Efficient Adsorption Capability Research Articles

A comparative study of electronic structure, adsorption properties, and optical responses of furan and tetrahydrofuran adsorbed pristine, Al and Ga doped B12X12 (X=N and P) nanocages

Removing pollutants like furan (F) and tetrahydrofuran (THF) from the environment is challenging, and adsorption can efficiently remove pollutants. Fullerene like inorganic nanocages B12N12 and B12P12 are known for their efficient adsorption capability. To address these concerns, we report here the adsorption of the F and THF on the pristine and Al and Ga-doped B12N12 and B12P12 nanocages and consequently the change in the electronic structure, property and optical responses. Doping Al and Ga at the nanocage diminishes the HOMO-LUMO energy gap by 2.9 to 0.4 eV compared to the pristine cage, making the doped cage surface more reactive. The doped surface of nanocage adsorbs F (F@AlB11N12 (-130.1 kJ/mole) and THF (THF@AlB11N12 (-202.3 kJ/mole) more effectively compared to pristine ones (F@B12N12 -28.7 kJ/mole, THF@B12N12 (-98.3 kJ/mole) at ωB97XD/6–31+G(d,p) level. For a given cage, THF is more strongly adsorbed (THF@B12N12 (-98.3 kJ/mole)) on the cage surface than F (F@B12N12 -28.7 kJ/mole). Interestingly, Al-doped cages exhibit the highest adsorption energy value ranging from -68.5 kJ/mole to -202.3 kJ/mole. Natural bonding orbital analysis, global reactivity descriptor, molecular electrostatic potential, frontier molecular orbital, etc. have been employed to comprehend the distinctive patterns of adsorption. The optical response properties of the studied complexes show that the complexes of B12P12 nanocages exhibit higher polarizability and second hyperpolarizability value (1.51 × 105 to 1.62 × 105 au) compared to its analogous B12N12 complex (3.62 × 104 to 4.15 × 104 au) at ωB97XD/6–311+G(d,p) level. Our theoretical results further demonstrate the capability of AlB11N12 and AlB11P12 as promising adsorbents of the toxic organic pollutants F and THF, and the computed higher second hyperpolarizability value of the B12P12 complexes indicates these nanomaterials could be used as potential optoelectronic materials.

MXene: An efficient hemoperfusion sorbent for the removal of uremic toxins

MXene, a family of two-dimensional (2D) transition metal carbides and nitrides have attracted extensive interests for many biochemical applications, including tumour elimination, biosensors, and magnetic resonance imaging (MRI). In this article, we firstly discovered that Ti3C2Tx MXene exhibited a highly efficient adsorption capability as hemoperfusion absorbent towards middle-molecular mass and protein bound uremic toxins in the end stage of renal disease (ESRD) treatment. Molecular scale investigations reveal that the high efficiency of MXene for the removal of uremic toxins could be attributed to synergistic effects of physical/chemical adsorption, electrostatic interaction surface of 2D MXene, and transformation of protein secondary structure. 2D MXene materials could be used as a new hemoperfusion sorbent with ultrahigh efficiency for removing uremic toxins during the treatment of kidney disease.

Protonation-induced site and field reconstruction for ultrafast adsorptive desulfurization over Cu[sbnd]N[sbnd

Simultaneously regulating adsorption thermodynamics/kinetics and site density to achieve efficient adsorption capability of single-atom materials is crucial for adsorption-related catalysis, separation, or purification, but remains challenging. Taking adsorptive desulfurization as a model, we report a simple protonation of the uncoordinated pyridinic-N strategy, which significantly enhanced the adsorption capability of CuNC for dibenzothiophene through the cation–π and Cu–S interaction. The uncoordinated pyridinic-NH+ both acted as an adsorption site and modulated the N-ligand field to lengthen the Cu–N bond to enhance the bonding strength of the single-atom Cu site for organosulfur by upshifting the d-band center, thereby causing a higher desulfurization capacity of CuNC than its counterparts. Furthermore, the protonation reconstructed the local positive electric field of CuNC to strongly attract electron-rich dibenzothiophene, which along with abundant porous channels accelerated mass transfer and accumulation of dibenzothiophene near the adsorption sites. This provided CuNC with 2–261-fold higher adsorption kinetics than most reported adsorbents, leading to an ultrafast decrease in sulfur levels (<10 ppm) within 70 s, considerably outstripping that of FeNC (∼900 s) and activated carbon (∼1800 s).

