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In this study, biochars with different structures were prepared through HNO3 oxidation and secondary pyrolysis to study the relationship between the structure of biochar and its selectivity for the adsorption of light and heavy aromatics in bio‐oil. The results showed that the adsorption rates of biochar with different structures ranged from 2.90 to 4.00 g bio‐oil per g biochar. The influence of pore structure was dominant, followed by the influence of O‐containing functional groups and the degree of graphitization. The higher the adsorption capacity of biochar for bio‐oil, the smaller the concentrations of the light aromatic model compounds in the absorbed bio‐oil (ABO). Among the five light aromatics, biochar has the best adsorption selectivity for dihydroxybiphenyl and the worst for eugenol and propyl phenol. This is attributed to the diphenyl ring structure of dihydroxybiphenyl, which makes it more susceptible to adsorption, and other light model compounds only have one benzene ring. In summary, biochar demonstrates better adsorption selectivity for heavy aromatics than light aromatics. The more developed the pore structure is, the more enriched O‐containing functional groups are, and the higher the graphitization degree of biochar is, the better the selective adsorption of aromatic compounds in bio‐oil. [ABSTRACT FROM AUTHOR]

As a cornerstone of the national economy, the iron and steel industry generates a significant amount of sintering dust containing both valuable lead resources and deleterious elements. Flotation is a promising technique for lead recovery from sintering dust, but efficient separation from Fe2O3 is still challenging. This study investigated the cooperative effect of sodium lauryl sulfate (SLS, C12H25SO4Na) and sodium pyrophosphate (SPP, Na4P2O7) on the selective flotation of lead oxide minerals (PbOHCl and PbSO4) from hematite (Fe2O3). Optimal flotation conditions were first identified, resulting in high recovery of lead oxide minerals while inhibiting Fe2O3 flotation. Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR) analysis, adsorption capacity analysis, and X-ray photoelectron spectroscopy (XPS) studies offer insights into the adsorption behaviors of the reagents on mineral surfaces, revealing strong adsorption of SLS on PbOHCl and PbSO4 surfaces and remarkable adsorption of SPP on Fe2O3. The proposed model of reagent adsorption on mineral surfaces illustrates the selective adsorption behavior, highlighting the pivotal role of reagent adsorption in the separation process. These findings contribute to the efficient and environmentally friendly utilization of iron ore sintering dust for lead recovery, paving the way for sustainable resource management in the iron and steel industry. [ABSTRACT FROM AUTHOR]

Inhibitors are important for flotation separation of quartz and feldspar. In this study, a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp. Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments. And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism. The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca2+ and SS in sequence under the optimal proportion of 1:5. A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired, and was found to be 90.70wt% and 83.70%, respectively. It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared (FT-IR) and adsorption capacity tests. The results of X-ray photoelectron spectroscopy (XPS) indicated that Ca2+ directly interacts with the surface of quartz to increase the adsorption of collectors. In contrast, the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na+ and Ca2+ taking the place of K+, resulting in the composite inhibitor forms a hydrophilic structure, which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site. The combination of Ca2+ and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector, thus achieving the effect of efficient separation. A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided. [ABSTRACT FROM AUTHOR]

Cesium-137 (Cs-(I)) is highly hazardous in low-level wastewater and is a major problem in low-level nuclear wastewater. Its effective removal from contaminated wastewater is crucial to ensuring environmental safety and public health. In this study, cesium ion-imprinted composite membranes (I-DBC) were developed for selective separation of Cs-(I) using dopamine modification and ion-imprinting techniques. Bacterial cellulose (BC) was used as a carrier in the membrane matrix, and the adsorption capacity of the material was greatly improved after hydrophilic dopamine mimetic bonding and ion blotting techniques. Rapid and highly selective adsorption of cesium ions from low concentration nuclear energy wastewater was realized. The researchers conducted both static and dynamic adsorption experiments on Cs-(I) to evaluate the performance of the I-DBC composite membranes. The results showed that the I-DBC composite membrane was more compatible with the Langmuir model and adsorbed Cs-(I) mainly by chemical monolayer adsorption, with a maximum adsorption capacity of 50.016 mg g–1 under optimal conditions. In low concentration wastewater, the maximum adsorption capacity of the I-DBC was 4.093 mg g–1. Furthermore, during dynamic permeation experiments, the breakthrough point of the I-DBC was approximately 20 min. The membrane demonstrated good flux properties, which underscores its potential for practical application in the treatment of nuclear wastewater. The findings suggest that the I-DBC composite membrane holds promising prospects for the efficient removal of cesium ions from contaminated water, contributing to safer and more effective nuclear wastewater management. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate frameworks based on 2-methylimidazolate linkers with different particle size (200–1000 nm) and controlled content of Zn2+ and Co2+ ions have been synthesized by microwave (MW) assisted technique according to original procedures and room-temperature method. The produced materials including monometallic ZIF-8 and ZIF-67 samples, bimetallic ZIF-Zn/Co (or ZIF-8/ZIF-67) system, and "core-shell" ZIF-8@ZIF-67 and ZIF-67@ZIF-8 composites have been studied in the practically relevant process of selective adsorption of ethane and methane (25 °C). The adsorption isotherms for both gases on the obtained ZIF materials were measured in a wide pressure range (1–20 atm) for the first time. For ZIF-67, the isosteric heats of adsorption for both gases were obtained also for the first time. It was found that the nature of the coordination centers in the ZIF frameworks influences their adsorption characteristics. Thus, the obtained materials with Co2+ ions show an increased adsorption capacity towards ethane, which exceEDX the capacity measured for the Zn2+-based samples, while the highest methane adsorption value is achieved on a "core-shell" ZIF-67@ZIF-8 composite. [ABSTRACT FROM AUTHOR]

Perfluoroalkyl acids (PFAAs) are widespread in the aquatic environment and also measurable in ground and drinking water. Because of the insufficient PFAA elimination in conventional water treatment processes, e. g. active carbon based methods, consumers in areas with contaminated water supplies are exposed to an elevated health hazard. For this purpose, the applicability of five differentially fluorinated silica-based adsorbents (HSU00107954-958) to remove the potentially human toxic perfluoroalkyl sulfonic acids(PFSAs) perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) from water was investigated with regard to removal efficiencies (REs) and equilibrium loadings. During the adsorbent screening at nanomolar concentrations (20.0–33.4 nmol L−1) maximum REs of 46.9% for PFBS (HSU00107954), 79.4% for PFHxS (HSU00107954), and between 86.5 to 96.7% for PFOS (HSU00107956, and HSU00107954, respectively) have been achieved. Even at picomolar concentrations (< 400 pmol L−1) HSU00107954 was still able to eliminate PFBS and PFHxS with an efficiency of 46.3–51.2% and 79.1–88.2%, respectively. Analyses of the equilibrium loadings of the functionalized adsorbents in the concentration range 40.1 pmol to 3.34 nmol L−1 resulted in appropriate linearized Freundlich isotherms for all investigated PFSA. Compared to literature-based Freundlich adsorption coefficients (KF) for granular activated carbon (GAC), the determined KF values (nmol(1−n) Ln m−2) of the most efficient adsorbents HSU00107956 and HSU00107954 for each PFSA were significantly 8–10 and 50–60 times higher, respectively. These proven increased adsorption capacities relative to activated carbon possibly indicate specific PFSA selectivities of the functionalized macroporous silica adsorbents. [ABSTRACT FROM AUTHOR]

