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Special Issue "Sorption Materials for Environment Purification"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 June 2017)

Special Issue Editor

Guest Editor
Dr. Eric Guibal

Ecole des mines d'Alès, Centre des Matériaux des Mines d'Alès (C2MA), 6, avenue de Clavières, 30319 Alès cedex, France
E-Mail
Phone: +33 (0)466782734
Interests: biopolymers; wastewater treatment; metal ion interactions with biopolymers; biopolymer conditioning; supported catalysis; encapsulation processes; ionic liquids

Special Issue Information

Dear Colleagues,

The standards and policies at an international level are becoming more and more stringent to preserve water resources and improve the quality of water for use in agriculture, drinking water and industry. Water treatment is therefore a challenging issue for industry and domestic applications. Pollutants such as metal ions, organic contaminants (endocrine disruptors, dyes, etc.) may strongly affect aquatic fauna and flora and may exert a cumulative effect in the food chain with a harmful impact on animal and human health.

Several processes may be used for wastewater decontamination: coagulation–flocculation, precipitation, etc. However, sorption processes are especially adapted to the treatment of low-concentration effluents (as the primary treatment or as a polishing step). Recent decades have seen not only the amazing development of new sophisticated materials (ion-exchange and chelating resins, imprinted polymers, extractant-impregnated polymers, composite sorbents, magnetic nano-based particles) but also the use of natural resources (biomass, biopolymers, waste materials from agriculture, etc.) for designing new wastewater treatments.

The design of these materials may take into account processing criteria (hydrodynamic constraints, solid/liquid separation properties), resource availability (cost and stock), performance (sorption capacities, mass transfer properties, selectivity criteria), recycling of materials (desorption/elution, re-use, life cycle) and valorization (recovery of valuable metals, for example). All these criteria may influence the conditioning of the sorbents (shaping, porosity, structure), their field of application (cost efficiency adjusted to flow rates), and the combination of different materials for achieving efficient and competitive wastewater treatment (in agreement with local discharge levels or regulations).

This fascinating research area is at the cross-point of chemical engineering and material sciences and the combination/collaboration of different actors is the key to successful design of new materials and new applications.

The interactions of sorbents with target molecules may also be used for designing new materials, for example the immobilization of metal ions onto sorbents has been used for manufacturing sensors, supported catalysts, etc.

It is my great pleasure to invite you to contribute a manuscript to this Special Issue. Your contribution could consist of full papers, communications or reviews. Thank you in advance for enriching our knowledge for the development of new sorbents and sorption processes.

Dr. Eric Guibal
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Sorbents and biosorbents
  • Ion-exchange and chelating resins
  • Impregnated resins
  • Imprinted polymers
  • Magnetic sorbents
  • Composite sorbents
  • Nano-sized sorbents
  • Wastewater treatment
  • Metal ions
  • Dyes
  • Organic contaminants

Published Papers (15 papers)

