Excellent Adsorption Selectivity Research Articles

An Amidoxime-functionalized chitosan dual-network hydrogel: Enhanced uranium-water separation capacity.

The source and after treatment of uranium, a key aspect of its use as a nuclear fuel, had been a topic of intense debate among developers. Therefore, a novel antimicrobial amidoxime-functionalized chitosan/polyacrylamide dual network hydrogel (CP-AO) had been developed utilizing a straightforward methodology. The results demonstrated excellent adsorption capacity and selectivity for uranium extraction under varying conditions, the U(VI) removal was above 94 % when pH was 4. Batch adsorption experiments revealed that CP-AO attained a maximum uranium adsorption capacity of 886.73 mg/g at 298 K, which was higher than most reported adsorbents. The kinetic and thermodynamic studies presented that adsorption process for CP-AO conformed to spontaneous monolayer chem-adsorption, and it can reach equilibrium quickly within 120 min. In addition, the adsorption mechanism revealed that the chemical-interaction between CP-AO hydrogel and U(VI) was attributed to -OH, -NH2 and amidoxime group. Notably, the hydrogel showed optimistic anti-biosludge performance against three common bacteria (E. coli, S. aureus and B. subtilis) owing to effects of chitosan. CP-AO also especially was susceptible to be recycled, its adsorption capacity was 2.8 mg/g and 38.67 mg/g in simulated and actual seawater, respectively. Hence, this work provides a promising material for the extraction of uranium resources and new insights.

An Adsorbent for Efficient and Rapid Gold Recovery from Solution: Adsorption Properties and Mechanisms.

Adsorption is an efficient and highly selective method for gold recovery. Introducing rich N/S organic groups to combine with metal-organic frameworks (MOFs) as adsorbents is regarded as a practical and efficient approach to enhance gold recovery. Herein, a MOF (zirconium isothiocyanatobenzenedicarboxylate MOF, UiO-66-NCS) was designed to combine with amidinothiourea (AT) to form UiO-66-AT (zirconium amidothiourea-benzenedicarboxylate MOF) for efficient and rapid adsorption. The prepared UiO-66-AT delivers an improved adsorption capacity (about 903.02 mg/g at 1000 mg·L-1 of the initial Au3+) and an impressive adsorption rate within minutes (about 10 min for 200 mg·L-1 Au3+). Meanwhile, it exhibits sustainable stability after 5 cycles with a retention rate of 99.52% and excellent adsorption selectivity of 98.76% in actual wastewater. According to advanced characterizations and Density Functional Theory (DFT) simulation, the mechanism might be elaborated as electrostatic adsorption, chelating coordination, and chemical reduction. The modified active groups of the MOF provide the adsorption sites for Au(III) and the rapid reduction of Au(0). UiO-66-AT maintains a large adsorption capacity and high surface reduction activity while realizing stable application in multiple cycles, which is of good practical application value.

Preparation of Porous Novel QuEChERS Adsorbent ZIF‐67/PAA/PES Composite Microspheres and Their Application for Rapid Adsorption of Triphenylmethane Dyes in Wastewater and Fish

ABSTRACTTriphenylmethane dyes have a wide range of applications in textiles, pharmaceuticals, food, and other fields. Malachite green (MG), fuchsin acid (FA), and crystalline violet (CV) were typical representatives of triphenylmethane dyes, and they are carcinogenic and mutagenic to aquatic organisms and environment. However, they need to be separated and enriched for their accurate quantification due to their low content. Therefore, it is important to develop a rapid and accurate enrichment method to monitor these dyes in aquatic systems for human health. In this paper, a novel QuEChERS adsorbent porous ZIF67/PAA/PES composite microspheres were prepared and applied for the rapid adsorption of triphenylmethane dyes in wastewater and fish samples, which improved the adsorption capacity and the analytical sensitivity of the targets. The experimental results demonstrated that the porous ZIF‐67/PAA/PES composite microspheres exhibited excellent selective adsorption capacity of MG, FA, and CV, and after six adsorption–desorption cycles, the material adsorption amount can reach more than 90% of its original adsorption amount in wastewater. In addition, the porous ZIF67/PAA/PES composite microspheres were applied as QuEChERS adsorbents for the enrichment of MG and CV dyes in fish, and the adsorption rates of the dyes were 99.11% and 99.03%, with the RSDs of 1.58% and 1.27%, respectively. The limits of detection were 0.0093 and 0.0127 mg/L for MG and CV. Through the Langmuir adsorption isotherm models to predict the MG, FA, and CV of the maximum adsorption capacity were 5417.3622, 2119.9011, and 1654.1026 mg/g, respectively. Thus, the novel porous ZIF67/PAA/PES composite microspheres are more advantageous as QuEChERS adsorbents for sample pre‐treatment and have very important research significance.

