Adsorbent Material Research Articles

Unveiling the Sorption Properties of Graphene Oxide-M13 Bacteriophage Aerogels for Advanced Sensing and Environmental Applications.

GraPhage13 aerogels (GPAs) are ultralow density, porous structures fabricated through the self-assembly of graphene oxide (GO) and M13 bacteriophage. Given GPA's high surface area and extensive porous network, properties typically associated with highly adsorbent materials, it is essential to characterize its sorption capabilities, with a focus on unlocking its potential for advanced applications in areas such as biomedical sensing and environmental monitoring. Herein, the water, ethanol and acetone sorption properties of GPA were explored using dynamic vapor sorption (DVS). GPA was found to be highly hygroscopic, with a sorption capacity of 0.68 ± 0.02 g/g, double that of conventional desiccant silica gels and 20% higher than GO laminates. This remarkable sorption capacity, along with its sorption kinetics, was influenced by both GPA's morphology and the strong interactions between the water molecules and the functional groups on the GO within GPA. The low hysteresis and stability of GPA during repeated sorption-desorption cycles highlight the reversibility of water sorption. While GPA shows lower capacity for ethanol and acetone, its tuneability presents opportunities for improving acetone sorption, and its ethanol sorption capacity exceeds that of similar carbon-based materials. These findings underscore GPA's capability and versatility in vapor adsorption, paving the way toward its integration into graphene-based devices for sensing applications.

Síntese e Caracterização de Bioadsorvente de Spondias mombin L. para Remoção de Azul de Metileno utilizando ClZn2, NaOH e Al2(SO4)3.14H2O

Objective – The objective of this study was to synthesize and characterize a bioadsorbent produced from Spondias mombin L.’s endocarp, using the chemical activators ClZn2, NaOH and Al2(SO4)3·14H2O, and evaluate its efficiency in removing methylene blue dye from aqueous solutions. Methodology - The research was structured in three stages: preparation and activation of activated charcoal at different temperatures and pyrolysis times; material characterization regarding ash content, moisture content, yield and pH; and carrying out adsorption tests to determine the efficiency of dye removal. Originality/relevance - This study addresses the theoretical gap related to the reuse of agricultural waste to produce adsorbent materials, promoting sustainable alternatives to the use of conventional adsorbents and highlighting their relevance for the treatment of effluents. Results - The adsorbents activated with NaOH and ClZn2 demonstrated greater efficiency, with emphasis on the materials NA250-3, ZN300-2 and ZN300-4, which presented adsorption capacities of 1.40 mg·g⁻¹, 1.39 mg·g⁻ ¹ and 1.37 mg·g⁻¹, removing 93.23%, 93.02% and 91.69% of the dye, respectively. The ZN250-4 material stood out for its balance between performance (1.33 mg·g⁻¹, 88.78% removal) and cost-benefit, due to its high yield (64.27%) compared to the others. Theoretical/methodological contributions: The research expands knowledge about ideal activation conditions and use of chemical activators, providing support for bioadsorbents applications. Social and environmental contributions: The research promotes sustainability by proposing the reuse of agricultural waste as raw materials for the production of biosorbents, reducing environmental pollution and offering solutions for the treatment of effluents.

Refinement of a kinetic adsorption model through Artificial Intelligence

The adsorption process involves capturing contaminants at active sites on adsorbent materials. Its economic efficiency and simplicity distinguish it as a preferred option amidst concerns about anthropogenic pollution. Traditional kinetic models present challenges in fitting nonlinear behaviors of porous materials, prompting the exploration of alternative approaches. Machine learning has a wide range of applications in various fields, including environmental engineering. These models possess generalization capabilities and are used as predictive tools, but they can lead to undesired behaviors if the system is complex and the model fails to capture this complexity. A novel methodology is proposed where the calibration of traditional models is studied using a machine learning model for adsorption kinetics, with hexavalent chromium as the adsorbate and activated carbon as the adsorbent. Furthermore, the technique of adding synthetic data to influence the model's capacity is studied, considering whether it leads to overfitting.Traditional models include pseudo first and second order kinetics, while multilayer perceptron is used as the machine learning model. The models obtained through the proposed methodology exhibit significant performance compared to traditional models. Additionally, an improved interpretability in their behavior compared to using only an artificial intelligence model is observed. Calibration ensures physical interpretation while enhancing generalization. The incorporation of synthetic data into the artificial intelligence model resulted in overfitting, subsequent ensemble methods effectively leveraged this, reducing bias related errors. The impact of synthetic data on calibration has demonstrated favorable outcomes.