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Research

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Open AccessFeature PaperArticle The Effect of Hydrogen Bonding in Enhancing the Ionic Affinities of Immobilized Monoprotic Phosphate Ligands
Materials 2017, 10(8), 968; doi:10.3390/ma10080968
Received: 16 June 2017 / Revised: 9 August 2017 / Accepted: 14 August 2017 / Published: 18 August 2017
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Abstract
Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl
[...] Read more.
Environmental remediation requires ion-selective polymers that operate under a wide range of solution conditions. In one example, removal of trivalent and divalent metal ions from waste streams resulting from mining operations before they enter the environment requires treatment at acidic pH. The monoethyl ester phosphate ligands developed in this report operate from acidic solutions. They have been prepared on polystyrene-bound ethylene glycol, glycerol, and pentaerythritol, and it is found that intra-ligand hydrogen bonding affects their metal ion affinities. The affinity for a set of trivalent (Fe(III), Al(III), La(III), and Lu(III)) and divalent (Pb(II), Cd(II), Cu(II), and Zn(II)) ions is greater than that of corresponding neutral diethyl esters and phosphonic acid. In an earlier study, hydrogen bonding was found important in determining the metal ion affinities of immobilized phosphorylated polyol diethyl ester coordinating ligands; their Fourier transform infrared (FTIR) band shifts indicated that the basicity of the phosphoryl oxygen increased by hydrogen bonding to auxiliary –OH groups on the neighboring polyol. The same mechanism is operative with the monoprotic resins along with hydrogen bonding to the P–OH acid site. This is reflected in the FTIR spectra: the neutral phosphate diethyl ester resins have the P=O band at 1265 cm−1 while the monoethyl ester resins have the band shifted to 1230 cm−1; hydrogen bonding is further indicated by the broadness of this region down to 900 cm−1. The monoprotic pentaerythritol has the highest metal ion affinities of the polymers studied. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Zinc Sorption Studies on Pectin-Based Biosorbents
Materials 2017, 10(7), 844; doi:10.3390/ma10070844
Received: 3 July 2017 / Revised: 18 July 2017 / Accepted: 19 July 2017 / Published: 22 July 2017
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Abstract
The previously-obtained and characterized hybrid pectin-based beads containing agar-agar and guar gum, as well as sole pectin beads (P, for comparison) were examined for zinc ions sorption and desorption properties. The sorption kinetics and equilibrium in the studied system was described by two
[...] Read more.
The previously-obtained and characterized hybrid pectin-based beads containing agar-agar and guar gum, as well as sole pectin beads (P, for comparison) were examined for zinc ions sorption and desorption properties. The sorption kinetics and equilibrium in the studied system was described by two kinetic models (pseudo-first- and pseudo-second-order) and two isotherms (Langmuir and Freundlich), respectively. The desorption kinetics and equilibrium was also investigated by applying various inorganic acids (nitric, hydrochloric, and sulfuric acid) of various concentrations. In the case of guar gum additive, no significant change in sorption capacity compared to sole pectin beads was observed (q: 37.0 ± 2.6 and 34.7 ± 2.0 mg/g, respectively). Addition of agar-agar significantly decreased the sorption capacity to 22.3 ± 1.0 mg/g, but stripping of zinc(II) ions from this biosorbent was complete even with very diluted acids (0.01 M). Total desorption of zinc from sole pectin and pectin-guar gum beads required acid solution of higher concentration (0.1 M). Sorption rates for all biosorbents are roughly the same and maximum sorption is achieved after 4–5 h. Obtained results and the advantage of our sorbent’s shape formation ability, make the pectin-based biosorbents interesting alternative for zinc(II) ions removal. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Microwave-Assisted Synthesis of Goethite Nanoparticles Used for Removal of Cr(VI) from Aqueous Solution
Materials 2017, 10(7), 783; doi:10.3390/ma10070783
Received: 31 May 2017 / Revised: 4 July 2017 / Accepted: 4 July 2017 / Published: 11 July 2017
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Abstract
The microwave-assisted synthesis of goethite nanoparticles has been studied. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and Brunauer–Emmett–Teller (BET) method. Goethite rod-like nanoparticles have been successfully synthesized in 10 min of
[...] Read more.
