A new compound 2,6-bis(4-methoxybenzoyl)-diaminopyridine (L) was used as an extractant for copper(II) ion recovery in a solvent extraction conducted at a temperature of 25 °C. The best results (99% recovery of copper(II) ions) were obtained when the aqueous phase contained 0.001 mol/dm3 Cu(II) and 0.2 mol/dm3 NH3 (pH~5.8), while the organic phase was a 0.001 mol/dm3 chloroform solution of 2,6-bis(4-methoxybenzoyl)-diaminopyridine. Spectrophotometry studies were used to determine the dissociation constant of the tested compound and determine the stability constant of the complex of subjected compound with copper(II) ions. The high-resolution mass spectrometry (HRMS) and higher energy collisional dissociation tandem mass spectrometry (HCD MS/MS) methods have been applied for the confirmation of the structure of 2,6-bis(4-methoxybenzoyl)-diaminopyridine and to determine its complexation with Cu(II) in solution.

Post combustion CO2 capture is still a rather energy intense, and therefore expensive, process. Much of the current research for reducing the process energy requirements is focused on the regeneration section. A good description of the vapor liquid equilibrium of the solvent is necessary for the accurate representation of the process. 3-(Diethylamino)-1,2-propanediol (DEA-12-PD) and 1-(2-hydroxyethyl)piperidine (12-HEPP) have been proposed as potential components in solvent blends for the membrane contactor. However, there are few available experimental data for these two tertiary amines making difficult to accurate simulate such process. In this work, we provide experimental data on the pure component saturation pressure (383 to 443 K) and on VLE of aqueous solutions of these amines (313 to 373 K) in order to fill part of the data gap. The data were used to estimate model parameters used to represent the data. The saturation pressure was modeled using the Antoine equation and the devi... [more]

The quality of electrospun poly(ethylene oxide) (PEO) nanofibrous mats are subject to a variety of input parameters. In this study, three parameters were chosen: molecular weight of PEO (100, 300, 600, and 1000 kg/mol), PEO concentration (in distilled water), and shear viscosity of PEO solution. Two relations free of any adjustable parameters were derived. The first, describing the initial stage of an electrospinning process expressing shear viscosity using PEO molecular weight and concentration. The second, expressing mean nanofiber diameter using concentration and PEO molecular weight. Based on these simple mathematical relations, it is possible to control the mean nanofiber diameter during an electrospinning process.

Over the last two decades, understanding of the attachment of colloids to fluid interfaces has attracted the interest of researchers from different fields. This is explained by considering the ubiquity of colloidal and interfacial systems in nature and technology. However, to date, the control and tuning of the assembly of colloids at fluid interfaces remain a challenge. This review discusses some of the most fundamental aspects governing the organization of colloidal objects at fluid interfaces, paying special attention to spherical particles. This requires a description of different physicochemical aspects, from the driving force involved in the assembly to its thermodynamic description, and from the interactions involved in the assembly to the dynamics and rheological behavior of particle-laden interfaces.

The sintering process is significantly important for the ironmaking in China because of the large amount of sinter consumed. Al2O3 is an important element determining the quality and quantity of sinter. However, different conclusions have been made regarding the effects of Al2O3 on the amount and fluidity of the liquid phase formed in the sinter phase. Therefore, it is necessary to examine the effects of Al2O3 content on the amount and fluidity of the liquid phase. The present work investigated the effects of different Al2O3 contents of iron ore fines on the liquid phase formation, mineral composition, and consolidation strength. The results showed that a small amount of Al2O3 increased the amount of calcium ferrite, making the liquid phase formation easier. As the Al2O3 content in iron ore fines increased, the liquidity index decreased continuously, while the fluidity and the consolidation strength of the sintered body were directly related to the content squared. The quality of the s... [more]

Long-term thermal stability of surfactants under harsh reservoir conditions is one of the main challenges for surfactant injection. Most of the commercially available surfactants thermally degrade or precipitate when exposed to high-temperature and high-salinity conditions. In this work, we designed and synthesized three novel betaine-based polyoxyethylene zwitterionic surfactants containing different head groups (carboxybetaine, sulfobetaine, and hydroxysulfobetaine) and bearing an unsaturated tail. The impact of the surfactant head group on the long-term thermal stability, foam stability, and surfactant−polymer interactions were examined. The thermal stability of the surfactants was assessed by monitoring the structural changes when exposed at high temperature (90 °C) for three months using 1H-NMR, 13C-NMR, and FTIR analysis. All surfactants were found thermally stable regardless of the headgroup and no structural changes were evidenced. The surfactant−polymer interactions were domin... [more]