Green synthesized nanoscale zero-valent iron impregnated tea residue biochar efficiently captures metal(loid)s for sustainable water remediation

Pristine or modified nanoscale zero-valent iron (nZVI) synthesized though conventional chemical reduction have been widely recommended for remediating metal(loid)-contaminated water. However, their eco-friendliness is often challenged with the concomitant bio-toxicity and secondary environmental risks. Alternatively, this study utilized waste tea leaves extract and remaining residue as the reducing agent and pyrolytic matrix to innovatively fabricate a green synthesized nZVI impregnated tea residue biochar (G-nZVI/TB). Since the performances, mechanisms, and potential applications of G-nZVI/TB for simultaneous removal of metal cation and metalloid anion remain unclear, typical synthetic aqueous solutions and real wastewaters were systematically tested. The adsorption isotherms showed that the calculated maximum adsorption capacities of G-nZVI/TB for various meta(loid)s were 1.4-10.7 fold higher than those of TB. Although Cd(II) competed with Pb(II) for adsorption on G-nZVI/TB, they synergistically promoted As(III) sequestration. The SEM and FTIR spectra demonstrated that G-nZVI nanoparticles were uniformly dispersed onto TB framework, whereas newly grafted groups like Fe-O, C=O, and C-N accelerated metal(loid)s bonding. The results of batch experiments, XRD, and XPS comprehensively elucidated that metal(loid)s were predominantly separated from polynary systems via electrostatic adsorption, ion exchange, co-precipitation, cation-π interaction, oxidation-complexation, and B-type ternary complexation. In synthetic industrial wastewater and real paddy field drainage with divergent environmental conditions, 0.5gL-1 optimized G-nZVI/TB efficiently captured over 92.4% metal(loid)s at their concentrations ranging from 0.04 to 3mgL-1, indicating its excellent selective adsorption effectiveness and extensive compatibility for practical application in reusing multi-metal(loid)s contaminated wastewater. Overall, these findings provide new insights into developing green nano-functional materials for sustainable water purification.

Fabrication and application of aminated metal–organic cages doped monolithic column for pipette tip micro solid-phase extraction of eight phenolic compounds in milk

A Zr-based metal–organic tetrahedron (ZrT-1-NH2) doped monolithic column was sythesized and applied for pipette tip micro solid-phase extraction (PT-μSPE) of 8 phenolic compounds. Scanning electron microscopy, energy dispersive spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis and N2 adsorption and desorption experiment were employed to characterize the morphology, composition, structure and thermal stability of the monolithic column. The experimental results showed that the monolithic column had good stability and excellent adsorption selectivity for phenolic compounds. The adsorption mechanism was speculated to be π-π stacking and H-bond interaction based on ESP maps. After the extraction conditions were optimized, a PT-μSPE-high performance liquid chromatography-ultraviolet detector (HPLC-UV) method was established for the detection of 8 phenolic compounds in milk. The PT-μSPE-HPLC-UV method has wide linearities (0.3–1000 μg L−1) (R2 > 0.997), low limits of detection (0.1–0.3 μg L−1), satisfactory recoveries (80.5–113.6 %) and high precision (RSDs < 6.7 %). Thus, the ZrT-1-NH2 doped monolithic column is an ideal medium for the separation and determinaton of phenolic compounds in milk.

