Preferential Adsorption Research Articles

Chemical Orderings in CuCo Nanoparticles: Topological Modeling Using DFT Calculations.

The orderings of atoms in bimetallic 1.6-2.1 nm-large CuCo nanoparticles, important as catalytic and magnetic materials, were studied using a combination of DFT calculations with a topological approach. The structure and magnetism of Cu50Co151, Cu101Co100, Cu151Co50, and Cu303Co102 nanoparticles; their resistance to disintegrating into separate Cu and Co species; as well as the exposed surface sites, were quantified and analyzed, showing a clear preference for Cu atoms to occupy surface positions while the Co atoms tended to form a compact cluster in the interior of the nanoparticles. The surface segregation of Co atoms that are encapsulated by less-active Cu atoms, induced by the adsorption of CO molecules, was already enabled at a low coverage of adsorbed CO, providing the energy required to displace the entire compact Co species inside the Cu matrices due to a notable adsorption preference of CO for the Co sites over the Cu ones. The calculated adsorption energies and vibrational frequencies of adsorbed CO should be helpful indicators for experimentally monitoring the nature of the surface sites of CuCo nanoparticles, especially in the case of active Co surface sites emerging in the presence of CO.

Beyond Mechanical Protection: The Electron-Shielding Effect of SWCNT for the Stabilized SiO Interface.

The single-walled carbon nanotube (SWCNT) commonly serves as a conductive additive for SiO-based anode materials due to the excellent conductivity and mechanical properties. However, the potential action mechanisms for the SWCNT beyond conductivity and mechanical features have rarely been studied. Herein, an interfacial electron-shielding effect and preferential adsorption to the electrolyte components for the SWCNT are revealed through a series of advanced characterizations and density functional theory (DFT) simulations. It can be determined that SWCNT networks could restrict the transmission of the electron from SiO interface to electrolyte with the reduced decomposition, because of the typical axial conductivity of the SWCNT. Moreover, the SWCNT shows stronger adsorption energy for LiPF6 and ethylene carbonate (EC) molecules, rather than nonselectivity of traditional carbon additives, facilitating the generation of inorganic-rich and denser solid electrolyte interface (SEI) film. As a result, benefiting from the electron-shielding effect, preferential adsorption, and mechanical protection, the SWCNT endows the SiO@C anode with a higher average Coulombic efficiency (CE) value of 99.4% over 100 cycles and a long cycling stability.

The electronic, magnetic, and optical behaviors of graphyne modulated by metal atoms adsorption: a first-principles study

The electronic, magnetic, and optical behaviors of graphyne modulated by various adsorbed metal atoms (Li, Na, K, Mg, Ca, Al, and Zn) from typical metal-ion batteries are studied by first-principles calculation. Notably, Mg and Zn adsorption systems are deemed unstable. In contrast, Li, Na, K, Ca, and Al systems exhibit two preferential adsorption sites, with the optimal position being the hollow center site within the large acetylenic ring. Upon the adsorption of these metal atoms, except for Ca adsorption systems exhibit semi-metallic behavior, while the other metal adsorption systems induced a transition from p-type to n-type semiconductors with decreased band gaps. Intriguingly, the inherent magnetism of the metal atoms vanished, resulting in a total magnetic moment of 0 μ B for the adsorption systems. Furthermore, the optical absorption and reflectivity peak positions for Ca adsorption systems show a significant redshift from violet to green and blue light regions. Conversely, other adsorption systems exhibit new absorption and reflection peaks in the infrared range, accompanied by an increase in both absorption coefficient and reflectivity across various spectral regions. These findings are conducive to the application in the field of novel optoelectronics and optical films.