Mesoporous spongy Ni–Co oxides@wheat straw-derived SiO2 for adsorption and photocatalytic degradation of methylene blue pollutants

The exploitation and employment of agricultural waste in polluted water treatment are one of the most important cost-effective approaches. Therefore, a novel mesoporous spongy adsorbent/photocatalyst was successfully synthesised through the grafting of nickel and cobalt oxides nanocomposites with wheat straw-derived SiO2 (WSS). Nickel and cobalt oxides were added to enhance the functionality of wheat straw-derived SiO2. This synthesis methodology presents a simplistic, cost-effective, and eco-approachable alternative to getting an adsorbent and photocatalyst for the adsorption and photocatalytic degradation of methylene blue (MB) pollutants from wastewater. The modified wheat straw-derived SiO2 (MWSS) was characterised via XRD, SEM, EDX, TGA, FTIR, and nitrogen adsorption. Molecular dynamics computational calculations were performed to comprehend the ability of methylene blue to adjust the MWSS surface. The adsorption and photodegradation trials were performed to optimise the pH, contact time, initial MB concentration, and temperature parameters. The optimum removal conditions were as follows: pH 10, dose 50 mg, contact time 45 min, temperature 25 ± 2 °C, and UV lamp (70 W) for photocatalytic degradation process. The obtained data indicated that the mesoporous MWSS adsorbent/photocatalyst provided efficient adsorption capability (79%), significant photocatalytic performance (93%), and higher solidity during reusability as well. Furthermore, kinetics and isotherm models were checked to explain the MB removal mechanism using mesoporous spongy MWSS. This study suggests an efficient composite that contributes to getting rid of the MB pollutants from wastewater.

Removing BaP from soil by biochar prepared with medicago and corn straw using batch and solid-phase extraction method.

Low-cost materials with a highly efficient adsorption capability prepared from corn straw and medicago (abbreviated to CB and MB), which can effectively remove benzo(a)pyrene (BaP) from contaminated soil, were prepared at a temperature of 350 °C under limited-oxygen conditions. The appearance traits, contents of C, H, N and functional group types of CB and MB were obtained by SEM, elemental analysis and FT-IR. Through the batch method, it was found that the adsorption of BaP by CB and MB was in accordance with pseudo-secondary kinetics because the correlation coefficients are 0.855 with CB and 0.948 with MB, respectively, and the maximum adsorption capacity in the fitting (CB: 78.2 mg kg-1, MB: 88.8 mg kg-1) was consistent with the actual measurement (CB: 79.8 mg kg-1, MB: 89.3 mg kg-1). Freundlich and Langmuir equations can well describe the isothermal adsorption data of CB and MB due to the correlation coefficients all being greater than 0.87. Soil samples treated with ASE were separated by solid-phase extraction (SPE) with different biochar contents in packed columns. It was found that the contributions of CB and MB to the removal of BaP increased from 58.5% and 60.4% to 80.6% and 82.1%, respectively, which could effectively reduce BaP in polluted soil.

Preparation of new triptycene- and pentiptycene-based crosslinked polymers and their adsorption behavior towards aqueous dyes and phenolic organic pollutants

• New triptycene- and pentiptycene-based crosslinked polymers namely P1 and P2 are successfully prepared. • The reaction is simple and can be conducted at a relatively mild temperature. • Both P1 and P2 exhibit good adsorption performance for dyes and phenolic organic pollutants at low concentrations. • Both P1 and P2 show highly selective adsorption capacities towards phenolic organic pollutants. Rigid triptycene- and pentiptycene-based monomers, with intrinsic hierarchical structures, were polymerized using tetrafluoroterephthalonitrile as the crosslinker to fabricate crosslinked porous architectures named P1 and P2. The reaction is simple and can be conducted at a relatively mild temperature. Both P1 and P2 exhibit good thermal stability, and good adsorption performance for dyes and phenolic organic pollutants including MB, MO, Pol and BPA. The removal efficiency of P2 is >99% within 10 min for BPA and an adsorption equilibrium for Pol can be reached within 5 min. The adsorption kinetics fit the pseudo-second-order model and the adsorption isotherms follow the Langmuir model and the maximum adsorption capacity of P1 and P2 for BPA can reach 212.06 mg g −1 and 330.02 mg g −1 , respectively. In addition, the obtained crosslinked polymers show a highly selective adsorption capacity towards phenolic organic pollutants. Featuring a simple synthesis, porous architecture and efficient adsorption capability, such triptycene-based and pentiptycene-based crosslinked polymers may be ideal adsorbents for water treatment and purification.

