercial water purification and separation technologies. Their ability to selectively adsorb gases (i.e., water vapor, carbon dioxide, and sulfur dioxide removal) from an air stream makes them suitable for applications in odor reducing media used in filtering facepiece respirators (FFRs). FFRs are multilayer products in which the most important role is played by high-performance melt-blown electret nonwovens modified with activated carbon to adsorb malodorous compounds. Replacing carbon sorbents with zeolites could increase the efficiency of odor abatement, thus alleviating work-related hazards for individuals exposed to malodorous substances with adverse effects on human well-being. The objective of the present work was to analyze the influence of the textural parameters of zeolite and mesoporous silica materials on the protective and functional properties of polymeric nonwoven composites containing them. In our experiments, the longest breakthrough time against ammonia vapor was found for a nonwoven composite containing the inorganic mesoporous silica material type MCM-41. It was also characterized by high filtration efficiency against aerosols with solid and liquid dispersed phases (97% and 99% for sodium chloride and paraffin oil mist, respectively) at an airflow resistance of approximately 330 Pa. In turn, the composites containing the molecular sieve (SM-zeolite ZSM-5) exhibited the longest breakthrough time for acetone and cyclohexane vapors at the maximum allowable concentrations of 235 ppm and 81 ppm, respectively. Basic filtration tests showed that the composite was 97% effective against both test aerosols at an airflow resistance of 283.5 Pa. Full article

(This article belongs to the Special Issue Advanced or Conventional Materials as Sorbent)

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