In-vitro drug release kinetics studies of mesoporous SBA-15-azathioprine composite

The mesoporous silica (or SBA-15) was loaded with azathioprine drug. Azathioprine drug was incorporated into mesoporous silica by post impregnation method to reduce its toxic effects by controlling the drug release property. The synthesized pure SBA-15 and SBA-15-azathioprine composite were characterized by UV–visible spectrophotometry, thermo-gravimetric analysis, small and large angle powder X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption–desorption analysis. The successful inclusion of azathioprine drug in host material SBA-15 was confirmed by the reduced surface area (114 m²/g) and pore diameter (6.5 nm) of the organic–inorganic composite material. The drug entrapment efficiency of 90.67 % and loading efficiency of 72.67 % was achieved. The azathioprine drug release process from the mesoporous silica to simulated gastric, intestinal and body fluid were examined and the controlled release effect of the azathioprine drug in all fluids were studied. The Korsmeyer–Peppas model fits well the drug release data with the non-Fickian diffusion model and zero order kinetics for produced mesoporous silica. The controlled drug release enhanced the bioavailability and reduces its repeated administration. Hence, the composite drug can reduce the toxicity and side effects of the azathioprine.     

Removal of glyphosate from aqueous solution by CuO coated MIL-101(Fe)

The composite of CuO coated MIL-101(Fe) (CuO@MIL-101(Fe)) was successfully prepared using a one-pot hydrothermal technology. X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Brunauer–Emmett–Teller (BET), and TG technologies were used to characterize its structural, morphological, and physicochemical properties. CuO@MIL-101(Fe) exhibited a better pH adaptivity, a faster removal ratio of 95.8% for glyphosate within 10 min at pH 7, and a higher selectivity of adsorption capacity, even reaching 231.6 and 233.5 mg g⁻¹ with coexisting Cl⁻ (10 mmol L⁻¹) and SO₄²⁻ (10 mmol L⁻¹). The enhanced adsorption performances of CuO@MIL-101(Fe) may be caused by Cu forming a coordination interaction with glyphosate. A possible mechanism of glyphosate removal was discussed on the basis of the FTIR and X-ray photoelectron spectroscopy (XPS) analysis. CuO@MIL-101(Fe) composite would be more favourable to capture glyphosate from wastewater.     

Porous silica supported Co2+-tetrachlorophthalocyanine (CoPcCl-APTES@SiO2): a novel and recyclable organic–inorganic hybrid catalyst for eco-friendly oxidation of secondary alcohols

A novel, selective and recyclable cobalt based catalyst has been synthesized by covalent grafting of Co²⁺-tetrachlorophthalocyanine (CoPcCl) onto porous silica functionalized with 3-aminopropyltriethoxysilane (APTES), and the resulting organic–inorganic hybrid porous material was found to be highly effective catalyst for peroxidative oxidation of secondary alcohols. The porous material was characterized by elemental analysis, diffuse reflectance UV–Visible spectroscopy, ¹³C CPMAS and ²⁹Si CPMAS NMR spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), BET surface area analysis, Energy dispersive X-ray fluorescence (ED-XRF), Fourier transform Infrared (FT-IR) and Atomic absorption spectroscopy (AAS) techniques. High turnover frequency, mild reaction conditions, high selectivity for ketones, and easy recovery and reusability of the catalyst renders the present protocol highly essential to address the industrial needs and environmental concerns.     

CuO/腐植酸复合材料的制备及其吸附性能

采用水热法合成了CuO-腐植酸（HA）纳米复合材料,研究了其对亚甲基蓝的初始吸附性能及再生吸附性能。运用扫描电镜/能谱仪（SEM/EDS）、傅里叶变换红外光谱仪（FTIR）、X射线粉末衍射仪（XRD）、激光粒度分析仪和比表面积测定仪（BET）对其结构进行了表征。研究了pH、亚甲基蓝初始浓度和反应温度等因素对CuO/HA吸附亚甲基蓝的影响,采用多种模型研究了CuO/HA复合材料对亚甲基蓝的吸附动力学和热力学行为。结果表明：合成的CuO/HA平均粒径约为135.0nm,比表面积为188.15m²/g。CuO/HA对亚甲基蓝（MB）的吸附动力学行为符合拟一级动力学模型,在60min内达到吸附平衡,较好地符合Frendlich吸附模型。在室温下pH=7时,CuO/HA复合材料初始饱和吸附量达172.01mg/g;循环使用8次,可保持初始吸附能力的89.27%,表明有较好的吸附性能,可作为一种有效除去水体中亚甲基蓝污染物的高容量吸附材料。     

