Selective Sorption Research Articles

N-cyanoguanidine modified-black peanut shell biochar: fabrication and its sorption for Cu(II) and Co(II) in a single and mixed solutions

A N-cyanoguanidine (NCY)-modified black peanut shell biochar was fabricated via NCY to modify waste black peanut shell. X-ray diffraction, Fourier transform infrared, scanning electron microscope–energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy were used to characterize its performance. Sorption experiments were made to perceive its sorption for Cu(II) and Co(II) and disclosed that Cu(II) had higher sorption selectivity in mixed binary and four-metal solution. Sorption kinetics showed that Cu(II) and Co(II) sorption fitted well with pseudo-1st–order kinetic and diffusion-chemisorption models. Sorption isotherms revealed that Langmuir model can better describe its sorption behavior for Cu(II) and Co(II) and its maximum Qm could reach up to 185.66 and 80.59 mg/g at 45 °C, respectively. Thermodynamic factors indicated that Cu(II) and Co(II) sorption on NCY-modified black peanut shell biochar was an endothermic and spontaneous manner. Both effective diffusion coefficients (kIp) and mass-transfer coefficients (DEx) proved that Cu(II) and Co(II) sorption comprised multiple-step paces. The major mechanism included electrostatic attraction, mass transfer, complex and chelation, and diffusion-chemisorption. This finding suggests that NCY-modified black peanut shell biochar can be potentially applied to dispose Cu(II) and Co(II)-bearing wastewater from spent new power batteries.

A Team for the Development and Characterization of Next‐Generation Hybrid Semiconductors

AbstractThis invited Team Profile was created by the Spanopoulos group, University of South Florida, Tampa (USA), the Guo group, Yale University, West Haven (USA), the Trikalitis group, University of Crete, Heraklion (Greece), the Zimbouche group, Lancaster University, Lancaster (UK), and the Reddy group, University of Lille, Lille (France). They recently published an article on the development of a new family of hybrid semiconductors, namely porous metal halide semiconductors (PMHS). The first member of this series was characterized by using a battery of techniques, shedding light on the corresponding structure–property relationships and its unparalleled water stability. This work provides a solution to address the stability deficiency of metal halide semiconductors and render them suitable for yet unexplored applications, such as solid‐state batteries, photonic crystals, sensing and environmental remediation: “Porous and Water Stable 2D Hybrid Metal Halide with Broad Light Emission and Selective H2O Vapor Sorption”, A. Azmy, S. Li, G. K. Angeli, C. Welton, P. Raval, M. Li, N. Zibouche, L. Wojtas, G. N. M. Reddy, P. Guo, P. N. Trikalitis, I. Spanopoulos, Angew. Chem. Int. Ed. Engl. 2023, 62, e202218429.

Salt transport of the carboxylated aromatic polyamide: Efforts to elucidate the structure-function relation of polyamide TFC desalination membranes

Five carboxylated polyamides with the number average molecular weight in the range of 15000–17000 Da, are synthesized via low-temperature solution polycondensation to study the effect of carboxyl group (-COOH) content on the carboxylated polyamide salt transport property. The glass transition temperature (Tg) of the carboxylated polyamide increases with the –COOH content due to the formation of more hydrogen bonds, which also leads to a decrease in free volume fraction (FFV). Interestingly, we observe that polymer having the –COOH content of 80%–100% possesses similar water uptake and KW, which provides a special perspective that how the –COOH group influences salt transport by excluding the effect of water content in polymer membranes. Water sorption can disrupt the hydrogen bonding within the –COOH groups, so setting out –COOH groups to bind water, leading to lower free water content and enhanced water/salt sorption selectivity. As the content of –COOH increases, the more negatively charged surface and stronger hydrogen bond interactions result in significant decrease in salt permeability (PS) and salt diffusivity (DS). These results implicate that the introduction of more –COOH groups to the polyamide layer can enhance the water/salt selectivity of TFC membrane without by changing the water sorption.

Simple lattice model explains equilibrium separation phenomena in glassy polymers.