It is imperative to devise effective removal strategies for high ionization potential (IP) organic pollutants in wastewater as their reduced electron-donating capacity challenges the efficiency of advanced oxidation systems in degradation. Against this backdrop, leveraging the metal-based carbon material structure meticulously, we employed metal-pyridine-N (M-N-C, M=Fe, Co, and Ni) as the electron transfer bridge. This distinctive design facilitated the ordered transfer of electrons from the adsorbent surface to the surface of high IP value pollutants, acting as a "supplement" to compensate for their deficient electron-donating capability, thereby culminating in the selective adsorption of these pollutants. Furthermore, this adsorbent also demonstrated effective removal of trace emerging contaminants (2 mg/L), displayed robust resistance to various salts, exhibited reusability, and maintained stability. These findings carry substantial implications for future carbon-based material design, offering a pathway toward exceptional adsorption performance in treating water pollution. [ABSTRACT FROM AUTHOR]

To develop cost-effective heavy metal adsorbents, we employed water-soluble lignin from black liquor to modify activated attapulgite, resulting in the creation of a novel adsorbent called Lignin-modified attapulgite (LATP). In this study, scanning electron microscopy and Fourier transform infrared spectrometer techniques were utilized to characterize the structural details of LATP. The results revealed that lignin occupies the micropores of attapulgite, while additional functional groups are present on the attapulgite surface. We conducted adsorption tests using LATP to remove five types of heavy metal ions (Cd2+, Pb2+, Zn2+, Mn2+, Cu2+), and it was found that LATP exhibited greater removal mass and binding strength for Pb(II) compared to the other ions. For further investigation, batch experiments were performed to evaluate the adsorptive kinetics, isotherms, and thermodynamics of Pb2+ removal from aqueous solutions using LATP. The results indicated that the adsorption capacity of Pb(II) on LATP decreased with decreasing pH, while the presence of Na+ had no effect on adsorption. The adsorption process reached equilibrium rapidly, and the Langmuir adsorption capacities increased with temperature, measuring 286.40 mg/g, 315.51 mg/g, and 349.70 mg/g at 298 K, 308 K, and 318 K, respectively. Thermodynamic analysis revealed positive values for ΔH0 and ΔS0, indicating an endothermic and spontaneous adsorption process. Furthermore, ΔG0 exhibited negative values, confirming the spontaneous nature of the adsorption. Consequently, LATP demonstrates great potential as an effective adsorbent for the removal of Pb(II). Therefore, LATP shows great potential as an effective adsorbent for the removal of Pb(II) from natural water environments, contributing to the sustainable development of man and nature. [ABSTRACT FROM AUTHOR]

Porous coordination polymers (PCPs) are an excellent class of porous crystalline materials with tunable properties and intriguing potential applications spanning multiple disciplines. In this work, we report the synthesis and characterization of a PCP (HI‐103) based on 4,4′‐dithiodibenzoic acid ligand and zinc nitrate with two DMF molecules residing in the porous network. The stability of the porous network was analyzed by heating the compound at 60.0 °C for two days, and the structural analysis revealed a new PCP (HI‐104) was formed with one of the DMF molecules, indicating a single‐crystal to single‐crystal (SCSC) transformation. The solvent molecules were completely removed by extensive drying (HI‐103‐dry), and the integrity of the porous network was verified by powder X‐ray diffraction (PXRD) and thermogravimetric analysis. The reversibility of SCSC transformation was confirmed by treating HI‐103‐dry with DMF molecules, resulting in HI‐103 after five days. The adsorption studies of HI‐103‐dry with other solvents revealed that SCSC transformation was not observed for DMA and DEA, but some structural changes were observed in the presence of DMSO. The adsorption studies performed in the presence of an equimolar mixture of DMF, DMA, and DMA indicated that HI‐103‐dry could selectively adsorb DMF molecules from the analogous mixture. [ABSTRACT FROM AUTHOR]

Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through inner-sphere coordination, strong competition for hydroxyl ions still hinders efficient water defluoridation. In addition, the critical issue of polysilicate scaling that results from the ubiquitous silicates must be addressed. To tackle these issues, an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Brønsted acidity is proposed. The feasibility of this approach is demonstrated by growing zirconium phosphate (ZrP) inside a gel-type anion exchanger, N201, to produce nanocomposite ZrP@N201, in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr4+ sites and Brønsted acidic monohydrogen phosphate groups (–O3POH). Compared with the Lewis acidic nano-zirconium oxide analog (HZO@N201), ZrP@N201 exhibited a greatly improved adsorption capacity (117.9 vs. 52.3 mg/g-Zr) and mass transfer rate (3.56 × 10−6vs. 4.55 × 10−7 cm/s), while bulk ZrP produced a thermodynamically stable α-phase with Brønsted acidity that exhibited negligible adsorption capability toward fluoride. The enhanced defluoridation activity of ZrP@N201 is attributed to Brønsted acidity and the increased outer electron density of Zr4+ sites, as corroborated using XPS and solid-state NMR analysis. Moreover, Brønsted acidity strengthens the resistance of ZrP@N201 to silicate, allowing its full regeneration during cyclic defluoridation. Column tests demonstrated 3–10 times the amount of clean water from (waste) for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum oxide. This study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications. [ABSTRACT FROM AUTHOR]

Large volumes of wastewater containing toxic contaminants (e.g., heavy metal ions, organic dyes, etc.) are produced from industrial processes including electroplating, mining, petroleum exploitation, metal smelting, etc., and proper treatment prior to their discharge is mandatory in order to alleviate the impacts on aquatic ecosystems. Adsorption is one of the most effective and practical methods for removing toxic substances from wastewater due to its simplicity, flexibility, and economics. Recently, hierarchical oxide composites with diverse morphologies at the micro/nanometer scale, and the combination advantages of oxides and composite components have been received wide concern in the field of adsorption due to their multi-level structures, easy functionalization characteristic resulting in their large transport passages, high surface areas, full exposure of active sites, and good stability. This review summarizes the recent progress on their typical preparation methods, mainly including the hydrothermal/solvothermal method, coprecipitation method, template method, polymerization method, etc., in the field of selective adsorption and competitive adsorption of hazardous substances from wastewater. Their formation processes and different selective adsorption mechanisms, mainly including molecular/ion imprinting technology, surface charge effect, hard-soft acid-base theory, synergistic effect, and special functionalization, were critically reviewed. The key to hierarchical oxide composites research in the future is the development of facile, repeatable, efficient, and scale preparation methods and their dynamic adsorption with excellent cyclic regeneration adsorption performance instead of static adsorption for actual wastewater. This review is beneficial to broaden a new horizon for rational design and preparation of hierarchical oxide materials with selective adsorption of hazardous substances for wastewater treatment. [ABSTRACT FROM AUTHOR]