Preparation of graphene oxide/carboxymethyl chitosan/polyvinyl alcohol composite nanofiber membranes by electrospinning for heavy metal adsorption

In this paper, a graphene-oxide/carboxymethyl-chitosan/polyvinyl-alcohol (GO/CMC/PVA) composite nanofiber membrane was prepared by electrospinning and cross-linking with glutaraldehyde (GA) to improve the water resistance. The composite nanofiber membrane can be used in the field of heavy metal adsorption. The membrane was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effects of GO concentration, adsorption time, and initial concentration of heavy-metal ion (Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺) solution on the adsorption performance of the fiber membranes were investigated. The results showed that the addition of GO can reduce the diameter of nanofibers. GO, CMC, and PVA exhibited good compatibility, and the intermolecular hydrogen bonding improved. The addition of GO also improved the crystalline properties of the composite fiber membrane. In the optimal cross-linking condition, GA was saturated by steam cross-linking for 6 h. The introduction of GO improved the adsorption capacity of the membrane for heavy metals in water. The utmost adsorption capacities for Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺ were 262.1, 237.9, 319.3, and 413.6 mg/g when using the cross-linked composite fiber membranes, respectively. The results of adsorption kinetics and thermodynamics showed that the adsorption process accorded with the pseudo-second-order kinetic model and Langmuir–Freundlich isotherm model.     

Sorption characteristics of lead cations on microporous organo-birnessite

The aim of this study was to examine the adsorption characteristics of cationic surfactant modified-birnessite for removal of Pb. For this purpose, Na-birnessite and tetramethylammonium (TMA) cation were used as an inorganic host and cationic surfactant, respectively. Na-birnessite was synthesized by the oxidation of Mn^2 + under alkaline condition, and TMA cation was intercalated in the interlayer of H-birnessite prepared from Na-birnessite.Batch isotherm tests were carried out to investigate the adsorption capacity of the TMA-birnessite for Pb. The characterization of all synthetic birnessites was carried out with powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) specific surface area measurements. Also, Fourier transform infrared spectroscopy (FT-IR) was used to investigate sorption behavior of Pb onto TMA-birnessite. TMA-birnessite was found to have higher adsorption ability for Pb than synthetic Na-birnessite and commercial granular activated carbon (GAC). This result suggests that the synthetic organo-birnessites could be effective sorbents for removal of heavy metals from groundwater.     

Synthesis of citric acid modified β-cyclodextrin/activated carbon hybrid composite and their adsorption properties toward methylene blue

In this article, citric acid modified β-cyclodextrin/activated carbon hybrid (CA-β-CD/AC) composites were synthesized by crosslinking reaction, and their adsorption properties for methylene blue were studied. The scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and Brunauer–Emmett–Teller (BET) method were used to characterize the structure and the morphology of composite materials. It was investigated that the effect of experiment parameters on the adsorption performance including weight fraction of AC in the composite, the adsorbent dose, the initial concentration of MB, the solution pH value, contact time, and temperature. The maximum adsorption capacity calculated by the Langmuir isotherm is 862.07 mg g⁻¹. Kinetic studies show that the adsorption process follows the pseudo-first-order and pseud-second-order reaction models. Thermodynamic analysis indicated that the adsorption behavior was an exothermic reaction. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48315.     