Adsorption Behaviors of ctDNA and Biological Activities Based on Polyvinyl Alcohol/Polyethylene Glycol/Quaternized Chitosan Composite Hydrogel

In this study, a polyvinyl alcohol/polyethylene glycol/hydroxypropyltrimethyl ammonium chloride chitosan (PVA/PEG/HACC) ternary composite hydrogel was synthesized using electron-beam radiation. The materials were thoroughly characterized via Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, Brunauer–Emmett–Teller analysis, gelation fraction tests, and swelling rate tests. Systematic adsorption experiments revealed that the rate of adsorption of calf thymus DNA (ctDNA) by the PVA/PEG/HACC hydrogel reached 89%. The adsorption process followed the Langmuir isotherm and pseudo-second-order kinetic model. This process was mainly characterized by monolayer chemical adsorption, with intraparticle diffusion playing a crucial role. In addition, the process was spontaneous, with higher temperatures enhancing adsorption. The possible adsorption mechanisms included electrostatic interactions, hydrogen bonding, and van der Waals forces. The maximum ctDNA desorption rate was 81.67%. The adsorption rate remained at 71.39% after five adsorption–desorption cycles. The bioactivity of the PVA/PEG/HACC hydrogel was validated by antibacterial, cytotoxicity, and apoptosis tests. The results of this study demonstrated the crucial application potential of adsorbent materials in DNA adsorption and biomedical applications.

Experimental, economic, and life cycle carbon footprint assessment of low‐cost adsorbents for siloxane removal from landfill gas

AbstractSiloxane impurities in landfill gas (LFG) pose a significant challenge for downstream processing equipment used in energy recovery. This study investigated the adsorption capacity, cost, and environmental impact of five low‐cost adsorbent materials: biochar, clinoptilolite, hydrochar, diatomaceous‐earth, and crushed glass. Gravimetric analysis was used to determine the adsorption capacity of these materials for octamethylcyclotetrasiloxane (D4). The results were then used to conduct a technoeconomic analysis (TEA) and life cycle assessment (LCA), comparing the selected adsorbents with activated carbon (AC), a commonly used adsorbent for siloxane removal. The TEA revealed that the cost of LFG purification with clinoptilolite, biochar, and AC was $0.035, $0.034, and $0.033/m3, respectively, for the base case studied. The cradle‐to‐gate LCA showed that clinoptilolite had significantly lower carbon emissions compared with the other adsorbents, both per kg of D4 captured and per kg of adsorbent produced. The potential fate of siloxanes after adsorption was discussed, emphasizing the importance of proper treatment and disposal of spent adsorbents. Surface modification techniques were recommended to enhance the adsorption capacity and regeneration of clinoptilolite, potentially reducing cost and carbon emissions in LFG purification. These findings highlight the potential of low‐cost adsorbents for sustainable LFG purification.

Silicon-Enhanced PVA Hydrogels in Flexible Sensors: Mechanism, Applications, and Recycling

Hydrogels, known for their outstanding water absorption, flexibility, and biocompatibility, have been widely utilized in various fields. Nevertheless, their application is still limited by their relatively low mechanical performance. This study has successfully developed a dual-network hydrogel with exceptional mechanical properties by embedding amino-functionalized polysiloxane (APSi) networks into a polyvinyl alcohol (PVA) matrix. This hydrogel effectively dissipates energy through dense sacrificial bonds between the networks, allowing for precise control over its tensile strength (ranging from 0.07 to 1.46 MPa) and toughness (from 0.06 to 2.17 MJ/m3) by adjusting the degree of crosslinking in the polysiloxane network. Additionally, the hydrogel exhibits excellent conductivity (10.97 S/cm) and strain sensitivity (GF = 1.43), indicating its potential for use in wearable strain sensors. Moreover, at the end of its life (EOL), the sensor waste can be repurposed as an adsorbent material for metal ions in water treatment, achieving the recycling of hydrogel materials and maximizing resource utilization.

