Solid Supported Liquid–Liquid Extraction of Chemical Warfare Agents and Related Chemicals from Water

Solid-supported liquid–liquid extraction was optimized to extract the chemical warfare agents and their non-toxic analogues from water. The developed method was compared to the conventionally used liquid–liquid extraction. This method yielded high recoveries (70–80%) of non-toxic analogues of chemical warfare agents and good recoveries (65–75%) of the nerve agent sarin and Lewisite-III. The limits of detection of non-toxic analogues of CWAs, and toxic sarin and Lewisite-III, in selected ion monitoring and full scan mode, varied from 0.01 to 0.5 μg mL^?1 and 0.1 to 1.0 μg mL^?1 respectively.     

The effect of calcination temperature on the texture of silica gel waste

In this work, the effect of temperature on the texture of silica gel waste is presented and water vapour adsorption in a different humidity is highlighted. It was found that silica gel waste is a mesoporous material with the parallel plates pores. Its specific surface area is equal to 4.61 m² g^?1, and the calculated total pore volume is equal to 9.01 × 10^?3 cm³ g^?1. The texture of silica gel waste changed during calcination in a 188–550 °C temperature interval: S_BET and ΣV_P increased to 11.32 m² g^?1 and 30.06 × 10^?3 cm³ g^?1, respectively. It was determined that the water vapour pressure influenced the mineralogical composition and the quantity of adsorbed water in the samples. The obtained results were confirmed by the differential scanning microcalorimetry, X-ray diffraction, BET and water vapour adsorption analysis data.

     

Radiation induced in-situ generation of conductivity in the blends of polyaniline-base with chlorinated-polyisoprene

Radiation induced acid doping of PANI to generate electrical conductivity was achieved by radiation induced HCl release from chlorinated-polyisoprene (ClPIP). Blends of PANI with ClPIP were prepared by mechanical mixing/grinding in the composition range of 9–43% ClPIP by weight and pelletized under 10 t press. The pellets were irradiated in ⁶⁰Co Gammacell in air at room temperature to doses up to 300 kGy. The maximum electrical conductivity increase was observed for the blend PANI43 which changed from 10^?10 to 10^?4 S cm^?1 when it was irradiated to 300 kGy dose. Radiation induced changes on the blends were also studied by UV–vis spectroscopy using reflection technique and FTIR spectroscopy. The broad absorption band in the visible range (630 nm) increased by increasing irradiation dose. The band (1110 cm^?1) in the IR spectra which is indicative of conductivity showed linear correlation with irradiation dose.     

Prediction of breakthrough curves for multicomponent adsorption in a fixed-bed column using logistic and Gompertz functions

In order to facilely predict the multicomponent breakthrough curves and avoid the complicated numerical solution, this work proposes two empirical models based on the logistic and Gompertz functions. The S-shaped and bell-like curves correspond to the adsorption and displacement processes respectively. The equilibrium loading of each component can be calculated by integration of the measured breakthrough curves. The effects of the model parameters on the breakthrough curves are investigated. The applicability of the two empirical models is validated by three binary and four ternary adsorption systems, including the gas–solid and liquid–solid adsorption. The residual plot and coefficient of determination (R²) are used to evaluate their fitting quality. The results indicate that the fitting curves agree well with the experimental data and all of the residuals are distributed randomly. The five model parameters (k, τ, k*, τ* and c) are easily obtained by the nonlinear regression. For example, the fitting results are k = 1.37 × 10^?2 min^?1, τ = 292 min, k* = 1.25 × 10^?2 min^?1, τ* = 453 min and c = 85.3 for adsorption of n-butyl acetate and p-xylene on granular activated carbon. On the whole, the Gompertz model is superior to the logistic model in terms of the fitting accuracy. The significance of this work is to provide a simple and practical method for prediction of the multicomponent breakthrough curves.     