The Cu(II) adsorption from aqueous solutions by magnetic biochar obtained from pine needles has been studied by means of batch-type experiments. The biochar fibers have been magnetized prior (pncm: carbonized-magnetized pine needles) and after oxidation (pncom: carbonized-oxidized-magnetized pine needles) and have been used as adsorbents to study the presence of carboxylic moieties on the magnetization and following adsorption process. The effect of pH (2−10), initial metal concentration (10−5−9·10−3 mol·L−1) and contact time (0−60 min) has been studied by varying the respective parameter, and the adsorbents have been characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) measurements prior and after Cu(II)-adsorption. FTIR measurements were performed to investigate the formation of surface species and XRD measurements to record possible solid phase formation and characterize formed solids, including the evaluation of their average crystal size. The data obtaine... [more]

Membrane technology has been widely applied for water treatment, while membrane fouling still remains a big challenge. The polysaccharides in extracellular polymeric substances (EPS) have been known as a significant type of foulant due to their high fouling propensity. However, polysaccharides have many varieties which definitely behave differently in membrane filtration. Therefore, in this study, different polysaccharides alginate sodium and xanthan gum were chosen to study their effects on membrane fouling in a wide concentration range. The results demonstrated that the filtration behaviors of alginate sodium and xanthan gum were completely different, which was due to their different molecular structures. Alginate had a small molecular weight and it was easy for alginate to penetrate membrane pores resulting in pore blocking. A series of concentrations of alginate including 5 mg/L, 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L, and 50 mg/L were examined and it was found that the permeate flux d... [more]

Repositories of historical tungsten mining tailings pose environmental risks, but are also potential resources for valuable metals. They still contain large tonnages of useful minerals and metals, reflecting the inefficient extraction methods and/or low metal prices at the time they were mined. The focus of this study is to evaluate the technical viability of reprocessing the tailings to recover some of the contained valuable minerals and metals, as well as reducing the negative environmental impact associated with the tailings. Geometallurgical studies were conducted on drill core samples taken from the Smaltjärnen tailings repository of the closed Yxsjöberg tungsten mine, Sweden. The collected samples were characterized physically, chemically, and mineralogically. Knelson concentrator dry low- and high-intensity magnetic separation methods were tested as potential beneficiation methods. The tailings are dominated by the −600 to +149 µm particles. The highest concentration of tungsten... [more]

Improperly treated or directly discharged into the environment, wastewater containing dyes can destroy the quality of water bodies and pollute the ecological environment. The removal of dye wastewater is urgent and essential. In this study, corn stalk was pyrolyzed to pristine biochar (CSBC) in a limited oxygen atmosphere and modified using KOH and H3PO4 (KOH-CSBC, H3PO4-CSBC, respectively). The biochars were characterized by surface area and pore size, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), as well as their behavior in adsorbing methylene blue (MB). Results indicated that the pore structure of CSBC became more developed after modification by KOH. Meanwhile, H3PO4-CSBC contained more functional groups after activation treatment. The pseudo-second-order kinetic and the Langmuir adsorption isotherm represented the adsorption process well. The maximum MB adsorption capacity of CSBC, KOH-CSBC, and H3PO4-CSBC was 43.1... [more]

In this research, structural, magnetic properties and photocatalytic activity of cobalt ferrite spinel (CoFe2O4) nanoparticles were studied. The samples were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), transmission electronic microscopy (TEM), Brunauer−Emmett−Teller (BET), Fourier transform infrared spectroscopy (FTIR), and UV-visible diffused reflectance spectroscopy (DRS) analysis. The XRD analysis revealed the formation of the single-phase CoFe2O4 with a cubic structure that is annealed at 500−700 °C in 3 h. The optical band gap energy for CoFe2O4 was determined to be in the range of 1.57−2.03 eV. The effect on the magnetic properties of cobalt ferrites was analyzed by using a vibrating sample magnetometer (VSM). The particle size and the saturation magnetization of cobalt ferrite nanoparticles increased with increasing annealing temperature. The photocatalytic activity of CoFe2O4 nanoparticles was investigated... [more]

