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A nitrogen-containing covalent organic framework obtained from the polymerization of 1,3-dicyanobenzene has been used as a starting material for the synthesis of Fe/N/C catalysts for the oxygen reduction reaction (ORR). In this work we report the effect of the thermal treatments on the nature and catalytic properties of the catalysts obtained after the thermal treatments. After the first thermal treatment, the catalysts obtained contain metallic iron and iron carbide particles, along with a minority fraction of inorganic FeNx sites. After acid leaching and a second thermal treatment, FeNx sites remain in the catalysts, along with a minor fraction of graphite-wrapped Fe3C particles. Both catalysts display high activity for the ORR, with the catalyst subjected to acid leaching and a second thermal treatment, 2HT-1,3DCB, displaying higher ORR activity and a lower production of H2O2. This observation suggests that iron particles, such as Fe3C, display ORR activity but mainly toward the two-electron pathway. On the contrary, FeNx ensembles promote the ORR via the four-electron pathway, that is, via H2O formation.

Muscovite flakes were applied in the synthesis of three types of sodalite with different morphologies by hydrothermal processes for 24 h, 48 h, and 72 h. The synthetic sample after 72 h (S-72) showed the best surface area (105 m2/g), morphological features, and ion exchange capacity (71.3 meq/100 g). The S-72 was applied for effective retention of both Se (VI) and Se (IV) ions in batch adsorption studies. The retention capacities of Se (VI) and Se (IV) ions using S-72 sodalite are 149 mg/g and 255 mg/g, respectively after an equilibration time of 300 min and 360 min. The kinetic assessment suggested Pseudo-second order behavior for the retention of both Se (VI) and Se (IV). The equilibrium studies of their retention reactions demonstrated Langmuir isotherm behavior and monolayer form for the homogeneously adsorbed Se (VI) and Se (IV) ions on the surface of sodalite. The Gaussian energies (> 8 KJ/mol), enthalpies (

In view of iridium's scarceness and high cost, Ir-containing catalysts for water electrolyzers should have low loadings and maximal utilization. Here, we studied low-Ir-content, highly active, double perovskites (Sr2MIrO6, M = Ni, Co, Sc and Fe) for the oxygen evolution reaction (OER) in acid combining electrochemical experiments, DFT, and advanced characterization techniques. The initial OER performance depends on Ir's oxidation state and the geometric features of IrO6 frameworks, which are tuned by the choice of M. Higher oxidation states, particularly Ir6+, enhance the OER activity: Sr2NiIrO6 and Sr2CoIrO6 display potentials of ∼1.53 V at 10 mA cm−2, comparable to the best Ir-based catalysts in the literature. However, because of their less symmetric structures, perovskites with Ir6+ are less stable, prone to surface reconstruction and their cations leach under OER conditions. These results show that improved iridium-based OER electrocatalysts in acid can be designed by balancing their activity and stability.

Muscovite/phillipsitic zeolite was introduced as a novel inorganic composite of stunning adsorption properties. The composite was investigated in the uptake reactions of Hg(II), As(V), and U(VI) as highly toxic water contaminants considering different adsorption factors. The adsorption properties of muscovite/phillipsitic zeolite are highly dependent on the pH values and the best decontamination percentages can be obtained at pH 4, pH 5, and pH 5 for Hg(II), As(V), and U(VI), respectively. The kinetic studies demonstrated adsorption equilibrium for Hg(II), As(V), and U(VI) after 360 min, 300 min, and 360 min, respectively. The equilibrium modeling suggested monolayer uptake for all the metals and represented mainly by the Langmuir model considering both the values of determination coefficient and chi-squared (χ2). The estimated maximum capacities are 117 mg/g (Hg(II)), 122.5 mg/g (As(V)), and 138.5 mg/g (U(VI)) which are higher values than several studied adsorbents. The Dubinin–Radushkevich adsorption energies of Hg(II) (19.4 kJ/mol), As(V) (25.6 kJ/mol), and U(VI) (26.47 kJ/mol) signify chemical adsorption mechanisms and close to the obtained values for the ion-exchange process. Additionally, the composite is of high reusability properties and was applied effectively for five decontamination cycles.

In this study, Zr-based metal organic frameworks (UiO-66) and graphene nanoplatelets UiO-66 nanocomposites (GNP/UiO-66) were prepared using acid promoted method, and used for adsorption of two different polyphenols; oleuropein and hydroxytyrosol. Different characterization techniques used for exploring the morphological and structure properties of the UiO-66 and GNP/UiO-66 nanocomposites. The adsorption of oleuropein and hydroxytyrosol was studied by UiO-66 and different GNP/UiO-66 nanocomposites and results showed that most of the oleuropein and hydroxytyrosol were removed from the solution in 60 min and 180 min, respectively. The kinetic modelling of adsorption was studied. The adsorption isotherms were constructed at different pH values.

An electrochemical sensor on a modified glassy carbon electrode (GCE) for the detection of 4-chlorophenol (4-CP) was investigated. A GCE was coated by a zinc oxide nanoparticle/graphene nanoplatelet/poly(o-phenylenediamine) polymer nanocomposite (GCE/ZnO/GNPs/MIP). The nanocomposite improved the electrochemical response and sensitivity of the sensor for the detection of 4-CP. The surface morphology and crystal structure of the prepared nanomaterial were characterized using different chemical and physical techniques, showing homogenous distributions of ZnO and GNPs over the electrode. The electrochemical behavior of the GCE/ZnO/GNPs/MIP nanocomposite-based sensor was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. Under optimized experimental conditions, the electrochemical sensor exhibited excellent analytical performance with a very low detection limit. The electrochemical sensor was utilized to determine 4-CP levels in real water samples; the sensor exhibited high selectivity, sensitivity, and repeatability. These results showed that the GCE/ZnO/GNPs/MIP sensor could be a facile, robust, practical, low-cost and rapid tool for potential on-line monitoring of 4-CP in water.

