Surface and internal modification of composite ion exchange membranes for removal of molybdate,phosphate, and nitrate from polluted groundwater

Al₂O₃/chitosan-multiwall carbon nanotubes (MWCNTs) were created to increase the exchange capacity of polyvinylidene fluoride (PVDF) ion-exchange membranes. The composite membranes were made by mixing Al₂O₃ nanoparticles into the PVDF cast solution, then applying a thin coating of chitosan functionalized carbon nano tubes (Cs-MWCNTs) to the PVDF membrane surface. The structure and characteristics of the hybrid membranes were described using XRD, SEM, IR, and TG-DTA. The Al₂O₃-PVDF/Cs-MWCNTs membrane beat the other Al₂O₃-PVDF/Cs, Al₂O₃-PVDF, and PVDF membranes in terms of molybdate, phosphate, and nitrate adsorption. The removal efficiency, pH solution, adsorption capacity, and desorption process of molybdate, phosphate, and nitrate anions by Al₂O₃-PVDF and PVDF membranes were investigated. The removal effectiveness of molybdate, phosphate, and nitrate, according to the testing findings, was 94.3, 65.6, and 85.78 %, respectively. The adsorption of MoO₄^2?, PO₄^3?, and NO₃^? increased as the pH increased initially until the best adsorption was achieved, and then decreased significantly as the pH increased further. The total adsorption capabilities of MoO₄^2?, PO₄^3?, and NO₃^?for the Al₂O₃-PVDF/Cs-MWCNTs membrane were 65.50, 61.22, and 59.77 mg/g, respectively. Using regeneration and reuse experiments for the simultaneous adsorption of molybdate, phosphate, and nitrate during three consecutive cycles, the adsorption/desorption of Al₂O₃-PVDF/Cs-MWCNTs was assessed. Al₂O₃-PVDF/Cs-MWCNTs offer a lot of promise when it comes to eliminating MoO₄^2?, PO₄^3?, and NO₃^?from actual wastewater samples.     

Measurement and modeling of metoclopramide hydrochloride (anti-emetic drug) solubility in supercritical carbon dioxide

Knowledge of drug solubility data in supercritical carbon dioxide (SC-CO₂) is a fundamental step in producing nano and microparticles through supercritical fluid technology. In this work, for the first time, the solubility of metoclopramide hydrochloride (MCP) in SC-CO₂ was measured in pressure and temperature range of 12 to 27 MPa and 308 to 338 K, respectively. The results represented a range mole fractions of 0.15 × 10^-5 to 5.56 × 10^-5. To expand the application of the obtained data, six semi-empirical models and three models based on the Peng-Robinson equation of state (PR + VDW, PR + WS + Wilson and PR + MHV1 + COSMOSAC) with different mixing rules and various ways to describe intermolecular interactions were investigated. Furthermore, total enthalpy, sublimation enthalpy and solvation enthalpy relevant to MCP solvating in SC-CO₂ were estimated.     

Preparation of Quercus mongolica leaf-derived porous carbon with a large specific surface area for highly effective removal of dye and antibiotic from water

Quercus mongolica leaf (QL), an easily available biomass, was used as the precursor for preparing the hierarchical porous carbon with a large specific surface area and high adsorption capacities toward the representative dye and antibiotic. After being carbonized, QL was further chemically activated, and potassium hydroxide was proved to be a better activator than sodium hydroxide. The QL-derived porous carbon (PCQL) exhibited abundant micro- and mesopores, and the specific surface area reached 3275 m² g^?1. The performances of PCQL were evaluated through adsorbing rhodamine B (RhB) and tetracycline hydrochloride (TC) from water. Four adsorption isotherm models (the Langmuir, Freundlich, Sips, and Redlich-Peterson models), three adsorption kinetic models (the pseudo-first-order, pseudo-second-order, and intra-particle diffusion models), and the thermodynamic equations were used to investigate the adsorption processes. The pseudo-second-order kinetic model and the Sips isotherm model fitted the experimental data well, which indicates that the adsorption processes were controlled by the amount of adsorption active sites on the surface of PCQL, and these adsorption active sites had different affinities for the adsorbates. The maximum adsorption capacities of PCQL toward RhB and TC were 1946.0 and 1479.6 mg g^?1, respectively, based on the Sips model. The thermodynamic analysis indicates that the adsorption of PCQL toward adsorbents was spontaneous physical processes accompanied by the increasing disorder degree. The adsorption mechanism was attributed to the combination of the pore-filling, hydrogen bond, and π-π interactions. Moreover, in the fixed-bed experiments, the Yoon-Nelson model fitted the breakthrough curves well, and about 8 L wastewater containing RhB (200 mg L^?1) may be effectively treated by 1.0 g of PCQL. Above results indicate that QL is a promising precursor for preparing functional porous carbon materials.     