Experimental and theoretical study of multiple active site-functionalized Spirulina residue-based porous carbon as an economical adsorbent for NH3 and SO2 adsorption: Micro- and macro-mechanistic investigations

Here, we successfully synthesized a cost-effective (7.88 USD/kg) multi-active site (CuCl2, CuO and KCl) functionalized Spirulina residue-based porous carbon (MMBC). This innovative synthesis method utilizes Spirulina residue, a sustainable and low-cost biomass source, making the production of MMBC economically viable and environmentally friendly. Under ambient conditions, MMBC exhibits competitive adsorption capacities for NH3 and SO2 compared to other adsorbents, reaching 3.01 mmol/g (i.e., 51.26 mg/g) and 0.70 mmol/g (i.e., 44.85 mg/g), respectively, and tolerable recoverability. These values are significant improvements over many existing adsorbents, highlighting MMBC's efficiency in removing toxic industrial chemicals (TICs). Additionally, even at low molar fractions of NH3 or SO2, such as 0.001, MMBC demonstrates significant ideal adsorption solution theory (IAST) selectivity for NH3/N2 and SO2/N2, with values of 12.02 and 4.19, respectively. This high selectivity at low concentrations underscores MMBC's potential for applications in environments with trace amounts of pollutants. Furthermore, extensive research has been conducted in this study to elucidate the microscopic and macroscopic adsorption mechanisms of NH3 and SO2 on MMBC. Specifically, investigations in statistical physics models and statistical thermodynamics reveal that the adsorption of NH3 and SO2 on MMBC adhere to a non-aggregative, multilayer, multi-anchorage, and spontaneous exothermic physicochemical behavior. And the adsorption orientation occurs either horizontally or both horizontally and non-horizontally, contingent upon the system and temperature. These findings provide a deeper understanding of the adsorption processes and provide innovative insights into the adsorption mechanisms at the molecular level and at the macroscopic scale. Besides, the material characterization results reveal that the above adsorption process involves both physical interactions (pore diffusion and van der Waals forces) and chemical interactions (CuCl2 with NH3, CuO and KCl with SO2), indicating a physicochemical adsorption mechanism. This dual mechanism of adsorption offers a comprehensive explanation of the high performance of MMBC. In summary, this study developed a cost-effective Spirulina residue-based adsorbent, exhibiting high removal efficiency and selectivity for TICs, and providing deep insights into adsorption mechanisms. The innovative use of Spirulina residue addresses waste management issues and promotes the development of sustainable materials in the field of environmental remediation, contributing to cleaner production.

Efficient separation of SO2/NO2 on in-situ synthesized NaA zeolite membrane

SO2 and NO2 mixture widely exists in the desorbed gas from industrial flue gas adsorption purification process, separating the mixture into pure gas provides the key step for success in recycling them into profitable chemicals. However, effective SO2/NO2 separation is challenged due to the similar properties of both gases. In this work, we report the synthesis of an industrially-favored NaA zeolite membrane and the utilization of this membrane for SO2/NO2 separation in order to address the above-mentioned challenge. Various characterizations illustrate that the in-situ synthesis endows the NaA zeolite membrane with well-intergrown crystals, high continuity, and crystal-comparable thickness. The separation measurements at different feed pressure, temperature, and gas composition demonstrate that the NaA zeolite membrane shows superior separation performance (SO2/NO2 separation factor of 40.0, SO2 permeance of 2.93 × 10−7 mol m−2 Pa−1 s−1 at 293 K and 0.2 MPa) with strong stability (more than 7 d) compared to the previous best-performing zeolite membrane. The strong competitiveness of SO2 over NO2 on the low-silica membrane is revealed through molecular simulation, showing that the great affinity of SO2 with highly-polar zeolite structure benefits the SO2 gas preferential adsorption and energetically barrier-free permeation through the eight-membered ring of NaA zeolite. This work not only showcases an efficient strategy for the SO2/NO2 separation, but also expands the gas separation application of zeolite membranes.

Organic carbon, major and trace element release from and adsorption onto particulate suspended matter of the Ob River, western Siberia