Traditional magnesite desilication flotation collectors struggle to efficiently remove quartz from low-grade magnesite, prompting the exploration of new, highly selective flotation collectors. Addressing this need has become a focal point in mineral processing research. This study introduced heptadecylamine ethylimidazoline quaternary ammonium salt (ODD) as a quartz flotation collector for separating quartz from magnesite. Flotation experiments involving single minerals and artificially mixed minerals demonstrated that magnesite and quartz could be effectively separated under specific conditions: an ODD concentration of 40mg/L and pH=7.0. Zeta potential assessments revealed that the adsorption of ODD increased the potential of quartz by 4.4 times compared to magnesite. Furthermore, contact angle measurements illustrated that ODD selectively increased the hydrophobicity of the quartz surface while not affecting the contact angle of magnesite. X-ray photoelectron spectroscopy (XPS) analysis indicated that ODD's selective adsorption at the quartz surface through interaction with the O sites on quartz rather than magnesite. Drawing from these findings, a flotation separation model from magnesite and quartz under the influence of ODD was formulated. [ABSTRACT FROM AUTHOR]

Abstract Perfluoroalkyl acids (PFAAs) are widespread in the aquatic environment and also measurable in ground and drinking water. Because of the insufficient PFAA elimination in conventional water treatment processes, e. g. active carbon based methods, consumers in areas with contaminated water supplies are exposed to an elevated health hazard. For this purpose, the applicability of five differentially fluorinated silica-based adsorbents (HSU00107954-958) to remove the potentially human toxic perfluoroalkyl sulfonic acids(PFSAs) perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorobutane sulfonic acid (PFBS) from water was investigated with regard to removal efficiencies (REs) and equilibrium loadings. During the adsorbent screening at nanomolar concentrations (20.0–33.4 nmol L−1) maximum REs of 46.9% for PFBS (HSU00107954), 79.4% for PFHxS (HSU00107954), and between 86.5 to 96.7% for PFOS (HSU00107956, and HSU00107954, respectively) have been achieved. Even at picomolar concentrations (

Microcystin-LR (MC-LR), the most common algal toxin in freshwater, poses an escalating threat to safe drinking water. This study aims to develop an engineered biofiltration system for water treatment, employing a composite of poly(diallyldimethylammonium chloride)-biochar (PDDA-BC) as a filtration medium. The objective is to capture MC-LR selectively and quickly from water, enabling subsequent biodegradation of toxin by bacteria embedded on the composite. The results showed that PDDA-BC exhibited a high selectivity in adsorbing MC-LR, even in the presence of competing natural organic matter and anions. The adsorption kinetics of MC-LR was faster, and capacity was greater compared to traditional adsorbents, achieving a capture rate of 98% for MC-LR (200 μg/L) within minutes to tens of minutes. Notably, the efficient adsorption of MC-LR was also observed in natural lake waters, underscoring the substantial potential of PDDA-BC for immobilizing MC-LR during biofiltration. Density functional theory calculations revealed that the synergetic effects of electrostatic interaction and π-π stacking predominantly contribute to the adsorption selectivity of MC-LR. Furthermore, experimental results validated that the combination of PDDA-BC with MC-degrading bacteria offered a promising and effective approach to achieve a sustainable removal of MC-LR through an "adsorption-biodegradation" process.

This study focused on synthesis of anionic magnetite nanoparticles (MNPs) immobilized with a bisphenol A (BPA)-specific peptide aptamer for selective BPA adsorption. The MNP surface was coated with anionic poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS) to provide water dispersibility and stability. These nanosorbents, with a saturation magnetization value of 47 emu/g, responded well to the change in zeta potential and hydrodynamic size with varying dispersion pH. The aptamer loading capacity of particles was 0.12 mg/mg MNPs, and the nanosorbents exhibited a 47% BPA adsorption capacity. Importantly, they shown high selectivity in capturing BPA over structurally similar molecules. [ABSTRACT FROM AUTHOR]

A surface-modified mesoporous silica nanoparticle containing dimercaprol monomers was created utilizing the sol–gel condensation process, using tetraethyl orthosilicate (TEOS) as the silica source and poloxamer as the structure directing agent. To accomplish this synthesis, 3-glycidoxypropyl triethoxysilane (GPTS, 20 mol%) was incorporated into the silica walls during the sol–gel condensation process, along with TEOS. Furthermore, dimercaprol (DM) monomers were incorporated onto silica surfaces by a ring-opening reaction between GPTS epoxy groups, and dimercaprol hydroxyl groups. The prepared dimercaprol-modified silica adsorbent (MSN-DT NPs) material has been studied using a variety of instruments, including XRD, FT-IR, N2 adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric (TG) analysis, and zeta potential analysis. The MSN-DT NPs material selectively adsorbs mercury ions, with a high adsorption amount of 125 mg/g and a removal capability of roughly ~ 90% from the original metal ion mixture comprising other competing metals such as Pb2+, Ni2+, Fe2+, and Zn2+. The MSN-DT NPs adsorbent shows recyclable qualities for up to five cycles when treated with an acidic aqueous solution (0.1 M HCl). As a result, the MSN-DT NPs adsorbent may be regenerated and reused up to five times without losing its adsorption effectiveness. The experimental findings showed that the MSN-DT NPs adsorbent may be employed to selectively remove hazardous Hg2+ ions from an aqueous solution. [ABSTRACT FROM AUTHOR]

Efficient recovery of gallium (Ga) from vanadium slag processing residue (VSPR) solution is of great significance for environmental protection and resource utilization, but improving its selective adsorption against the coexisting Sc3+ and In3+ is still challenging. Herein, a novel adsorbent consisting of 4-amino-3-hydrazino-1,2,4-triazol-5-thiol (AHTZT)-modified graphene oxide (GO-AHTZT) was successfully synthesized that exhibits a higher adsorption selectivity for Ga3+ in VSPR solution with coexisting Sc3+ and In3+. Under optimal conditions, the adsorption capacity of GO-AHTZT for Ga3+ can reach 23.92 mg g−1, which is 4.9 and 12.6 times higher than that for Sc3+ (4.87 mg g−1) and In3+ (1.90 mg g−1) adsorption, indicating the excellent anti-interference ability of GO-AHTZT against Sc3+ and In3+. The process and mechanism of Ga3+ adsorption onto GO-AHTZT was also studied and discussed in detail. By measuring the adsorption process and by characterizing the adsorbent before and after adsorption, we demonstrate that the selective interaction between the Ga3+- and N-containing groups in AHTZT is the main reason for the improved adsorption selectivity. This work opens up an avenue for the design and synthesis of highly selective adsorbents for Ga3+ in complex VSPR solutions. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) graphene oxide (GO)-based aerogels, GO and 4-methyl-5-thiazoleethanol (MTZE) composites, were prepared by a facile hydrothermal method. Due to the hydrogen bonding and π-π stacking interactions, the produced 3D GO-MTZE composites possessed large cylindrical structures. The morphologies, composition, and chemical states of 3D GO-MTZE3:1 composite were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and N2 adsorption–desorption isotherms based on the Brunauer–Emmett–Teller (BET) method. The existence of nitrogen (N)-containing heterocyclic system and oxygen (O)-containing branched chain of MTZE contributed to the formation of 3D structures, while the complexation effect of heterocyclic sulfur (S)- and N-containing functional groups of MTZE for metal cations dominated the adsorption performance of 3D GO-MTZE3:1 composite, which could selectively adsorb copper ions (Cu2+). In addition, the better hydrophobic property of 3D GO-MTZE3:1 composite facilitates its facile recycling from aqueous solution after adsorption. The adsorption data of 3D GO-MTZE3:1 composite toward Cu2+ fitted well (R2 = 0.9996) with the linear pseudo-second-order kinetic model, giving an equilibrium rate constant (k2) of 0.0187 g mg−1 min−1. The linear Langmuir isothermal model could more accurately describe the experimental data, indicating the adsorption process is mainly dominated by the complexation interactions between MTZE and Cu2+. The thermodynamic parameters of ΔG° (< 0), ΔH° (> 0), and ΔS° (> 0) further indicate that the adsorption is a spontaneous and endothermic, confirming that the complexation between Cu2+ and 3D GO-MTZE3:1 composite occurs. Due to its high selectivity for Cu2+, good hydrophobicity, and excellent stability, the developed 3D GO-MTZE3:1 composite possesses might be promisingly used in the aqueous selective enrichment/removal of Cu2+. [ABSTRACT FROM AUTHOR]

