Adsorption最新文献

This study addresses the challenges of desulfurizing natural gas condensate through selective adsorption using hexagonal boron nitride (h-BN) material. h-BN was synthesized from thermal process of boric acid and mixture of urea and melamine with high specific surface area to be examined for light mercaptans removal from liquid fuel. characterization of synthesized adsorbent was done using X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscopy (FESEM), elemental analysis (CHN and ICP), and nitrogen adsorption/desorption analysis. Our findings confirmed synthesizing h-BN with high specific surface area of 1263 m²/g and hydroxyl group. This product was used as the adsorbent of ethyl, propyl and butyl mercaptans from the solution of n-heptane as the model molecule of the gas condensate liquid to obtain the equilibrium isotherms’ and kinetic adsorption data. It was revealed that the adsorption capacities were determined as 89.29 mg S/g for ethyl mercaptan, 103.66 mg S/g for propyl mercaptan, and 120.91 mg S/g for butyl mercaptan, significantly surpassing the commercial zeolite 13X adsorbent by 233% at room temperature. Kinetic experiments revealed that the pseudo-second-order model could best describe the rate of mercaptans’ adsorption. Notably, the synthesized h-BN was easily regenerated through the thermal treatment at moderate temperature of 150 °C, highlighting its potential for cyclic adsorption processes of desulfurization.

Nanoporous materials are frequently characterized as simple geometries such as slit-like, cylindrical, or spherical pores. However, these approximations cannot account for the surface roughness and chemical heterogeneity inherent to clay minerals. Here, we present a comprehensive computational examination of methane (CH(_4)) adsorption in nanoporous clay minerals, applying three complementary approaches-three-dimensional classical Density Functional Theory (3D-cDFT), one-dimensional (1D) cDFT, and Grand Canonical Monte Carlo (GCMC) simulations-to elucidate the roles of fluid-solid interactions and fluid-fluid correlations under confinement. We show that 3D-cDFT accurately captures high-pressure adsorption phenomena in illite and provides a powerful framework for reconstructing pore size distributions from experimental data, thereby enabling a more nuanced characterization of heterogeneous nanoporous materials.

Novel structured graphene oxide@microalgae-based nanohybrids have been prepared by incorporating green microalgae biomass (Algae) with graphene oxide (GO) or N-doped graphene oxide (NGO) in different ratios (e.g., 3:1, 1:1 and 1:3). Biogenic GO-Algae and NGO-Algae nanohybrids were synthesized via a self-assembly method. Morphological and structural characterizations and adsorption performance of the nanostructured material towards Cr(VI) species were studied extensively. The removal of Cr(VI) species by GO-Algae and NGO-Algae nanohybrids was highly pH dependent, with the maximum adsorption removal occurring at pH 2. The results indicate that the adsorption of Cr(VI) by GO-Algae and NGO-Algae nanohybrids was as follows: GO@Algae-3:1 (90.5%) < GO@Algae-1:1 (98.7%) < GO@Algae-1:3 (99.6%) and NGO@Algae-3:1 (79.2%) < NGO@Algae-1:1 (82.3%) < NGO@Algae-1:3 (92.6%), respectively. The GO: Algae-1:3 and NGO: Algae-1:3 nanohybrids with a high microalgae content ratio exhibited high maximum removal, owing to the presence of more active sites within their lattice compared to their counterparts. On the other hand, pseudo-first-order, pseudo-second-order, intraparticle diffusion, Langmuir, and Freundlich models adequately simulated adsorption mechanisms, suggesting that the adsorption process involved a combination of external mass transfer and chemisorption, with electrostatic and complexation interactions being the dominant mechanisms for Cr(VI) removal. Additionally, GO@Algae-1:3 and NGO@Algae-1:3 displayed outstanding reusability. Therefore, these structured graphene@microalgae-based nanohybrids can simultaneously serve as adsorbents for Cr(VI) removal from wastewater and contaminated water sources.