The microwave-assisted synthesis of goethite nanoparticles has been studied. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA) and Brunauer–Emmett–Teller (BET) method. Goethite rod-like nanoparticles have been successfully synthesized in 10 min of microwave treating at 100 °C. Particle size is in the range from 30 to 60 nm in width and from 200 to 350 nm in length. BET analysis indicated that the surface area of the product is 158.31 m2g−1. The feasibility of Cr(VI) removal fromaqueous solution depends on the pH of the solution and contact time. The maximum adsorptionis reached at pH 4.0 and 540 min of contact time. The adsorption kinetics was analyzedby the pseudo-first- and second-order models and the results reveal that the adsorption process obeys the pseudo-second-order model. The adsorption data were fitted well with the Langmuir adsorption isotherm. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Zinc Sorption on Modified Waste Poly(methyl methacrylate)
Materials 2017, 10(7), 755; doi:10.3390/ma10070755
Received: 13 June 2017 / Revised: 28 June 2017 / Accepted: 30 June 2017 / Published: 6 July 2017
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Abstract
The new one-pot hydrolysis-crosslinking reaction was used to synthesize a new, waste poly(methyl methacrylate) (PMMA)-based material for zinc(II) ions removal. The alkaline hydrolysis of PMMA in diethylene glycol diethyl ether was used to obtain polymer matrix and it was then crosslinked with Ca
[...] Read more.
The new one-pot hydrolysis-crosslinking reaction was used to synthesize a new, waste poly(methyl methacrylate) (PMMA)-based material for zinc(II) ions removal. The alkaline hydrolysis of PMMA in diethylene glycol diethyl ether was used to obtain polymer matrix and it was then crosslinked with Ca and Mg ions to obtain the sorbent. As a result, the macroporous materials were obtained with a yield of 87% when waste PMMA was used, and about 95% when the commercial PMMAs were used. The degree of hydrolysis was similar, from 32% to 35%. New materials were then tested for their affinity towards zinc(II) ions. Two kinetic models (pseudo-first and pseudo-second order), as well as two isotherms (Langmuir and Freundlich), were used to describe the kinetics and equilibrium of zinc(II) ion sorption on the studied materials, respectively. All the prepared PMMA-based sorbents showed similar or higher sorption capacity (q up to 87.7 mg/g) compared to commercially available materials in a broad pH range (4–7). The study shows sorption was fast—above 80% of equilibrium capacity was achieved after ca. 0.5 h. Presented results show that waste PMMA may be an interesting raw material for the preparation of sorbents for zinc(II) ions removal. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Application of Synthetic Layered Sodium Silicate Magadiite Nanosheets for Environmental Remediation of Methylene Blue Dye in Water
Materials 2017, 10(7), 760; doi:10.3390/ma10070760
Received: 13 May 2017 / Revised: 30 June 2017 / Accepted: 3 July 2017 / Published: 6 July 2017
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Abstract
The removal of methylene blue (MB) dye from water was investigated using synthetic nano-clay magadiite (SNCM). SNCM was synthesized by a hydrothermal treatment under autogenous pressure. A rosette-shaped single mesoporous magadiite phase with 16.63 nm average crystallite size and 33 m2∙g
[...] Read more.
The removal of methylene blue (MB) dye from water was investigated using synthetic nano-clay magadiite (SNCM). SNCM was synthesized by a hydrothermal treatment under autogenous pressure. A rosette-shaped single mesoporous magadiite phase with 16.63 nm average crystallite size and 33 m2∙g−1 Braunauer-Emmet-Teller (BET)-surface area was recorded. The adsorption results indicated the pronounced affinity of the SNCM to the MB dye molecules, which reached an adsorption uptake of 20.0 mg MB dye/g of SNCM. The elimination of MB dye by the SNCM was kinetically and thermodynamically considered; a pseudo-second-order kinetic model was attained, and its spontaneous, chemical, and endothermic nature was verified. SNCM was shown to be robust without a detectable reduction in the adsorption capacity after up to four times re-use. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Ultrasonic Measurements on β Cyclodextrin/Hydroxyapatite Composites for Potential Water Depollution
Materials 2017, 10(6), 681; doi:10.3390/ma10060681
Received: 15 May 2017 / Revised: 14 June 2017 / Accepted: 15 June 2017 / Published: 21 June 2017
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Abstract
This paper presents structural, morphological and preliminary ultrasonic characterizations of the β-Cyclodextrin/hydroxyapatite (CD-HAp) composites synthesized by an adapted co-precipitation method. The structural and morphological properties were evaluated by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The specific surface area, pore
[...] Read more.