Synergistic effect of nitrogen and molybdenum on activated carbon matrix for selective adsorptive Desulfurization: Insights into surface chemistry modification

This study reports the synthesis of mesoporous metal-modified nitrogen doped activated carbon (AC-N-Mo) from date seeds by ZnCl₂ activation and its applicability for selective adsorptive desulfurization of dibenzothiophene (DBT). The AC-N-Mo exhibits higher adsorption capacity for DBT at 100 mg-S/L with the maximum removal percentage of 99.7 % corresponding to 19.94 mg-S/g at room temperature than the unmodified carbon with 17.96 mg-S/g despite its highest surface area and pore volume of 1027 m²g^?1 and 0.55 cm³g^?1 respectively. The adsorption capacity breakthrough follows the order AC-N-Mo > AC-Mo > AC > AC-N. Also, AC-N-Mo displays excellent selectivity in the presence of aromatics (toluene, naphthalene, and 1-methylisoquinoline). The enhancement in the DBT uptake capacities of AC-N-Mo is attributed to the synergistic effect of nitrogen heteroatom that aids the dispersion of molybdenum nanoparticles on carbon surface thereby improving its surface chemistry and promising textural characteristics. The kinetic studies showed that the DBT adsorption proceeds via pseudo-second order kinetics while the isotherm revealed that Langmuir fit the data more accurately for the adsorbents. The physical properties (surface area, pore volume, particle size, etc.) and chemical properties (carbon content, etc.) of as-prepared adsorbents namely; AC, AC-N, AC-N-Mo, and AC-Mo were characterized by N₂– physisorption, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Spectroscopy/Energy Dispersive Spectroscopy (SEM/EDS), Raman Spectroscopy (RS), Fourier Transform Infrared Spectroscopy (FTIR) and Ammonia-Temperature-Programmed Desorption (NH₃-TPD).     

Preparation of dummy‐imprinted polymers by Pickering emulsion polymerization for the selective determination of seven bisphenols from sediment samples

The dummy molecularly imprinted polymers were prepared by Pickering emulsion polymerization. 4,4′‐(1‐Phenylethylidene) bisphenol was selected as the dummy template to avoid the leakage of the target bisphenols. The microsphere particles were characterized by scanning electron microscopy and nitrogen adsorption–desorption measurements, demonstrating that the regular‐shaped and medium‐sized particles (40–70 μm) were obtained with a specific surface area of 355.759 m²/g and a total pore volume of 0.561 cm³/g. The molecular imprinting properties of the particles were evaluated by static adsorption and chromatographic evaluation experiments. The association constant and maximum adsorption amount of bisphenol A were 0.115 mmol/L and 3.327 μmol/g using Scatchard analysis. The microsphere particles were then used as a solid‐phase extraction sorbent for selective extraction of seven bisphenols. The method of dummy molecularly imprinted solid‐phase extraction coupled with high‐performance liquid chromatography and diode array detection was successfully established for the extraction and determination of seven bisphenols from environmental sediment samples with method detection limits of 0.6–1.1 ng/g. Good recoveries (75.5–105.2%) for sediment samples at two spiking levels (500 and 250 ng/g) and reproducibility (RSDs < 7.7%, n = 3) were obtained.     

High contrast ratio and fast switching polymeric electrochromic films based on water-dispersible polyaniline-poly(4-styrenesulfonate) nanoparticles

We prepared polyaniline-poly(4-styrenesulfonate) nanoparticles (PANI/PSS-NPs) by chemical oxidation polymerization in aqueous solution. We investigated the potential of the PANI/PSS-NPs to be used as an anode electrode for electrochromic devices and the effect of Li⁺ insertion (or deinsertion) kinetics and diffusion of Li⁺. A uniform electrochromic layer of PANI/PSS-NPs with a size of ca. 28 nm could be obtained by a solution process, specifically spin coating. The PANI/PSS-NPs film has a high Li⁺ diffusion coefficient (～7.7 × 10^?9 cm² s^?1) and low charge transfer resistance (～99 Ω), which result in its having a fast electrochromic response time (coloring time <1.7 s, bleaching time <2.4 s), and high coloration efficiency (>108 cm² C^?1).     

Graphene oxide doped polyaniline for supercapacitors

A novel high-performance electrode material based on fibrillar polyaniline (PANI) doped with graphene oxide sheets was synthesized via in situ polymerization of monomer in the presence of graphene oxide, with a high conductivity of 10 S cm^?1 at 22 °C for the obtained nanocomposite with a mass ratio of aniline/graphite oxide, 100:1. Its high specific capacitance of 531 F/g was obtained in the potential range from 0 to 0.45 V at 200 mA/g by charge–discharge analysis compared to 216 F/g of individual PANI. The doping and the ratio of graphene oxide have a pronounced effect on the electrochemical capacitance performance of the nanocomposites.     