Fretting occurs during orthodontic treatment or wearing prosthesis. Although weight of particles is marginal, the total releasing area is more of a concern due to amount and volume of molecules. The aim of the study was to examine the fretting wear resistance of orthodontic and prosthetic alloy Ni-Cr-Mo samples coated with Ti(C, N) and to compare them with samples without any coating. Five groups of cylindrical shape samples (S1−S5) made of Ni-Cr-Mo were coated with Ti(C, N) layers with different content of C and N. The control group (S0) was without layer. The alloys underwent fretting wear resistance tests with amplitude 100 μm, at frequency 0.8 Hz with averaged unit load: 5, 10, and 15 N for 15 min. The samples were subjected to microscopic observations using scanning electron microscope and a laser scanning microscope. Samples with Ti(C, N) coatings revealed higher fretting wear resistance. The wear in each case with Ti(C, N) coatings was over twice as low. The lowest wear and thus... [more]

Triangular silver nanoplates were prepared by using the seeding growth approach with the presence of citrate-stabilized silver seeds and a mixture of gelatin−chitosan as the protecting agent. By understanding the critical role of reaction components, the synthesis process was improved to prepare the triangular nanoplates with high yield and efficiency. Different morphologies of silver nanostructures, such as triangular nanoplates, hexagonal nanoprisms, or nanodisks, can be obtained by changing experimental parameters, including precursor AgNO3 volume, gelatin−chitosan concentration ratios, and the pH conditions. The edge lengths of triangular silver nanoplates were successfully controlled, primarily through the addition of silver nitrate under appropriate condition. As-prepared triangular silver nanoplates were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), UV-Vis, Fourier transform infrared spectroscopy (FT-IR), and X-Ray diffraction (XRD). Si... [more]

The effect of CuO as a sintering additive on the electrolyte of solid oxide electrolysis cells (SOECs) was investigated. 0.5 wt% CuO was added into Sc0.1Ce0.05Gd0.05Zr0.89O2 (SCGZ) electrolyte as a sintering additive. An electrolyte-supported cell (Pt/SCGZ/Pt) was fabricated. Phase formation, relative density, and electrical conductivity were investigated. The cells were sintered at 1373 K to 1673 K for 4 h. The CuO significantly affected the sinterability of SCGZ. The SCGZ with 0.5 wt% CuO achieved 95% relative density at 1573 K while the SCGZ without CuO could not be densified even at 1673 K. Phase transformation and impurity after CuO addition were not detected from XRD patterns. Electrochemical performance was evaluated at the operating temperature from 873 K to 1173 K under steam to hydrogen ratio at 70:30. Adding 0.5 wt% CuO insignificantly affected the electrochemical performance of the cell. Activation energy of conduction (Ea) was 72.34 kJ mol−1 and 74.93 kJ mol−1 for SCGZ and... [more]

Membrane technology has been one of the most promising techniques to solve the water problem in future. Unfortunately, it suffers from the fouling problem which is ubiquitous in membrane systems. The origin of the bewilderments of the fouling problem lies in the lack of deep understanding. Recent studies have pointed out that the molecular structure of foulant affects its fouling propensity which has been ignored in the past. In this study, the filtration behaviors of alginate blocks derived from the same source were comprehensively explored. Alginate blocks share the same chemical composition but differ from each other in molecular structure. The alginate was first extracted from natural seaweed using calcium precipitation and ion-exchange methods. Extracted alginate was further fractionized into MG-, MM- and GG-blocks and the characteristics of the three blocks were examined by Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) obse... [more]

Global warming due to the emission of carbon dioxide (CO2) has become a serious problem in recent times. Although diverse methods have been offered, adsorption using activated carbon (AC) from agriculture waste is regarded to be the most applicable one due to numerous advantages. In this paper, the preparation of AC from rubber-seed shell (RSS), an agriculture residue through chemical activation using potassium hydroxide (KOH), was investigated. The prepared AC was characterized by nitrogen adsorption−desorption isotherms measured in Micrometrices ASAP 2020 and FESEM. The optimal activation conditions were found at an impregnation ratio of 1:2 and carbonized at a temperature of 700 °C for 120 min. Sample A6 is found to yield the largest surface area of 1129.68 m2/g with a mesoporous pore diameter of 3.46 nm, respectively. Using the static volumetric technique evaluated at 25 °C and 1.25 bar, the maximum CO2 adsorption capacity is 43.509 cm3/g. The experimental data were analyzed using... [more]