Modified gum ghatti based hybrid hydrogel nanocomposite as adsorbent material for dye removal from wastewater

A hybrid hydrogel nanocomposite based on the polysaccharide-gum ghatti, has been made and evaluated as an adsorbent material for wastewater treatment. The nanocomposite is composed of a network of gum ghatti-graft-poly(2-acrylamido-2-methylpropane sulfonic acid) with magnetite nanoparticles embedded within. This functional material Ggh-g-PAMPS/Fe3O4 has been characterized by FTIR, TGA, SEM, EDS, XRD, BET and VSM techniques. The presence of magnetite nanoparticles imparted superparamagnetic property to the adsorbent material enabling its easy separation after use with an external magnet. The characterization data indicated mesoporous nature of the nanocomposite adsorbent with mean pore diameter of 4.9 nm. The nanoparticles imparted high surface area to the adsorbent material the value being 4.7 m2g−1 based on nitrogen adsorption experiments. The suitability of the material as an adsorbent for removal of cationic dyes from water was checked with two cationic dyes namely, rhodamine 6G and methylene blue. The maximum adsorption capacity of the nanocomposite Ggh-g-PAMPS/Fe3O4 towards rhodamine 6G and methylene blue were observed to be 403.2 and 427.8 mg g−1 respectively from their individual solutions of concentration 500 mg L−1. The pH dependence on swelling and surface charge indicated medium of pH of 7.0 as the ideal condition for effective adsorption. Freundlich isotherm model and pseudo second order kinetic model are observed to be the most befitting models to describe adsorption. Further, the thermodynamic studies revealed the adsorption to be a spontaneous and endothermic process. The desorption study portrayed the reusability of the adsorbent material. The excellent adsorption performance and magnetic nature of the developed nanocomposite suggests its potential application as an adsorbent material in wastewater treatment.

Chitosan extracted from the feather of Dosidicus gigas crosslinked with glutaraldehyde for use as a 99Mo adsorbent

The production of Technetium-99 m (99mTc) is important for cancer diagnosis. The solvent extraction is the most widely used method to obtain 99mTc; however, due to the evaporation of the polluting solvent into the environment, a radiochemical separation using a chromatographic column system based on adsorbent materials would be cleaner and more efficient.In this study, squid feather (Dosidicus gigas) chitosan (SFC) polymers have been synthesized and crosslinked with glutaraldehyde solutions at concentrations of 50, 40 and 25 % to study the adsorption of 99Mo with the aim of test a promising material to produce 99mTc in the chromatographic column of the 99Mo/99mTc generator. Likewise, the same methodology of synthesis was performed using a commercial chitosan (CC) as a control. Deacetylation degree was measured obtaining 74.15 % and 77.65 % for the SFC and CC polymers, respectively. The molecular weight obtained was 990.72 kDa for SFC and 722.72 kDa for CC and the characterization of the biopolymers was performed with FTIR, SEM, XRD, TGA y FT Raman techniques. Equilibrium time, adsorbent mass and pH effect were evaluated as factors that influence the adsorption process of 99MoO4-2. The zero load point (pHPZC) analysis confirmed the positive charge of the crosslinked polymers, improving the adsorption capacity of 99MoO4-2 at low pH values between 2 and 4, following a pseudo-first order model. With respect to the adsorption isotherms, they exhibit maximum values of 99MoO42- of 482 mg g−1 SFCG40 and 502 mg g−1 CCG25 with a better fit to the Langmuir theoretical model.

Tackling water contamination by oncologic drugs: Supported ionic liquids as sustainable adsorbents for cyclophosphamide removal