Petrography,textural, morphological and structural characteristics of tuffite for Cu(II) removal. Effect of adsorption process variables

Tuffite has been studied for Cu(II) adsorption from aqueous and ammoniacal solutions. Tuffite was characterized by mercury porosimetry, Brunnauer–Emmet–Teller (BET), scanning electron microscopy–energy X-ray dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectra (FTIR), X-ray powder diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-OES) and petrographic microscopy. The equilibrium time was 50 min. The second-order model is the best model to describe the process. It was determined that the intraparticle diffusion was not the only limited step. Process variables were studied to improve the adsorption process. The material washed contributes to increase the Cu(II) adsorption from 213.05 to 276 mg/g. The flow countercurrent system requires at least 6 g of tuffite to achieve 90% of removal.     

Electrosynthesis of polyaniline-based composite films and their electrochemical activity

Herein, we report the synthesis of organic–inorganic hybrids of polyaniline-rGO-ZnO (PRZ) ternary composite materials for a potential application in dye-sensitized solar cell (DSSC). A facile all-electrochemical method was adopted for the deposition of PRZ films on FTO-coated glass substrate. The PRZ hybrid assembly was subsequently characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), cyclic voltammetry, and photoelectrochemical measurements. Further, the morphological and elemental composition features of PRZ were monitored by field emission SEM and EDX, respectively. Electrochemical impedance spectra suggest that the charge–transfer resistance for the ternary composite is distinctly decreased. The maximum conversion efficiency of DSSC with PRZ counter electrode reaches 2.84%, which is higher than that of polyaniline-reduced graphene oxide (rGO) counter electrode. This ternary composite (PRZ) with organic–inorganic hybrid architecture showing an enhanced photoelectrochemical activity might be exploited in future as a promising material for application in next-generation solar devices.     

Triton X-100 directed synthesis of mesoporous γ-Al2O3 from coal-series kaolin

Mesoporous γ-Al₂O₃ has been successfully synthesized by using calcined coal-series kaolin as raw material and Triton X-100 (TX-100) as template. The effect of TX-100/Al^3 + ratio on the structural and textural properties of mesoporous γ-Al₂O₃ was investigated. Physical properties of obtained samples were characterized by X-ray diffraction (XRD), N₂ adsorption–desorption, transmission electron microscopy (TEM), thermogravimetric analysis (TG), scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDAX) and Fourier transform infrared spectroscopy (FTIR). The results indicated that the amount of TX-100 influenced the structure and porous properties of mesoporous γ-Al₂O₃ significantly. When TX-100/Al^3 + ratio was in the range of 0.03–0.15, all samples had mesoporous structures with BET surface area of 193.0–261.0 m²/g and pore size of 5.04–6.71 nm. In addition, the reaction mechanism involved in the process was proposed and discussed.     

The adsorption behavior of C.I. Acid Blue 9 onto calcined Mg–Al layered double hydroxides

Mesoporous calcined Mg–Al layered double hydroxides with different Mg/Al molar ratios were investigated for their ability to adsorb the commercial dye, C.I. Acid Blue 9, with a view to exploring their suitability as inorganic pigments in Ink Receptive Layer formulation. Uptake capacity was characterized using the Langmuir model and the resulting L-2/H-2 type plots indicated that the acid dye anions were adsorbed onto the surface by strong interactions. Optimum dye adsorption was achieved for a Mg/Al molar ratio ≈5.6. A surface adsorption mechanism is proposed to account for the adsorption of the dye onto the calcined Mg–Al layered double hydroxides. X-ray powder diffraction analysis indicated that given sufficient time it is possible to intercalate the dye within the layered double hydroxides' interlayer via a reconstruction mechanism. Scanning electron microscopy, N₂ adsorption–desorption analysis and helium pycnometry were employed to examine the textural properties of the materials, which were correlated with their adsorption properties.     

Phosphate removal,mechanism, and adsorption properties of Fe-Mn-Zn oxide trimetal alloy nanocomposite fabricated via co-precipitation method

ABSTRACT

Fe-Mn-Zn oxide trimetal alloy nanocomposite (FMZONC) fabricated and surface properties of the composite material revealed via several characterization methods. Porous nature and alloy type mixing of metals deduced from transmission electron microscopy analysis. Field emission scanning electron microscopy image revealed composite material is of size between 7 and 16 nm. The adsorption properties investigated through isotherm and kinetic experiments. In addition, pH effects and desorption properties were also studied. Maximum adsorption capacity (q max) 149 mg/g for phosphate removal observed at pH 6 and 0.20 g/L of adsorbent. Chemical interaction between metal hydroxide and phosphate elaborated from Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).     