Submicron carbon-based hybrid nano-pour-point depressant with outstanding pour point depressant and excellent viscosity depressant

We have investigated the effective utilization potential of carbon nanomaterials in the field of pour point depressants, and reported three kind of carbon-based hybrid nano-pour-point depressants with different dimensions. In this paper, poly-α-olefins-acrylate high-carbon ester pour point depressant (PAA-18) was prepared by esterification and polymerization as the basic pour point depressant. Then, the basic pour point depressant PAA18 was modified by solvothermal method with graphene oxide (GO), carbon nanospheres (Cna) and carbon nanotubes (OCNTs). The morphology and structure of the composites were analyzed by SEM, FTIR and XRD. The results showed that PAA18 was successfully in situ polymerized on GO, Cna and OCNTs. We took the simulated oil as the experimental object, and evaluated its pour point, rheological properties and wax crystal morphology, and achieved excellent results. In the three carbon-based hybrid nano-pour-point depressants with different carbon contents, the oxidation carbon nanotubes composite pour point depressant (PAA18-1 % OCNTs) with carbon content of 1 % had the best pour point and viscosity reduction effect when the dosage was 1250 ppm, which could make the pour point of the simulated oil containing wax decrease by 16 °C. PAA18-1 % OCNTs reduced the pour point by 5 °C more than PAA18. This paper provides reference for the application of carbon nanomaterials in the field of pour point depressant.     

Design of fluorescence system based on rutin functionalized gold nanoparticles: Sensitive detection of etimicin via a smartphone in the food and human samples

The abuse and contamination of antibiotics have long been a hot issue of global concern. On the basis of inner filter effect (IFE), this article established the fluorescence detection system of a mixture of Rutin-AuNPs and 7-hydroxycoumarin, realizing the rapid and sensitive detection of etimicin. The system was also successfully applied to actual samples through a smartphone sensing platform. Due to the antioxidant property of rutin, Rutin-AuNPs were green synthesized with uniform particle size, good monodispersity, and favorable stability. As a good fluorescent quencher, Rutin-AuNPs could effectively quench the fluorescence of 7-hydroxycoumarin based on IFE with a quenching percent of 89.81 %. However, etimicin could bind tightly to the surface of Rutin-AuNPs through charge attraction, Au-N bond, and affinity between sugars, leading to the replacement of 7-hydroxycoumarin. In addition, one or more of the above effects caused aggregation of Rutin-AuNPs, leading to fluorescence recovery rapidly. A linear response between the fluorescence system and etimicin was reasonably established with detection limits as low as 0.12 μM. This system was successfully applied to real sample detection. Moreover, the great potential smartphone sensing platform was also built for practical application owing to its advantages of digitalization and portability.     

Adatom Defect Induced Spin Polarization of Asymmetric Structures

The spin polarization of carbon nanomaterials is crucial to design spintronic devices. In this paper, the first-principles is used to study the electronic properties of two defect asymmetric structures, Cap-(9, 0)-Def [6, 6] and Cap-(9, 0)-Def [5, 6]. We found that the ground state of Cap-(9, 0)-Def [6, 6] is sextet and the ground state of Cap-(9, 0)-Def [5, 6] is quartet, and the former has a lower energy. In addition, compared with Cap-(9, 0) CNTs, the C adatom on C₃₀ causes spin polarization phenomenon and Cap-(9, 0)-Def [6, 6] has more spin electrons than Cap-(9, 0)-Def [5, 6] structure. Moreover, different adsorb defects reveal different electron accumulation. This finding shows that spin polarization of the asymmetric structure can be adjusted by introducing adatom defects.     