Particulate suspended matter (PSM) of rivers is a significant factor for carbon, nutrient, and trace metal transfer from land to ocean. Towards better understanding the role that PSM exerts on major and trace elements in riverine systems, here we report the results of an experimental study which utilizes a two-fold approach to assess interaction between PSM and riverine solutes. First, we measured element leaching (via desorption and dissolution in distilled water, simulating snow melt) from PSM of the largest Siberian river, the Ob River. Second, we quantified the capacity of PSM to adsorb dissolved organic carbon (DOC), macro- and micronutrients and trace elements from organic-rich waters of the river floodplain. We documented sizable desorption of organic carbon, some major and trace metals, oxyanions and insoluble elements from PSM; the majority (>50 %) of elements were released over the first hour of reaction. In contrast, PSM of the Ob River was capable of removing 20 to 90 % of dissolved OC, nutrients (Si, P), and trace elements from the tributary and floodplain fen. Our experiments demonstrated preferential adsorption of aromatic compounds large molecular size colloids. Taken together, the adsorption of solutes by PSM can sizably decrease the concentration and modify the molecular size distribution, and therefore the potential bioavailability of major (DOC, P, Si) and trace micronutrients. Overall, the PSM of the Ob River exhibited high reactivity with respect to natural waters and was capable of modifying the elemental composition of the tributary and floodplain fen waters. This transfer of organic carbon and nutrients in the surface-adsorbed (particulate) form is especially important during spring flood and requires specific consideration in short-term biogeochemical cycles of elements in continental waters.

Metal edge confined platinum atoms in metal/hydroxide hierarchy structure for multiple hydrogen conversion and evolution

Single-atom catalysts (SACs), as a thriving subfield of catalysis, have progressed tremendously. However, the contradiction between the isolated dispersion feature of metal sites and the high mass-specific activity of the catalyst inhibits the advances of the SACs. Herein, the Pt atoms are confined at the metallic Co phase edge in two-dimensional Co/Co(OH)2 hierarchy structure (PtSA-Co@Co-Co(OH)2) by the defect inducted order electrodeposition strategy. Both integrations of in-situ/ex-situ experimental characterizations and theoretical calculation reveal that such metal edge confined Pt atoms possess an enlarged atom exposure ratio, high stability, and the like-metal electronic state contributed by metal Co 3d, which enables the Pt atoms with more suitable affinity to simultaneously bind the multiple H atoms for durable H*-H2 conversion and H2 evolution. Moreover, the metallic PtSA-Co collaborated Co/Co(OH)2 interfaces demonstrate a strong H2O dissociation capacity by the preference adsorption of H* on metallic PtSA-Co and OH*on Co/Co(OH)2 interfaces. Combining a further enhancement of constructing the catalysts on an Ag nanowire network to form a seamlessly conductive nanostructure, the PtSA-Co@Co-Co(OH)2 achieves a high mass activity with 5.92 A mg−1 at the overpotential of 100 mV in alkaline condition, 37 times to that of the benchmark Pt/C catalyst and significantly outperforming the reported catalysts. While our work has focused on the hydrogen evolution reaction, this class of metal edge collaborated single-atom catalysts may be conducive to unlock the low mass-specific activity of atomically dispersed catalysts for various processes, such as oxygen evolution reactions (OER), CO2 reduction, and biomass conversion, etc.

Polynuclear Cobalt Cluster-Based Coordination Polymers for Efficient Nitrate-to-Ammonia Electroreduction.

The electrocatalytic nitrate reduction reaction (NITRR) holds great promise for purifying wastewater and producing valuable ammonia (NH3). However, the lack of efficient electrocatalysts has impeded the achievement of highly selective NH3 synthesis from the NITRR. In this study, we report the design and synthesis of two polynuclear Co-cluster-based coordination polymers, {[Co2(TCPPDA)(H2O)5]·(H2O)9(DMF)} and {Co1.5(TCPPDA)[(CH3)2NH2]·(H2O)6(DMF)2} (namely, NJUZ-2 and NJUZ-3), which possess distinct coordination motifs with well-defined porosity, high-density catalytic sites, accessible mass transfer channels, and nanoconfined chemical environments. Benefitting from their intriguing multicore metal-organic coordination framework structures, NJUZ-2 and NJUZ-3 exhibit remarkable catalytic activities for the NITRR. At a potential of -0.8 V (vs. RHE) in an H-type cell, they achieve an optimal Faradaic efficiency of approximately 98.5% and high long-term durability for selective NH3 production. Furthermore, the electrocatalytic performance is well maintained even under strongly acidic conditions. When operated under an industrially relevant current density of 469.9 mA cm-2 in a flow cell, a high NH3 yield rate of up to 3370.6 mmol h-1 g-1cat. was observed at -0.5 V (vs. RHE), which is 20.1-fold higher than that obtained in H-type cells under the same conditions. Extensive experimental analyses, in combination with theoretical computations, reveal that the great enhancement of the NITRR activity is attributed to the preferential adsorption of NO3- and the reduction in energy input required for the hydrogenation of *NO3 and *NO2 intermediates.