The Robeson bound is a theoretical limit that applies to kinetics-driven membrane separations of gas mixtures. However, this bound does not apply to sorption-driven membrane processes such as CO2/N2 separation, which lacks a theoretical explanation. As a result, we are uncertain about the factors that control the limiting behavior of sorption-driven separations. To address this issue, we employed a simple lattice model and dynamic mean field theory to examine the transport properties of disordered model structures, isolating sorption effects from purely kinetic effects. Our findings indicate that transport effects play a crucial role in sorption-driven processes, and perm-selectivity is consistently lower than sorption selectivity, which is an unattainable limit. We used basic geometric fragments of the structure to explain how transport effects emerge and manifest themselves in sorption-driven processes.

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

The need to take into account the adsorption processes theory at the clinical and economic evaluation of the adsorption technologies (to the article «Clinical and Economic Evaluation of the Extracorporeal Blood Purification with Selective Sorption Techniques in ICU Patients)

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A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

A Hybrid Membrane for the Simultaneous Selective Sorption of Cesium in the Ionic and Colloid Forms

Fabrication of novel 3D PEI-functionalized ZIF-8@alginate aerogel composites for efficient elimination of Pb(II) and Cd(II) from aqueous solution

ZIF-8, a metal-organic framework, has large sorption capacities for a series of heavy metals. However, it is difficult to be separated from aqueous solution, limiting its practical application in wastewater treatment. Herein, ZIF-8 was in-situ grown on the polyethyleneimine-functionalized alginate to construct the ZIF-8 @ALG-PEI aerogels with a three-dimensional network structure. This synthesis strategy not only overcomes the above-mentioned defects of ZIF-8, but also provides more functional groups, pores, and channels. The synthesized ZIF-8 @ALG-PEI aerogels exhibit outstanding removal performance towards Pb(II) and Cd(II) with maximum sorption capacity values of 295.986 and 249.838 mg·g−1, respectively. The sorption of Pb(II) and Cd(II) on ZIF-8 @ALG-PEI is strongly affected by pH, but little influenced by ionic strength. In the multi-component sorption systems, ZIF-8 @ALG-PEI shows better sorption affinity and selectivity for Pb(II) than for Cd(II). The three-dimensional network structure constructed by alginate makes Pb(II) and Cd(II) easier to contact with the surfaces of ZIF-8 @ALG-PEI. The strong surface complexation of the O- and N-containing functional groups provided by ZIF-8 and PEI with Pb(II) and Cd(II) makes the largest contribution to the removal of Pb(II) and Cd(II) by ZIF-8 @ALG-PEI. In summary, the experimental findings of this work prove that the synthesized ZIF-8 @ALG-PEI aerogels have promising applications in practical wastewater treatment.

Hydrogen production from biomass via moving bed sorption-enhanced reforming: Kinetic modeling and process simulation

This study explored a process intensification approach for hydrogen production through biomass gasification. Sorption-enhanced reforming (SER) in an autothermal countercurrent moving bed reformer is proposed as an alternative to multiple units traditionally required for syngas conditioning. This process utilizes the selective sorption and catalytic properties of calcium oxide to integrate multiple reforming reactions into a moving bed reactor. A multistage kinetic model was used to analyze and optimize the key operating parameters of the reformer. Results showed that the moving bed reformer completely converts all tars and increases the hydrogen concentration of syngas from 23 mol% to 80 mol% (dry basis). A comparison between equally sized models showed that the moving bed reformer outperforms a fluidized bed reformer under similar conditions. Simulation of the entire process showed that the hydrogen yield of the proposed SER process is 5% higher than the conventional process. In addition, the proposed process produces surplus electricity, while the conventional process has a 26% power deficit. The overall efficiency of the proposed process is 3.5% higher than the conventional process. The improved process efficiency, coupled with the potentially lower costs of a streamlined process, indicates that the proposed process is a promising route for green hydrogen production.