Cu(II) ions removal from wastewater using starch nanoparticles (SNPs): An eco-sustainable approach

The complex structured starch particles were reduced to the nanoscale size range through hydrolysis utilizing low concentration acid assisted by ultrasound irradiation. The synthesized starch nanoparticles (SNPs) were characterized by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD) techniques. The synthesized SNPs possessed surface activated entities, as many cationic functional groups were confirmed through the FTIR spectrum. Also, these SNPs were effectively utilized to separate heavy Cu metal ions from the synthetic ion solution. The SNPs were characterized using field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis for the surface modification after the adsorption process. The weak electrostatic interaction between the SNP surface and Cu ion was confirmed by the XPS spectrum and energy-dispersive X-ray spectroscopy. The maximum efficiency of Cu ions removal was about 93% at an optimal pH 5 and 25 mg/ml dosage. The adsorption equilibrium was obtained in 60 min. The nitrogen isotherm BET analysis of SNPs after adsorption shows a higher specific surface area of 18.552 m²/g, attributed to the interaction and presence of Cu ions on the SNP surface. The process feasibility was validated by the Langmuir isotherm model. The process exhibits pseudo-second-order adsorption kinetics and follows the Langmuir isotherm. The R_L predicted by the Langmuir isotherm mechanism is 0.017, implying favourable adsorption. The process is reproducible and allows for the separation of heavy metal ions from the wastewater through biosorption effectively.     

Development of an activated carbon-geopolymer composite for treatment of Pb(II) polluted water and soil

An activated carbon-geopolymer composite (ACGC) was prepared by using fly ash as raw materials via a simple geopolymerization process for treating the Pb(II) contaminant in wastewater and soil. The phase composition, microtopography, pore structure, and surface groups of the composites were studied by X-ray diffractometer, field emission scanning electron microscopy, X-ray photoelectron spectroscopy, N₂ adsorption-desorption isotherm, and Fourier transform infrared spectroscope. It was discovered that there was a synergistic effect between geopolymer matrix and activated carbon (AC), that is, addition of AC particles could increase the pores in geopolymer while strong alkalis condition provided by geopolymer enhanced the contents of oxygenic groups of AC. When the composite was used as the adsorbent, the sample containing 20 wt% AC (40ACGC) showed the maximum adsorption capacity (319.72 mg/g), and its adsorption isotherm fitted the Langmuir model well, suggesting the monolayer adsorption of Pb²⁺ on the 40ACGC. The kinetics of Pb²⁺ adsorption on the 40ACGC belonged to the pseudo-second-order model, indicating that Pb²⁺ adsorption on the composite followed chemical adsorption. In addition, the 40ACGC sample showed excellent stabilization performance for Pb²⁺ in soil. This work offered a new thinking to the application of geopolymers into remediation of heavy metal-polluted soil.     

Preparation of Ag@AgI-intercalated K4Nb6O17 composite and enhanced photocatalytic degradation of Rhodamine B under visible light

In this study, a novel plasmonic photocatalyst, Ag@AgI intercalated layered niobate, was synthesized via a microwave-assisted ion-exchange method. The composite materials prepared were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray fluorescence spectrometry (XRF), Brunauer–Emmett–Teller (BET) and ultraviolet–visible diffuse reflection spectra (UV–vis). The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photocatalytic performance for the degradation of Rhodamine B (RhB) and up to 83% of RhB was degraded in 40 min under visible light irradiation. The mechanism of separation of the photo-generated electrons and holes at the K₄Nb₆O₁₇/Ag@AgI composite was discussed.     

