Metal Research Articles

Pinpointing Conditions for a Metabolic Origin of Life: Underlying Mechanisms and the Role of Coenzymes.

ConspectusFamously found written on the blackboard of physicist Richard Feynman after his death was the phrase, "What I cannot create, I do not understand." From this perspective, recreating the origin of life in the lab is a necessary condition for achieving a deep theoretical understanding of biology. The "metabolism-first" hypothesis is one of the leading frameworks for the origin of life. A complex self-organized reaction network is thought to have been driven into existence as a chemical path of least resistance to release free energy in the environment that could otherwise not be dissipated, rerouting energy from planetary processes to organic chemistry. To increase in complexity, the reaction network, initially under catalysis provided by its geochemical environment, must have produced organic catalysts that pruned the existing flux through the network or expanded it in new directions. This boot-strapping process would gradually lessen the dependence on the initial catalytic environment and allow the reaction network to persist using catalysts of its own making. Eventually, this process leads to the seemingly inseparable interdependence at the heart of biology between catalysts (coenzymes, enzymes, genes) and the metabolic pathways that synthesize them. Experimentally, the primary challenge is to recreate the conditions where such a network emerged. However, the near infinite number of microenvironments and sources of energy available on the early Earth or elsewhere poses an enormous combinatorial challenge. To constrain the search, our lab has been surveying conditions where the reactions making up the core of some of the most ancient chemolithoautotrophic metabolisms, which consist of only a small number of repeating chemical mechanisms, occur nonenzymatically. To give a fresh viewpoint in the first part of this account, we have organized the results of our search (along with important results from other laboratories) by reaction mechanism, rather than by pathway. We expect that identifying a common set of conditions for each type of reaction mechanism will help pinpoint the conditions for the emergence of a self-organized reaction network resembling core metabolism. Many of the reaction mechanisms were found to occur in a wide variety of nonenzymatic conditions. Others, such as carboxylate phosphorylation and C-C bond formation from CO2, were found to be the most constraining, and thus help narrow the scope of environments where a reaction network could emerge. In the second part of this account, we highlight examples where small molecules produced by metabolism, known as coenzymes, mediate nonenzymatic chemistry of the type needed for the coenzyme's own synthesis or that turn on new reactivity of interest for expanding a hypothetical protometabolic network. These examples often feature cooperativity between small organic coenzymes and metal ions, recapitulating the transition from inorganic to organic catalysis during the origin of life. Overall, the most interesting conditions are those containing a reducing potential equivalent to H2 gas (electrochemical or H2 itself), Fe in both reduced and more oxidized forms (possibly with other metals like Ni) and localized strong electric fields. Environments that satisfy these criteria simultaneously will be of prime interest for reconstructing a metabolic origin of life.

Multifaceted natural drought response mechanisms in three elite date palm cultivars uncovered by expressed sequence tags analysis.

This study extends our prior research on drought responses in three date palm cultivars (Khalas, Reziz, and Sheshi) under controlled conditions. Here, we investigated their drought stress adaptive strategies under ambient environment. Under natural field drought conditions, three date palm cultivars experienced significantly (p ≤ 0.05) varying regulations in their physiological attributes. Specifically, chlorophyll content, leaf RWC, photosynthesis, stomatal conductance, and transpiration reduced significantly, while intercellular CO2 concentration and water use efficiency increased. Through suppression subtraction hybridization (SSH), a rich repertoire (1026) of drought-responsive expressed sequence tags (ESTs) were identified: 300 in Khalas, 343 in Reziz, and 383 in Sheshi. Functional analysis of ESTs, including gene annotation and KEGG pathways elucidation, unveiled that these cultivars withstand drought by leveraging indigenous and multifaceted pathways. While some pathways aligned with previously reported drought resilience mechanism observed under controlled conditions, several new indigenous pathways were noted, pinpointing cultivar-specific adaptations. ESTs identified in three date palm cultivars were enriched through GSEA analysis. Khalas exhibited enrichment in cellular and metabolic processes, catalytic activity, and metal ion binding. Reziz showed enrichment in biological regulation, metabolic processes, signaling, and nuclear functions. Conversely, Sheshi displayed enrichment in organelle, photosynthetic, and ribosomal components. Notably, ca. 50% of the ESTs were unique and novel, underlining the complexity of their adaptive genetic toolkit. Overall, Khalas displayed superior drought tolerance, followed by Reziz and Sheshi, highlighting cultivar-specific variability in adaptation. Conclusively, date palm cultivars exhibited diverse genetic and physiological strategies to cope with drought, demonstrating greater complexity in their resilience compared to controlled settings.