Organic dyes can inflict environmental harm and pose risks to human health, thereby presenting challenges in their treatment within industrial wastewater. Currently, numerous research groups have conducted investigations on the adsorption of organic dyes in industrial wastewater. Herein, this work focuses on the selective adsorption approach towards dyes molecules based on an Anderson-type polyoxometalate (noted as POM-1) as potential adsorbent, which has been functionalized with organic ligands to enhance its negative charge. Adsorption experiments revealed that POM-1 displayed efficient adsorption capabilities towards the cationic dye methyl blue with almost complete adsorption within 25 min, and the adsorption rate was calculated as 98%. A rapid and consecutive filtering experiments have also been performed and further proved the excellent adsorption behavior of POM-1 towards MB. [ABSTRACT FROM AUTHOR]

In this study, UiO‐66 was employed for the first time as an adsorbent to separate phenolic acid analogues, specifically 4‐hydroxyisophthalic acid and salicylic acid, from impurities. Synthesized in‐house, UiO‐66 was shown to exhibit high selectivity towards 4‐HIPA/4‐HBA and SA/4‐HBA when a molar equivalent of acetic acid modulator to terephthalic acid was set at 44. The adsorption capacities for 4‐HBA, 4‐HIPA, and SA were determined to be 56.34, 55.02, and 60.34 mg/g, respectively. Furthermore, it was observed that after six regeneration cycles, the adsorption capacity for 4‐HBA remained nearly unchanged, whereas those for 4‐HIPA and SA decreased by 5.6% and 2.6%, respectively. FTIR and XPS analyses revealed that all three compounds were adsorbed at the same dominant Zr cluster site on UiO‐66, primarily through hydrogen bonding and electrostatic interaction. Dynamic adsorption experiments revealed that 4‐HBA was the first to elute, maintaining the residual contents of 4‐HIPA and SA below 0.1 wt%. Compared to traditional separation techniques, this paper provided a simple and effective method to purify industrial grade 4‐hydroxybenzoic acid. [ABSTRACT FROM AUTHOR]

The surface characteristics of nanoparticles have a huge impact on adsorption effects. In this paper, thiol‐functional mesoporous silica nanospheres (MSNs−SH) are successfully prepared through simple one‐step hydrolysis and co‐condensation of tetraethyl orthosilicate and (3‐mercaptopropyl) triethoxysilane with hexadecyltrimethylammonium bromide and sulfobetaine 12 as dual‐template. The obtained MSNs−SH have high surface area (1260 m2 g−1), accessible mesopores (2.2 nm), great pore volume (1.7 cm3 g−1), and uniform adjustable diameter (90 nm). Furthermore, the diameter and pore‐size of MSNs−SH can be controlled via adjusting the ethanol content in the synthesis system. MSNs−SH exhibit a fast adsorption kinetics, marked adsorption capacity of cationic rhodamine B (RB 534.2 mg g−1), and remarkable selective adsorption for cationic dyes. Theoretical analysis reveals the adsorption behavior of RB on MSNs−SH follows the Langmuir isotherm models and pseudo‐second‐order kinetic. Additionally, the thermodynamic results indicate that the adsorption process is a spontaneous process driven by temperature. The results demonstrate that MSNs−SH are greatly potential for effectively removing cationic dyes from wastewater, with the advantages of simple preparation, high adsorption performance and perfect selectivity. [ABSTRACT FROM AUTHOR]

The development of an advanced dye adsorbent that possesses a range of beneficial characteristics, such as high adsorption capacity, swift adsorption kinetics, selective adsorption capability, and robust reusability, remains a challenge. This study introduces a facile method for fabricating an amine-rich porous adsorbent (ARPA), which is specifically engineered for the adsorptive removal of anionic dyes from aqueous solutions. Through a comprehensive assessment, we have evaluated the adsorption performance of ARPA using two benchmark dyes: amaranth (ART) and tartrazine (TTZ). Our findings indicate that the adsorption process reaches equilibrium in a remarkably short timeframe of just 20 min, and it exhibits an excellent correlation with both the Langmuir isotherm model and the pseudo-second-order kinetic model. Furthermore, ARPA has demonstrated an exceptional maximum adsorption capacity, with values of 675.68 mg g−1 for ART and 534.76 mg g−1 for TTZ. In addition to its high adsorption capacity, ARPA has also shown remarkable selectivity, as evidenced by its ability to selectively adsorb TTZ from a mixed dye solution, a feature that is highly desirable for practical applications. Beyond its impressive adsorption capabilities, ARPA can be efficiently regenerated and recycled. It maintains a high level of original removal efficiency for both ART (76.8%) and TTZ (78.9%) even after five consecutive cycles of adsorption and desorption. Considering the simplicity of its synthesis and its outstanding adsorption performance, ARPA emerges as a highly promising material for use in dye removal applications. Consequently, this paper presents a straightforward and feasible method for the production of an effective dye adsorbent for environmental remediation. [ABSTRACT FROM AUTHOR]

The recovery of valuable gold from wastewater is of great interest because of the widespread use of the precious metal in various fields and the pollution generated by gold-containing wastes in water. In this paper, a water-insoluble cross-linked adsorbent material (TE) based on cyanuric chloride (TCT) and ethylenediamine (EDA) was designed and used for the adsorption of Au(III) from wastewater. It was found that TE showed extremely high selectivity (D = 49,213.46) and adsorption capacity (256.19 mg/g) for Au(III) under acidic conditions. The adsorption rate remained above 90% eVen after five adsorption–desorption cycles. The adsorption process followed the pseudo-first-order kinetic model and the Freundlich isotherm model, suggesting that physical adsorption with a multilayer molecular overlay dominates. Meanwhile, the adsorption mechanism was obtained by DFT calculation and XPS analysis, and the adsorption mechanism was mainly the electrostatic interaction and electron transfer between the protonated N atoms in the adsorbent (TE) and AuCl4−, which resulted in the redox reaction. The whole adsorption process was the result of the simultaneous action of physical and chemical adsorption. In conclusion, the adsorbent material TE shows great potential for gold adsorption and recovery. [ABSTRACT FROM AUTHOR]

Rhenium separation from molybdenum in molybdenite minerals and waste leachate has become an emerging challenge. Addressing this challenge, we prepared a set of protein-based alkylamine/alkylammonium salts complexes as extradants for selective uptake of rhenium from molybdenum, where the protein component turned into the insoluble amyloid-like structure when its internal disulfide bonds were reduced, namely phase-transition process. Among them, the phase-transited lysozyme and methyletrioctyleammonium chloride complex (PTL-N263) exhibited the most efficient adsorption at the alkaline condition for the electrostatic interaction between negatively charged metal ions with positively charged center (R4N+) in N263, where negatively charged protein residues hindered the ion exchange of Cl− in N263 for larger size Mo species (Mo7O246−) than smaller size Re species (ReO4−). The adsorption follows the Freundlich model and pseudo-second-order kinetics, which exhibits top-level adsorption performance with a maximum adsorption capacity of 124 mg/g and a separation factor (βRe/Mo) of 2.78 × 103 for Re. The adsorption capacity per unit area (57.2 mg/(g m2)) is 1.6–41 times higher than previously reported adsorbents, and the cost for adsorbing 1 g of Re (VII) is $1.07, indicating its industrial capability. This adsorption strategy can be applied to separating Re from Mo in binary solutions and industrial wastewater with other competing ions. [ABSTRACT FROM AUTHOR]