Efficient and selective adsorption of Ni(II) and Mo(VI) utilizing novel materials derived from in situ aminated Co/Zn-ZIF-Modified biochar

The imperative need for efficient and selective adsorption of Ni(II) and Mo(VI) is crucial for resource utilization and environmental protection. However, this process faces a challenge due to the scarcity of adsorbents that can adeptly adsorb both metal ions simultaneously. To address this, this study introduces a novel composite adsorbent material, denoted as BECZN, achieved through composite cross-linking of waste orange peel biochar with in situ aminated cobalt/zinc-zeolitic imidazolate frameworks (Co/Zn-ZIF-NH2). The incorporation of Co/Zn-ZIF-NH2 enhances the availability of active groups within BECZN. The aerogel structure of BECZN prevents ZIF material collapse and agglomeration, thereby improving active site exposure. BECZN exhibits notable adsorption capacities, reaching 151.84 mg/g for Ni(II) at pH = 7 and 842.54 mg/g for Mo(VI) at pH = 3. Further investigations indicated that the adsorption of Ni(II) and Mo(VI) obeys the Langmuir isotherm model, while exhibiting pseudo-second-order kinetics and intraparticle diffusion characteristics. Notably, BECZN selectively adsorbs Ni(II) and Mo(VI) efficiently under acidic and neutral conditions, respectively. It can maintain high capacity under the interference of various cations and anions. Meanwhile, this excellent selective adsorption of Ni(II) and Mo(VI) by Co/Zn-ZIF-NH2 is revealed at the atomic level using density functional theory (DFT) calculations. This study offers a theoretical basis and experimental reference for the design and synthesis of ZIF and biomass-based composite adsorbents.

Gas-specific adsorption capability of titanium dioxide and MXene nanocomposite thin films prepared by ultrasonic spray printing using inks oxidized at room temperature

The development of two-dimensional (2D) layered MXene materials has opened new possibilities for gas adsorption applications due to their high specific surface area, tunable surface chemistry, and excellent selectivity towards specific gases. These materials exhibit tremendous potential in adsorption-based gas separation and detection, particularly due to their strong interactions with target gas molecules, making them highly effective in gas removal and detection applications. However, currently available methods for synthesizing these oxidized nanocomposite inks are limited by the typically high temperatures involved. The present work addresses this issue by developing titanium dioxide and MXene (TiO2/Ti3C2 MXene) nanocomposite inks, where TiO2 nanoparticles are formed between the layers of the Ti3C2 MXene via oxidation in solution state under extended exposure in an oxygen rich atmosphere at room temperature. As a proof of concept, gas adsorption studies are conducted by applying the TiO2/Ti3C2 MXene nanocomposite inks onto gold-coated silicon wafers via an ultrasonic spray printing method. The gas adsorption results demonstrate that the TiO2/Ti3C2 MXene nanocomposites possess excellent adsorption selectivity toward methane and butane among alkane gases, and can achieve maximum adsorption capacities of 8.62 and 18.8 cm3/g, respectively. The results of ultrasonic spray printing quality tests conducted for different numbers of printed layers using the proposed TiO2/Ti3C2 MXene nanocomposite ink demonstrate that the film thickness can be regulated by controlling the number of printed layers, and the average thin film thickness remains only 0.313 μm for 10 printed layers. Meanwhile, the average roughness of the films resides between 0.130 μm (3 layers) and 0.220 μm (8 layers), which is uniformly and less than the average roughness of 0.225 μm measured for the original gold-plated silicon wafer. Hence, by employing facile ink-based printing techniques, such as ultrasonic spray printing, thin films with controlled thickness can be fabricated, thereby laying the foundation for their practical applications in environmental monitoring and industrial gas separation.

Ordered mesoporous SiO2 as hemoperfusion adsorbents for enhanced selectivity of bilirubin removal from blood

Excessive bilirubin poses a significant risk factor in the progression of chronic liver disease. However, due to its nature as an albumin-bound toxin, bilirubin cannot be efficiently eliminated through conventional hemodialysis therapy or existing hemoperfusion adsorbents, presenting a challenge in selective removal. It is widely acknowledged that adjusting the pore properties of adsorbents can impact the adsorption efficiency of a hemoperfusion adsorbent. However, few studies have been working on improving the selectivity of bilirubin removal through precise regulation of pore size. In this paper, we aim to demonstrate that the selectivity of bilirubin removal can be achieved and enhanced by fine-tuning the pore size of ordered mesoporous materials. Ordered mesoporous SiO2 (OMS) is selected as the research object due to its highly organized and uniform porous structure, as well as its excellent biocompatibility. The results indicate that OMS nanoparticles with a pore diameter of 2.5 nm (OMS-2.5 nm) exhibit superior adsorption capacity for bilirubin in both pure and albumin-rich solutions, suggesting the potential for achieving efficient and selective bilirubin removal through pore size optimization. Furthermore, to demonstrate the feasibility of OMS nanoparticles in practical applications (i.e. their inheritability of selectivity), we engineered OMS nanoparticles into polyvinyl alcohol (PVA) microspheres, forming OMS/PVA composite microspheres. The incorporation of OMS nanoparticles significantly enhances the bilirubin adsorption capacity of PVA microspheres while simultaneously reducing their albumin adsorption. The excellent selective adsorption efficacy of OMS-2.5 nm is preserved in the composite microspheres, underscoring its potential therapeutic benefits for treating diseases with excessive bilirubin levels.