Effect of Co-exposure to Additional Substances on the Bioconcentration of Per(poly)fluoroalkyl Substances: A Meta-Analysis Based on Hydroponic Experimental Evidence.

A consensus has yet to emerge regarding the bioconcentration responses of per(poly)fluoroalkyl substances under co-exposure with other additional substances in aqueous environments. This study employed a meta-analysis to systematically investigate the aforementioned issues on the basis of 1,085 published datasets of indoor hydroponic simulation experiments. A hierarchical meta-analysis model with an embedded variance covariance matrix was constructed to eliminate the non-independence and shared controls of the data. Overall, the co-exposure resulted in a notable reduction in PFAS bioaccumulation (cumulative effect size, CES = - 0.4287, p < 0.05) and bioconcentration factor (R2 = 0.9507, k < 1, b < 0) in hydroponics. In particular, the inhibition of PFAS bioconcentration induced by dissolved organic matter (percentage form of the effect size, ESP = - 48.98%) was more pronounced than that induced by metal ions (ESP = - 35.54%), particulate matter (ESP = - 24.70%) and persistent organic pollutants (ESP = - 18.66%). A lower AS concentration and a lower concentration ratio of ASs to PFASs significantly promote PFAS bioaccumulation (p < 0.05). The bioaccumulation of PFASs with long chains or high fluoride contents tended to be exacerbated in the presence of ASs. Furthermore, the effect on PFAS bioaccumulation was also significantly dependent on the duration of co-exposure (p < 0.05). The findings of this study provide novel insights into the fate and bioconcentration of PFAS in aquatic environments under co-exposure conditions.

Metal-phenolic network composites: from fundamentals to applications.

Composites with tailored compositions and functions have attracted widespread scientific and industrial interest. Metal-phenolic networks (MPNs), which are composed of phenolic ligands and metal ions, are amorphous adhesive coordination polymers that have been combined with various functional components to create composites with potential in chemistry, biology, and materials science. This review aims to provide a comprehensive summary of both fundamental knowledge and advancements in the field of MPN composites. The advantages of amorphous MPNs, over crystalline metal-organic frameworks, for fabricating composites are highlighted, including their mild synthesis, diverse interactions, and numerous intrinsic functionalities. The formation mechanisms and state-of-the-art synthesis strategies of MPN composites are summarized to guide their rational design. Subsequently, a detailed overview of the chemical interactions and structure-property relationships of composites based on different functional components (e.g., small molecules, polymers, biomacromolecules) is provided. Finally, perspectives are offered on the current challenges and future directions of MPN composites. This tutorial review is expected to serve as a fundamental guide for researchers in the field of metal-organic materials and to provide insights and avenues to enhance the performance of existing functional materials in applications across diverse fields.

Amorphous Nanobelts for Efficient Electrocatalytic Ammonia Production.