Emissive fluoren-triangles for solid-state fluorochromism and selective gas sorption

•A fluorescent fluoren-triangle macrocycle is crafted •Intriguing solid-state fluorochromism capabilities are shown •Selective gas sorption performance is demonstrated In this work, we first present a new class of fluorescent synthetic macrocycle, named fluoren-triangle (FT), which we designed by creatively integrating the fluorene fluorophore into the resorcinarene backbone. Single-crystal analysis of FT revealed isosceles-triangle conformations accompanied by a layer-like molecular assembly in the solid state. Fluorescence experiments demonstrated its aggregation-induced emission character and tunable solid-state fluorescence emission, and per-methylated FT (MeFT) also exhibited an intriguing excitation-wavelength-dependent (Ex-De) capability with different emission color-switching processes. Significantly, the activated powders of per-hydroxylated FT (OHFT) and MeFT with both nonporous and amorphous features displayed remarkable potential in constructing adsorptive separation materials for CO2 and CH4 capture, affording good selectivities of 31/1 for CO2/N2 (by OHFT) and 8/1 for CH4/CO2 (by MeFT), respectively. The discovery of FT will provide new perspectives in constructing novel fluorescent macrocycles and functional photo-responsive materials, unleashing new inspirations in molecular sorbents for gas adsorption and separation. In this work, we first present a new class of fluorescent synthetic macrocycle, named fluoren-triangle (FT), which we designed by creatively integrating the fluorene fluorophore into the resorcinarene backbone. Single-crystal analysis of FT revealed isosceles-triangle conformations accompanied by a layer-like molecular assembly in the solid state. Fluorescence experiments demonstrated its aggregation-induced emission character and tunable solid-state fluorescence emission, and per-methylated FT (MeFT) also exhibited an intriguing excitation-wavelength-dependent (Ex-De) capability with different emission color-switching processes. Significantly, the activated powders of per-hydroxylated FT (OHFT) and MeFT with both nonporous and amorphous features displayed remarkable potential in constructing adsorptive separation materials for CO2 and CH4 capture, affording good selectivities of 31/1 for CO2/N2 (by OHFT) and 8/1 for CH4/CO2 (by MeFT), respectively. The discovery of FT will provide new perspectives in constructing novel fluorescent macrocycles and functional photo-responsive materials, unleashing new inspirations in molecular sorbents for gas adsorption and separation.

Functionalization of thiosemicarbazide/gellan gum for the enhancement of cadmium removal from aqueous solutions – Grafting of tributyl phosphate derivative

Two sorbents are successfully synthesized based on the chemical modification of gellan gum (GG). First, thiosemicarbazide is grafted onto GG to produce GEG-C. In a second step, GEG-C is functionalized with a derivative of tributyl phosphate (dTBP, giving GEG-P sorbent). The sorption properties are compared for recovery of Cd(II) from aqueous solutions. GEG-C is expected to bind Cd(II) through carboxylic, amine, and thiocarbonyl groups, while phosphate groups in GEG-P contribute to increase metal sorption. The chemical modification improves not only the uptake kinetics (equilibrium time ≈30 min, vs. 45 min) but also the sorption capacities (≈2.79 vs. 1.60 mmol Cd g−1), at optimum pH (i.e., pH 5). The functionalization also improves (a) the sorbent stability (weaker reduction of the loss in sorption efficiency after five cycles of reuse compared with GEG-C) and (b) the sorption selectivity in the presence of competitor ions (from equimolar multicomponent solutions), especially at pH 4. Different sorption mechanisms may be involved depending on the pH (deprotonation of reactive groups) including chelation (onto deprotonated amine and phosphonate groups) and ion exchange (protonated groups with metal cations). Cadmium sorption is reversed by contact with 0.3 M HCl solution. The functionalization (GEG-P) strongly increases the selectivity coefficient for Cd(II) against major elements in mining effluent, especially at pH higher than 5. These results confirm the interest of multifunctionality in the development of new sorbents based on renewable resources (such as gellan gum).

Crystal Chemistry, Thermal and Radiation-Induced Conversions and Indicatory Significance of S-Bearing Groups in Balliranoite