New Insight on Carbon Dioxide-Mediated Hydrogen Production**

A new approach to hydrogen production from water is described. This simple method is based on carbon dioxide-mediated water decomposition under UV radiation. The water contained dissolved sodium hydroxide, and the solution was saturated with gaseous carbon dioxide. During saturation, the pH decreased from about 11.5 to 7–8. The formed bicarbonate and carbonate ions acted as scavengers for hydroxyl radicals, preventing the recombination of hydroxyl and hydrogen radicals and prioritizing hydrogen gas formation. In the presented method, not yet reported in the literature, hydrogen production is combined with carbon dioxide. For the best system with alkaline water (0.2 m NaOH) saturated with CO₂ under UV-C, the hydrogen production amounted to 0.6 μmol h⁻¹ during 24 h of radiation.     

FeO(OH)@C-Catalyzed Selective Hydrazine Substitution of p-Nitro-Aryl Fluorides and their Application for the Synthesis of Phthalazinones

An efficient hydrazine substitution of p-nitro-aryl fluorides with hydrazine hydrates catalyzed by FeO(OH)@C nanoparticles is described. This hydrazine substitutions of p-nitro-aryl fluorides bearing electron-withdrawing groups proceeded efficiently with high yield and selectivity. Similarly, hydrogenations of p-nitro-aryl fluorides containing electron-donating groups also smoothly proceeded under mild conditions. Furthermore, with these prepared aryl hydrazines, some phthalazinones, interesting as potential structures for pharmaceuticals, have successfully been synthesized in high yields.     

Flexible carbon membrane supercapacitor based on γ-cyclodextrin-MOF

Supercapacitors (SCs) with high energy density and power density are a research hotspot. Herein, we report a flexible porous carbon membrane supercapacitor prepared by electrospinning polyacrylonitrile (PAN) with γ-cyclodextrin-MOF (γ-CD-MOF) and then carbonizing at 900 °C. BET results showed that the supercapacitor retained the skeleton of γ-CD, γ-CD-MOF and the pores formed by the spun-fibers, which were 0.73, 1.09 and 23–186 nm, respectively, showing a high specific surface area of 134.7 m²/g. The hierarchically porous structures ensure rapid charge transfer and ion diffusion, resulting in the PAN/γ-CD-MOF carbon electrode with a high capacity of 283.3 F/g. Moreover, the supercapacitor had a high energy density up to 17.5 Wh/kg and power density up to 6 kW/kg. Significantly, it showed excellent cycle stability with a capacitance retention of 97.5% after 6000 cycles. This work provides a supramolecular strategy to construct a flexible porous carbon membrane, which has potential for supercapacitor applications.     

Synthesis of activated carbon foams with high specific surface area using polyurethane elastomer templates for effective removal of methylene blue

Carbon foams have gained significant attention due to their tuneable properties that enable a wide range of applications including catalysis, energy storage and wastewater treatment. Novel synthesis pathways enable novel applications via yielding complex, hierarchical material structure. In this work, activated carbon foams (ACFs) were produced from waste polyurethane elastomer templates using different synthesis pathways, including a novel one-step method. Uniquely, the produced foams exhibited complex structure and contained carbon microspheres. The ACFs were synthesized by impregnating the elastomers in an acidified sucrose solution followed by direct activation using CO₂ at 1000 ℃. Different pyrolysis and activation conditions were investigated. The ACFs were characterized by a high specific surface area (S_BET) of 2172 m²/g and an enhanced pore volume of 1.08 cm³/g. Computer tomography and morphological studies revealed an inhomogeneous porous structure and the presence of numerous carbon spheres of varying sizes embedded in the porous network of the three-dimensional carbon foam. X-ray diffraction (XRD) and Raman spectroscopy indicated that the obtained carbon foam was amorphous and of turbostratic structure. Moreover, the activation process enhanced the surface of the carbon foam, making it more hydrophilic via altering pore size distribution and introducing oxygen functional groups. In equilibrium, the adsorption of methylene blue on ACF followed the Langmuir isotherm model with a maximum adsorption capacity of 592 mg/g. Based on these results, the produced ACFs have potential applications as adsorbents, catalyst support and electrode material in energy storage systems.