One-dimensional (1D) amorphous nanomaterials combine the advantages of high active site concentration of amorphous structure, high specific surface area and efficient charge transfer and mass transport of 1D materials, so they present promising opportunities for catalysis. However, a significant challenge involves achieving a balance between the high orientation of 1D morphology and the isotropy of amorphous structure, which severely obstructs the controllable preparation of 1D amorphous materials. Guided by the hard-soft acids-bases theory, here we develop a general strategy for preparing 1D amorphous nanomaterials through the precise modulation of bond strength between metal ions and organic ligands for a moderated fastness. The soft base dodecanethiol (DT) is multifunctionally served as both structure-regulating agent and morphology-directing agent. Compared with the borderline acids (e.g. Fe2+, Co2+, Ni2+) to construct amorphous structure, soft acid of Cu+ which produced crystalline nanobelts can still be amorphized by reducing the hardness of Cu ions through redox reaction to weak Cu-SR bond. Due to the combined advantages of amorphous structure and one-dimensional morphology, amorphous CuDT nanobelts exhibited excellent electrocatalytic activity in electrochemical nitrate reduction, outperformed the most of the reported Cu-based catalysts. This work will effectively bridge the gap between traditional 1D crystalline nanomaterials and amorphization preparation.

Construction of 2D zinc(II) MOFs with tricarboxylate and N-donor mixed ligands for multiresponsive luminescence sensors and CO2 adsorption.

The solvothermal reactions of ZnCl2·6H2O, benzene-1,3,5-tribenzoic acid (H3btb), and N-heterocyclic ancillary imidazole (Im) or aminopyrimidine (a mp) ligands led to the creation of two-dimensional (2D) zinc(II) based metal-organic frameworks (MOFs), (Me2NH2)2[Zn2(btb)2(Im)2]·2DMF·3MeOH (1) and (Me2NH2)2[Zn2(btb)2(amp)]·H2O·2DMF·MeOH (2). The btb3- ligands in 1 and 2 form an anionic 2D layered structure with a (63) honeycomb (hcb) topology by linking to Zn(II) centres through their carboxylate groups. The incorporation of N-heterocyclic auxiliary ligands Im and amp into the hcb nets resulted in the formation of a 2D hydrogen-bonded and covalently pillared bilayer structure featuring two-fold interpenetrating networks. Each of these networks consists of small channels that are occupied by Me2NH2 cations and solvent molecules. Both 1 and 2 emit blue luminescence emissions in the solid state at room temperature and exhibit a great selectivity and sensitivity for the detection of acetone and multiple heavy metal ions including Hg2+, Cu2+, Fe2+, Pb2+, Cr3+, and Fe3+ ions. At 1 bar, activated 1 and 2 demonstrate moderate capacities for adsorbing CO2 at room temperature, with a preference for CO2 over N2. Notably, at higher pressures (up to 20 bar), their activated samples 1 and 2 show a temperature-dependent enhancement of CO2 uptake while retaining good stability.

Exploring the biosorption of nickel and lead by Fusarium sp. biomass: kinetic, isotherm, and thermodynamic assessment.

Fungal biomass is as a cost-effective and sustainable biosorbent utilized in both active and inactive forms. This study investigated the efficacy of inactivated and dried biomass of Fusarium sp. in adsorbing Ni2+ and Pb2+ from aqueous solutions. The strain underwent sequential cultivation and was recovered by filtration. Then, the biomass was dried in an oven at 80 ± 2°C and sieved using a 0.1-cm mesh. The biosorbent was thoroughly characterized, including BET surface area analysis, morphology examination (SEM), chemical composition (XRF and FT-IR), thermal behavior (TGA), and surface charge determination (pH-PZC and zeta potential). The biosorption mechanism was elucidated by fitting equilibrium models of kinetics, isotherm, and thermodynamic to the data. The biosorbent exhibited a neutral charge, a rough surface, a relatively modest surface area, appropriate functional groups for adsorption, and thermal stability above 200°C. Optimal biosorption was achieved at 25 ± 2°C, using 0.05g of adsorbent per 50mL of metallic ion solution at initial concentrations ranging from 0.5 to 2.0mg L-1 and at pH 4.5 for Pb2+ and Ni2+. Biosorption equilibrium was achieved after 240min for Ni2+ and 1440min for Pb2+. The process was spontaneous, mainly through chemisorption, in monolayer for Ni2+ and multilayer for Pb2+, with efficiencies of over 85% for both metallic ion removal. These findings underscore the potential of inactive and dry Fusarium sp. biomass (IDFB) as a promising material for the biosorption of Ni2+ and Pb2+.