Crystal-chemical features of a sulfide-bearing variety of the cancrinite-group mineral balliranoite from the Tuluyskoe lapis lazuli deposit, Baikal Lake area, Siberia, Russia, have been investigated using a multimethodic approach based on infrared (IR), Raman, and electron spin resonance (ESR), as well as ultraviolet, visible and near infrared (UV–Vis–near IR) absorption spectroscopy methods, luminescence spectroscopy, electron microprobe analysis, selective sorption of CO2 and H2O from annealing products, and single-crystal X-ray structure analysis. Holotype balliranoite and its sulfate analogue, davyne, were studied for comparison. The crystal-chemical formula of the studied sample from Tultuyskoe is Na5.4K0.1Ca2.4(Si6Al6O24)Cl2[(CO3)0.7(SO4)0.18S*0.95Cl0.1(H2O)0.16], where the content of the wide zeolite channel is given in square brackets; S* is total sulfide sulfur occurring as disordered S2●−, cis- and trans-S4, S52−, minor S3●−, and HS− groups. The presence of S52− and HS− groups, the absence of CO2 molecules, and the association with pyrrhotite and Fe-free pargasite indicate that the studied sample crystallized under highly reducing, low-temperature conditions, unlike holotype balliranoite whose formation was related to the Somma-Vesuvius volcanic complex, Italy. Irradiation of balliranoite from Tultuyskoe with X-rays results in the transformations of polysulfide groups other than S3●− into S3●− in accordance with the scheme: S52− → S2●− + S3●−; 3S2●− → 2S3●− + e−; S4 + S2●− + e− → 2S3●−; S4 + S2●− + e− → 2S3●−; S4 + S52− + e− → 3S3●− (e− = electron).

Integrated Soft Porosity and Electrical Properties of Conductive‐on‐Insulating Metal‐Organic Framework Nanocrystals

AbstractA one‐stone, two‐bird method to integrate the soft porosity and electrical properties of distinct metal–organic frameworks (MOFs) into a single material involves the design of conductive‐on‐insulating MOF (cMOF‐on‐iMOF) heterostructures that allow for direct electrical control. Herein, we report the synthesis of cMOF‐on‐iMOF heterostructures using a seeded layer‐by‐layer method, in which the sorptive iMOF core is combined with chemiresistive cMOF shells. The resulting cMOF‐on‐iMOF heterostructures exhibit enhanced selective sorption of CO2 compared to the pristine iMOF (298 K, 1 bar, S from 15.4 of ZIF‐7 to 43.2–152.8). This enhancement is attributed to the porous interface formed by the hybridization of both frameworks at the molecular level. Furthermore, owing to the flexible structure of the iMOF core, the cMOF‐on‐iMOF heterostructures with semiconductive soft porous interfaces demonstrated high flexibility in sensing and electrical “shape memory” toward acetone and CO2. This behavior was observed through the guest‐induced structural changes of the iMOF core, as revealed by the operando synchrotron grazing incidence wide‐angle X‐ray scattering measurements.

Integrated Soft Porosity and Electrical Properties of Conductive-on-Insulating Metal-Organic Framework Nanocrystals.

A one-stone, two-bird method to integrate the soft porosity and electrical properties of distinct metal-organic frameworks (MOFs) into a single material involves the design of conductive-on-insulating MOF (cMOF-on-iMOF) heterostructures that allow for direct electrical control. Herein, we report the synthesis of cMOF-on-iMOF heterostructures using a seeded layer-by-layer method, in which the sorptive iMOF core is combined with chemiresistive cMOF shells. The resulting cMOF-on-iMOF heterostructures exhibit enhanced selective sorption of CO2 compared to the pristine iMOF (298 K, 1 bar, S from 15.4 of ZIF-7 to 43.2-152.8). This enhancement is attributed to the porous interface formed by the hybridization of both frameworks at the molecular level. Furthermore, owing to the flexible structure of the iMOF core, the cMOF-on-iMOF heterostructures with semiconductive soft porous interfaces demonstrated high flexibility in sensing and electrical "shape memory" toward acetone and CO2 . This behavior was observed through the guest-induced structural changes of the iMOF core, as revealed by the operando synchrotron grazing incidence wide-angle X-ray scattering measurements.