This paper presents structural, morphological and preliminary ultrasonic characterizations of the β-Cyclodextrin/hydroxyapatite (CD-HAp) composites synthesized by an adapted co-precipitation method. The structural and morphological properties were evaluated by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The specific surface area, pore size and pore volume were determined using the methods of Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH), respectively. The novelty of our study consists in preliminary ultrasonic measurements conducted on CD-HAp composite, uniformly dispersed in distilled water. The benefit of this non-destructive method was to facilitate and simplify the characterization techniques of nanoparticles. Our experiments proved that the efficiency of lead ion removal by CD-HAp composites depended on the initial concentration of lead. The maximum adsorption capacity of the solid phase, for Pb2+ indicated a higher rate of removal by the CD-HAp_2. These adsorption results bring valuable insight into the beneficial contribution of our compounds, for the removal of heavy metal ions from aqueous solutions. Furthermore, in the present study, was evaluated the toxic effect of lead ions adsorbed by hydroxyapatite from contaminated water on HeLa cells. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessFeature PaperArticle Recovery of Silver Using Adsorption Gels Prepared from Microalgal Residue Immobilized with Functional Groups Containing Sulfur or Nitrogen
Materials 2017, 10(6), 636; doi:10.3390/ma10060636
Received: 16 May 2017 / Revised: 7 June 2017 / Accepted: 7 June 2017 / Published: 10 June 2017
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Abstract
Although biodiesel oil extracted from microalgae attracts much attention as one of the most promising green energies, its high production cost is a big problem, impeding its extensive use. In order to lower the production cost, the effective use of microalgal residue after
[...] Read more.
Although biodiesel oil extracted from microalgae attracts much attention as one of the most promising green energies, its high production cost is a big problem, impeding its extensive use. In order to lower the production cost, the effective use of microalgal residue after extracting biofuel was investigated as a feed material of functional materials. In the present work, a new adsorbent for silver(I) was prepared by immobilizing functional groups of polyethylene-polyamine or dithiooxamide, which exhibita high affinity for soft Lewis acids such as silver(I) ions. Their adsorption behaviors for silver(I) were investigated from aqueous nitrate and acidothiourea media. The effects of the concentrations of nitrate and thiourea, as well as of sulfuric acid, were qualitatively interpreted. From the study of adsorption isotherms on these gels, they were found to exhibita higher adsorption capacity than the majority of those reported to date. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Extractant Immobilization in Alginate Capsules (Matrix- and Mononuclear-Type): Application to Pb(II) Sorption from HCl Solutions
Materials 2017, 10(6), 634; doi:10.3390/ma10060634
Received: 20 April 2017 / Revised: 1 June 2017 / Accepted: 6 June 2017 / Published: 9 June 2017
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Abstract
The decontamination of dilute industrial effluents is a critical challenge for decreasing the environmental impact of mining and metallurgical activities. As an alternative to conventional processes, new extractant impregnated resins (EIRs) have been synthesized by the immobilization of Cyanex 301 and Cyanex 302
[...] Read more.
The decontamination of dilute industrial effluents is a critical challenge for decreasing the environmental impact of mining and metallurgical activities. As an alternative to conventional processes, new extractant impregnated resins (EIRs) have been synthesized by the immobilization of Cyanex 301 and Cyanex 302 in alginate capsules using two different procedures (matrix-type immobilization vs. mononuclear encapsulation). These materials have been tested for Pb(II) sorption from acidic solutions. The Langmuir equation fitted well the sorption isotherms and the maximum sorption capacities vary between 24 and 80 mg·g−1 at pH 1, depending on the type and loading of the extractant in the EIR. Uptake kinetics were controlled by the resistance to intraparticle diffusion; though both the Crank equation (intraparticle diffusion) and pseudo-second order rate equation equally fitted uptake profiles. The amount of extractant immobilized in mononuclear capsules is lower than in matrix-type beads; this leads to lower sorption capacities but slightly better mass transfer properties. The balance between the advantages and drawbacks of the different systems makes more promising matrix-type capsules. The desorption of Pb(II) is possible using 1 M HNO3 solutions: metal ions were completely desorbed. However, the probable oxidation of the extractants (conversion to oxidized forms more sensitive to pH) reduces the sorption efficiency when they are re-used. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Synthesis, Characterization and Hexavalent Chromium Adsorption Characteristics of Aluminum- and Sucrose-Incorporated Tobermorite
Materials 2017, 10(6), 597; doi:10.3390/ma10060597
Received: 21 April 2017 / Revised: 22 May 2017 / Accepted: 23 May 2017 / Published: 30 May 2017
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Abstract
Tobermorites were synthesized from the lime-quartz slurries with incorporations of aluminum and sucrose under hydrothermal conditions, and then used for adsorption of Cr(VI). The chemical components, and structural and morphological properties of tobermorite were characterized by X-ray diffraction (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC),
[...] Read more.