Improvement of tetracycline removal using amino acid ionic liquid modified magnetic biochar based on theoretical design

In current research, biochar is widely used to remove antibiotic contamination from the environment. However, original biochar produced through direct pyrolysis has significant limitations in removing antibiotics. In this paper, response surface methodology provided the laudable choice for magnetic poplar biochar (MPBC) considering the synergistic effect of multi-factors as well as the restrictions abundance experiments during the preparation of MPBC. Amino acid ionic liquids (AAILs) are a class of ionic liquids in which amino acids act as the anionic component, combining the tunable properties of ionic liquids with the biocompatibility and functionality of amino acids. To ameliorate adsorption capacity of MPBC, tetra-ethylammonium glycinate ([TEA][Gly]) with the best affinity for tetracycline (TC) were screened from 600 AAILs based on theoretical predictions using the conductor-like screening model for real solvents (COSMO-RS) without extensive experimental. Furthermore, AAILs-modified magnetic biochar (MPBC-AAIL) was synthesized chemically for the first time. Adsorption kinetics, isotherms, and thermodynamic analyses revealed that TC adsorption by both MPBC and MPBC-AAIL is a monolayer, spontaneous, and exothermic chemical process. Moreover, MPBC-AAIL exhibited a maximum adsorption capacity of 305.9 mg·g−1. Meanwhile, MPBC-AAIL maintains superior adsorption performance for TC in different impurity solutions as well as in real water samples. The excellent reusability and selective adsorption capacity of the material demonstrate the superiority of the theoretical based design. The characterization reveals that the adsorption mechanisms include pore filling, π-π interactions, surface complexation, hydrogen bonding, and electrostatic interactions. In addition, theoretical calculations showed that ionic liquid modification altered the adsorption sites between TC and MPBC-AAIL, leading to enhanced adsorption. This comprehensive study introduces an innovative modification of biochar, providing a novel approach to designing biochar composites and promoting their application in the remediation of complex environmental pollution.

Unraveling nitrogen-doped and vacancy-engineered synergistically modified molybdenum oxide promoting gallium selective adsorption

Sustainable recovery of strategic element gallium from wastewater carries great significance for economic development and environmental conservation. In this study, nitrogen-doped and vacancy-engineered synergistically modified molybdenum oxide nanowires (α-MoOx/N) were rationally designed for efficiently adsorbing gallium ions in the range of 1–200 mg L-1 under acidic conditions. The introduction of moderate amount of ethylenediamine induced the transition of α-MoOx to the amorphous state. Mixed-valence α-MoOx/N-0.53 (Mo(V) and Mo(VI)) with abundant active sites notably enhanced the adsorption kinetics of gallium ions, accompanied by 98.9 % of gallium ions being adsorbed within 60 min. Advantageously over most gallium adsorbents, α-MoOx/N-0.53 exhibited the maximum adsorption capacity of 464.8 mg g-1 (298 K), mainly attributed to the synergistic effect of electrostatic adsorption, ion exchange with H+ as well as surface complexation with Mo-O and pyridinic N. Self-enhanced adsorption mechanism and oxygen vacancies as gallium ion adsorption traps in α-MoOx/N-0.53 augmented the opportunities for capturing gallium ions. Excellent selective adsorption of gallium ions from binary and multivariate systems containing Zn2+, Al3+, Cu2+, Ni2+ and robust cyclic stability further endorse α-MoOx/N as the promising candidate for recovering gallium ions from complex wastewater.