Concurrent removal of Fe(II), Cu(II), and Zn(II) cations from acid mine drainage by an industrial solid waste - steel slag: Behaviors and mechanisms

Acid mine drainage (AMD) contamination poses a severe environmental threat and is a significant risk to human health. There is an urgent need to develop environmentally sustainable and technically viable solutions for water contamination caused by heavy metals. In this study, steel slag (SS) was used as a secondary resource to concurrently remove Fe(II), Cu(II), and Zn(II) from AMD. Because of the loose and porous structure, abundant functional groups, fast sedimentation velocity, and excellent solid-liquid separation, SS showed exceptional removal performance for heavy metal ions. The adsorption kinetic data of Fe(II), Cu(II), and Zn(II) showed good regression with the pseudo-second-order model. Besides, the adsorption of Fe(II) by SS conformed to the Freundlich model, whereas the adsorption of Cu(II) and Zn(II) followed the Langmuir model, with the maximum adsorption amounts of Cu(II) and Zn(II) being 170.69 and 155.98 mg/g. Furthermore, competitive adsorption was observed among Fe (II), Cu (II), and Zn (II) in a multi-component system, with the adsorption priority being Fe (II) > Cu (II) > Zn (II). The removal mechanism of Fe(II), Cu(II), and Zn(II) in AMD by SS mainly includes electrostatic attraction, chemical precipitation, and surface complexation. Interestingly, the leached concentrations of Fe(II), Cu(II), and Zn(II) from the spent slag after calcination were all within the detection limit of the Chinese emission standard, demonstrating excellent environmental stability. Theoretically, this renders it a viable candidate for use as an additive in construction materials. Meaningfully, the work offers a practical approach for energy-efficient and eco-friendly heavy metal ions adsorption, and the secondary utilization of SS also contributes to the sustainable development of the steel industry. It is beneficial to implement the development concepts of clean production and efficient utilization of industrial solid waste.

Development of a sustainable stabilized macadam road base using steel slag as supplementary cementitious material

As the main waste product of iron and steel industry, steel slag possesses considerable cementitious activity, making it a promising alternative to cement in Cement Stabilized Macadam (CSM). However, CSM was inevitably exposed to groundwater and rainwater when served as the pavement base course, leading to concerns over poor early strength and potential pollutant leakage, which are the main factors that may hinder the widespread utilization of steel slag in CSM base. To address these issues, this study investigated the feasibility of using steel slag powder to produce CSM. Steel Slag Powder-Cement Stabilized Macadam (SSCSM) samples were prepared and the hydration products, microstructure, mechanical properties, water damage resistance and heavy metal ions leaching behavior were investigated. The results show that the nucleation effect of steel slag powder accelerates the early hydration, but the C-S-H produced by hydration is not sufficient to form a stable hydration product network, so the microstructure of SSCSM is looser than that of CSM. The addition of steel slag powder improved the shrinkage performance of SSCSM, and the mechanical properties and heavy metal ion leaching concentration of SSCSM meet the engineering application requirements when the steel slag powder replacement level does not exceed 30 %. It was also found that the addition of steel slag powder promoted the development of pores in SSCSM samples after dry-wet cycles, resulting in the reduction of water damage resistance. Compared with conventional CSM, the use of SSCSM can not only reduce 4 % of raw material cost and 23.5 % of equivalent CO2 emission, but also mitigate the heavy metal ions leaching risk associated with steel slag, making it an effective and sustainable solution for steel slag recycling.