Tobermorites were synthesized from the lime-quartz slurries with incorporations of aluminum and sucrose under hydrothermal conditions, and then used for adsorption of Cr(VI). The chemical components, and structural and morphological properties of tobermorite were characterized by X-ray diffraction (XRD), thermogravimetric-differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS) and N2 adsorption–desorption measurements. The formation and crystallinity of tobermorite could be largely enhanced by adding 2.3 wt.% aluminum hydroxide or 13.3 wt.% sucrose. Sucrose also played a significantly positive role in increasing the surface area. The adsorption performances for Cr(VI) were tested using a batch method taking into account the effects of pH, the adsorption kinetics, and the adsorption isotherms. The adsorption capacities of the aluminum- and sucrose-incorporated tobermorites reached up to 31.65 mg/g and 28.92 mg/g, respectively. Thus, the synthesized tobermorites showed good adsorption properties for removal of Cr(VI), making this material a promising candidate for efficient bulk wastewater treatment. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Functionalization of Magnetic Chitosan Particles for the Sorption of U(VI), Cu(II) and Zn(II)—Hydrazide Derivative of Glycine-Grafted Chitosan
Materials 2017, 10(5), 539; doi:10.3390/ma10050539
Received: 19 April 2017 / Revised: 5 May 2017 / Accepted: 9 May 2017 / Published: 16 May 2017
Cited by 1 | PDF Full-text (1474 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A new magnetic functionalized derivative of chitosan is synthesized and characterized for the sorption of metal ions (environmental applications and metal valorization). The chemical modification of the glycine derivative of chitosan consists of: activation of the magnetic support with epichlorohydrin, followed by reaction
[...] Read more.
A new magnetic functionalized derivative of chitosan is synthesized and characterized for the sorption of metal ions (environmental applications and metal valorization). The chemical modification of the glycine derivative of chitosan consists of: activation of the magnetic support with epichlorohydrin, followed by reaction with either glycine to produce the reference material (i.e., Gly sorbent) or glycine ester hydrochloride, followed by hydrazinolysis to synthesize the hydrazide functionalized sorbent (i.e., HGly sorbent). The materials are characterized by titration, elemental analysis, FTIR analysis (Fourrier-transform infrared spectrometry), TGA analysis (thermogravimetric analysis) and with SEM-EDX (scanning electron microscopy coupled to energy dispersive X-ray analysis). The sorption performances for U(VI), Cu(II), and Zn(II) are tested in batch systems. The sorption performances are compared for Gly and HGly taking into account the effect of pH, the uptake kinetics (fitted by the pseudo-second order rate equation), and the sorption isotherms (described by the Langmuir and the Sips equations). The sorption capacities of the modified sorbent reach up to 1.14 mmol U g−1, 1.69 mmol Cu g−1, and 0.85 mmol Zn g−1. In multi-metal solutions of equimolar concentration, the chemical modification changes the preferences for given metal ions. Metal ions are desorbed using 0.2 M HCl solutions and the sorbents are re-used for five cycles of sorption/desorption without significant loss in performances. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Enhanced CO2 Adsorption on Activated Carbon Fibers Grafted with Nitrogen-Doped Carbon Nanotubes
Materials 2017, 10(5), 511; doi:10.3390/ma10050511
Received: 6 April 2017 / Revised: 3 May 2017 / Accepted: 5 May 2017 / Published: 7 May 2017
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Abstract
In this paper, multiscale composites formed by grafting N-doped carbon nanotubes (CNs) on the surface of polyamide (PAN)-based activated carbon fibers (ACFs) were investigated and their adsorption performance for CO2 was determined. The spaghetti-like and randomly oriented CNs were homogeneously grown onto
[...] Read more.
In this paper, multiscale composites formed by grafting N-doped carbon nanotubes (CNs) on the surface of polyamide (PAN)-based activated carbon fibers (ACFs) were investigated and their adsorption performance for CO2 was determined. The spaghetti-like and randomly oriented CNs were homogeneously grown onto ACFs. The pre-immersion of cobalt(II) ions for ACFs made the CNs grow above with a large pore size distribution, decreased the oxidation resistance, and exhibited different predominant N-functionalities after chemical vapor deposition processes. Specifically, the CNs grafted on ACFs with or without pre-immersion of cobalt(II) ions were characterized by the pyridine-like structures of six-member rings or pyrrolic/amine moieties, respectively. In addition, the loss of microporosity on the specific surface area and pore volume exceeded the gain from the generation of the defects from CNs. The adsorption capacity of CO2 decreased gradually with increasing temperature, implying that CO2 adsorption was exothermic. The adsorption capacities of CO2 at 25 °C and 1 atm were between 1.53 and 1.92 mmol/g and the Freundlich equation fit the adsorption data well. The isosteric enthalpy of adsorption, implying physical adsorption, indicated that the growth of CNTs on the ACFs benefit CO2 adsorption. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Chromium(VI) Removal from Aqueous Solution by Magnetite Coated by a Polymeric Ionic Liquid-Based Adsorbent