Due to the increasing incidence of cancer, the consumption of highly toxic oncological drugs is continuously growing. Given the current lack of efficient technologies to remove/treat these toxic drugs in wastewater treatment plants, the environmental quality is compromised, and aquatic organisms are at risk. To address this critical environmental burden, a new strategy based on supported ionic liquids (SILs) for the simultaneous removal of oncologic drugs and toxicity reduction of aqueous samples is here proposed. Silica-based SILs functionalized with imidazolium-based and quaternary ammonium-based ILs were designed and kinetics and isotherm adsorption studies performed. Aiming to develop an adsorbent able to reduce the toxicity of aqueous samples contaminated with oncological drugs, the toxicity reduction was appraised using the model organism Danio rerio. The obtained results disclose that among the studied SILs, the [Si][N3888]Cl (silica functionalized with propyltrioctylammonium chloride) is the best adsorption material (maximum adsorption capacity, qmax = 67.64 mg g−1), with a fast adsorption rate (<20 min). Furthermore, [Si][N3888]Cl was able to remove the toxicity of the treated aqueous samples towards D. rerio embryos, as assessed by lethal and several sublethal endpoints, demonstrating that this material holds remarkable potential for oncological drugs pollution remediation.

A newly NH2-UiO-66 composite functionalized by molecularly imprinted polymer for selective and rapid removal of sulfamethoxazole

Metal–organic frameworks (MOFs) are used as novel adsorption materials owing to their large surface area and tunable pore size. However, the lack of selectivity considerably limits their application. Consequently, designing functionalized MOFs with specific recognition abilities is essential for enhancing their adsorption performance. Herein, we synthesized a functionalized NH2-UiO-66 composite modified by molecularly imprinted polymers (MIP@NH2-UiO-66) via a one-step polymerization process in which NH2-UiO-66 and MIP were formed simultaneously. Results demonstrate that MIP@NH2-UiO-66 effectively recognized sulfamethoxazole (SMX) in complex matrices. The adsorption equilibrium was reached in only 30 min, and this fast SMX adsorption on MIP@NH2-UiO-66 was described by the Avrami kinetic model, which indicates a spontaneous and exothermic adsorption process. Within the pH range of 3.0–10.0, MIP@NH2-UiO-66 exhibited an optimal binding capacity for SMX, and the maximum adsorption of SMX was 68.36 mg g−1 at 25°C, which exceeded those of existing adsorption materials (< 60.10 mg g−1). Additionally, MIP@NH2-UiO-66 was regenerated for ∼17 cycles compared to less than eight cycles for the other adsorbents. MIP@NH2-UiO-66 effectively removed 90.58%–99.60% of SMX from river water, rainwater, soil, sediment, chicken, pork, and milk samples, with a relative standard deviation of less than 4.43%. The superior adsorption of SMX on MIP@NH2-UiO-66 was primarily driven by the synergistic effects of the imprinting sites, hydrogen bonding, and electrostatic forces. The one-step polymerization method substantially simplified the synthesis process and reduced the costs, which are promising factors for the synthesis of MOFs with high selectivity.

Involvement of CN Sites in Solvothermally Engineered Metal-Free Carbon Material From Weed Lantana camara for the Detection of Mercury Ions: Experimental and DFT Insights.

Embarking on a journey to decipher the role of active sites in the detection and removal of toxic mercury(II) ions from polluted water, the surface of thermally engineered biomass derived carbon matrix NC-180 was customized with nitrogen atoms. The HR-TEM and XRD analyses revealed the amorphous nature of Lantana camara derived carbon material with small spherical flakes embedded in it. XPS analysis indicated the presence of pyrrolic, pyridinic, and graphitic N atoms, which was further confirmed by FT-IR analysis. The material shows quenching effect in presence of Hg2+ ions resulting in the "turn off" effect with a detection limit of 7.2 nM. The activity of NC-180 was recovered through "turn on" effect in the presence of L-cysteine. Furthermore, the mystery of binding of mercury(II) ions with N-sites is clarified through its comparison with other materials bearing sulfur and oxygen functional groups designated as AC-180, SC-180, and NSC-180. The conclusive evidence for efficient binding of nitrogen sites in NC-180 with mercury(II) ions is derived from various analyses, including 1H-NMR, FT-IR, XPS, and density functional theory. Notably, sustainability is achieved through utilization of toxic weed L. camara for the preparation of this selective carbon material for detection and adsorption of mercury(II) ions.

