Study Of Selective Adsorption Research Articles

Promoted growth of 1 T/2 H mixed-crystalline-phase Ca(II)-doped MoS2 nanoflower (100) crystallites: A study of efficient and selective adsorption of Pb(II)

The aim of this study is to selectively remove Pb(II) in real water bodies. Therefore, based on the theory of selective adsorption-soft and hard acid-base theory, MoS2, which is capable of binding specifically to soft acid Pb(II), was selected as the substrate material. A simple one-step hydrothermal doping with an alkaline earth metal element (CaCl2) was used to greatly increase the proportion of the active phase (1 T phase), thus exposing more active sites for S adsorption. Subsequently, stable complexes were produced with partition coefficients (25.97 L g−1) as well as selectivity coefficients (236.09) approaching or exceeding those reported for materials in the literature. Qualitative constitutive relationships (QSAR) were used to analyze the correlation between the Pb(II) metal ion parameters and the adsorbent materials. Freundlich and pseudo-second-order kinetic models were well fitted, with high adsorption capacity and fast adsorption rates over a wide pH range (1−6), with a maximum adsorption capacity (123.5 mg g−1) reached within 40 min. Therefore, the material can be recycled 6 times with Na2-EDTA as the eluent and has excellent regeneration performance.

Synthesis and Properties of Cefixime Core-Shell Magnetic Nano-Molecularly Imprinted Materials.

Novel core-shell magnetic molecularly imprinted polymers (MMIPs) were synthesized using the sol-gel method for the adsorption of cefixime (CFX). Fe3O4@SiO2 is the core, and molecularly imprinted polymers (MIPs) are the shell, which can selectively interact with CFX. The preparation conditions, adsorption kinetics, adsorption isotherms, selective adsorption ability, and reutilization performance of the MMIPs were investigated. The adsorption capacity of MMIPs for CFX was 111.38 mg/g, which was about 3.5 times that of MNIPs. The adsorption equilibrium time was 180 min. The dynamic adsorption experiments showed that the adsorption process of MMIPs to CFX conformed to the pseudo-second-order model. Through static adsorption study, the Scatchard analysis showed that MMIPs had two types of binding sites-the high-affinity binding sites and the low-affinity binding sites-while the Langmuir model fit the adsorption isotherms well (R2 = 0.9962). Cefepime and ceftiofur were selected as the structural analogs of CFX for selective adsorption studies; the adsorption of CFX by MMIPs was higher than that of other structural analogs; and the imprinting factors of CFX, cefepime, and ceftiofur were 3.5, 1.7, and 1.4, respectively. Furthermore, the MMIPs also showed excellent reusable performance.

Microporous Gd(III)-MOF with imidazole decorated pores for selective CO2 adsorption and molecular docking study

via applying a dual-functional imidazole-carboxylic ligand 2-(4-carboxyphenyl)-4,5-imidazole dicarboxylic acid (H4CpIDC), a new Gd(III)-containing metal-organic framework (MOF) whose chemical formula is {[Gd(HCpIDC)(H2O)2]·2H2O}n (1) has been prepared. Due to the presence of a large amount of open metal sites along with uncoordinated imidazole groups in the pores, activated 1 displays a higher CO2 adsorption ability than for N2 as well as CH4 under ideal adsorbed solution theory (IAST) selectivities [CO2/N2: 40 (298 K); CO2/CH4: 12 (298 K)], with separation performance comparably high among MOF-based sorbents for selective CO2 capture. Furthermore, the estimated binding free energy and the calculated binding interactions suggested that the Gd complex possesses excellent biological activities and therefore, exhibits attractive potential as a pharmacology candidate.

Highly selective toluene adsorption studies of holey graphene oxide thin film using scanning Kelvin probe

Chemical-oxidative etching was used to create in-plane nanopores to synthesize holey graphene oxide (HGO) towards volatile organic compounds (VOCs) adsorption studies. HR-TEM revealed the uniform distribution of pores across the whole basal plane. The HGO thin films subjected to scanning Kelvin probe (SKP) measurements in the presence of VOCs revealed enhanced response, and selectivity to toluene vapours when compared to acetone, ethanol and triethylamine under UV light illumination. The dominant response towards toluene was discussed through Knudsen diffusion mechanism. Our discussions provide a fundamental understanding for the development of different VOCs gas sensors.

Temperature-Dependent Superhydrophobic Functionalized Coordination Polymers (SFCPs) for Selective Adsorption of C2H4 over C2H6.