Treating wastewater contaminated with toxic pollutants is becoming increasingly challenging for chemical processes and allied industries due to stringent environmental legislation and the focus on sustainability. Conventional wastewater treatment processes involve multiple stages with many unit operations and processes. To meet the growing technical, economical, and environmental sustainability needs, industries are interested in innovative processes and technologies offering compact, small-sized equipment with improved mass transport, heat, and momentum and reduced capital and operating expenses. The Process Intensification (PI) approach is gaining importance in wastewater treatment as it offers these advantages. Among the various separation methods involved in wastewater treatment, adsorption is considered to be one of the most robust methods in the series of treatments for removing low concentrations of contaminants. The design of adsorption columns with alternate bed geometries is desirable to meet the requirements of less installation cost, small footprint area, and compact adsorption columns without compromising performance. However, there is limited literature are available related to bed geometries (helical and tapered) other than the vertical fixed type. Therefore, a systematic literature review was performed with an interest in adsorption bed configuration and separation performance. Key technical aspects are explored, including the influence of bed geometry, adsorbent stratification (normal and reverse), and flow dynamics on mass transfer kinetics. Computational Fluid Dynamics (CFD) modeling employs governing equations such as the Advection-Dispersion Equation and Darcy’s Law, which aids in optimizing column performance. The incorporation of adsorption isotherms, such as Langmuir and Freundlich models, provides a deeper understanding of pollutant-adsorbent interactions. The study also evaluates economic aspects, comparing CAPEX and OPEX across configurations. Fixed beds feature low initial costs but face challenges like clogging and pressure drops. Tapered beds, while more expensive to fabricate, achieve efficient flow distribution and reduced adsorbent usage. With their intricate design, Helical coil columns demand higher manufacturing and operational investments but excel in compactness and efficiency. The review can help the researchers to leverage the potential of process intensification to enhance the adsorption column design and advance in wastewater treatment.

“Molecular sieving”-based separation of similar-sized gases (e.g., CO₂, N₂, and CH₄) is both desirable and challenging due to the difficulty of obtaining adsorbents with pore sizes that permit exclusive admission. The “molecular trapdoor effect” offers a promising solution, focusing on the difference in gases’ ability to dynamically open a “door” via interaction with the “door-keeper” in adsorbents, rather than relying on size-sieving. In this study, we studied Na and K-exchanged zeolites with Si/Al ratios ranging from 1 to 2.2 and demonstrate that potassium form zeolite LTA with a Si/Al ratio of 2.2 (referred to as r2KLTA) exhibits the molecular trapdoor mechanism, as evidenced by CO₂/N₂ separation, gas adsorption, and in situ powder X-ray diffraction experiments. The K⁺ ion, acting as the door-keeper, is situated at the eight-membered ring (8MR) pore aperture of LTA, enabling the exclusive separation. Notably, this separation mechanism diverges from the traditional static sieving model and suggests that gas molecule admission is regulated by dynamic door-opening. In contrast to previous reports showing negligible CO₂ adsorption in r1KLTA (3 A zeolite), our findings reveal a significant CO₂ uptake, which points to the trapdoor mechanism as the key factor. This study offers new insights into the classical zeolite molecular sieve (3 A) for gas separation, where gas selectivity is governed by dynamic door-opening rather than static interactions. The demonstrated molecular trapdoor effect in r2LTA zeolites opens new possibilities for designing adsorbents with high selectivity and enhanced kinetics at optimal temperatures.

Graphical Abstract

Uranyl ions (UO₂²⁺) are the form of uranium usually dissolved in water and are radioactive and can cause serious damage to the environment. Adsorption of uranyl ions is a critical method for removing and safely storing radioactive materials that harm the environment. It is also an important tool for combating water and soil contamination, managing nuclear waste and environmental sustainability. Polymer-based composites were developed for this purpose. Polymer-based composites enable the efficient removal of harmful and radioactive uranium compounds from water and soil. Through the incorporation of polymers and fillers (such as zeolite), materials with specific properties capable of adsorbing uranyl ions with high efficiency can be designed. The ratio of the components constituting the composites can be adjusted to optimize the adsorption capacity, as well as the chemical and thermal behaviors. Two composites were created: P(MA-Z50), consisting of ethylene glycol dimethacrylate (EGDM), methacrylic acid (MA), and zeolite, and P(MA-Z75), which contained a higher amount of zeolite. These composites were synthesized at room temperature and analyzed using various techniques such as Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The study investigated the effects of adsorbent quantity, adsorbate concentration, temperature, time, and pH on adsorption efficiency and capacity. The Langmuir adsorption isotherm provided the best fit for uranium (VI) adsorption. The results showed that rapid adsorption occurred within the first 100 min, with the rate slowing down until equilibrium was reached after 360 min. The pseudo-second-order kinetic model best described the adsorption process.