Synthesis, Characterization and Identification of Mononuclear Transition Metals Complexes 1, 3-Bis-((5-methyl-1H-Imidazol-4-yl) Methyleneamino) Propan-2-ol Ligand

The ligand 1,3-bis-((5-methyl-1H-imidazol-4-yl)methyleneamino)propan-2-ol (H3L) derived from 1,3-diaminopropan-2-ol and 5-methyl-1H-imidazole-4-carbaldehyde has been synthetized and used to prepare five complexes in which the ligand acts in tetradentate fashion. Complexes formulated as [Mn(H3L)(H2O)2].2SCN (1), [(Co(H3L)].2SCN (2), [(Ni(H3L)].2SCN (3), [(Cu(H3L)(NO3)].(NO3).2H2O (4), and [(Zn(H3L)].2SCN (5) were synthesized by mixing an equimolar amount of an methanol solution containing the appropriate nitrate salt and KSCN, in 1:2 ratio, in the case of 1, 2, 3 and 5 and an ethanol solution containing the appropriate ligand H3L. The complex 4 has been synthetized in the absence of KSCN. In all the complexes the ligand acts in its neutral form and in tetradentate fashion, its hydroxy group remaining free and non-deprotonated. The ligand is coordinated to metal ion through two azomethine nitrogen atoms and two pyrazole sp2 nitrogen atoms. The complexes are characterized by elemental analysis, conductance and room temperature magnetic moments measurements, UV–Vis and IR spectroscopic studies. The structure of the copper(II) complex 4 is confirmed by X-ray diffraction. 4 crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 8.5459 (3) Å, b = 10.9177 (3) Å, c = 22.4562 (6) Å, b = 96.954 (3)°, V = 2079.79 (11) Å3, Z = 4, R1 = 0.050 and wR2 = 0.131. The CuII cation in N4O inner is situated in a distorted square pyramidal environment.

Heat and mass transfer performance of multi-solute electroplating wastewater in spray evaporation separation process

Electroplating wastewater is complex in composition and contains many harmful substances. Based on the single droplet heat and mass transfer method, a one-dimensional mathematical model for the evaporation separation heat and mass transfer process of multi-solute electroplating wastewater is established. In order to validate the model, the experimental system of evaporation separation tower is established, and Nusselt numbers corresponding to metal ion solutions are fitted, reliabilities of models are also verified. The maximum relative errors of mathematical models are within 10.0 %. In addition, effects of the type and concentration of metal ions and air inlet temperature on heat and mass transfer characteristics of spray separation tower are investigated. Experimental results show that when the wastewater inlet concentration is the same, the improvement effects of increasing air inlet temperature on evaporation and separation performance from high to low are ZnCl2, CuCl2, and NiCl2 solutions. When the air inlet temperature increases from 90 °C to 130 °C, the evaporation speed of ZnCl2, CuCl2 and NiCl2 solutions increase by 90.3 %, 84.3 % and 45.7 %, respectively. When the air inlet temperature is the same, with the increase of wastewater inlet concentration, the evaporation separation performance of electroplating wastewater in descending order is ZnCl2, CuCl2, and NiCl2 solutions.

Extraction of flavonoid dyes from vine tea (Ampelopsis grossedentata) waste and application in bleached pulp dyeing

AbstractNatural dyes are receiving more attention due to wide and renewable resources and their functionalities. This study delved into the optimal conditions for extracting Ampelopsis grossedentata flavonoid dyes (AGFDs) from vine tea waste, resulting in a dye sample with a total flavonoid extraction percentage of 27.4 %. Ultraviolet (UV), Fourier‐transform infrared (FTIR) and liquid chromatography–mass spectrometry (LC–MS) analysis revealed the presence of 18 flavonoids in AGFD. Additionally, various factors, including pH, light exposure, temperature, metal ions, and redox agents were found to impact the stability of AGFD. Moreover, the dyeing performance of AGFD for the bleached chemical pulp was investigated. Under optimal conditions, the AGFD‐dyed pulp displayed a vibrant yellow hue and excellent colour fastness when using aluminum potassium sulphate dodecahydrate (KAl(SO4)2·12H2O) as a mordant with a dyeing uptake level up to 88 %. FTIR and scanning electron microscopy (SEM) analysis demonstrated that AGFD chemically bound to the pulp fibre. Remarkably, the hand sheet made from the AGFD‐dyed pulp exhibited thermal stability, physical strength properties and antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, the peroxide value of cheese packaged with the AGFD‐dyed pulp hand sheet was only 43 % of that of the undyed one, indicating its good antioxidant properties. This study highlights the promising potential of AGFD in the production of functional coloured paper.