Enhanced Refractive Index Sensitivity through Combining a Sol-Gel Adsorbate with a TiO2 Nanoimprinted Metasurface for Gas Sensing.

We combine a gas-adsorbent microporous hybrid silica layer and a dense TiO2 Mie resonator array (metasurface), both obtained by sol-gel deposition and nanoimprint lithography, to form nanocomposite systems with high sensitivity for refractive index (RI) variations induced by gas adsorption. Using optical transduction based on direct specular reflection, we show spectral shifts of 4470 nm/RIU corresponding to 0.2 nm/ppm gas (air concentration) and reflection intensity changes of R* = 17 (R/RIU) and 0.55 × 10-3 R/ppm (air concentration). The metasurface is composed of hexagonally arranged TiO2 nanopillar arrays, whereas the surrounding sensitive material is a class II microporous hybrid silica, containing methyl and phenyl covalently bonded organic functions. This hybrid layer shows efficient adsorption capability of volatile organic molecules such as isopropanol, which is used to induce slight variations of RI around the TiO2 antennas. Specular reflectance variations at 45° incidence and refractive index measurements are performed using a spectroscopic ellipsometer. The presence of the titania metasurface enhances the signal by almost an order of magnitude with respect to the 2D counterpart (simulated as an effective medium approximation) and is attributed to the antenna effect, enhancing the interaction of the confined electromagnetic wave with the sensitive microporous medium. This sol-gel nanocomposite system presents many advantages such as high throughput and low-cost elaboration of elements and a high chemical, mechanical, and thermal resistance, ensuring high stability as a potential gas-sensitive nanocomposite layer for long periods. This work is a case study of improving the sensitivity of sol-gel gas-sensitive materials in optical transduction, which will be exploited in further works to develop artificial noses.

Calixarene-tethered textile fabric for the efficient removal of hexavalent chromium from polluted water

This study describes the tethering of dimethylamionomethyl bonded calixarene (DMAM-calixarene) onto cotton fabric surface functionalized with poly(glycidyl methacrylate) (PGMA) linker layer using initiated chemical vapor deposition (iCVD) technique and the efficient adsorption capability of DMAM-calixarene functional textiles for the toxic hexavalent chromium from polluted water. The characterization of DMAM-calixarene-tethered textile fabric was performed by FTIR and XPS spectroscopy. Cr(VI) solutions was passed over packed DMAM-calixarene-tethered textile fabric adsorbent and the highest adsorption was observed at pH 2 in dichromate anion form of COS. The regeneration and selectivity studies indicate that the DMAM-calixarene-tethered textile fabric has outstanding adsorbent features in used experimental conditions for hexavalent chromium. Moreover, it was observed that both H-bonding and electrostatic interactions were significant factors in the dichromate anion adsorption process. Thus, this study clearly revealed that any DMAM-calixarene-tethered textile fabric can be easily used as a selective hexavalent chromium capture filter in geographic regions lacking appropriate wastewater purification systems.

Efficient adsorption capability of banana and cassava biochar for malachite green: Removal process and mechanism exploration

In this study, banana biochar (BB) and cassava biochar (CB) were roasted in a tube furnace at 400℃ for 2 h, and their adsorption effects on malachite green (MG) were studied. The removal of MG with respect to the solution concentration and reaction time was also investigated. The results show that the optimal amount of biochar is 2 g/L. Studies of the adsorption kinetics and adsorption isotherms show that the pseudo-second-order kinetics can most accurately reflect the adsorption process. Freundlich model fits the experimental data well. The theoretical saturated adsorption capacities of BB and CB are 1,092.80 mg/g and 261.42 mg/g, respectively. SEM-EDS, TGA, BET, FTIR, XRD, element analysis and other characterization techniques were used to explore the adsorption mechanism. Based on the characterization results, it is speculated that the adsorption of BB and CB for MG mainly includes chemical adsorption and physical adsorption.