Materials 2017, 10(5), 502; doi:10.3390/ma10050502
Received: 7 April 2017 / Revised: 26 April 2017 / Accepted: 28 April 2017 / Published: 6 May 2017
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Abstract
An evaluation of the chromium(VI) adsorption capacity of four magnetite sorbents coated with a polymer phase containing polymethacrylic acid or polyallyl-3-methylimidazolium is presented. Factors that influence the chromium(VI) removal such as solution pH and contact time were investigated in batch experiments and in
[...] Read more.
An evaluation of the chromium(VI) adsorption capacity of four magnetite sorbents coated with a polymer phase containing polymethacrylic acid or polyallyl-3-methylimidazolium is presented. Factors that influence the chromium(VI) removal such as solution pH and contact time were investigated in batch experiments and in stirred tank reactor mode. Affinity and rate constants increased with the molar ratio of the imidazolium. The highest adsorption was obtained at pH 2.0 due to the contribution of electrostatic interactions. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Characterizing Adsorption Performance of Granular Activated Carbon with Permittivity
Materials 2017, 10(3), 269; doi:10.3390/ma10030269
Received: 29 November 2016 / Revised: 27 February 2017 / Accepted: 1 March 2017 / Published: 7 March 2017
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Abstract
A number of studies have achieved the consensus that microwave thermal technology can regenerate the granular activated carbon (GAC) more efficiently and energy-conservatively than other technologies. In particular, in the microwave heating industry, permittivity is a crucial parameter. This paper developed two equivalent
[...] Read more.
A number of studies have achieved the consensus that microwave thermal technology can regenerate the granular activated carbon (GAC) more efficiently and energy-conservatively than other technologies. In particular, in the microwave heating industry, permittivity is a crucial parameter. This paper developed two equivalent models to establish the relationship between effective complex permittivity and pore volume of the GAC. It is generally based on Maxwell-Garnett approximation (MGA) theory. With two different assumptions in the model, two quantificational expressions were derived, respectively. Permittivity measurements and Brunauer–Emmett–Teller (BET) testing had been introduced in the experiments. Results confirmed the two expressions, which were extremely similar. Theoretical and experimental graphs were matched. This paper set up a bridge which links effective complex permittivity and pore volume of the GAC. Furthermore, it provides a potential and convenient method for the rapid assisted characterization of the GAC in its adsorption performance. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Open AccessArticle Separation of Lead with a Novel Ion Separating Agent Prepared by Clothing a Chitin Whisker on a Potassium Tetratitanate Whisker
Materials 2017, 10(3), 262; doi:10.3390/ma10030262
Received: 12 January 2017 / Revised: 22 February 2017 / Accepted: 24 February 2017 / Published: 6 March 2017
PDF Full-text (5060 KB) | HTML Full-text | XML Full-text
Abstract
Separation of Pb2+ from Cu2+-Pb2+ mixed solution by a newly-developed ion separating agent was examined, which was obtained by clothing chitin whiskers (ChW) on the surface of potassium tetratitanate whiskers (PTW). The separation capability and mechanism of the ion
[...] Read more.
Separation of Pb2+ from Cu2+-Pb2+ mixed solution by a newly-developed ion separating agent was examined, which was obtained by clothing chitin whiskers (ChW) on the surface of potassium tetratitanate whiskers (PTW). The separation capability and mechanism of the ion separating agent (ChW-PTW) was determined, based on the difference of the adsorption isotherm pattern and the adsorption kinetics model between ChW and PTW on Cu2+ and Pb2+, respectively. The results showed that the adsorption process of ChW could be described by Freundlish isotherm. The adsorption affinity of Cu2+ (kF = 0.085·g−1) on ChW was greater than Pb2+ (kF = 0.077 g−1). The adsorption pattern of PTW was inclined to the Langmuir isotherm, and Pb2+ (kL = 310.59 L·mmol−1) could be obviously more easily adsorbed on PTW than Cu2+ (kL = 25.85 L·mmol−1). The experimental data both fitted well with the pseudo-second order kinetics. The reaction rate of Pb2+ (k2 = 4.442 for ChW and k2 = 0.846 for PTW) was greater than that of Cu2+ on both ChW and PTW, while the diffusion rate of intra-particles of PTW was much higher than ChW. The adsorption model of ChW and PTW could illustrate well the separation mechanism of ChW-PTW and allowed for relevant results. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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Review