Experimental overview of nanoferrites: synthesis, characterization and performance evaluation in wastewater treatment

Abstract This study investigates the potential of ferrite nanoparticles (BaFe12O19, MnFe2O4, NiFe2O4, and Co1-0.5Ni0.5Fe2O4) as eco-friendly adsorbents for the removal of heavy metals (Zn2+, Ni2+, Co2+, and Mn2+) from wastewater. Moreover, the adsorption experiments were conducted under varying contact times (30 min, 1 h, 2 h, and 4 h) and pH levels (2, 7, and 12) for five cycles to evaluate their significant dynamic effects on the removal efficiency. All ferrite nanoparticles were synthesized by the co-precipitation method and characterized (XRD, FT-IR, and SEM) to ascertain their crystal structure, morphology, size distribution, and crystallographic structures before wastewater treatments. The results demonstrated that BaFe12O19 had a particle size of 8.65 nm and achieved maximum adsorption ability of 93, 91, 94, and 91% for Zn2+, Ni2+, Co2+, and Mn2+, respectively, at a pH of 7 after 4 hours of treatment. Since the neutral pH value affects the binding of heavy metal ions, therefore governing the adsorption efficiency and selectivity. In contrast, NiFe2O4 (1.41 nm) revealed maximum removal of Zn2+, Ni2+, Co2+, and Mn2+ were 78, 71, 88, and 83%, respectively, at a pH of 12 after 4 hr. This was attributed to the negatively charged surface leading to stronger electrostatic attractions between the positively charged metal ions and the adsorbent surface, resulting in higher adsorption uptake. Notably, the higher removal rate was observed during initially 1 h, suggesting a decline in efficiency rate with extended treatment time. Additionally, the experimental study over five cycles concluded that the adsorbent could be effectively regenerated and reused.

Functionalization of activated carbon with melamine binder for adsorption of metallic species from aqueous environments

ABSTRACT In the face of the increasing exposure to heavy metals in the environmental scenario, there arose the need for further research by the scientific community. In this perspective, the present work reports the application of a material made from Typha sp. leaf, activated and functionalised with molecules of 1,3,5-Triazine-2,4,6-triamine (melamine), for the selective adsorption of metal ions Cu(II), Cd(II), and Pb(II) in aqueous solutions. Confirmation of material functionalization occurred through infrared vibrational spectroscopy, revealing bands at 3467, 3424, and 1338 cm−1 associated with the stretching vibration of -NH2. These results provide evidence of the possible anchoring of the ligand on the material surface. Elemental nitrogen analysis corroborated the results of infrared spectroscopy and showed 2.21% nitrogen in the functionalised material, while 1.30% in activated carbon. X-ray photoelectron spectroscopy showed the modification of the material surface composition after the functionalization reaction. The specific surface area was calculated as 193.876 m2/g. Adsorption studies revealed a rapid kinetics, best described by the pseudo-second-order model. The optimised pH for adsorption was 6.0 (pHPZC = 7.5), aligning with conditions found in natural waters. The maximum adsorption capacity was 0.4388, 0.4025, and 0.2792 mmol g−1 for Cu(II), Pb(II), and Cd(II), respectively, following the Langmuir model. Furthermore, to facilitate practical application, parameters such as mass and flow rate were optimised. The results suggest that the developed material exhibits promising adsorptive properties, emerging as a potential solution for remediating areas contaminated by metallic species.