This study examined change in pore structure and microstructure of nanoporous carbon after surface oxidation and how it affects the adsorption performance of metronidazole antibiotics. The surface oxidation was performed by hydrogen peroxide at 60 °C. The properties of porous carbon were investigated by N2-sorption analysis (pore structure), scanning electron microscopy (surface morphology), the Boehm titration method (quantification of surface functional group), and Fourier transform infrared spectroscopy (type of surface functional group). The results showed that the oxidation of porous carbon by hydrogen peroxide has a minor defect in the carbon pore structure. Only a slight decrease in specific surface area (8%) from its original value (973 m2g−1) was seen but more mesoporosity was introduced. The oxidation of porous carbon with hydrogen peroxide modified the amount of oxide groups i.e., phenol, carboxylic acid and lactone. Moreover, in the application the oxidized carbon exhibited... [more]

Ionic liquids, which are classified as new solvents, have been identified to be potential solvents in the application of CO2 capture. In this work, six ammonium-based protic ionic liquids, containing ethanolammonium [EtOHA], tributylammonium [TBA], bis(2-ethylhexyl)ammonium [BEHA] cations, and acetate [AC] and butyrate [BA] anions, were synthesized and characterized. The thermophysical properties of the ammonium-based protic ionic liquids were measured. Density, ρ, and dynamic viscosity, η, were determined at temperatures between 293.15 K and 363.15 K. The density and viscosity values were correlated using empirical correlations and the thermal coefficient expansion, αp, and molecular volume, Vm, were estimated using density values. The thermal stability of the ammonium-based protic ionic liquids was investigated using thermogravimetric analyzer (TGA) at a heating rate of 10 °C·min‒1. The CO2 absorption of the ammonium-based ionic liquids were measured up to 20 bar at 298.15 K. From th... [more]

As a promising candidate for expanding the capacity of drug loading in silica nanoplatforms, hollow mesoporous silica nanoparticles (HMSNs) are gaining increasing attention. In this study, porous nanosilica (PNS) and HMSNs were prepared by the sol-gel method and template assisted method, then further used for Rhodamine (RhB) loading. To characterize the as-synthesized nanocarriers, a number of techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen absorption-desorption isotherms, dynamic light scattering (DLS), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were employed. The size of HMSN nanoparticles in aqueous solution averaged 134.0 ± 0.3 nm, which could be adjusted by minor changes during synthesis, whereas that of PNS nanoparticles was 63.4 ± 0.6 nm. In addition, the encapsulation of RhB into HMSN nanoparticles to form RhB-loaded nanocarriers (RhB/HMSN) was successful, achieving high loading efficiency... [more]

Focusing on the bottlenecks of traditional physical activation method for the preparation of activated carbons (ACs), we established a simple and scalable method to control the physicochemical structure of ACs and study their CO2 adsorption performance. The preparation is achieved by ammonia activation at different volume fractions of ammonia in the mixture (10%, 25%, 50%, 75%, and 100%) to introduce the nitrogen-containing functional groups and form the original pores and subsequent chemical vapor deposition (CVD) at different deposition times (30, 60, 90, and 120 min) to further adjust the pore structure. The nitrogen content of ACs-0.1/0.25/0.5/0.75/1 increases gradually from 2.11% to 8.84% with the increase of ammonia ratio in the mixture from 10% to 75% and then decreases to 3.02% in the process of pure ammonia activation (100%), during which the relative content of pyridinium nitrogen (N-6), pyrrolidine (N-5), and graphite nitrogen (N-Q) increase sequentially but nitrogen oxygen... [more]