Advances in deep eutectic Solvent-Based synthesis of nanomaterials for environmental remediation

The application of eco-friendly deep eutectic solvents (DES) in the functionalization and synthesis of adsorbent materials has gained significant research interest in recent times. These materials, employed for treating polluted water primarily through degradation or adsorption, are emerging as sustainable alternatives to traditional technologies. However, the information regarding the functionalization and synthesis of adsorbent materials using DES is dispersed throughout the literature. This review aims to consolidate and clarify the extensive information available on the synthesis and functionalization of DES-based adsorbents, their application in water treatment as nanomaterials, and the future prospects of such technologies. DES presents an ideal alternative to conventional solvents for modifying and functionalizing adsorbents due to their lower toxicity, cost-effectiveness, and environmental friendliness. Most DESs effectively introduce desired functionalities and enhance the surface area of adsorbents, thereby greatly enhancing the removal of pollutants. This review compiles recent literature on the synthesis and modification of graphene oxides, carbon nanotubes, metal oxides, and other materials for the degradation/adsorption of pharmaceuticals, herbicides, dyes, pesticides, heavy metal ions, and other water contaminants. Besides this, DES-based nanomaterials have potential future applications in nanotechnology, nanofluids, nanocatalysts, biosensors, environmental remediation, among others. The anticipated exponential growth in these areas underscores the urgent need for such a review.

Selective adsorption of arsenic by water treatment residuals cross-linked chitosan in co-existing oxyanions competition system

Selective adsorption of arsenic in co-existing oxyanions competition systems remains a significant challenge in water treatment due to the limitations of adsorbent materials that often overlook competitive adsorption, resulting in an overestimation of their actual purification potential for target contaminants. In this study, a novel hydrogel bead adsorbent, composed of water treatment residuals (WTRs) and chitosan (Chi), was developed to selectively remove arsenic, while minimizing the interference from phosphate, which is the strongest and most representative competitor in multi-oxyanion systems. The WTRs-Chi beads (WCB) adsorbents were optimized by adjusting the ratios of WTRs:Chi, with characterization results indicating that increased WTR doping improved the degree of crosslinking and the formation of bidentate complexes with enhanced electrostatic selectivity. Importantly, the co-existence of phosphate had minimal adverse effects on arsenic removal compared to other reported adsorbents. The maximum adsorption capacity for As (Ⅴ) in the binary system was 34.12 mg/g, and the adsorption behavior was fitted well by the pseudo-second-order kinetic model and the extended Langmuir isotherm model. The experimental results, supported by X-ray photoelectron spectroscopy analysis (XPS), revealed that both As (Ⅴ) and P (Ⅴ) adsorption in the single system were driven by electrostatic attraction and ligand exchange. However, in the binary system, the inhibition of P (V) adsorption was attributed to competitive desorption caused by electrostatic repulsion, which hindered the formation of inner-sphere complexes. This study provides a practical approach for developing selective adsorbents to address arsenic contamination in complex water environments and promotes the recycling of municipal solid waste.

Preparation of nitrogen-doped lignin porous carbon using low dosage KHCO3 for efficient methylene blue adsorption: Activation mechanism and adsorption performance

The previous requirement for activation of porous carbon adsorbents commonly exceeded several times the mass of the carbon precursor. Therefore, it was crucial to develop cost-effective and efficient carbon adsorbent materials for long-term environmental remediation. In this study, biorefinery lignin was utilized to fabricate porous carbon with an ultrahigh specific surface area (3423 m2 g−1) and pore volume (1.52 cm3 g−1) by employing melamine as the nitrogen source and a low dosage of KHCO3 as the activator. Multiple activations during the carbonization process contributed to the exceptional characteristics of the porous carbon, including well-developed pore structure, high specific surface area, and reasonable nitrogen doping. The porous carbon demonstrated remarkable adsorption capabilities with a maximum methylene blue (MB) adsorption capacity of 1457 mg g−1. Structural characterization conducted before and after adsorption revealed that electrostatic interactions, pore filling, hydrogen bonding, and π-π stacking were among the main mechanisms employed by lignin porous carbon for effective MB adsorption. The proposed method is a simple, green, highly efficient, and environmentally friendly approach that can be applied to treat lignin from various industrial sources. It provides valuable insights into the development of advanced carbon materials suitable for adsorption and capacitor applications.