We prepared two new superhydrophobic functionalized coordination polymers (SFCPs) [Zn4(OH)2(BTMB)2(4,4'-Bipy)2]∞ ⊃ solvent, 1, and [Cd4(OH)2(BTMB)2(4,4'-Bipy)3]∞ ⊃ solvent, 2, by solvothermal methods. For 1, the single-crystal XRD structure revealed that it contains two crystallographically distinct Zn2+ ions with two different types of coordination geometries of 4 and 6, exhibiting a unique superhydrophobic behavior with microporosity. Compound 1 exhibits superhydrophobicity with a contact angle of 155.5° (at 30 °C), which is stable even at high temperatures, whereas for the SFCP 2, all of the Cd2+ ions have only 6-coordination and exhibit a superhydrophobic character at room temperature with a contact angle of 156.7°(at 30 °C). However, surprisingly, this superhydrophobic character is stable only up to 60 °C, above which it is converted to hydrophilic nature, in contrast to the SFCP 1. Moreover, in this study, we also report a selective gas adsorption study of two C2 gases with similar kinetic diameters (∼3.9 Å) of ethylene over ethane.

Graphene oxide incorporated chitosan/acrylamide/itaconic acid semi-interpenetrating network hydrogel bio-adsorbents for highly efficient and selective removal of cationic dyes

In recent years, polymeric bio-adsorbents offers high removal efficiency, superior adsorption capacity and selectivity against various pollutants in aqueous medium. While designing these adsorbents, their environmental friendliness, sustainability, renewability, easy accessibility, and cost-effectiveness should be considered. In this study, GO incorporated semi-interpenetrating network (semi-IPN) nanocomposite hydrogels (CS/AAm/IA/GO) were obtained by free radical copolymerization of acrylamide (AAm) and itaconic acid (IA) in the presence of chitosan (CS) as an environmentally friendly bio-adsorbent. GO significantly improved the thermal stability, compressive strength, and percentage swelling of the hydrogel. The selective adsorption studies demonstrated that methylene blue (MB) was the most efficiently removed dye from both individual and mixed dye systems with 99.8 % removal efficiency. The adsorption capacity was found to be 247.47 mg g−1 using 0.025 g hydrogel adsorbent containing 0.5 wt% of GO and an initial MB concentration of 5 mg L−1 at pH 8 over 90 min at room temperature. The kinetic and isotherm studies revealed that the adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption isotherm. Thermodynamic studies suggested the spontaneous and endothermic nature of MB adsorption. Also, the MB removal efficiency above 96 % was obtained after 7 consecutive adsorption-desorption cycles while maintaining the structural stability of the bio-adsorbent.

In Silico Study of Selective Adsorption and Separation of Co2 from Flue Gas Mixtures by Znli5+ Cluster

In Silico Study of Selective Adsorption and Separation of Co2 from Flue Gas Mixtures by Znli5+ Cluster

Selective Adsorption Study of Lu(Iii) on Phosphorylated Zif-8-Derived Nitrogen-Doped Porous Carbon

Selective Adsorption Study of Lu(Iii) on Phosphorylated Zif-8-Derived Nitrogen-Doped Porous Carbon

Facile synthesis of Fe-modified lignin-based biochar for ultra-fast adsorption of methylene blue: Selective adsorption and mechanism studies

A novel Fe-modified lignin-based biochar (Fe-LB) was fabricated via a facile one-step carbonization method for methylene blue (MB) removal from wastewater. Fe-LB exhibited a high specific surface area (885.97 m2/g) and micropore volume (0.3203 m3/g), and demonstrated high affinity for MB with the maximum adsorption capacity of 2.7-fold by Fe-LB than LB. It was found that quick adsorption could be achieved in 15 min with the MB removal efficiency of 100% and adsorption capacity reached 200 mg/g. Selective adsorption studies indicated that Fe-LB preferentially adsorbed MB in high salt and multiple dye systems (binary, ternary, and quaternary) over a wide pH range from 2 to 12. The removal efficiency of CR was greatly improved due to the synergistic effect between MB and CR in the binary system. This work demonstrated that Fe-LB can effectively remove dye contaminants and possessed great potential in the treatment of MB polluted dye wastewater.

Synthesis and characterization of water stable polymeric metallo organic composite (PMOC) for the removal of arsenic and lead from brackish water

In the present study, highly water stable polymeric metallo organic composite (PMOC) has been synthesized and incorporated into water solution for selective adsorption study. For elucidation of structure, FTIR, P-XRD, SEM, and BET techniques were applied. Several factors related to water chemistry and adsorption analysis were also investigated. The maximum adsorption capacity was 1271.33 and 157.11 mg/g for Pb(II) and As(V), respectively. Chemisorption, monolayer adsorption and homogeneous adsorption takes place for adsorptive confiscation of these metals as studied from kinetics. From consequences, it was established that increase in number of active sites can dramatically increase the adsorption capacity of adsorbent.

Husk of Agarwood Fruit-Based Hydrogel Beads for Adsorption of Cationic and Anionic Dyes in Aqueous Solutions.