Construction of functionalized microcapsule adsorbents using emulsion templates for simultaneous thermal storage and selective adsorption of uranium

The treatment of nuclear wastewater generates substantial amount of uranium (U(VI)) contaminated wastewater, along with waste heat. Efficiently extracting U(VI) while managing nuclear waste heat is crucial. In this study, the functionalized microcapsule adsorbent (PDA-PO43−/PEG) was synthesized using an emulsion template method. The synthesis involved the oxidative polymerization of dopamine with the grafting of phosphoric acid functional groups. The resulting black shell layer enabled the conversion of light energy into heat energy, while the inner phase of the microcapsule, composed of polyethylene glycol (PEG), served as a heat storage material. The maximum adsorption capacity of PDA-PO43−/PEG at 298 K was 242.59 mg g−1, reaching equilibrium within 30 min. The removal efficiency of U(VI) by PDA-PO43−/PEG exceeded 99 %, even in the presence of various competing metal ions. Thermal and near-infrared light tests demonstrated that a concentration of 2.0 mg mL−1 of PDA-PO43−/PEG dispersion reached temperature above 80 °C after just 5.0 min of laser irradiation. Furthermore, the latent heat of phase transition was measured at 164.13 J g−1. The PDA-PO43−/PEG microcapsule demonstrated excellent adsorption capacity and selectivity. It's combined high uranium adsorption performance, selectivity, strong photothermal conversion, and thermal storage capabilities make it a material of significant interest industrial applications.

Sheet nanocomposites of sorghum stalk loaded with hydrated ferric oxide for Cu(Ⅱ) deep removal from water

Novel sheet porous nanocomposites were developed for Cu(II) deep removal form water utilizing waste crop stalks. Hydrated ferric oxide (HFO) was coated onto the surface of sorghum crop stalk (SCS) through a simple and cleaner impregnation-surface deposition method to fabricate the nanocomposite adsorbent SCS-HFO. BET, SEM-EDX, FTIR and XPS characterization proved that HFO with a particle size of 10–50 nm was successfully loaded on the sorghum stalk surface. High level of coexisting cations such as Na+, Mg2+ and Ca2+ in aqueous solution had little influence on the Cu2+ adsorption capacity, showing that SCS-HFO had excellent adsorption selectivity. The adsorption of Cu2+ onto SCS-HFO fitted to Langmuir isothermal model, and the adsorption process conformed to the quasi-secondary kinetics, which indicates that monolayer chemical adsorption is dominant. The fixed-bed column of SCS-HFO could effectively reduce the Cu2+ concentration in 6.8 L of simulated wastewater to less than 0.01 mg/L. The NaCl-NH3·H2O mixed solution can regenerate SCS-HFO, and the adsorption efficiency of SCS-HFO still reaches more than 90 % after multiple adsorption-desorption cycles, indicating good stability of the prepared material. This study successfully constructed and fabricated a green and cost-effective nanocomposite adsorbent based on agricultural waste.

One-step green synthesis of melamine-modified cellulose nanofiber composite aerogels for efficient removal of Pb(II) and Cu(II): Experiments and DFT calculations

A composite aerogel (CGMA) with high porosity (98.32 %) and multiple active sites was prepared for the adsorption of Pb(II) and Cu(II) by sol-gel combined with freeze-drying process using melamine and (3-Glycidyloxypropyl)trimethoxysilane as cellulose nanofiber modifying materials. Characterized by SEM-EDS, XPS, FTIR, BET, MIP and TG, CGMA has a hierarchical pore structure and abundant adsorption sites. At pH = 6, the adsorption reached equilibrium within 120 min, following the Pseudo second-order kinetic model and the Langmuir model, with maximum capacities of 268.1 mg/g for Pb(II) and 152.6 mg/g for Cu(II). The process was primarily governed by homogeneous chemisorption. The coexisting ion, organic matter, and water quality experiments confirmed the excellent anti-interference properties of CGMA. Competitive adsorption experiments showed that CGMA has excellent selective adsorption performance for Pb(II). After 5 cycles, Pb(II) and Cu(II) adsorption performance decreased to 79.21 % and 83.40 %, respectively. FTIR, XPS, DFT and RDG analysis showed that amino groups and oxygen-containing groups were the main sites of adsorption. CGMA forms coordination bonds and complexes with Pb(II) and Cu(II) via amine and oxygen groups and adsorbs via electron transfer, hydrogen bonding, and van der Waals forces, with Pb(II) being more selective. CGMA has good prospects for application in heavy metal ion treatment.