An SFG/DFG investigation of CN− adsorption at an Au electrode in 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ionic liquid

In this paper we report an SFG/DFG investigation of the adsorption of CN^? – used as a probe molecule to study the electrochemical double-layer structure – at a polycrystalline Au electrode in 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl) amide ([BMP][TFSA]) room-temperature ionic liquid (RTIL). The adsorption of CN^? yielded single SFG and DFG bands in the range from ca. 2125 to 2135 cm^?1, exhibiting a Stark tuning of ca. 3 cm^?1 V^?1. Vibrational resonances – corresponding to modes of the RTIL coadsorbed with CN^?, were found in the range from ca. 1200 to 1500 cm^?1. The study of the double-layer structure was complemented by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements, from which the differential double-layer capacity (C_DL) was estimated.     

Optical and electrical conducting properties of Polyaniline/Tin oxide nanocomposite

Polyaniline(PANI)/Tin oxide (SnO₂) hybrid nanocomposite with a diameter 20–30 nm was prepared by co-precipitation process of SnO₂ through in situ chemical polymerization of aniline using ammonium persulphate as an oxidizing agent. The resulting nanocomposite material was characterized by different techniques, such as X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform Infrared spectroscopy (FT-IR) and Ultraviolet–Visible spectroscopy (UV–Vis), which offered the information about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology of the nanocomposite materials and the distribution of the metal particles in the nanocomposite material. SEM observation showed that the prepared SnO₂ nanoparticles were uniformly dispersed and highly stabilized throughout the macromolecular chain that formed a uniform metal-polymer nanocomposite material. UV–Vis absorption spectra of PANI/SnO₂ nanocomposites were studied to explore the optical behavior after doping of nanoparticles into PANI matrix. The incorporation of SnO₂ nanoparticles gives rise to the red shift of π–π¹ transition of polyaniline. Thermal stability of PANI and PANI/SnO₂ nanocomposite was investigated by thermogravimetric analysis (TGA). PANI/SnO₂ nanocomposite observed maximum conductivity (6.4 × 10^?3 scm^?1) was found 9 wt% loading of PANI in SnO₂.     

Application of horseradish peroxidase/polyaniline/bis(2-aminoethyl) polyethylene glycol-functionalized carbon nanotube composite as a platform for hydrogen peroxide detection with high sensitivity at low potential

Polyaniline/O,O′-bis (2-aminoethyl) polyethylene glycol-functionalized multiwalled carbon nanotube (PANI/PEG–MWCNT) composite-modified electrode was successfully prepared by electropolymerization. The ionic transport in PANI/PEG–MWCNT film and its effects on the composite performance are presented. Both protonic and anionic participation in the charge compensation processes were calculated and they indicated that the presence of the PEG–MWCNT in the PANI film suppress the anionic transportation and improve the composite ability in fixing horseradish peroxidase enzyme. Finally, the adsorption between the negatively charged PANI/PEG–MWCNT nanocomposite and the positively charged Horseradish peroxidase resulted in a high sensitivity (1.01 μA L cm^?2 μmol^?1) to hydrogen peroxide. This sensor exhibited a good reproducibility and stability at an applied potential of ?100 mV vs Ag/AgCl.     

Analysis of phenanthrene biodegradation by using FTIR,UV and GC–MS

The aim of this paper is to assess the biodegradation of phenanthrene by Flavobacteria FCN2 which was isolated from coke plant sludge via a classical shaken liquid medium enrichment method. The strain FCN2 can decompose phenanthrene (50 mg l^?1) completely within 5 days. The values of pH decrease to 6.7 from 7.2 during degradation periods. And a detailed phenanthrene metabolism was assayed by using FTIR, UV and GC–MS. For FTIR, appearance of new broad absorption bands at 2858 cm^?1, 2927 cm^?1, 2955 cm^?1 and another new strong absorption band at 1734 cm^?1 in metabolites demonstrates that carboxyl group produced during phenanthrene degradation. Besides this, a very strong absorption band appears at 1260 cm^?1. It is ascribed to C–C stretching vibration band in carbonyl group of arone. Two weak adsorption at 334 nm and 349 nm in UV spectra were assigned to the n-π* transition of CO of aldehyde. Two metabolites, phenanthrene-dihydrodiol and naphthalene-1-diol were identified in neutral fraction of phenanthrene degradation by using GC–MS. As a result carboxylic acids and arone were generated during biodegradation of phenanthrene by Flavobacteria FCN2.     