In the present study, amorphous mesoporous silicon oxycarbide materials (SiOC) were successfully synthesized via a low-cost facile method by using potassium hydroxide activation, high temperature carbonization, and acid treatment. The precursors were obtained from floating plants (floating moss, water cabbage, and water caltrops). X-ray diffraction (XRD) results confirmed the amorphous Si−O−C structure and Raman spectra revealed the graphitized carbon phase. Floating moss sample resulted in a rather rough surface with irregular patches and water caltrops sample resulted in a highly porous network structure. The rough surface of the floating moss sample with greater particle size is caused by the high carbon/oxygen ratio (1: 0.29) and low amount of hydroxyl group compared to the other two samples. The pore volumes of these floating moss, water cabbage, and water caltrops samples were 0.4, 0.49, and 0.63 cm3 g−1, respectively, resulting in thermal conductivities of 6.55, 2.46, and 1.14 W... [more]

A bimetallic metal−organic framework material, which was generated by bridging iron (III) cations and nickel (II) cations with 1,4-Benzenedicarboxylic anions (Fe2Ni-BDC), was synthesized by a solvothermal approach using nickel (II) nitrate hexahydrate and iron (III) chloride hexahydrate as the mixed metal source and 1,4-Benzenedicarboxylic acid (H2BDC) as the organic ligand source. The structure of samples was determined by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and nitrogen physisorption measurements. The catalytic activity and recyclability of the Fe2Ni-BDC catalyst for the Michael addition amidation reaction of 2-aminopyridine and nitroolefins were estimated. The results illustrated that the Fe2Ni-BDC catalyst demonstrated good efficiency in the reaction under optimal conditions. Based on these results, a reaction mechanism was proposed. When the molar ratio of 2-aminopyridine and trans-β-nitrostyrene was 1:1, and the sol... [more]

The development of sustainable lightweight materials is a promising field solution in this era. The production of sustainable materials by replacing coarse aggregates with some lightweight alternative provides a good quality construction material. In this study, rocky coarse aggregates were replaced by an ultra-lightweight material (i.e., expanded polystyrene beads) to produce an equivalent rock-solid mass of concrete. Using an M15 grade of concrete composition, expanded polystyrene (EPS) beads were added in place of aggregates in amounts ranging from 5% to 40% at a water−cement (w/c) ratio of 0.60. The specimen size as per American Society for Testing and Materials (ASTM) specification was 150 mm in diameter and 300 mm in length. Furthermore, statistical analysis for the relationship study for destructive testing (DT) (i.e., compressive test machine) and non-destructive testing (NDT) (i.e., rebound hammer and ultrasonic pulse velocity (UPV)) has been performed at developed specimens u... [more]

The purpose of this study was to mask the bitter taste of nizatidine (NZD) using cation-exchange resins. Amberlite IRP-69 and Dowex-50 containing cross-linked polystyrene backbones were used. The drug resin complexes were prepared by batch process using drug: resin ratios of 1:1, 1:3, and 1:5. The optimum drug: resin ratio and the time required for maximum percentage drug loading into the complexes were determined. The selected drug-resin complexes were evaluated for morphology, drug release, and taste. The NZD-Dowex complex was obtained at a drug: resin ratio of 1:5 using a stirring time of 1 h in order to get 100% loading of NZD. The NZD-Dowex complex had a spherical shape and smooth texture similar to Dowex resin. The NZD-Dowex complex with a ratio of 1:5 showed that in vitro drug release of 4.27% at 5 min in simulated salivary fluid of pH 6.8 and 99.67% at 1 h in simulated gastric fluid of pH 1.2. NZD’s bitter taste was effectively masked when it formed a complex with Dowex at a ra... [more]

The micro direct methanol fuel cell (MicroDMFC) is an emergent technology due to its special interest for portable applications. This work presents the results of a set of experiments conducted at room temperature using an active metallic MicroDMFC with an active area of 2.25 cm². The MicroDMFC uses available commercial materials with low platinum content in order to reduce the overall fuel cell cost. The main goal of this work is to provide useful information to easily design an active MicroDMFC with a good performance recurring to cheaper commercial Membrane Electrode Assemblies MEAs. A performance/cost analysis for each MEA tested is provided. The maximum power output obtained was 18.1 mW/cm² for a hot-pressed MEA with materials purchased from Quintech with very low catalyst loading (3 mg/cm² Pt⁻Ru at anode side and 0.5 mg/cm² PtB at the cathode side) costing around 15 euros. Similar power values are reported in literature for the same type of micro fuel cells working at higher oper... [more]