Biochar rich in amino ligand for copper selective recollection in wastewater

The coexistence with other similar valence counterparts greatly hinders the selective recovery of metals, resulting in serious resource waste and environmental pollution. Herein, biochar with numerous surface –NO2 and –COOH groups was prepared, and in-situ ammonization reaction was catalyzed by electricity to transform those attached –NO2 into –NH2. The as-obtained biochar with stable ligand of –NH2 (BC-NH2) exhibited an excellent selective adsorption efficiency for copper. Among six bi-valence ions of copper, lead, cadmium, zinc, magnesium and calcium, the above adsorbent could selective recollect 88.76 % and 73.61 % of copper from aqueous and soil respectively. More importantly, the other existent bi-valence ions can be effectively substituted by Cu(II) with a high efficiency up to 91.92 %, even they were saturated on the BC-NH2. The Linear sweep voltammetry curves (LSV) and density functional theory (DFT) demonstrate the strongest affinity between Cu(II) and BC-NH2 than that of other heavy metals, indicating the keynote of the selective mechanism should be the formation of ultra-stable complex between –NH2 and copper ions. Besides, –COOH group participate the pathway for the transformation from –NO2 to –NH2. This study provides a new concept, and an ideal material as well as novel preparing stratagem, for selective recollecting copper through chelating.

Regulating the Surface State of Carbon Dots as Ultrahigh-Capacity Adsorbents for Water Treatment.

Adsorption is one of the most widely researched and highly effective methods for mitigating the environmental threat posed by recalcitrant dyes in aqueous solutions. This paper presents a solvent-free synthesis method for the rapid and large-scale production of nitrogen (N) and phosphorus (P) co-doped carbon dots (N, P-CDs) which possess specific surface states and outstanding dye adsorption properties. Compared to the undoped CDs, the N, P-CDs not only exhibit a higher yield of solid-state luminescence but also endow them with the efficient adsorption and removal of Congo red (CR) from water. Due to the synergistic effects of π-π stacking, hydrogen bonding and electrostatic attraction, the N, P-CDs exhibit an ultra-high adsorption capacity (3118.87mgg-1) and a removal efficiency (97.4%, at 500mgL-1) for CR, and also display excellent selective adsorption in both single-dye and dual-dye systems. This method offers a rational strategy for synthesizing novel CDs-based adsorbents for CR, which provides a demonstration for future dye adsorption studies and practical wastewater treatment applications of CDs.

Molecularly imprinted polymer gel with superior recognition and adsorption capacity for amphenicol antibiotics in food matrices

A molecular-imprinted polymer (MIP) gel with high effective recognition of amphenicol antibiotics was synthesized for the first time based on layered double hydroxide (LDH) as the support and initiator, and functionalized β-cyclodextrin (β-CD) as the functional monomer. The synergistic effect of molecular imprinting recognition and β-CD host-guest affinity enabled MIP gel to exhibit excellent selectivity (imprinted factors: 3.9–9.4) and high adsorption capacity (28.9–75.4 mg g−1) for amphenicol antibiotics. Different adsorption isotherms and kinetics models were followed, suggesting heterogeneous single-layer recognition and chemical adsorption. After 5 cycles of adsorption and desorption, the adsorption capacity of MIP gel retained above 83.6 %, demonstrating favorable reproducibility and stability. Under optimal conditions, the method validation showed a satisfactory limit of detection (5–10 μg L−1), good correlation (r2 > 0.9967), and respectable recovery (82.6–105.3 %). The MIP gel was applied to extract amphenicol antibiotics from food matrices, achieving recoveries in the range of 78.3–104.5 %. Importantly, the recognition mechanism was studied in detail using density functional theory. Therefore, the established method demonstrates high sensitivity and can be applied as a new tactic for detecting amphenicol antibiotics in food matrices.

Mechanistic insights into cadmium removal from environmental waters using silicon-enhanced lignin-derived hydrochar and pyrochar