Metal-organic framework (MOF)/polymer composites provide the possibility of combining the desired reactive and sorptive properties of highly porous MOFs with the desired mechanical properties of polymers to develop novel functional materials. Both MOF and polymer chemistries are complex leading to various degrees of material compatibility. It is desired to develop a facile measurement of the accessibility of MOF pore space within the composite matrix. Traditionally, N₂ isotherms at 77 K have been used to characterize pore space in porous materials. We found that using N₂ isotherms to assess pore accessibility in MOF/polymer composites underestimates the true accessibility at operational conditions. This is mostly due to the cryogenic temperature of the measurement being below the glass transition temperature of polymers. However, composite synthesis and morphology also play a role in the measurement. Measuring CO₂ isotherms at 0 °C was shown to be a facile, more accurate measurement of pore accessibility in MOF/polymer composites.

This study investigates sensing capabilities of C₆N₈ (carbon nitride) for the detection of harmful gases, specifically phosgene (COCl₂) and thionyl chloride (SOCl₂). Utilizing quantum simulation techniques, we perform Density Functional Theory (DFT) to evaluate Frontier Molecular Orbitals (FMO), natural bond orbitals (NBO), Quantum Theory of Atoms in Molecules (QTAIM), Partial Density of States (PDOS), and Non-Covalent Interaction (NCI) of the complexes COCl₂@C₆N₈ and SOCl₂@C₆N₈. Our results of negative interaction energy indicated that phosgene and thionyl chloride were physiosorbed on the C₆N₈ surface. The results of all analyses indicated that the complexes’ stability trend is SOCl₂@C₆N₈ > COCl₂@C₆N₈. The generation of new states in PDOS spectra indicates the interaction of the C₆N₈ surface with analytes (COCl₂ and SOCl₂). The recovery time of the complexes was calculated at 300 K, which showed that C₆N₈ is a reliable sensing material for phosgene and thionyl chloride. Overall, this study proves that the detection of phosgene and thionyl chloride gases on C₆N₈ may be possible and appears to be a good nanosensor for phosgene and thionyl chloride gases in the future.

Graphical abstract

Bathroom, and laundry greywater (GW) components are considered significant urban wastewater and are classified as hazardous substances that contaminate groundwater resources. Thus, achieving permitted levels for GW before discharging into the environment requires the removal or reduction, which has become a challenge. Various techniques have been developed to decontaminate GW from wastewater, comprising biological, chemical, filtration, adsorption, membrane separation, and photocatalytic degradation. Due to the simplicity, cost-effectiveness, abundance of materials, and capacity for facile scaling-up for remediation purposes, adsorption and photocatalysis technologies have been widely utilized in GW wastewater treatment. This review thus first explains the sources of GW and components found within this particular wastewater, which are critical for removal. The second part reviews various adsorbents or photocatalysts, including materials of macro, micro, and nanosize utilized for GW treatment. The review highlights the significance of activated carbon among all adsorbents under adsorption technology reviewed with the highest removal rate of chemical oxygen demand (COD), and biochemical oxygen demand BOD in GW. Moreover, the doped titanium dioxide photocatalyst also presented significant removal of COD, and BOD in GW within a shorter space of time. The impact of surface area and chemical functionalities of the adsorbent, and whilst aspect of nanostructure and absorptivity of photocatalyst in the visible region of the solar spectrum on the expedited removal of GW was also highlighted. Furthermore, this review emphasizes photocatalyst nanomaterial achieving a complete mineralization of different components present in GW, into mineral products.

Herein, the oxidized biochar (OBC) derived from rice straw was prepared and homogeneously embedded into TEMPO-mediated oxidized cellulose nanofiber (TOCNF). The resulting colloidal suspension, when mixed with OBC and crosslinked via ionic interaction using branched polyethyleneimine, forms nanocomposites with promising potential. The characterization of these composites, including SEM, EDX, surface morphology, and spatial elemental composition, reveals their unique properties. The effect of adding OBC to TOCNF at different ratios is estimated by surface area analysis following the BET and BJH methods. The adsorption settings for the as-formed composites were investigated to optimize the adsorption effectiveness of the fabricated sorbents. These conditions included contact time, Cd(II) concentration, pH, and sorbent dosage. With greater adsorption effectiveness of 70% and 90% at 1 h and 2 h, the nanocomposite with an equal ratio of OBC and TOCNF was discovered to be a valuable sorbent for Cd(II) elimination (0.15 g of BCC3 composite in 50 mL of 100 mg/L Cd(II) at pH 7.0). The adsorption process was modeled using kinetic and isotherm models. The correlation coefficients for the pseudo-first and second-order kinetics are similar and closest to 1.0 based on the data. Thus, Cd(II) adsorption may involve both physio-sorption and chime-sorption. Additionally, the linear fitting of the Freundlich isotherm model demonstrated a heterogeneous and multilayer surface interaction with the greatest adsorption capability of 44 mg/g. Suggesting potential applications in environmental engineering and materials science.