Hydrogel beads based on the husk of agarwood fruit (HAF)/sodium alginate (SA), and based on the HAF/chitosan (CS) were developed for the removal of the dyes, crystal violet (CV) and reactive blue 4 (RB4), in aqueous solutions, respectively. The effects of the initial pH (2–10) of the dye solution, the adsorbent dosage (0.5–3.5 g/L), and contact time (0–540 min) were investigated in a batch system. The dynamic adsorption behavior of CV and RB4 can be represented well by the pseudo-second-order model and pseudo-first-order model, respectively. In addition, the adsorption isotherm data can be explained by the Langmuir isotherm model. Both hydrogel beads have acceptable adsorption selectivity and reusability for the study of selective adsorption and regeneration. Based on the effectiveness, selectivity, and reusability of these hydrogel beads, they can be treated as potential adsorbents for the removal of dyes in aqueous solutions.

Elucidation of selective adsorption study of Congo red using new Cadmium(II) metal-organic frameworks: Adsorption kinetics, isotherm and thermodynamics

Herein, we report the syntheses, characterization, thermodynamic and kinetic properties and application of two Cd(II) containing metal-organic frameworks, namely [Cd (5-aip) (bpy)] (1) and [Cd (5-hip) (bpy)] (2), where 5-aip ​= ​5-aminoisophthalate ion, 5-hip ​= ​5-hydroxyisophthalalate ion and bpy ​= ​2,2′-bipyridine respectively. Structural analyses showed that both MOFs displayed a two-dimensional (2D) framework structure, anchored with free –NH2 and –OH groups, for 1 and 2 respectively. The dye adsorption behaviors of both MOFs were explored in detail, which showed that both MOFs efficiently and selectively adsorbed anionic dye Congo red (CR) over cationic dyes. Linear as well as nonlinear kinetics and isotherm data of CR removal by MOFs were thoroughly studied to predict the optimum models. The experimental data fitted well with the Langmuir adsorption isotherm model and followed pseudo second order kinetics. A spontaneous and feasible nature of CR adsorption process was elucidated from the thermodynamic parameters.

Silica-coated magnesium ferrite nanoadsorbent for selective removal of methylene blue

This paper demonstrates the adsorption capability of silica-coated magnesium ferrite nanoparticles (MgFe2O4@SiO2 NPs) for the selective adsorption of methylene blue (MB). The MgFe2O4@SiO2 NPs were generated from MgFe2O4 NPs by coating with a thin silica shell. After fully characterizing the MgFe2O4@SiO2 NPs, selective adsorption studies were carefully investigated by using three types of representative dyes: cationic (MB, rhodamine B, and malachite green), anionic (methyl orange and Congo red), and neutral (neutral red) dyes. Efficient removal of MB by the MgFe2O4@SiO2 adsorbents was observed for both individual and mixed dye systems, demonstrating excellent selectivity for MB. To optimize the adsorption capacity for MB removal, several parameters (i.e., initial solution pH, initial dye concentration, and contact time) were carefully investigated. In all cases, the magnetoresponsive adsorbents were easily separated from the solution by using an external magnet. Regeneration of the MgFe2O4@SiO2 NPs for MB removal was also performed to investigate the stability and reusability of the adsorbent. The recycling tests revealed that the MB removal efficiencies remained high after ten adsorption-desorption cycles. On the whole, the MgFe2O4@SiO2 NPs were found to be efficient, selective, and reusable adsorbents for MB removal.

Computer simulation aided preparation of molecularly imprinted polymers for separation of bilobalide.

In this study, the preparation of molecularly imprinted polymers for bilobalide (BBMIPs) was successfully achieved by bulk polymerization with methacrylamide (MAM), trimethylolpropane triacrylate (TMPTA), and acetonitrile (ACN) as functional monomer, cross-linker, and solvent, respectively. After Gaussian software simulation and single factor experiments, the prepared MIPs with a molar ratio of 1:4:15 for BB-MAM-TMPTA were systematically characterized. The hydrogen bonding interaction between BB and MAM was confirmed by a combination of FTIR and NMR analysis. Thermal gravimetric analysis results displayed that MIPs have excellent thermal stability under high temperature. Additionally, the average pore size and surface area of MIPs were found to be higher than those of NIPs through nitrogen adsorption results. The results of static adsorption and kinetic adsorption suggested that the adsorption equilibrium concentration was 0.6mg/mL and the equilibrium time was 5h, and the Langmuir and pseudo-second-order kinetic models were proven to fit with static and kinetic adsorption behaviors, respectively. Meanwhile, the selective adsorption study revealed that MIPs show high adsorption and great selectivity towards BB in comparison with other substances having similarly structure. MIPs also possessed a good performance on reusability, maintaining a high recovery rate after being reused 5 times. The application experiment further indicated that MIPs can effectively separate BB from low purity samples. Therefore, the prepared MIPs had a great potential for BB separation.