Adsorption characteristics and mechanism of novel ink melanin composite modified chitosan for Cd(II) in water

In this study, chitosan (CS), carboxymethyl chitosan (CMCS), and chitosan quaternary ammonium salt (HACC) were successfully loaded with ink melanin (ME) as efficient adsorbents for Cd(II) removal. The results of batch adsorption experiments and structural characterization showed that the modified CS loaded with ME improved the adsorption capacity of the composites for Cd(II). The pseudo-second-order kinetic and Langmuir equations were better suited to describe the batch adsorption experiments. The adsorption of Cd(II) was chemisorption with desirable adsorption effect when the concentration of the three composites was 0.5 mg/mL and the pH value was neutral. Among them, HACC-ME demonstrated remarkable Cd(II) adsorption performance (107.18 mg/g) and sustained an 85 % efficiency in Cd(II) removal over five adsorption-desorption cycles. Ion exchange, complexation, electrostatic attraction, and hydrophobic interaction were the primary mechanisms for Cd(II) removal. Overall, HACC-ME could be employed as a low-cost and highly efficient new natural adsorbent material for the removal of Cd(II) ions from wastewater. These findings illuminate pathways for the development of efficient and novel natural adsorbent materials for environmental cleanup purposes.

A novel recyclable surface ion-imprinted graphene aerogels for high selective adsorption of lithium in salt lake brine

To mitigate the growing pressure of lithium resource supply and requirement, the exploration of abundant lithium from salt lake brine has emerged as a novel avenue for lithium resource acquisition. Surface ion imprinting technology with specific recognition could achieve selective lithium adsorption. However, existing Li+-imprinted adsorption materials exhibit poor adsorption performance and difficult recovery. To address these issues, the novel recyclable Li+-imprinted graphene aerogels were synthesized by using graphene oxide as the skeleton material, and thiourea dioxide as the reducing agent, assisted by DMF and NH3·H2O. The imprinted aerogels demonstrate excellent structural stability (bearing 10000 times of its weight), superior adsorption capacity (31.66 mg g−1), high selectivity and good regeneration performance (91.0% after six cycles). The selection factors for Li+ over Na+, K+ and Mg2+ reach 10.00, 5.71 and 4.00, respectively. This is attributed to the strong metal coordination interreaction between 2-Hydroxymethyl-12-crown-4 and Li+, thereby specifically recognizing and adsorbing Li+. This research offers a fresh material for the enrichment and recovery of lithium resources in salt lake brine.

Mass granulation of Al-promoted CaO-based sorbent via moulding-crushing methods for cyclic CO2 capture

Calcium looping (CaL) process, as an effective way to achieve CO2 mitigation from high-temperature flue gas streams, is one of the most promising alternatives to amine scrubbing (a well-established technology for industrial post-combustion CO2 capture). CaO sorbent is considered to be an ideal CO2 adsorption material. Moreover, the development of granulation/pelletization techniques along with the mass preparation of the CaO-based sorbent is imperative for realistic large-scale applications. This work proposes two practicable moulding-crushing techniques for the scale-up granulation of CaO-based sorbents, in which the kilogram-scale produced Al-promoted CaO-based sorbent powders were first moulded and subsequently crushed into the granules of target sizes. Three types of organic acids–acetic acid, citric acid and malonic acid were employed as peptizing agents to optimize the granulation process. As a result, the anti-attrition properties and compressive strength of the synthetic sorbents were elevated owing to the introduction of an appropriate amount of acetic or malonic acid, for it expedited the disintegration of the pseudo-boehmite (served as binder agent) particles into sol particles, which allowed for tighter bonding of sorbent particles. In addition, corncob powder acted as a pore-forming agent, enhancing the porous structure of the sorbent particles due to the gases released from the thermal decomposition of organic groups during calcination. Nevertheless, the results revealed that the porous and loose structure adversely affected the mechanical strength of the granules.