Thermal effects of organic porous media on absorption and desorption behaviors of carbon dioxide

As a result of global warming, people are increasingly concerned about greenhouse gas emissions, particularly carbon dioxide (CO2). Many countries have been promoting carbon capture, storage (CCS) projects in order to alleviate climate degradation and achieve net zero carbon emissions. To study the thermal effects of organic porous media on CO2 absorption and desorption, molecular dynamics coupled with Monte Carlo (MDMC) were used in this study. A part of the CO2 molecules will be trapped within kerogen matrix due to its complex porous structure. The affinity of kerogen to CO2 facilitates CO2′s adsorption within the kerogen porous media, resulting in a heterogeneous distribution of CO2. The kerogen forms high potential energy peaks and low potential energy wells in the matrix, which provide preferred adsorption sites for CO2 in the porous space. The low stress state of CO2 also indicates that it prefers adsorption in the matrix as CO2 performs a lower potential energy state in the kerogen matrix than in the bulk phase. This study examines different thermal effects of kerogen, and results indicate that increasing CO2 thermal motion facilitates its absorption, while a high temperature matrix promotes CO2 desorption. Adsorbed layer provides resistance for CO2′s diffusion behaviors. The free energy of CO2′s diffusion is analyzed in relation to its mechanism, revealing that irregular thermal motion causes uncertainty in the adsorption capacity.

Tuning Preferential Molecular Adsorption and Self-Assembled Molecular Network Formation at the Liquid–Solid Interface: The Impact of Annealing and Confinement

Tuning Preferential Molecular Adsorption and Self-Assembled Molecular Network Formation at the Liquid–Solid Interface: The Impact of Annealing and Confinement

Nanoscopic catalyst-loaded porous metal oxide hollow frameworks using porous block copolymer templates for high performance formaldehyde sensors

Porous and hollow nanostructures functionalized with nanoscopic catalysts have attracted considerable interest in a wide range of applications depending on surface reactions. In this study, we present an efficient and versatile synthetic strategy of porous metal oxide hollow frameworks (HFs) decorated with noble metal nanoparticles (NPs). The key lies in the use of porous and bicontinuous polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) microparticles as templates, which feature pores on the order of several hundred nanometers in size. Homogeneous Pt loading on the surface of the porous microparticles is achieved through the preferential adsorption of Pt precursors onto the P4VP block via electrostatic interactions. Subsequent SnO2 thin film deposition and calcination ultimately yield honeycomb-like SnO2 HFs with macropores and uniform distribution of Pt NPs. The Pt NP-loaded SnO2 HFs exhibit exceptional formaldehyde (HCHO) sensing capabilities, characterized by remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm), ultra-low detection limit of 10 ppb, and remarkable cross-selectivity. These outstanding features result from their high surface area, gas permeability within porous hollow structures, and well-dispersed Pt NPs, which catalytically activate the sensor. Our study provides great promise for advancing surface catalytic reactions due to their exceptional surface area and gas permeability, paving the way for future applications.

Indigenous microbial influence on REE enrichment and fractionation in South China weathering crusts: Insights from experimental simulations

The activity of microorganism plays an important role on the enrichment, migration and fractionation of rare earth elements (REEs) in the supergene environment. To investigate the characteristics of indigenous microorganisms on the enrichment and fractionation of REEs, we studied the adsorption efficiencies of REEs by 30 indigenous microbial strains that were isolated and cultured from the weathering profile of a regolith-hosted REE deposit in South China. Most microbial strains exhibited high adsorption efficiencies for REEs, ranging from 2.3 to 42.9 mg g−1. Notably, the taxonomic classification of microorganisms significantly influenced the adsorption selectivity. Gram-positive bacteria exhibited a pronounced enrichment of the heavy REEs, while gram-negative bacteria showed no obvious adsorption preference. The tetrad effects were observed in REE adsorption patterns of gram-negative bacteria and fungi; however, fungi demonstrated a much higher affinity for light and medium REEs. Chemically modified microbial cells were employed to investigate the adsorption mechanism, revealing that distinct functional groups of microbial cells corresponded to the adsorption preference of microorganisms towards REE. Carboxyl and phosphate groups contributed to a relatively high adsorption capacity for light REEs and heavy REEs, respectively. The findings of our study suggest that the distinct composition of microbial groups may exert a significant influence on the biogeochemical cycle of REE in weathering profiles.