Use of Chrysosporium/carbon nanotubes for preconcentration of ultra-trace cadmium levels from various samples after extensive studies on its adsorption properties

Carbon nanotubes were used to immobilize Chrysosporium fungus for building an adequate adsorbent to be used as an desirable sorbent for preconcentration and measurement of cadmium ultra-trace levels in various samples. After characterization, the potential of Chrysosporium/carbon nanotubes for the sorption of Cd(II) ions was scrutinized by the aid of central composite design, and comprehensive studies of sorption equilibrium, kinetics and thermodynamic aspects were accomplished. Then, the composite was utilized for preconcentration of ultra-trace cadmium levels, by a mini-column packed with Chrysosporium/carbon nanotubes, before its determination with ICP-OES. The outcomes vouchsafed that (i) Chrysosporium/carbon nanotube has a high tendency for selective and rapid sorption of cadmium ion, at pH 6.1, and (ii) kinetic, equilibrium, and thermodynamic studies showed a high affinity of the Chrysosporium/carbon nanotubes for cadmium ion. Also, the outcomes displayed that cadmium can quantitatively be sorbed at a flow speed lesser than 7.0 mL/min and a 1.0 M HCl solution (3.0 mL) was sufficient to desorbe the analyte. Eventually, preconcentration and measurement of Cd(II) in different foods and waters were successfully accomplished with good accuracy, high precision (RSDs ≤5.65%), and low limit of detection (0.015 μg/L).

High-efficiency selective removal of U(VI) by phosphate-functionalized graphitic carbon nitride activated using guanidine phosphate

Given the efficient reaction of P-containing species with radionuclide U(VI), phosphate-modified carbon nitrides (GPCNs) were prepared with enhanced surface areas (16.9–102.0 m2/g) and abundant phosphate groups (15.8–9.1 at% of P) and applied to capture aquatic U(VI). GPCNs presented a fast equilibrium of 8 h, efficient capture capability (maximum 333.5 mg/g at pH 5.0 and T 278 K), excellent selectivity and favorable reusability. The enrichment of U(VI) from the artificial nuclide wastewater (101.5 mg/g) and seawater (89.3 mg/g) were evaluated. Spectroscopic studies proved that the formation of hydrogen uranite was dominant for the high-efficiency selective sorption of U(VI). Under the illumination of visible-light, GPCNs showed a ∼4.9-fold faster kinetics for the photocatalytic reduction of U(VI) than CNs. Moreover, the origin of the photocatalytic activity of GPCNs including the role of phosphate modification was also discussed in detail. This study provided a valuable reference for the facile preparation of porous phosphate-modified carbon nitrides as well as a meaningful option for the extraction of radionuclides from aqueous solutions.

Synthesis of a magnetic nanomaterial with core–shell structure for effective Au(III) recovery from solution with superior separation and one-step reduction

To synthesize a novel magnetic nanomaterial for effective Au(III) recovery from the aqueous phase with excellent capability, superior selectivity, one-step reduction and ease of separation after loading Au(III) still remains a huge challenge. In this study, a magnetic nanomaterial (γ-Fe2O3@PDA-NAM) with a core–shell structure was synthesized for effective Au(III) recovery by sorption. The maximum Au(III) sorption capacity by γ-Fe2O3@PDA-NAM reached 2910 mg/g at pH = 6.10 ± 0.15, 44.29 times that by γ-Fe2O3 (65.7 mg/g). Its Au(III) sorption efficiency was over 97.75% at very low concentrations (i.e., 5.5 × 10-4 and 5.5 × 10-5 mg/mL). TEM, XPS and FTIR analysis verified that excellent Au(III) recovery by γ-Fe2O3@PDA-NAM resulted from N/S-containing soft base moieties introduced to different layers. N and/or S elements at these sites provided lone pair electrons to Au(III) to form stable coordination bond. Meanwhile, the hydrogen bond between O-containing (–OH, -C=O) and N-containing (-C-N, -N(-C)-N-, -C=N) moieties on γ-Fe2O3@PDA-NAM and –OH on the main speciations of Au(III) (AuCl3(OH)-, AuCl2(OH)2-, and AuCl(OH)3-) also greatly enhanced Au(III) recovery. About 78.03% of Au(III) was directly reduced to elemental gold by -C-S- and -N(-C)-N- group on the tertiary amine structure during sorption. More than 98.84% of Au(III) was selectively sorbed on γ-Fe2O3@PDA-NAM at pH 4.0 even though Pt(IV), Cu(II), Zn(II), Pb(II), and Ni(II) were co-present at the same concentration as that for Au(III) (0.01 mg/mL). In contrast, sorption efficiency of other interfering ions was within 1.75–26.05%. A relatively poor sorption selectivity for Pt(IV) could be acceptable because it is also a noble metal.