Dyeing and printing wastewater is a significant cause of water pollution. Adsorption is considered a highly promising method for removing organic pollutants from wastewater. While aluminum oxide clusters (AlOCs) have recently become a popular research topic, there is a lack of research on the adsorption of organic dyes by AlOCs. This study investigates the adsorption properties of AlOCs and reveals their selective adsorption capability for organic dyes. Specifically, AlOCs exhibit exceptional adsorption efficiency for anionic organic dyes with a linear structure. Notably, the adsorption capacity of AlOCs for methyl orange removal is remarkable, achieving a high removal percentage of 97% and an impressive adsorption capacity of 1346 mg/g. However, the adsorption percentage for the sterically hindered cationic dye, crystal violet, is less than 10%. The process follows the pseudo-second order adsorption kinetics and Langmuir isotherm model, suggesting monolayer, homogeneous, chemisorption. Importantly, the adsorbents display high efficiency and capacity, making them applicable for wide-ranging dye removal. [ABSTRACT FROM AUTHOR]

Selective adsorption of heavy metal ions from industrial effluent is important for healthy ecosystem development. However, the selective adsorption of heavy metal pollutants by biochar using lignin as raw material is still a challenge. In this paper, the lignin carbon material (N-BLC) was synthesized by a one-step hydrothermal carbonization method using paper black liquor (BL) as raw material and triethylene diamine (TEDA) as nitrogen source. N-BLC (2:1) showed excellent selectivity for Cr(VI) in the binary system, and the adsorption amounts of Cr(VI) in the binary system were all greater than 150 mg/g, but the adsorption amounts of Ca(II), Mg(II), and Zn(II) were only 19.3, 25.5, and 6.3 mg/g, respectively. The separation factor (SF) for Cr(VI) adsorption was as high as 120.0. Meanwhile, FTIR, elemental analysis and XPS proved that the surface of N-BLC (2:1) contained many N– and O– containing groups which were favorable for the removal of Cr(VI). The adsorption of N-BLC (2:1) followed the Langmuir model and its maximum theoretical adsorption amount was 618.4 mg/g. After 5th recycling, the adsorption amount of Cr(VI) by N-BLC (2:1) decreased about 15%, showing a good regeneration ability. Therefore, N-BLC (2:1) is a highly efficient, selective and reusable Cr(VI) adsorbent with wide application prospects. [ABSTRACT FROM AUTHOR]

The highly selective capture and efficient utilization of recovered Cu(II) ions using a multifunctional material holds substantial practical significance. In this study, a novel type of magnetic adsorbent, MSBA-IIA, was successfully synthesized by grafting a Cu(II) ion-imprinted quaternized salicylaldehyde Schiff base coating onto the surface of magnetic mesoporous silica, aiming to enhance the recognition and separation selectivity for target ions during the adsorption process. Batch Cu(II) ion adsorption experiments demonstrated a dependence of adsorption efficiency on the solution pH level. The Cu(II) adsorption behavior onto MSBA-IIA followed the pseudo-second-order adsorption kinetic model and Langmuir isothermal model. MSBA-IIA exhibited a maximum adsorption capacity of 32.7 mg/g, surpassing that of the non-ion-imprinted counterpart MSBA-NIIA. Thermodynamic study unveiled the spontaneous and exothermic nature of the adsorption process. The relative separation factors α' of MSBA-IIA for Cu(II) were determined to be much more than 1, suggesting that the imprinted adsorbent exhibited superior selectivity for Cu(II) ions in the presence of other co-existing metal ions when compared to the MSBA-NIIA. Due to its magnetic collection and regenerable nature, the proposed approach holds promise for the selective removal of Cu(II) ions from water. Highlight: MSBA-IIA with surface Cu(II) ion-imprinted coating was prepared. MSBA-IIA is capable of selectively adsorbing and recovering Cu(II) ions. The maximum adsorption capacity is 32.7 mg/g for Cu(II) ions. The adsorbent shows excellent reusability. [ABSTRACT FROM AUTHOR]

Chlorinated volatile organic compounds (CVOCs) are often found in combination with 1,4-dioxane which has been used as a solvent stabilizer. It would be desirable to separate these compounds since biodegradation of 1,4-dioxane follows an aerobic pathway while anaerobic conditions are needed for biodegrading CVOCs. Conventional adsorbents such as activated carbon (AC) and carbonaceous resins have high adsorption capacities for 1,4-dioxane and CVOCs but lack selectivity, limiting their use for separation (Liu et al., 2019). In the current work, two macrocyclic adsorbents, β-CD-TFN and Res-TFN, were examined for selective adsorption of chlorinated ethenes in the presence of 1,4-dioxane. Both adsorbents exhibited rapid adsorption of the CVOCs and minimal adsorption of 1,4-dioxane. Res-TFN had a higher adsorption capacity for CVOCs than β-CD-TFN (measured linear partition coefficient, Kd 2140 -9750 L·kg−1 versus 192-918 L·kg−1 for 1,1, DCE, cis-1,2-DCE and TCE, respectively) and was highly selective for CVOCs(TCE Kd ∼117 Kd for 1,4-dioxane). By comparison, TCE and 1,4-dioxane adsorption on AC was approximately equal at 100 µg·L−1 and approximately 1/3 of the adsorption of TCE on the Res-TFN. The greater adsorption and selectivity of Res-TFN suggest that it can be used as a selective adsorbent to separate CVOCs from 1,4-dioxane to allow separate biodegradation.

The urgent problem to solve is how to design a kind of green and porous adsorbent that can effectively remove dye pollutants in the field of the sewage treatment. The objectives of this investigation are to incorporate zeolitic imidazolate frameworks‐8 (ZIF‐8) particles in situ onto the surface of multiwalled carbon tubes (MWCNTs) and integrate them into an agarose‐sodium alginate (ASA) double network hydrogel. The resulting composite hydrogel beads, denoted as MWCNTs/ZIF‐8/ASA (MZASA), are synthesized using calcium ion crosslinking. The addition of agarose is employed to create a dual‐crosslinked hydrogel, thereby enhancing the mechanical properties of the ASA hydrogel. By incorporating MWCNTs/ZIF‐8 nanoparticles, the surface area of the MZASA hydrogel is augmented, leading to an enhancement in dye adsorption capacity. In batch sorption mode, the maximum absorbency of the resulting hydrogel beads for methylene blue (MB) is 493.799 mg/g, which was a third greater than that of pure SA beads. Absorption of MB obeys the pseudo‐second‐order kinetic model and Langmuir isotherm model, suggesting monolayer chemisorption adsorption. Analysis of the thermodynamics proves that the entire adsorption process is exothermic and spontaneous. Moreover, the MZASA hydrogel beads show high selectivity for cationic dyes in the mixed dye test. Hence, the synthesized MZASA hydrogel beads serve as a highly effective, innovative, and reusable adsorbent for eliminating cationic dyes from water‐based solutions. [ABSTRACT FROM AUTHOR]