Electrodeposition of polyaniline on high electroactive indium tin oxide nanoparticles-modified fluorine doped tin oxide electrode for fabrication of high-performance hybrid supercapacitor

In this study, hierarchical polyaniline (PANI) nanosheets were electrochemically deposited on indium tin oxide nanoparticles coated fluorine-doped tin oxide glass (ITONPs-FTO) substrate from an aqueous solution containing 0.5 M aniline and 1 M H₂SO₄. The ITONPs provide efficient support with high electroactive surface area in the electrochemical deposition of PANI and produce excellent PANI films. The developed PANI film deposited on the ITONPs-FTO electrode was characterized via field-emission scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. A hybrid supercapacitor (HSC) was fabricated using the developed PANI deposited ITONPs-FTO as a positrode and the jute sticks derived activated carbon nanosheets coated FTO (JAC-FTO) as a negatrode. Because of its high capacitive performance, unique structures of electrode materials, and optimum operating potential window, the fabricated PANI-ITONPs-FTO//JAC-FTO HSC performed excellently in 0.1 M HCl aqueous electrolyte, delivering a high areal capacitance of 318 mF/cm² at a 1.0 mA/cm² current density and exhibit a high energy density of 28 µWh/cm² at a high power density of 400 µW/cm². Moreover, the HSC exhibits excellent cyclic stability with ～ 87% Coulombic efficiency and ～ 91% capacitance retention after 1000 charge–discharge cycles.     

Near infrared spectroscopy of stearic acid adsorbed on montmorillonite

The adsorption of stearic acid on both sodium montmorillonites and calcium montmorillonites has been studied by near infrared spectroscopy complimented with infrared spectroscopy. Upon adsorption of stearic acid on Ca–Mt additional near infrared bands are observed at 8236 cm^?1 and is assigned to an interaction of stearic acid with the water of hydration. Upon adsorption of the stearic acid on Na–Mt, the NIR bands are now observed at 5671, 5778, 5848 and 5912 cm^?1 and are assigned to the overtone and combination bands of the CH fundamentals. Additional bands at 4177, 4250, 4324, 4337, 4689 and 4809 cm^?1 are attributed to CH combination bands resulting from the adsorption of the stearic acid. Stearic acid is used as a model molecule for adsorption studies. The application of near infrared spectroscopy to the study of this adsorption proved most useful.     

Encapsulation of polyaniline in 3-D interconnected mesopores of silica KIT-6

Composite material PANI/KIT-6, with polyaniline (PANI) chains encapsulated in the 3-D interconnected pore channels of mesoporous silica, KIT-6, has been synthesized via a gas-phase method. The composite formation and the presence of PANI inside the pore channels of KIT-6 were evidenced by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), small-angle X-ray scatter (SAXS), transmission electron microscopy (TEM), and N₂ adsorption–desorption isotherms. The PANI/KIT-6 composite showed good electrical conductivity (2.4 × 10^?3 S/cm) due to the formation of 3-D networks of PANI inside the 3-D interconnected channels of KIT-6. The resistance of PANI/KIT-6 composite at different relative humidities (RH) was investigated. An essentially linear relationship between the relative resistance of the composite and the relative humidity of the environment was found from 11.3% to 97.3% RH.     

Sacrificial template synthesis of ultrathin polyaniline nanosheets and their application in highly sensitive electrochemical dopamine detection

Unique functional nanomaterials as electroactive media for efficiently electrochemical biosensing have always been an ever-increasing topic in biotechnology and environmental fields. In this study, we report a simple sacrificial template-guided polymerization strategy to fabricate ultrathin two-dimensional (2D) polyaniline (PANI) nanosheets for electrochemical detection of dopamine (DA). By using vanadium pentoxide nanosheets as both sacrificial templates and oxidants, the resulting PANI nanosheets show an ultrathin thickness of ca. 4 nm with a favorable electrical conductivity of ca. 10 S cm^?1. Furthermore, PANI nanosheets have been modified on a glass carbon electrode for highly sensitive DA detection. The proposed DA sensor delivers a linear range of 0.5–300 μM with a low detection limit of 0.118 μM (S/N = 3). In addition, the as-fabricated electrochemical sensor exhibits an outstanding selectivity, stability, reproducibility, and repeatability, enabling its feasible application for DA detection in real samples. Therefore, the ultrathin PANI nanosheets reported here are good candidates as electrodes for the sensitive and selective DA detection.     