Revitalizing CO2 photoreduction: Fine-tuning electronic synergy in ultrathin g-C3N4 with amorphous (CoFeNiMnCu)S2 high-entropy sulfide nanoparticles for enhanced sustainability

Sustainability is a key issue in developing stable and efficient catalysts for solar-catalyzed CO2 conversion. The concept of structural stabilization by quenching the Gibbs free energy, which is achieved by increasing the configurational entropy level of the system, introduced high-entropy materials. However, because alloying immiscible multimetallic atoms into a unit system is still an arduous process, the potential of high-entropy materials has not yet been fully exploited. Surprisingly, although metal sulfide photocatalysts have an enviable reputation for CO2 photoreduction (CO2-PR) owing to their optical/electronic merits and more negative redox potential than other materials, the capability of high-entropy metal sulfides has been completely disregarded. Herein, an adaptable, self-templating metal alkoxide appropriately addresses the immiscibility of metallic constituents by the well-blended metal ions with polyalcohol in the metal glycerate. Consequently, (CoFeNiMnCu)S2 high-entropy metal sulfide nanoparticles (HEMS-Nps) were grown in situ on crossed ultrathin g-C3N4 (UCN) monolayers during the sulfidation of the metal glycerate. The as-synthesized HEMS-Np has a crystalline–amorphous structure, which is conducive to the acceleration of charge transfer to/from reaction sites, and a convincing orientation for CO2 adsorption. These features are combined with synergistic electronic multimetallic interactions, facilitating a heterogeneous valence electron distribution and atomic disorder. The CO2-PR power of the (CoFeNiMnCu)S2@UCN nanostructure was noticeable in realizing added-value products in both the liquid–solid (1063 µmol/g h of syngas and 250 µmol/g h of methane) and gas–solid phases (1883 µmol/cm2 h of syngas and 321 µmol/cm2 h of methane). To prove its utility, long-term and corresponding time-equivalent cycling experiments were conducted, demonstrating a highly stable system that endured for a long time. Overall, this approach simultaneously exploits the advantages of sulfide-based materials and high-entropy materials in stable structures to generate sustainable CO2-PR materials.

Atomic-level into the microscopic mechanism of gold capture by FeS during gold collection in matte process

Understanding the microscopic mechanisms involved in gold capture by FeS at the atomic level is crucial for optimizing the matte process and improving the gold recovery from gold concentrate containing arsenic and antimony. Herein, the DFT method was employed to explore the adsorption structure and electronic characteristics of a gold (Au) atom on the FeS surface. Furthermore, the effects of Fe/S vacancy and As/Sb dopant on Au adsorption were also investigated. The results reveal that the FeS(100) with S termination exhibits the smallest surface energy (0.56 J/m2) and possesses the highest stability amongst the low-index surfaces. Furthermore, the Au atom exhibits a preference for adsorption on the Fe-bridge site of FeS(100) through chemisorption due to the formation of a strong Au-Fe metallic bond, large adsorption energy (−5.40 eV), and small adsorption distance. Moreover, the presence of S vacancy enhances the Au capture capability of FeS(100) with an adsorption energy of −6.35 eV, while the Fe vacancy slightly weakens it. Additionally, the doping of As and Sb enhances the adsorption of Au atoms on FeS(100), and the Sb doping showcases a more distinct enhancement in Au capture efficiency. The findings of this work contribute to the advancement of matte processing technology, enabling enhanced gold recovery and potentially opening new avenues for the treatment of refractory gold ores.