Fe3O4-FeMoS4: Promise magnetite LDH-based adsorbent for simultaneous removal of Pb (II), Cd (II), and Cu (II) heavy metal ions

There have always been numerous challenges to designing a cost-effectiveness, reusable and robust adsorbents for simultaneous heavy metal ion remediations from wastewaters. Herein, a novel kind of nanocomposite relying on the synergic impact of magnetic Fe3O4, FeMoS4−2, and magnesium-aluminum layered double hydroxide (MgAl-LDH) using loading the FeMoS4−2 on protonated Fe3O4 and adhered to the surface of Mg/Al-LDH (Fe3O4/FeMoS4/MgAl-LDH). The nanocage structures adsorbent was characterized via FT-IR, XRD, FE-SEM, EDX, and VSM techniques and demonstrated having an efficient adsorption capability to common cationic pollutants (Pb (II), Cd (II) and Cu (II) by batch experiments. Disparate chief parameters affecting adsorption performance, including Fe3O4/FeMoS4/MgAl-LDH mass, metal ion concentrations, solution pH, and contact time were considered and optimized through central composite design (CCD) in detail. Its supreme adsorption efficiency toward Pb (II), Cd (II), and Cu (II) accounted for 190.75, 140.50, and 110.25 mg g−1, respectively, which acquired by the Langmuir model under the parameter set at 60 min contact time, solution pH at 5, 0.03 g the Fe3O4/FeMoS4/MgAl-LDH and metal ion concentrations ranging from 10 to 300 mg L−1. Such enhancement stemmed from the coordinated complexes in the LDH interlayer region and electrostatic attraction between Fe3O4/FeMoS4/MgAl-LDH and metal ions. Furthermore, the adsorption conducts were more consistent with the pseudo-second-order model and the Langmuir isotherm model, respectively. Likewise, the features such as the superior regeneration and reusability allow the Fe3O4/FeMoS4/MgAl-LDH nanocomposite to constitute as one of the promising materials for heavy metals remediation in wastewater.

An oxamide-functionalized ternary indium-organic framework

Solvothermal one-pot reaction between indium nitrate and an oxamide-functionalized tetracarboxylate linker affords a rare ternary MOF, which exhibits two distinct SBUs based on sole metal ions and pure homo-functional ligands, in contrast to other multicomponent MOFs constructed from either mixed-metals with hetero-functional linker or mixed-linkers with sole metal. The MOF also demonstrates relatively efficient adsorption capability toward MB and tunable blue-to-green photoluminescence upon variation of excitation wavelengths.

β-Cyclodextrin functionalized coaxially electrospun poly(vinylidene fluoride) @ polystyrene membranes with higher mechanical performance for efficient removal of phenolphthalein

Core-shell structured fibers of poly (vinylidene fluoride) and polystyrene (PVDF@PS) were coaxially electrospun from two kinds of polymer solutions. The presence of PVDF as a core component greatly enhanced the mechanical properties of PVDF@PS fiber membranes due to the crystallization of PVDF, and the tensile strength as well as the elongation at break were 12.3 and 28.2 times higher than that of individual PS respectively. Then β-cyclodextrin (β-CD) molecules were attached onto the surface of PVDF@PS fibers using polydopamine (PDA) as an intermediate layer, achieving the functionalization of fiber membranes (PVDF@PS/PDA/β-CD). In comparison with other adsorbents containing β-CD, the as-prepared membranes exhibited an efficient adsorption capability of 19.24 mg/g for phenolphthalein (php) by the formation of inclusion complexes with β-CD and the interaction of hydrogen bond with PDA to some extent. Moreover, the membranes could be regenerated easily and retained about 86% of adsorption efficiency after five cycles. These results demonstrated the promise of PVDF@PS/PDA/β-CD membranes for removal of organic compound from aqueous media.

Leaching characteristics of biomass fly ash in water and a TMP spent liquor: a case study

Fly ash is considered as an under-utilized product of pulp and paper industry and is mainly land-filled. However, it can be repurposed as an adsorbent for organics of wastewater effluents. Despite efficient adsorption capability, its metal components may dissolve in wastewater and harm the environment. This investigation focused on the leaching behavior of metals from biomass-based fly ash in water at pH 6 and 12.5. A similar investigation was performed in the spent liquor of a pulping process to evaluate the extraction of metals from fly ash in such an environment that fly ash could be used as an adsorbent. The results revealed that the predominant metals leached from fly ash in water and the spent liquor were Ca, K, Mg, Mn, Na, and Si. The trace metals including Al, Ba, Sr, and Zn were also detected to a significant extent. Interestingly, the extraction of metals from fly ash in spent liquor was more limited than in water, which is beneficial for the application of fly ash in spent liquors.