Jump to: Research

Open AccessReview Biosorbents for Removing Hazardous Metals and Metalloids
Materials 2017, 10(8), 857; doi:10.3390/ma10080857
Received: 12 May 2017 / Revised: 5 July 2017 / Accepted: 7 July 2017 / Published: 26 July 2017
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Abstract
Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II), Cr(VI), Sb(III and V), and As(III and V) were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and
[...] Read more.
Biosorbents for remediating aquatic environmental media polluted with hazardous heavy metals and metalloids such as Pb(II), Cr(VI), Sb(III and V), and As(III and V) were prepared from lignin waste, orange and apple juice residues, seaweed and persimmon and grape wastes using simple and cheap methods. A lignophenol gel such as lignocatechol gel was prepared by immobilizing the catechol functional groups onto lignin from sawdust, while lignosulfonate gel was prepared directly from waste liquor generated during pulp production. These gels effectively removed Pb(II). Orange and apple juice residues, which are rich in pectic acid, were easily converted using alkali (e.g., calcium hydroxide) into biosorbents that effectively removed Pb(II). These materials also effectively removed Sb(III and V) and As(III and V) when these were preloaded with multi-valent metal ions such as Zr(IV) and Fe(III). Similar biosorbents were prepared from seaweed waste, which is rich in alginic acid. Other biosorbents, which effectively removed Cr(VI), were prepared by simply treating persimmon and grape wastes with concentrated sulfuric acid. Full article
(This article belongs to the Special Issue Sorption Materials for Environment Purification)
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