Monte Carlo simulations of squalane in the Gibbs ensemble

We investigate the liquid–vapour coexistence curve of 2,6,10,15,19,23-hexamethyltetracosane (squalane) near the critical point with a new Lennard–Jones parameter set and compare our results to existing simulation data as well as to recent experimental vapour pressure data. Comparison of the liquid–vapour coexistence curve to previous simulation data reveals that this new force field, which includes tail corrections to the truncation of the non-bonded interactions increases the liquid density. We determine the critical temperature to 829 K and 825 K (with roughly 1% error) for two different system sizes, 72 and 108 molecules, and the critical density to 0.211 g/cm³ and 0.228 g/cm³, respectively. We extrapolate experimental vapour pressure data by use of Antoine's law to the temperature range covered by simulation and yield good agreement between simulation and experiment. We note that the vapour pressure in simulation is essentially governed by the ideal vapour pressure.     

Adsorption of basic green 4 onto gasified Glyricidia sepium woodchip based activated carbon: Optimization,characterization, batch and column study

The abundance of gasification char residues which contributed to solid waste management problem is one of the major concerns in biomass gasification industry. This study focuses on synthesizing gasified Glyricidia sepium woodchip based activated carbon (GGSWAC) for the removal of basic green 4 (BG4) dye, evaluating the GGSWAC physicochemical properties and assessing the BG4 adsorption performance in batch and fixed-bed column systems. The optimal conditions of GGSWAC synthesis were at radiation power, time, and impregnation ratio (IR) of 616 W, 1 min and 1.93 g/g, respectively. The surface area (S_BET) and total pore volume (TPV) of GGSWAC were 633.30 m²/g and 0.34 cm³/g, respectively. The Fritz–Schlünder best fitted to the experimental data at all temperatures in the isothermal studies, indicating a monolayer adsorption. The kinetic study showed that BG4 adsorption followed Avrami kinetic model. Based on thermodynamic parameters, the adsorption of BG4 dye onto GGSWAC was an endothermic and spontaneous process. In continuous operation, the Thomas and Yoon–Nelson models successfully predicted BG4 adsorption onto GGSWAC. The low production cost of 0.54 USD/kg showed that GGSWAC is economically feasible for commercialization.     

Optimization and mass transfer simulation of remazol brilliant blue R dye adsorption onto meranti wood based activated carbon

Remazol brilliant blue R dye (RBBR) brings toxicity to living organisms once it enters the environment. This study utilized response surface methodology (RSM) and Polymath software for optimization and mass transfer simulation purposes, respectively. RSM revealed that the optimum preparation conditions of meranti wood-based activated carbon (MWAC) were 441 W, 5.76 min, and 1.35 g/g for radiation power, radiation time, and KOH:char impregnation ratio (IR), respectively, which translated into 86.39 mg/g of RBBR uptakes and 31.94 % of MWAC’s yield. The simulation study predicted the mass transfer rate, r_m to be 112.20 to 1007.50 s^?1 and the adsorption rate, k₁ to be 3.96 to 4.34 h^?1. The developed model predicted the adsorption surface area, a_m to be 790.04 m²/g and this value is highly accurate as compared to the actual mesopores surface area of 825.58 m²/g. Mechanism analysis divulged that the interaction that occurred between RBBR molecules and MWAC’s surface were hydrogen bond (methylene and alkyne), dipole–dipole force (alkyl carbonate, terminal alkyne, and methoxy), and ion–dipole force (primary amine). The isotherm and kinetic studies found that the adsorption data obeyed the Freundlich model and pseudo-first-order (PFO) model the best, respectively. The Langmuir maximum adsorption capacity, Q_m was computed to be 327.33 mg/g. Thermodynamic parameters were calculated to be ?4.06 kJ mol^?1, 0.06 kJ mol^?1 K^?1, –22.69 kJ mol^?1, and 16.03 kJ mol^?1 for ΔH°, ΔS°, ΔG°, and E_a, respectively, which signified the adsorption process studied was exothermic, spontaneous and governed by physisorption.     

Thermodynamic properties of saturated and compressed liquid difluorochloromethane

In an isochoric study the thermodynamic behaviour of liquid difluorochloromethane was experimentally investigated. New measurements of (p, ?, T) have been carried out at densities from 0.83 to 1.36 g·cm^?3 (reduced densities from 1.6 to 2.7) and pressures up to 60 MPa. In addition new results for the vapour pressure of liquid difluorochloromethane are reported at temperatures from 312 to 369 K. Saturated liquid densities were obtained from the extrapolation of the isochoric results to the vapour-liquid coexistence curve.