Removal of organic contaminant by municipal sewage sludge-derived hydrochar: kinetics, thermodynamics and mechanisms

In this work, a microporous municipal sewage sludge-derived hydrochar (MSSH) with relatively high surface area and abundant surface organic functional groups was produced through hydrothermal carbonization. Based on the adsorption results over a wide range of conditions, the prepared MSSH was suggested as a promising adsorbent for CV because of its high and efficient adsorption capability. The experimental data were fitted to several kinetic models. Based on calculated respective parameters such as rate constants, equilibrium adsorption capacities and correlation coefficients, the pseudo second-order model proved the best in describing the adsorption behavior of MSSH. Through kinetics, thermodynamic modeling studies and material characterization, a plausible adsorption process was discussed under the conditions used in this study. It can be confirmed that the adsorption of CV onto MSSH is via both physical interactions (electrostatic interaction and Van der Waals' force) and chemical interactions (formation of H-bonding).

Versatile magnetic gel from peach gum polysaccharide for efficient adsorption of Pb2+ and Cd2+ ions and catalysis

In this paper, we report a facile approach to prepare magnetic gel based on the simultaneous formation of Fe3O4 nanoparticles and crosslinking of natural peach gum polysaccharide. The obtained magnetic gel with porous structure, high specific surface area and numerous oxygen-containing functional groups exhibited fast and efficient adsorption capability towards Pb2+ and Cd2+ ions. The adsorption isotherms and kinetics presented good correlation with Langmuir isotherm and pseudo-second-order model, respectively. The maximum adsorption capacity of the magnetic gel for Pb2+ and Cd2+ ions can reach 277.0 and 141.4mgg−1, respectively, which is much higher than many other reported magnetic adsorbents. In addition, the magnetic gel can serve as a magnetic support for in situ growth of Pt nanocatalyst with high catalytic activity, as demonstrated by the reduction of 4-nitrophenol. Moreover, the magnetic gel exhibited excellent magnetic separation capability and superior reusability both for the adsorption and catalysis applications.

Material Exhibiting Efficient CO2 Adsorption at Room Temperature for Concentrations Lower Than 1000 ppm: Elucidation of the State of Barium Ion Exchanged in an MFI-Type Zeolite.

Carbon dioxide (CO2) gas is well-known as a greenhouse gas that leads to global warming. Many efforts have been made to capture CO2 from coal-fired power plants, as well as to reduce the amounts of excess CO2 in the atmosphere to around 400 ppm. However, this is not a simple task, particularly in the lower pressure region than 1000 ppm. This is because the CO2 molecule is chemically stable and has a relatively low reactivity. In the present study, the CO2 adsorption at room temperature on MFI-type zeolites exchanged with alkaline-earth-metal ions, with focus on CO2 concentrations <1000 ppm, was investigated both experimentally and by calculation. These materials exhibited a particularly efficient adsorption capability for CO2, compared with other presented samples, such as the sodium-form and transition-metal ion-exchanged MFI-type zeolites. Ethyne (C2H2) was used as a probe molecule. Analyses were carried out with IR spectroscopy and X-ray absorption, and provided significant information regarding the presence of the M(2+)-O(2-)-M(2+) (M(2+): alkaline-earth-metal ion) species formed in the samples. It was subsequently determined that this species acts as a highly efficient site for CO2 adsorption at room temperature under very low pressure, compared to a single M(2+) species. A further advantage is that this material can be easily regenerated by a treatment, e.g., through the application of the temperature swing adsorption process, at relatively low temperatures (300-473 K).

Preparation and characterization of magnetic Fe3O4@sulfonated β-cyclodextrin intercalated layered double hydroxides for methylene blue removal

Nanocage structures derived from sulfated β-cyclodextrin (SCD) intercalated MgAl layered double hydroxides (MgAl-NO3 LDHs) were prepared through ion-exchange reactions. Coprecipitation method was used to prepare the composites of magnetic Fe3O4@sulfonated β-cyclodextrin intercalated LDH (Fe/SCD-LDH), which was demonstrated having an efficient adsorption capability to cationic pollutants and an excellent reuseability. X-ray diffraction and Fourier transform infrared spectroscopy confirmed that SCD was intercalated successfully and the basal spacing was expanded to 1.63 nm. N2-adsorption/desorption and scanning electron microscopy displayed that the resulting Fe/SCD-LDH possessed high crystallinity, hierarchical structure as well as large specific surface area. Energy-dispersive X-ray spectroscopy was used to investigate the type and content of the elements in Fe/SCD-LDH. Batch adsorption experiments were carried out to investigate the removal of methylene blue (MB) from aqueous solution using Fe/SCD-LDH as the adsorbent. MB was selected owing to its toxic and carcinogenic features as a kind of cationic dye. The adsorption process could be well described by the pseudo-second-order kinetic model and fitted well with the Langmuir isotherm model.