Adsorption behaviors and mechanisms of porous polyvinyl alcohol/xanthan gum hydrogel for methylene blue and Pb2+

Faced with extensive water pollution caused by dyes and heavy metals, it is imperative to create cost-effective adsorbents that can effectively eliminate residual pollutants in wastewater. The synthesis of polyvinyl alcohol/xanthan gum (PVA/XG) hydrogels involved a combination of freeze-thaw cycling technique and the adsorption characteristics and mechanisms of methylene blue (MB) and heavy metal ions Pb2+ were investigated. In comparison to pure PVA hydrogels, the swelling behavior of PVA/XG3 hydrogel exhibited a 185 % increase in swelling rate. The adsorption test results suggested that PVA/XG3 hydrogel was effective in absorbing MB (27.39 mg/g) and Pb2+ (17.07 mg/g) from a 50 mg/L pollutant solution. The adsorption process of MB and Pb2+ by PVA/XG3 hydrogel followed Langmuir adsorption isotherm and the QFO models, indicating a preference for homogeneous physical adsorption. Specifically, the Langmuir isothermal model predicted that the qmax of MB and Pb2+ by PVA/XG3 hydrogel were 94.47 and 58.50 mg/g, respectively. Therefore, this essay has created a cost-effective and environmentally friendly method for producing versatile PVA/XG hydrogels specifically intended for water treatment purposes.

Magnetic hybrid spheres of glauconite/calcium alginate interface for methylene blue adsorption: Synthesis, characterization, and novel physicochemical insights through theoretical treatment

Fe3O4 nanoparticles were embedded within a glauconite‑calcium alginate (G/CA) matrix to create magnetic hybrid spheres (MNPs-G/CA), with the aim of purifying water from methylene blue (MB) at temperatures of 25, 40, and 50 °C. MNPs-G/CA adsorbent was characterized using numerous techniques, including elemental mapping, zeta potential, FTIR, FESEM, XRD, EDX, and TEM. The greatest amount of the removed MB was achieved under definite conditions of solution pH 8.0, MNPs-G/CA mass (25 mg), interaction time (2 h), and 200 mg/L of MB concentration. The MB uptake process kinetic followed a pseudo-second-order equation (R2 > 0.99) at all tested temperatures. The equilibrium data were fitted to a statistical physics multilayer model in conjunction with the Langmuir and Freundlich equations. The steric n parameter reveals that MNPs-G/CA adsorbent possesses a mixed adsorption orientation (i.e., ranging from 0.69 to 0.93) across various temperatures. The amount of MNPs-G/CA active positions (the NM parameter) was progressively increased from 245 mg/g to 419 mg/g. The measured adsorption capacities (Qsat) ranged from 466.49 to 664.37 mg/g, and the removal of MB molecules was consistent with an endothermic interaction. The interface between the MNPs-G/CA-MB was principally dictated by electrostatic attractions, as evidenced by the values of adsorption energies (∆E), which varied from 16.75 to 21.52 kJ/mol. The regenerated MNPs-G/CA offered over 80 % of its adsorption strength after the fourth adsorption–desorption cycle. This study contributes to our understanding of the physicochemical parameters controlling the MB adsorption mechanism on multifunctional hybrid adsorbents, like the interface between glauconite, alginate, and MNPs.

Ion Selectivity, Current, and Water Flow Regulation in Ti3C2 MXene Nanopores.

Recent years have seen a growing interest in zero-dimensional (0D) transport phenomena occurring across two-dimensional (2D) materials for their potential applications to nanopore technology such as ion separation and molecular sensing. Herein, we investigate ion transport through 1 nm-wide nanopores in Ti3C2 MXene using molecular dynamics simulations. The high polarity and fish-bone arrangement of the Ti3C2 MXene offer a built-in potential and an atomic-scale distortion to the nanopore, causing an adsorption preference for cations. Our observation of variable cation-specific ion selectivity and Coulomb blockade highlights the complex interplay between adsorption affinity and cation size. The cation-specific ion selectivity can induce both the ion current and electro-osmotic water transmission, which can be regulated by tailoring the ions' preferential pathways through electric field tilting. Our finding underscores the pivotal role of the atomic arrangement of MXenes in 0D ion transport and provides fundamental insight into the application of 2D material in nanopores-based technologies.