Amine Functionalized Magnetite GO‐MWCNT as an Efficient 3D Hybrid Aerogel for the Remediation of Copper(II) from Wastewater: Box‐Behnken Design Optimization

AbstractThis work focuses on the sequestration of Cu(II) from aqueous environment owing to the risks posed to human health. A magnetic hybrid aerogel (mGO‐TETA‐MWCNT) was synthesized by one‐pot self‐assembly of magnetic graphene oxide (mGO) and multiwalled carbon‐nanotubes (MWCNT) post functionalization with triethylenetetramine (TETA) through hydrothermal reduction. The prepared adsorbent was characterized and employed for efficient removal of Cu(II). The aerogel, mGO‐TETA‐MWCNT presented maximum adsorption capacity (Qmax) of 232.22 mg g−1 at Box‐Behnken design optimized conditions: pH 5.6, time 36.7 min, and concentration 999.7 mg L−1. The Brouers‐Sotolongo (BS) isotherm and Fractal‐like pseudo‐second‐order (FLPSO) kinetic model fitted best representing heterogeneity of the hybrid adsorbent. The presence of interferent metal ions(Ni(II), Pb(II), Cd(II), Zn(II)) showed negligible effect on the selective sorption of Cu(II). The prepared adsorbent could be regenerated upto five cycles (>95 % removal) when eluted using 0.5 m HCl. The aerogel was successfully utilized to remove Cu(II) from wastewater, river‐water, and groundwater.

Efficient removal of uranium (VI) from water by a hyper-cross-linked polymer adsorbent modified with polyethylenimine via phosphoramidate linkers

Practical adsorbents with high efficiency are essential to effectively treating wastewater. Herein, a novel porous uranium adsorbent (PA-HCP) having a considerable amount of amine and phosphoryl groups was designed and synthesized by grafting polyethyleneimine (PEI) on a hyper-cross-linked fluorene-9-bisphenol skeleton via phosphoramidate linkers. Furthermore, it was used to treat uranium contamination in the environment. PA-HCP exhibited a large specific surface area (up to 124 m2/g) and a pore diameter of 2.5 nm. Batch uranium adsorptions on PA-HCP were investigated methodically. PA-HCP demonstrated a uranium sorption capacity of >300 mg/g in the pH range of 4–10 (C0 = 60 mg/L, T = 298.15 K), with its maximum capacity reaching 573.51 mg/g at pH = 7. The uranium sorption process obeyed the pseudo-second-order model and fitted well with the Langmuir isothermal. In the thermodynamic experiments, uranium sorption on PA-HCP was revealed to be an endothermic, spontaneous process. Even in the presence of competing metal ions, PA-HCP exhibited excellent sorption selectivity for uranium. Additionally, excellent recyclability can be achieved after six cycles. Based on FT-IR and XPS measurements, both the PO and –NH2 (and/or –NH–) groups on PA-HCP contributed to efficient uranium adsorption as a result of the strong coordination between these groups and uranium. Furthermore, the high hydrophilicity of the grafted PEI improved the dispersion of the adsorbents in water and facilitated uranium sorption. These findings suggest that PA-HCP can be used as an efficient and economical sorbent to remove U(VI) from wastewater.

Formation of Porosity toward Acetylene upon Vitrification of Non-porous Photochromic Coordination Polymer Crystals

Designing permanent microporosity in a glassy state of coordination polymer (CP) and metal–organic framework (MOF) has been challenging due to densification of the structures upon vitrification. Here, we propose a new approach to create porosity in CP/MOF glasses derived from nonporous 1D crystal structures. Glassy states of two dense 1D crystal structures [Ag2(cis-dbe) (CF3SO3)2] and [Ag2(cis-dbe) (CF3CO2)2], where cis-dbe = cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl)ethene, were prepared by ball milling. Glass structures and dynamics were characterized by synchrotron X-ray, solid-state NMR, and thermal analyses. Loosened assembly of 1D chains through glass formation enabled representation of permanent microporosity and resulted in selective gas sorption behaviors of acetylene over CO2. It elucidated that the property of gas uptake is affected by the glass dynamics and interaction with anions. Reversible photochromism of cis-dbe is preserved in the glasses, leading to multi-functional glass materials.