• BW has strong acid resistance (pH ≥ 1). • BW selectively separates lead from complex heavy metal solutions. • The selective immobilization is due to its specific composite structure. The development of bio-adsorbents with highly selective immobilization properties for specific heavy metals is a great challenge, but has important application value. Biogenic whewellite (BW) with high selectivity for Pb(II) was synthesized by mineral microbial transformation. The selective immobilization properties and mechanism of BW for Pb(II) were analyzed by combining mineral characterization technology and batch adsorption research methods. The results indicated that BW can efficiently and selectively immobilize Pb(II) in single or composite heavy metal adsorption solutions, and the immobilized Pb(II) is difficult to desorb. BW undergoes monolayer adsorption on Pb(II), Q max ≈ 1073.17 mg/g. The immobilization of Pb(II) by BW is a physico-chemical adsorption process with spontaneous heat absorption and an accompanying increase in entropy. In addition, the sequestration of Pb(II) by BW remains around 756.99 mg/g even at pH = 1. The excellent selective immobilization properties of BW for Pb(II) are closely related to its smaller K sp , electrostatic repulsion effect, organic-inorganic composite structure, acid resistance and the formation of Pb(II) oxalate. This study provides beneficial information about the recycling of lead in acidic lead-containing wastewater and composite heavy metal contaminated water bodies. [Display omitted] [ABSTRACT FROM AUTHOR]

Water pollution poses a global threat to human health, particularly in terms of ensuring a safe supply of drinking water. The accumulation of heavy metals from various water sources is increasing, driving the search for effective and environmentally friendly approaches and materials for metal removal. This review investigates the selective adsorption of Pb2+ by humic acid (HA) in a multi-metal coexistence solution. The focus is on discussing approaches to the structural identification of HA, highlighting that separation techniques are an effective method to reduce its heterogeneity. Starting from the key structural units of HA, the study reveals the interaction between HA and heavy metals. Approaches to enhance Pb2+ selective adsorption are explored, proposing that introducing activating groups, Ca ion exchange, and optimizing pore structures are effective approaches for improving lead ion selective adsorption. Ca2+ activation is suggested as a future research direction for lead-selective adsorption. Additionally, attaining lead selective adsorption through pH regulation's significance is emphasized. This research contributes to a fundamental understanding of HA's role as a selective lead adsorbent while offering practical implications for developing environmentally friendly adsorbent materials. The results aim to advance knowledge in environmental science and water treatment. [ABSTRACT FROM AUTHOR]

The composition of biomass pyrolysis gas is complex, and the selective separation of its components is crucial for its further utilization. Metal-incorporated nitrogen-doped materials exhibit enormous potential, whereas the relevant adsorption mechanism is still unclear. Herein, 16 metal-incorporated nitrogen-doped carbon materials were designed based on the density functional theory calculation, and the adsorption mechanism of pyrolysis gas components H2, CO, CO2, CH4, and C2H6 was explored. The results indicate that metal-incorporated nitrogen-doped carbon materials generally have better adsorption effects on CO and CO2 than on H2, CH4, and C2H6. Transition metal Mo- and alkaline earth metal Mg- and Ca-incorporated nitrogen-doped carbon materials show the potential to separate CO and CO2. The mixed adsorption results of CO2 and CO further indicate that when the CO2 ratio is significantly higher than that of CO, the saturated adsorption of CO2 will precede that of CO. Overall, the three metal-incorporated nitrogen-doped carbon materials can selectively separate CO2, and the alkaline earth metal Mg-incorporated nitrogen-doped carbon material has the best performance. This study provides theoretical guidance for the design of carbon capture materials and lays the foundation for the efficient utilization of biomass pyrolysis gas. [ABSTRACT FROM AUTHOR]

Biopolymer-based materials for the adsorption of toxic dyes represent an interesting class of materials for environmental applications. Here we report on chitosan as the starting material for synthesizing dye adsorbents. In particular, the synthesis, characterization, and cationic dye adsorption properties of chitosan hydrogel adsorbents are reported. Polyanionic itaconated chitosan derivatives were synthesized in solvent-less conditions for the first time. Itaconated chitosan was cross-linked using thiol-ene chemistry to obtain hydrogels. The influence of the incorporated carboxylate groups and the cross-linker fraction on the adsorption of Methylene Blue (MB) was investigated. In addition, the impact of pH, adsorbent dose, initial concentration, and ionic strength were investigated to determine the optimum conditions for MB uptake, and the dye uptake kinetics, adsorption isotherms, selectivity, and reusability of the adsorbents were unveiled. A maximum adsorption capacity of 556 mg/g could be achieved, outperforming commercial activated charcoal and ion exchange resins. Furthermore the chitosan hydrogel adsorbents were shown to capture >90 % of cationic MB from a binary equimolar mixture with the anionic dye Methyl Orange. Since the adsorbents can be regenerated and re-used afterwards at least 20 times, retaining a high dye adsorption fraction of >95 %, these materials are promising candidates for environmental applications. [ABSTRACT FROM AUTHOR]

Water pollution caused by dyes is a pressing environmental challenge due to their persistence and difficulty in degradation. Herein, an anionic adsorbent (HS-PAANa) was synthesized by grafting polyacrylic acid (PAA) onto the agricultural waste-hemp stem (HS). The obtained HS-PAANa adsorbent exhibited rapid adsorption kinetics, high adsorption capacity, and a favorable preference for cationic dyes, such as methylene blue (MB) and crystal violet (CV). The experimental data fit well with the pseudo-second-order kinetic model and Langmuir isotherm, demonstrating the efficiency of HS-PAANa in dye removal. Notably, the optimal adsorption capacities of HS-PAANa for MB and CV were found to be 1296.65 mg/g and 1451.43 mg/g, respectively. In the cationic/anionic dyes (MB/MO) binary systems, HS-PAANa exhibited enhanced selective adsorption of cationic dyes (MB), indicating its potential for targeted removal of specific dyes from mixed solutions. Moreover, HS-PAANa adsorption shows an excellent recyclability, after five cycles, HS-PAANa still maintained MB and CV removal rates of 93.85% and 95.08%, respectively. Therefore, the bioadsorbent HS-PAANa exhibits high potential as a highly efficient adsorbent for the effective treatment of cationic pollutants in wastewater. [ABSTRACT FROM AUTHOR]

Research on recycling of used rare earth elements has been of great interest. Adsorption is one of the advantageous methods to recover gadolinium with high value. In the process of adsorption and separation of gadolinium from materials, the selectivity of materials for gadolinium can be significantly improved by using ion imprinting technique. However, gadolinium elution process is a traditional pickling process, which may affect the construction of imprinting sites. In this study, bacterial cellulose with three-dimensional spatial structure was used as the base material of aerogel material, and functional materials containing a large number of carboxyl groups were introduced by chemical grafting method. In combination with ion imprinting technology and N-polyacrylamide as intelligent temperature control valve, intelligent imprinting aerogel (PNBC-IIPS) with specific selectivity to gadolinium was prepared. The properties of aerogel materials were analyzed by SEM, FT-IR, and BET characterization. The experimental analysis shows that the desorption of gadolinium can be achieved by controlling the temperature change. The adsorption experiments show that PNBC-IIPS can selectively adsorb gadolinium ions from aqueous solution. The maximum adsorption capacity reached 95.51 mg g−1. Compared with unimprinted aerogel, the maximum adsorption capacity of gadolinium ion is significantly increased, which proves that the introduced ion imprinting technique plays a key role in the adsorption process. Cyclic experiments show that the adsorption capacity of PNBC-IIPS can still maintain 88% of the original adsorption capacity after 5 times of adsorption and desorption. In conclusion, PNBC-IIPS is a green adsorbent for selective recovery of gadolinium ions. [ABSTRACT FROM AUTHOR]