Adsorption Characteristics of Antibiotic Oxytetracycline on CoFe2O4@Au nanocomposite

Oxytetracycline (OTC) is a widely used broad-spectrum antibiotic for treating bacterial infections in humans and animals. Gold nanoparticles (AuNPs) and cobalt iron oxide (CFO) were combined to create composite magnetic materials designed for the selective adsorption of OTC. The strong affinity of AuNPs for the amine group in the OTC molecule allows for the preferential adsorption of OTC. Simultaneously, the high magnetism of CFO enables the efficient retrieval of materials from the sample solution. The CFO@Au nanomaterials showed an enhanced adsorption capacity of 23.75 mg/g at optimum conditions of pH 7.0; an adsorption time of 90 min, and an adsorbent mass of 0.05g. The adsorption isotherm was in accordance with a Langmuir monolayer model while the kinetic adsorption follows pseudo–second-order kinetic model.. This study provides a simple method for the effective adsorption of OTC as well as a suggestion for the adsorption of other amine-containing substances.

Removal and Recovery of Europium with a New Functionalized Mesoporous Silica-Based Adsorbent

The discharge of acid mine drainage (AMD), characterized by a high concentration of rare earth elements (REEs), poses a significant threat to the health of ecosystems surrounding water sources. The global market demand for REEs has experienced a notable surge in the past decade. Consequently, recovering REEs from waste streams like AMD not only benefits the environment but also offers financial advantages. Europium (Eu), the rarest among REEs, constitutes only 0.1% w/w in monazite and bastnaesite ores. Eu is extensively used in the production of phosphors, alloys, and additives, and is a critical raw material for developing smart devices, ranging from high-resolution color screens to circuitry. Traditional adsorbents typically exhibit limited selectivity towards REE recovery. Mesoporous silica materials, such as SBA15 (Santa Barbara Amorphous-15), provide excellent tunability and modification capabilities, making them an attractive and cost-effective alternative. This research focused on two key aspects: (i) evaluating the dynamic adsorption column performance of granulated SBA15–NH–PMIDA to preferentially recover Eu, and (ii) employing mathematical modeling to optimize the dynamic adsorption column’s operating conditions for real-world applications with a minimal number of experimental runs. Granulated SBA15–NH–PMIDA was chosen as the adsorbent due to its high adsorptive capacity and selectivity in capturing Eu. The study revealed that granulated SBA15–NH–PMIDA exhibited 57.47 mg/g adsorption capacity and an 81% selectivity towards Eu. Furthermore, SBA15–NH–PMIDA demonstrated preferential adsorption toward Eu in complex multi-component solutions, such as AMD. The linear driven force approximation model (LDFAM) provided an acceptable simulation (R2 > 0.91) under varying operational conditions. This validates the use of the model as a tool to effectively simulate and optimize column experiments that used granulated SBA15–NH–PMIDA to recover Eu.

Preferential adsorption of medium molecular weight proteins in extracellular polymeric substance alleviates toxicity of small-sized microplastics to Skeletonema costatum

Extracellular polymeric substances (EPS) secreted by organisms tend to encapsulate microplastics (MPs), forming an EPS-corona that affects the fate of MPs in marine ecosystems. However, the impact of the EPS-corona on the biotoxicity of MPs to marine organisms remains poorly understood. Herein, the effect of the EPS-corona on the toxicity of polystyrene (PS) MPs of different sizes (0.1 and 1 µm) to Skeletonema costatum (S. costatum) was investigated. The preferential adsorption of medium molecule weight (∼55 kDa) proteins onto PS MPs mainly contributed to the EPS-corona formation, decreasing the surface charge negativity of small-sized PS MPs (0.1 µm) by 72.4 %. Nitrogen (N) and oxygen (O) moieties in polysaccharides and proteins were identified as the preferential adsorption sites in the EPS-PS MPs interaction. Density functional theory (DFT) calculations confirmed the nuclear magnetic resonance spectroscopy (NMR) results, revealing that the binding mode between EPS and PS MPs was mainly hydrogen bonding. In addition, EPS-corona increased the cell density of S. costatum by 35.5–36.0 % when exposed to small-sized PS MPs (0.1 µm, 25–50 mg/L). These findings provide new insights into how EPS-corona affects the environmental fate and ecological risks associated with micro- and nano-sized plastics in marine ecosystems.