This study explores the improved cadmium (Cd2+) removal from environmental waters using silicon-modified hydrochar and silicon-modified pyrochar derived from industrial lignin. Despite the widespread use of lignin-based chars in environmental remediation, the specific role of silicon in enhancing these materials’ properties and their mechanisms for Cd2+ removal remain inadequately studied. Physicochemical analyses indicate that the introduction of silicon promotes the consumption of C–O bonds in hydrochar, facilitating the formation of Si–O bonds. In pyrochar, silicon introduction enhances the synthesis of silicate minerals. Results showed that silicon-modified pyrochar, in particular, exhibited a markedly higher Cd2+ adsorption capacity in environmental water, being 14.71, 16.83, and 1.87 times that of hydrochar, pyrochar, and silicon-modified hydrochar, respectively. Silicon-modified pyrochar also demonstrated excellent selective adsorption and reusability for Cd2+, showing optimal performance in actual water bodies. Notably, silicon-modified pyrochar maintained a high Cd2+ removal rate of up to 99 % after multiple cycles. Adsorption experiments revealed that the main mechanisms in lignin–based carbons are ion exchange and complexation precipitation, contributing about 70 % of the adsorption capacity. Specifically, silicon-modified hydrochar removes Cd2+ mainly through complexation precipitation with oxygen–containing groups (CO and SiO), while silicon-modified pyrochar relies mainly on mineral precipitation (Na2SiO3 and Na2CO3) and the ion exchange process. These findings underscore the transformative impact of silicon modification on lignin-derived chars, offering valuable insights for developing more effective and sustainable solutions for heavy metal remediation in aquatic environments.

Selectively recovering rare earth elements with carboxyl immobilized metal-organic framework from ammonium-rich wastewater

The material with high adsorption capacity and selectivity is essential for recovering rare earth elements (REES) from ammonium (NH4+-N)-rich wastewater. Although the emerging metal-organic framework (MOF) has gained intensive attention in REES recovery, there are scientific difficulties unsolved regarding restricted adsorption capacity and selectivity, hindering its extensive engineering applications. In this work, a diethylenetriamine pentaacetic (DTPA)-modified MOF material (MIL-101(Cr)-NH-DTPA) was prepared through an amidation reaction. The MIL-101(Cr)-NH-DTPA showed enhanced adsorption capacity for La(III) (69.78 mg g−1), Eu(III) (103.01 mg g−1) and Er(III) (83.41 mg g−1). The adsorption isotherm and physical chemistry of materials indicated that the adsorption of REEs with MIL-101(Cr)-NH-DTPA was achieved via complexation instead of electrostatic adsorption. Such complexation reaction was principally governed by -COOH instead of -NH2 or -NO2. Meanwhile, the resulting material remained in its superior activity even after five cycles. Such a constructed adsorbent also exhibited excellent selective adsorption activity for La(III), Eu(III), and Er(III), with removal efficiency reaching 70% in NH4+-N concentrations ranging from 100 to 1500 mg L−1. This work offers underlying guidelines for exploitation an adsorbent for REEs recovery from wastewater.

Selective adsorption of aldehyde impurities from propylene oxide using perethylated pillar[5]arene enabled by spatial size matching effect

Effective removal of acetaldehyde and propionaldehyde from propylene oxide is important for polyether industry but remains a significant challenge due to their similar molecular sizes and relatively close volatilities. Herein, we studied flexible molecular materials, perethylated pillar[n]arene crystals (n = 5, 6), which can be used to separate acetaldehyde and propionaldehyde in propylene oxide. Through a space size matching effect, perethylated pillar[5]arene demonstrates excellent adsorption selectivity of 95 % and 100 % for aldehydes in ternary mixture and binary mixture of propylene oxide, acetaldehyde and propionaldehyde, respectively. These impressive selective adsorption is achieved based on their differential host–guest interactions. Density functional theory calculations provide a comprehensive explanation of the adsorption process, revealing that the adsorption mechanisms of perethylated pillar[5]arene for acetaldehyde and propionaldehyde primarily involve C-H···O hydrogen bonding and C-H···π interactions. This study also provides a novel method for achieving one-step purification of propylene oxide in industrial applications.

A novel imprinted porous liquid for lithium extraction

AbstractPorous liquids (PLs) are a novel material that combines the advantages of porous solids and liquid fluidity. In this study, we propose an imprinted porous liquid (IPL) with imprinted polymers as the porous framework and a mixture of TOP + FeCl3 as sterically hindered solvents. Quantum chemical computations and characterization results demonstrate the presence of unoccupied pore structure in IPLs. The prepared IPLs exhibit excellent selective adsorption and extraction performance for lithium extraction, achieving a Li/Mg separation factor of 1540 and a single‐stage Li+ extraction efficiency of 86%. The Li+ extraction efficiency remains above 84% even after eight cycles. Analytical characterization along with quantum chemical computations elucidates the mechanism underlying the coupling between extraction and adsorption in IPLs, enabling efficient lithium extraction. By combining imprinting technology with PLs, IPLs expand upon existing frameworks for PLs materials while providing new insights for designing functional solvents.