Combined experimental and computational studies on preferential CO2 adsorption over a zinc-based porous framework solid

Synthesis, characterization and study of selective CO2 adsorption over other small gas molecules on a Zn-based porous framework compound.

Tetrazole-based porous metal-organic frameworks for selective CO2 adsorption and isomerization studies.

Tetrazole-based molecules have numerous bridging coordination modes which afford great synthetic possibilities for the preparation of porous metal-tetrazolate architectures for many applications, such as carbon capture. We reported here three tetrazole-based MOFs: 1, {[Cu12(ttz)8/3Cl5(H2O)16]11+·11Cl-}n (H3ttz = N2,N4,N6-tris(4-(1H-tetrazol-5-yl)phenyl)-1,3,5-triazine-2,4,6-triamine), contains highly positively charged Cu12 clusters and the largest mesopores (32 Å) among the reported MOFs based on a tri-topic tetrazole ligand. 2 and 3 are two MOF isomers built by using CuII and 2-(1H-tetrazol-5-yl)pyrimidine. 3 contains nonporous layers, while 2 contains 1D channels and showed high selectivity for adsorbing CO2, which should be attributed to the high density of free nucleophilic tetrazole N atoms on the pore surfaces. We found that the isomerization between 2 and 3 was caused by the diverse coordination modes of tetrazole-based ligands and can be controlled in synthesis processes.

Mechanistic study of selective adsorption and reduction of Au (III) to gold nanoparticles by ion-imprinted porous alginate microspheres

In this paper, a novel technique combining ion-imprinting and direct templating was applied to synthesize Au (III) imprinted epicholorohydrin/thiourea modified porous alginate adsorbent. The adsorbent has demonstrated outstanding selectivity towards Au (III) from multi-metallic solutions, and the porous structure generated from urea hydrolysis has provided fast adsorption kinetics. The maximum uptake capacity of Au (III) is 184.82 mg/g at 323 K, which is outstanding as a recyclable polysaccharide-based adsorbent. Photo-reduction of Au (III) to gold particles was observed in the adsorption process under UV light exposure, while visible light is not capable of stimulating electrons from the synthesized adsorbent. FT-IR, XPS, and DFT calculation have proved that hydroxyl, carboxyl, and NCS functional groups were involved in the adsorption-photoreduction of Au (III).

Mechanistic study of selective adsorption of Hg2+ ion by porous alginate beads

Porous alginate beads prepared by template-assisted emulsion polymerization were investigated as selective adsorbents for Hg2+ ions from tri-metallic solutions containing the same molar concentration of Hg2+, Cd2+ and Pb2+. We observed experimentally that mechanisms of selective adsorption of Hg2+ ion by the porous alginate beads are complicated and highly dependent on solution pH. Interactions between metal cations and the porous adsorbent at different pH values were further characterized by IR and XPS analyses. Results indicated that metal uptake at low solution pH is regulated predominantly by cation exchange, making the adsorbent extremely selective to Hg2+. Nonetheless, metal binding by electrostatic attraction and complexation become important with the increase of solution pH. To validate the sorption mechanisms, density functional theory (DFT) was employed to study the binding properties of metal cations with the porous alginate adsorbent. Our computational results are completely consistent with our experimental findings, providing the theoretical basis and explanations for selective adsorption of Hg2+ by porous alginate beads.

Synthesis and characterization of acrylate cyanide bridged dimeric fac-Rhenium(I) complex: Photophysical, selective CO2 adsorption and theoretical studies

Reaction of ethyl 2-cyano-3-(2-hydroxy-5-methyl-3-(p-tolylimino)methyl)phenyl)acrylate) (HL) based on 2, 6-diformyl-4-methylphenol with [Re(CO)5Cl] in toluene afforded a product of composition [Re2(CO)6(L)2]. X-ray structure of the representative complex [Re2(CO)6(L)2] was determined to confirm the molecular species unequivocally. The molecular structure of the rhenium complex exhibited distorted octahedral geometry around the Re(I) center, consistent with the d6 configuration. The complex exhibited excellent photoluminescence behavior in acetonitrile solution. To gain a deeper insight into the ground and excited-state geometries, absorption, and emission properties of the binuclear Re(I) core, complex was further scrutinized by DFT and TDDFT methods. In addition, the synthesized binuclear Re(I) complex was used as a porous material for the selective adsorption of CO2 gas at low temperature (273 K), as well as at ambient condition (298 K). To the best of our knowledge, this compound is the first Re(I)-based binuclear complex which efficiently adsorbs CO2 selectively.

Selective anionic dye adsorption, topology and luminescence study of structurally diverse cadmium(ii) coordination polymers

Out of four, three coordination polymers have been successfully explored as topology, luminescence and highly selective anionic dyes (methyl orange and congo red) adsorption aspects.