Synthesis of activated carbon/MgO monolith using Astragalus material for carbon dioxide adsorption

ABSTRACT Adsorption technology has emerged as a viable approach to reducing CO2 emissions. Generally, activated carbons-based adsorbents, in particular, are promising due to their abundant availability, tunable physicochemical properties, and suitability over a wide temperature range. In this study, activated carbons (ACC) modified with magnesium oxide (MgO) was evaluated for carbon dioxide capture in an adsorption process. ACC, the feedstock, was produced using the fast pyrolysis of Astragalus. The availability and cheapness of the Astragalus material next to MgO led to the synthesis of a new compound called ACC/MgO. The aim of this new synthetic compound was to achieve a cost-effective approach to carbon dioxide adsorption. This approach somehow shows the innovation of the work. Another innovation is adsorbent moulding (monolith) and its industrialisation. The synthetic material underwent various analyses, including FTIR, XRD, SEM, BET, and EDX. Fifteen experiments were designed using the response surface methodology-Box-Behnken (RSM-BBD) design to determine the maximum carbon dioxide adsorption capacity (ADC). One of the optimal points, with the highest carbon dioxide ADC (1.355 mmol/g), was determined at an initial MgO loading of 13.26 wt.%, an average ACC particle size of 0.58 mm, and a Polyvinyl alcohol (PVA) content of 6.34 wt.%. Kinetic models and isotherm models were employed to analyse the adsorption data. The findings indicated that the entire adsorption range could be described by employing the fractional-order model. Investigation into the diffusion mechanism revealed that both film diffusion and intraparticle diffusion predominantly governed the rate-limiting steps. The adsorbent exhibited favourable regeneration at lower temperatures and demonstrated consistent regenerability following seven cycles of adsorption and regeneration. This research demonstrated that ACC modified with MgO is a suitable adsorbent due to its high capacity and efficiency in carbon dioxide capture.

Enhancing Methylene Blue Adsorption Performance of Ti3C2Tx@Sodium Alginate Foam Through Pore Structure Regulation.

Pore structural regulation is expected to be a facile way to enhance the adsorption performance of MXene. In this work, spherical foam composites consisting of Ti3C2Tx and sodium alginate (SA) were synthesized via a vacuum freeze-drying technique. By varying the solution volume of Ti3C2Tx, four distinct Ti3C2Tx@SA spherical foams with honeycomb-like and lamellar structures with a pore diameter in the range of 100-300 μm were fabricated. Their methylene blue (MB) adsorption performances were then systematically compared. The results revealed that the honeycomb-like porous-structured spherical foams have a significantly higher adsorption capacity than their lamellar counterparts. Notably, the Ti3C2Tx@SA honeycomb-like porous foam exhibited a remarkable maximum adsorption capacity (qm) of 969 mg/g, positioning it at the forefront of MB adsorbent materials. Respective analysis of the adsorption kinetics, thermodynamics, and isotherm model indicated that this MB adsorption of Ti3C2Tx@SA honeycomb-like porous foam is characterized to be a physical, endothermic, and monolayer adsorption. The Ti3C2Tx@SA honeycomb-like porous foam also demonstrated excellent resistance to ion interference and good reusability, further attesting to its substantial potential for practical applications. X-ray photoelectron spectroscopy (XPS) analysis was employed to elucidate the adsorption mechanism, which was found to involve the synergistic effect of electrostatic adsorption and amidation reaction. This work not only offers new avenues for the development of high-performance adsorption materials but also provides crucial insights into the structural design and performance optimization of porous materials.

Novel metal-organic framework hydrogel for enhanced selective removal of uranyl ions from nuclear wastewater

The efficient removal of uranium (U(Ⅵ)) from nuclear wastewater presents a significant challenge due to the high concentrations of uranium and various interfering ions. In this study, we developed and used metal-organic framework hydrogel (MOFH) as a highly efficient adsorbent for uranium removal. The MOFH, synthesized with ferrocyanides and functional groups (Fe(Ⅱ)-CN-Fe(Ⅲ), OH, -COOH, and -NH2), exhibited good chemical stability, large separation capacity, and high selectivity. The hydrogel's three-dimensional network, crosslinked with chitosan and alginic acid, significantly enhanced uranium removal. Even in the presence of high concentrations of coexisting cations and organic matter, the MOFH maintained a high removal rate (>95%) and distribution coefficient (Kd), and thus demonstrated strong resistance to interference from coexisting ions and showed great applicability in complex wastewater. The study also explored the MOFH's potential in treating uranium-contaminated wastewater from a smelting mine, showing effective uranium removal with minimal impact on other wastewater components. This research contributes to the development of novel adsorption materials and the understanding of their removal mechanisms, offering a comprehensive solution for the efficient removal of uranium from aqueous systems.