[Display omitted] Nitrate (NO 3 −) is a widespread pollutant in the water environment. Due to its physicochemical properties, such as negative monovalent charge, traditional adsorption treatment processes have low selectivity for NO 3 − removal, resulting in low removal efficiency of NO 3 − by adsorbents in the presence of interfering ions. Therefore, to improve the adsorption selectivity and efficiency of NO 3 −. In this study, we used organosilicon quaternary modified derived nickel–iron layered double hydroxide (NiFe-MLDH/OQAS) for selective removal of NO 3 −. NiFe-MLDH/OQAS has a flowery globular structure, with interconnected nanosheets on the surface providing more adsorption sites for NO 3 −, which improves the adsorption rate and adsorption amount. What's more, the nitrate removal rate of NiFe-MLDH/OQAS only decreased by about 14.36% in the presence of the same concentration of interfering ions, and the maximum adsorption amount reached 61.05 mg/g, showing good selectivity and adsorption amount. Various characterization analyses indicate that the nitrate selectivity of NiFe-MLDH/OQAS is attributed to its unique layer spacing, as well as the abundant functional groups on the material surface. Finally, we demonstrated through experiments that NiFe-MLDH/OQAS has good cyclic regeneration ability and environmental safety. These findings demonstrate the great potential of NiFe-MLDH/OQAS for selective adsorption of NO 3 −. [ABSTRACT FROM AUTHOR]

Research on the efficient flotation desilication of low-grade magnesite is of great significance for the sustainable development of magnesium resources. Traditional collectors usually have some disadvantages, such as poor selectivity, severe environmental pollution, and weak water solubility. To strengthen the desilication flotation process of magnesite ore, the biodegradable surfactant, cocamidopropyl amine oxide (CPAO), was first utilized as the collector for the separation of the magnesite and quartz. The selective adsorption behavior and mechanism of the quartz and magnesite with the CPAO as the collector were studied through the micro-flotation experiments of the single mineral and the artificially mixed mineral, contact angle and atomic force microscopy (AFM) measurements, fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation results indicated that the CPAO showed good selectivity and could effectively separate magnesite and quartz. When the concentration of the CPAO was 10.0 mg/L in the natural pulp pH (about 7.2), the concentrates with 97.67% MgO recovery and 45.62% MgO grade were obtained. The contact angle and AFM measurements indicated that the CPAO could selectively adsorb on the quartz surface rather than the magnesite surface to improve the interface difference between them, especially its surface hydrophobicity. The results of the FTIR and XPS analyses indicated that the CPAO is selectively adsorbed on the surface of the quartz, mainly through electrostatic interaction and hydrogen bonding. In conclusion, the CPAO had good selectivity and great potential as an effective collector in the reverse flotation desilication progress of magnesite. [ABSTRACT FROM AUTHOR]

This study delves into the potential of vermiculite-based adsorbents for phosphate removal from aqueous solutions. CTAB and zirconium-modified natural vermiculite slices (CZV) were employed, with XRF analysis confirming successful zirconium loading. The Langmuir model indicated monolayer adsorption behavior, suggesting a preferential adsorption characteristic. The presence of coexisting ions showed varied effects on phosphate removal, with increasing CO32− concentrations slightly inhibiting phosphate removal by CZV, while increasing NO3−, SO42−, and Cl− concentrations improved phosphate removal by all adsorbents. Notably, the vermiculite adsorbents, despite their larger particle size, demonstrated a competitive adsorption capacity when compared to other adsorbents. The practicality of these adsorbents is further emphasized by their potential direct application in artificial wetlands and lakes without posing ecological risks. Moreover, the reutilization of used vermiculite adsorbents is highlighted as a sustainable approach, considering their beneficial effects on the growth of submerged macrophytes and sediment microecological environments. The adsorption mechanism is attributed to surface complexation and ligand exchange. This research underscores the efficacy of modified natural vermiculite slices in phosphate adsorption, paving the way for broader environmental applications and offering a promising solution to water purification challenges. [ABSTRACT FROM AUTHOR]

Selective adsorption using nanoporous materials is an efficient strategy for separating gas mixtures. In a nanoporous material, pores can exist in different shapes and can have different degrees of inter-connectivity. In recent studies, both pore connectivity and tortuosity have been found to affect the adsorption and dynamical properties of ethane and CO2 in silicalite differently. Here, using Monte Carlo simulations, we investigate if these two attributes can affect the selective adsorption of one component from a mixture of ethane and CO2 in silicalite. For this, the adsorption of an equimolar mixture of ethane and CO2 is simulated in 12 models of silicalite—SnZm (n, m = 0, 1, 2, 3 or 4; with n and m denoting, respectively, the fraction (out of 4) of straight and zigzag channels of silicalite that are available for adsorption)—differing in degrees of pore connectivity and tortuosity. The adsorption selectivity in this system is found to exhibit a reversal with the adsorption dominated by ethane at low pressures (below ~1 atm) and by CO2 at higher pressures (above ~10 atm). Pore connectivity is found to suppress the selective adsorption of CO2 at higher pressures and also shifts the selectivity reversal to higher pressures. The selectivity reversal results from a competition between the polarizability-affected adsorption at lower pressures and efficient packing at higher pressures. The efficient packing of CO2 is a compounded effect resulting from the larger effective pore volume available for CO2 due to its stronger interaction with the pore surface and smaller molecular volume. CO2 molecules show a preference to adsorb in non-tortuous pores, and this preference is found to be stronger in the presence of ethane. The effects of pore connectivity and tortuosity elucidated here should be applicable to a wide range of natural and engineered nanoporous materials, and this knowledge could be used to identify materials with better capability for separating and storing CO2 based on their pore attributes. [ABSTRACT FROM AUTHOR]

In this study, we systematically investigate the rheological behavior and microstructure formation of the anode slurries containing silicon (Si), carbon black (CB), and carboxymethyl cellulose (CMC) from the perspective of interactions between the constituent components, aiming to provide a fundamental understanding of the dispersion characteristics of Si-based anode slurries. The CMC adsorbs onto both particles (CB/Si) but has different effects on the inter-particle interactions (CB–CB and Si–Si). It stabilizes the CB particles through electro-steric interactions, whereas it agglomerates the Si particles through bridging interactions, in aqueous medium. In the meanwhile, the CMC selectively adsorbs onto CB particles among the two particles. Therefore, at a CMC content lower than the optimum graft density where CB particles are adsorbed and saturated by CMC, it acts as a dispersant in the slurries. However, at a higher content, the CMC that remains after adsorption on CB particles adsorbs onto Si particles and acts as a flocculant for the particles in the slurries. The origin of selective adsorption is understood in terms of the driving forces for adsorption and the surface energy analysis. We anticipate our findings provide a useful guideline for the Si slurry design in terms of its dispersion and contribute to the development of Si anode technology. [ABSTRACT FROM AUTHOR]