Metal-Cation-Induced Tiny Ripple on Graphene

Ripples on graphene play a crucial role in manipulating its physical and chemical properties. However, producing ripples, especially at the nanoscale, remains challenging with current experimental methods. In this study, we report that tiny ripples in graphene can be generated by the adsorption of a single metal cation (Na+, K+, Mg2+, Ca2+, Cu2+, Fe3+) onto a graphene sheet, based on the density functional theory calculations. We attribute this to the cation–π interaction between the metal cation and the aromatic rings on the graphene surface, which makes the carbon atoms closer to metal ions, causing deformation of the graphene sheet, especially in the out-of-plane direction, thereby creating ripples. The equivalent pressures applied to graphene sheets in out-of-plane direction, generated by metal cation–π interactions, reach magnitudes on the order of gigapascals (GPa). More importantly, the electronic and mechanical properties of graphene sheets are modified by the adsorption of various metal cations, resulting in opened bandgaps and enhanced rigidity characterized by a higher elastic modulus. These findings show great potential for applications for producing ripples at the nanoscale in graphene through the regulation of metal cation adsorption.

Effectively Sieving Alkali Metal Ions Using Functionalized Graphene Oxide Membranes by Exploiting Water-Repellent Interactions.

Sieving membranes capable of discerning different alkali metal ions are important for many technologies, such as energy, environment, and life science. Recently, two-dimensional (2D) materials have been extensively explored for the creation of sieving membranes with angstrom-scale channels. However, because of the same charge and similar hydrated sizes, mostly laminated membranes typically show low selectivity (<10). Herein, we report a facile and scalable method for functionalizing graphene oxide (GO) laminates by dually grafting cations and water-repellent dimethylsiloxane (DMDMS) molecules to achieve high selectivities of ∼50 and ∼20 toward the transport of Cs+/Li+ and K+/Li+ ion pairs, surpassing many of the state-of-the-art laminated membranes. The enhanced selectivity for alkali metal ions can be credited to a dual impact: (i) strong hydrophobic interactions between the incident cations' hydration shells and the water-repellent DMDMS; (ii) the efficient screening of electrostatic interactions that hamper selectivity.

Probing the Closed Association of Oligoquinoline Foldamers by Time-Resolved Fluorescence Anisotropy.

The metal-mediated dimerization of oligoquinoline foldamers terminated at one end with an oligo(phenylenevinylene) and at the other with a carboxylic acid (OPV-QnA, where n = 4, 8, 17, and 33), and the complexation of OPV-Q8A and Q16A was promoted in chloroform by the addition of a concentrated 16 M aqueous sodium hydroxide solution. UV-vis absorption and time-resolved fluorescence anisotropy (TRFA) experiments were conducted to determine, respectively, the concentration and the average rotational time ⟨ϕ⟩ of the mixture of unassociated and associated foldamers across a range of foldamer concentrations spanning 5 orders of magnitude. Plots of ⟨ϕ⟩ as a function of acid group concentration revealed that ⟨ϕ⟩ increased with increasing foldamer concentration only when the foldamer solution in chloroform was vigorously mixed with the 16 M sodium hydroxide aqueous solution. Furthermore, all plots showed that ⟨ϕ⟩ reached a plateau at high foldamer concentration. The increase in ⟨ϕ⟩ reflected the association of foldamers into larger objects through metal ion coordination with the carboxylate anions generated by deprotonation of the carboxylic acid of OPV-QnA with NaOH, while the plateau obtained at high foldamer concentration indicated that these interactions led to the dimerization of the foldamers via a closed association mechanism. Analysis of the ⟨ϕ⟩ trends yielded the equilibrium constants (K) describing the foldamer dimerization, whose value equaled 1.0 (±0.2) × 106 M-1 for the three longer OPV-QnA foldamers, but was about 10 times smaller for the shortest one (n = 4). Association of OPV-Q8A and Q16A yielded a complex with a ⟨ϕ⟩ matching that of OPV-Q24A, and K for this complexation was similar to that for dimerization. These experiments illustrate the robust nature of TRFA as an experimental method to probe the size of rigid, self-assembled foldamers in solution.