Electrically conductive polyaniline-titanium(IV)molybdophosphate cation exchange nanocomposite: Synthesis,characterization and alcohol vapour sensing properties

Electrically conductive polyaniline-titanium(IV)molybdophosphate (PANI-TMP) cation exchange nanocomposite was studied as sensing material for aliphatic alcohols (methanol, ethanol and 1-propanol) at room temperature. The nanocomposite was synthesized by sol–gel mixing of polyaniline (PANI) into inorganic precipitate of titanium(IV)molybdophosphate (TMP) and characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA) and ultraviolet-visible spectroscopy (UV-Vis). The composite showed good ion-exchange capacity, electrical conductivity and resistivity response towards alcohol vapours. It was observed that the sensor show good reversible response towards methanol vapours compared to ethanol and 1-propanol vapours. These studies suggest that the nanocomposite cation exchanger could be a good sensing material for methanol vapours at room temperature (25 °C).     

Facile preparation of Bi-doped ZnO/β-Bi2O3/Carbon xerogel composites towards visible-light photocatalytic applications: Effect of calcination temperature and bismuth content

This work aimed to study the development and properties of Bi-doped ZnO/β-Bi₂O₃/Carbon xerogel composites towards visible light photocatalysis applications. The materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, dispersive energy spectroscopy, infrared spectroscopy, nitrogen adsorption isotherms, Raman spectroscopy, diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activity of the developed composites was evaluated through the photodegradation of the 4-chlorophenol molecule and by chronoamperometry tests. The results obtained show that the calcination temperature poses a major influence in the final structure of the materials developed. The calcination temperature of 600 °C resulted in the formation of the β-Bi₂O₃ and Bi⁰ phases, consequently enhancing the photocatalytic activity of the composites due to the increased charge mobility provided by the heterojunctions between zinc oxide, carbon xerogel, bismuth oxide and metallic bismuth. The composite with intermediate bismuth composition (XC/ZnO–Bi₂O₃ 5%) displayed the best photocatalytic response among the materials tested, which was confirmed by its increased photocurrent generation capability. The photocatalytic mechanism is highly dependent in the generation of hydroxyl radicals and the composite presents good reusability properties.     

Synthesis, characterization and electrochemical properties of the V2O5·nH2O/AlO(OH)·nH2O xerogel composite

In this work, we report the synthesis, characterization and electrochemical properties of a new multicomponent material obtained from the polymerization of vanadium pentoxide in an inorganic matrix (alumina xerogel), forming a xerogel composite. The material has been characterized by X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, electron microscopy, energy dispersive X-ray spectrometry, cyclic voltammetry and impedance spectroscopy. It was found that the V₂O₅ xerogel is dispersed in the alumina matrix, but its lamellar structure is not strongly affected, thus, its conductivity properties are maintained. Moreover, the electrochemical behaviour of the V₂O₅ xerogel dispersed in the alumina matrix is quite similar to that found for the V₂O₅ xerogel alone and the inorganic matrix leads to stabilization of V₂O₅ xerogel structure.     

PPy–TiO2–phenylalanine composites as anticorrosive coatings electrodeposited over Fe–C steel surface in the marine environment

Abstract

Electro-polymerized pyrrole composite incorporated with TiO₂ and phenylalanine (Phe) was electrodeposited over Fe–C steel sheet at time intervals of 1200?s and 1500?s using chronopotentiometry. The composite (PPy–TiO₂–Phe) was evaluated against corrosion in 3.5% NaCl solution on Fe–C steel. The composite coated (CC) steel was studied and compared through scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). The anticorrosive impact of CC steel was investigated through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and weight loss techniques in the marine environment and found that the CC steel exhibited the maximum inhibition efficiency up to 90%. A brief overview of the protection mechanism is also proposed.     

Anticorrosion organic coating with layered double hydroxide loaded with corrosion inhibitor of tungstate

Mg–Al layered double hydroxides, loaded with tungstate anions, were synthesized via the co-precipitation method. The obtained compounds were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), inductively coupled plasma (ICP), and transmission electron microscopy (TEM), respectively. The ICP results demonstrated the partial anion-exchange process, involving the release of tungstate anions from layered double hydroxide by the chloride anions. Polarization measurements showed that the filtrate as electrolyte possessed a low corrosion current density value of 3.042 μA/cm². The electrochemical impedance spectroscopy (EIS) exhibited that the coating could effectively protect the alloy from corrosion. The function of the layered double hydroxide loaded with tungstate doped in organic coating was also discussed.