A novel epichlorohydrin and thiourea grafted porous alginate adsorbent (UA-Ca/IIP) was synthesized using ion-imprinting and direct templating to remove copper ions (Cu(II)) and tetracycline (TC) in aqueous solution. UA-Ca/IIP demonstrated great selectivity for Cu(II) and TC among different coexisting anions (CO32−, PO43− and SO42−), cations (Ca2+, Mg2+ and NH4+), and antibiotics (oxytetracycline and sulfamethoxazole). The adsorption of TC and Cu(II) by UA-Ca/IIP was significantly affected by the pH of the solution, and the quantity of TC and Cu(II) adsorbed reached a maximum at pH 5. A pseudo-second-order model better fitted the kinetic data; the Langmuir model predicted the maximum adsorption quantities 3.527 mmol TC g−1 and 4.478 mmol Cu(II) g−1 at 298 K. Thermodynamic studies indicated that the TC and Cu(II) adsorption was more rapid at a higher temperature. Antagonistic and synergistic adsorption experiments showed that the adsorption capacity of TC would increase significantly with the increase of Cu(II) concentration. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated that along with the influence of pH, electrostatic interaction and complexation were the main mechanisms of TC and Cu(II) adsorption. Regeneration experiments revealed that TC and Cu(II) were removed efficiently and that UA-Ca/IIP was recyclable over the long term. These results show that the modified porous alginate microsphere is a green and recyclable adsorbent, which has good selectivity and high adsorption performance for the removal of TC and Cu(II). [ABSTRACT FROM AUTHOR]

Owing to the poor treatment efficiency of wastewater containing fluoroquinolones (FQs), effective removal of such pollutants has become a significant issue in waste management. In this study, a ternary covalent organic polymer anchored with SO3H (COP-SO3H) was designed using the Schiff reaction and a multicomponent solvent thermal method. The synthesized COP-SO3H polymer possesses multiple functional binding sites, including amide groups, sulfonic groups, and aromatic frameworks, enabling it to effectively adsorb ciprofloxacin (which belongs to FQs) through mechanisms such as pore-filling effects, electrostatic interactions, hydrogen bonding, π-π electron donor–acceptor (EDA) interactions, and hydrophilic–lipophilic balance. COP-SO3H demonstrated outstanding adsorption performance for ciprofloxacin, exhibiting a high adsorption capacity, broad pH stability, strong resistance to ionic interference, and good regenerability. Moreover, it displayed preferential selectivity toward fluoroquinolone antibiotics. The present study not only investigates the intricate structural and functional design of COP-SO3H materials but also presents potential applications for the efficient adsorption of specific antibiotics. [ABSTRACT FROM AUTHOR]

In this research, a novel collector cetyl trimethyl ammonium chloride (CTAC) was used to separate hematite from quartz via reverse flotation for the first time. Micro-flotation tests showed that CTAC had a strong ability to selectively collect quartz and that a separation of hematite from quartz could be accomplished with a concentration of 0.00263 mmol/L CTAC. Zeta-potential measurements indicated that the positive CTAC+ species could selectively increase the surface potential of quartz, but that it had rather a weak effect on the hematite. X-ray photoelectron spectroscopy (XPS) detection indicated that CTAC had a stronger binding affinity to oxygen sites on the surface of quartz than on hematite, resulting in a large amount of CTAC being predominantly adsorbed onto quartz. This was supported by the atomic concentration of C1s and N1s of quartz after CTAC treatments were 4.25 and 2.84 times higher than hematite, respectively. [ABSTRACT FROM AUTHOR]

A kind of hydroxycamptothecin (HCPT) hybrid molecularly imprinted polymer (AT/MA-HMIPs) with high selectivity and hard silicon skeleton was successfully prepared based on double hybrid monomers. The relationship between templates and functional monomers was studied through computer molecular simulation and experiments. Three single-monomer molecularly imprinted polymers were prepared as controls. The Langmuir isotherm and pseudo-second-order kinetic models were found to fit well with the adsorption results. The maximum adsorption capacity was 18.79 mg/g, and equilibrium was reached within 20 min. Moreover, it shows excellent selectivity (imprinting factor is 10.73) and good recoverability (after 10 adsorption-desorption cycles, the adsorption capacity only decreases by 7.75%) for HCPT. The purity of HCPT can reach 80.86% after being put into a solid phase extraction column and used in an actual sample, and the yield was 61.43%. This study lays the fundament for the development of excellent HCPT molecularly imprinted composites. [ABSTRACT FROM AUTHOR]

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Grapefruit (Citrus × paradisi Macf.) peel, a by-product of the citrus-processing industry, possesses an important economic value due to the richness of bioactive compounds. In this study, boron-linked covalent organic frameworks integrated with molecularly imprinted polymers (CMIPs) were developed via a facile one-pot bulk polymerization approach for the selective extraction of naringenin from grapefruit peel extract. The obtained CMIPs possessed a three-dimensional network structure with uniform pore size distribution, large surface areas (476 m2/g), and high crystallinity. Benefiting from the hybrid functional monomer APTES-MAA, the acylamino group can coordinate with the boronate ligands of the boroxine-based framework to form B-N bands, facilitating the integration of imprinted cavities with the aromatic skeleton. The composite materials exhibited a high adsorption capacity of 153.65 mg/g, and a short adsorption equilibrium time of 30 min for naringenin, together with favorable selectivity towards other flavonoid analogues. Additionally, the CMIPs captured the template molecules through π–π* interaction and hydrogen bonding, as verified by FT-IR and XPS. Furthermore, they had good performance when employed to enrich naringenin in grapefruit peels extract compared with the common adsorbent materials including AB-8, D101, cationic exchange resin, and active carbon. This research highlights the potential of CMIPs composite materials as a promising alternative adsorbent for naringenin extraction from grapefruit peel.

Large volumes of wastewater containing toxic contaminants (e.g., heavy metal ions, organic dyes, etc.) are produced from industrial processes including electroplating, mining, petroleum exploitation, metal smelting, etc., and proper treatment prior to their discharge is mandatory in order to alleviate the impacts on aquatic ecosystems. Adsorption is one of the most effective and practical methods for removing toxic substances from wastewater due to its simplicity, flexibility, and economics. Recently, hierarchical oxide composites with diverse morphologies at the micro/nanometer scale, and the combination advantages of oxides and composite components have been received wide concern in the field of adsorption due to their multi-level structures, easy functionalization characteristic resulting in their large transport passages, high surface areas, full exposure of active sites, and good stability. This review summarizes the recent progress on their typical preparation methods, mainly including the hydrothermal/solvothermal method, coprecipitation method, template method, polymerization method, etc., in the field of selective adsorption and competitive adsorption of hazardous substances from wastewater. Their formation processes and different selective adsorption mechanisms, mainly including molecular/ion imprinting technology, surface charge effect, hard-soft acid-base theory, synergistic effect, and special functionalization, were critically reviewed. The key to hierarchical oxide composites research in the future is the development of facile, repeatable, efficient, and scale preparation methods and their dynamic adsorption with excellent cyclic regeneration adsorption performance instead of static adsorption for actual wastewater. This review is beneficial to broaden a new horizon for rational design and preparation of hierarchical oxide materials with selective adsorption of hazardous substances for wastewater treatment.