Integrating ANSYS Fluent Simulation and Aspen Plus for efficient heavy metal ion removal with de-oiled cake

In this study bio-flocculant extracted from the de-oiled cake, a common waste generated while producing oil was used to treat an electroplating industrial effluent. A comprehensive analysis of flocculation efficiency in a simulated reactor using ANSYS Workbench - Fluent, with a focus on optimizing impeller position was carried out. The findings reveal that the optimal impeller position is 2 cm from the tank base, where maximum turbulent kinetic energy (0.02577 m2/s2) and dissipation rate (22.19 m2/s3) were achieved at 200 RPM, enhancing flocculation efficacy. Furthermore, the study identifies 0.5 g L−1 as the optimal flocculant dosage, resulting in 72.70 % and 89.38 % removal of Ni(II) and Cr(VI), respectively. The flocculation process was determined to follow second-order kinetics, with significant improvements in collision efficiency and particle aggregation at the optimized dosage. Fourier Transform Infrared spectroscopy analysis confirmed chemical interactions leading to flocculation, while zeta potential and particle size distribution studies corroborated the stability and effectiveness of the process. A techno-economic analysis was conducted, estimating the total capital investment required for pilot and industrial-scale implementations, highlighting the feasibility and scalability of the proposed treatment method. A holistic framework for enhancing industrial effluent treatment processes by integrated computational fluid dynamics, kinetic studies, and economic evaluation, is the novelty of this research.

Ammonothermal Synthesis of Luminescent Imidonitridophosphate Ba4P4N8(NH)2:Eu2.

The structural variability of a compound class is an important criterion for the research into phosphor host lattices for phosphor-converted light-emitting diodes (pc-LEDs). Especially, nitridophosphates and the related class of imidonitridophosphates are promising candidates. Recently, the ammonothermal approach has opened a systematic access to this substance class with larger sample quantities. We present the successful ammonothermal synthesis of the imidonitridophosphate Ba4P4N8(NH)2:Eu2+. Its crystal structure is solved by X-ray diffraction and it crystallizes in space group Cc (no.9) with lattice parameters a=12.5250(3), b=12.5566(4), c=7.3882(2)Å and β=102.9793(10)°. For the first time, adamantane-type (imido)nitridophosphate anions [P4N8(NH)2]8- are observed next to metal ions other than alkali metals in a compound. The presence of imide groups in the structure and the identification of preferred positions for the hydrogen atoms are performed using a combination of quantum chemical calculations, Fourier-transform infrared, and solid-state NMR spectroscopy. Eu2+ doped samples exhibit cyan emission (λmax=498nm, fwhm=50nm/1981cm-1) when excited with ultraviolet light with an impressive internal quantum efficiency (IQE) of 41%, which represents the first benchmark for imidonitridophosphates and is promising for potential industrial application of this compound class.

Application of waste gypsum as novel selective depressant in the flotation separation of apatite from dolomite

The accumulation of gypsum slag not only causes resource wastage, but also poses serious environmental hazards, therefore, utilizing the resources of the main components in gypsum slag is an imperative task. In this study, gypsum was used as an inorganic depressant for the flotation separation of apatite from dolomite through the selective adsorption of gypsum on the surface of dolomite. Micro-flotation experiments showed that sodium oleate exhibited a good ability to collect apatite and dolomite, but poor ability to collect gypsum. At pH 9.5, when 3.75 g/L gypsum was added to the slurry, the recovery of dolomite decreased from 76.77 % to 18.34 %, whereas that of apatite was 86.45 %. Atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy were employed to elucidate the adsorption characteristics of gypsum on the apatite and dolomite surfaces. The results showed that gypsum was selectively adsorbed on the raised particles on the dolomite surface and combined with the active sites of Ca and Mg metal ions. However, the adsorption of gypsum on the surface of apatite was weak and had little effect on the flotation performance. Density functional theory calculations showed that the O in gypsum reacted easily with Ca and Mg metal ions on the mineral surface. The adsorption energies of gypsum at the Ca and Mg sites on the dolomite surface were −81.97 and −86.18 kJ/mol, respectively, whereas the adsorption energy on the apatite surface was only −34.20 kJ/mol. Gypsum is the main component of gypsum slag, and this study provides a potential recycling method for gypsum slag resources.