Diatomite/kaolinite-based geopolymer (GP) was synthesized and incorporated in zeolitization process (Z/GP) to investigate the role of the zeolite phases in inducing its retention capacity of the dissolved Sr (II) ions in water. The retention of Sr (II) ions using Z/GP in comparison with GP was evaluated based on both batch and fixed-bed column studies. In the batch study, the zeolitized geopolymer (Z/GP) shows enhancement in the Sr (II) retention capacity (193.7 mg/g) as compared to the normal geopolymer (102 mg/g). Moreover, the recyclability studies demonstrate higher stability for Z/GP than GP with a retention percentage higher than 90% for five reusing runs. The kinetic and the equilibrium properties of the occurred Sr (II) retention reactions follow the assumption of the Pseudo-Second order model (R2 > 0.96) and Langmuir model (R2 > 0.97), respectively. The Gaussian energies (15.4 kJ/mol (GP) and 11.47 kJ/mol (Z/GP)) related to retention mechanism of chemical type and within the suggested range for the zeolitic ion exchange processes. The Sr (II) retention reactions by GP and Z/GP are of spontaneous and exothermic properties which qualifies the products to be used at low-temperature conditions (20 °C). The column studies also declared higher performance for the Z/GP fixed bed as compared to the normal GP bed considering the total Sr (II) retention percentage (72.9%), treated volume (8 L), saturation time (1620 min), and a maximum capacity of Z/GP particles in the bed (567.6 mg/g).

In this work, a novel decorated and combined N-doped graphene oxide hydrogel with shrimp shell magnetic biochar (NGO3DH-MSSB) biosorbent was fabricated as an effective material for Cr(VI) removal. Three-dimensional self-assembled graphene oxide hydrogel was synthesized using nitrogen source, ethylenediamine (EDA). Characterizations of NGO3DH-MSSB biosorbent were established by FT-IR, TGA, SEM and BET, where high surface area (398.05 m2/g) compared with that of MSSB (138.64 m2/g) was characterized. The maximum achieved swelling ratio (800%) was only after 300 min. The binding mechanisms between Cr(VI) ions and NGO3DH-MSSB biosorbent were controlled by electrostatic adsorption (ion-pair), pore filling, and reduction-coordination reaction. Adsorption was described by the pseudo-second order kinetic (R2 = 0.9994, 0.9983 and 0.9992) at 10, 50 and 100 mg/L and Langmuir isotherm model (R2 = 0.9997, 0.9957 and 0.9912) at 25, 40 and 50 °C. The adsorption capacity (350.42 mg/g) was achieved at pH 1.0, using initial Cr(VI) concentration (100 mg/L) and contact time (180 min) at room temperature. NGO3DH-MSSB biosorbent could be successfully reused after eight cycles. The percentage removal of Cr(VI) were confirmed as 99.79%, 99.20% and 98.00% from tap water, sea water and wastewater, respectively.

Novel MgO/CaO nanocomposite (MgO/CaO NRs) was synthesized by the hydrothermal method using diatomite porous frustules as a substrate under the microwave irradiation. The composite appeared as well crystalline rod-like nanoparticles with 52.3 nm as average particle size and 112.8 m2/g as BET surface area. The synthetic MgO/CaO NRs were addressed as a novel adsorbent for promising removal of levofloxacin (LVX) as pharmaceutical residuals. The adsorption studies revealed effective uptake of levofloxacin by MgO/CaO NRs with theoretical qmax of 106.7 mg/g and the equilibrium time of 720 min considering the best pH value (pH 7). The equilibrium studies highly fitted with the Langmuir model of monolayer adsorption considering the values of Chi-squared (χ2) and determination coefficient. The estimated adsorption energy from Dubinin–Radushkevich (0.2 kJ/mol) signifies physisorption mechanisms that might be coulombic attractive forces considering the kinetic studies. The thermodynamic addressing for the reactions verified their spontaneous and exothermic nature within a temperature range from 303 to 333 K. Additionally, the prepared MgO/CaO NRs show significant recyclability properties to be used in realistic remediation process and its uptake capacity is higher than several studied adsorbents in literature.

A hydrothermal method was used to prepare Gd(OH)3 nanoparticles; then palladium was doped into the surface of Gd(OH)3 nanoparticles by a photoassisted deposition method. Different characterization techniques such as XRD, PL, UV–vis, XRD, TEM and BET surface area were used for characterization of Gd(OH)3 and Pd/ Gd(OH)3 nanoparticles samples. The photocatalytic performance of Gd(OH)3 and Pd/ Gd(OH)3 nanoparticles samples was studied for the photocatalytic reduction of CO2 under visible light. The results reveal that weight percent of doped palladium plays important role in control band gap of Gd(OH)3 nanoparticles and prevent electron-hole recombination rate. Also, it was noticed that BET surface area of Gd(OH)3 nanoparticles was decreased from 55 to 42 m2/g by changing weight percent of palladium from zero to 0.8 wt%, respectively, due to blocking of some pores of Gd(OH)3 nanoparticles by deposition of palladium. XPS results reveal that palladium was doped as metallic palladium. 0.6 wt% Pd-Gd(OH)3 nanoparticles photocatalyst has the highest photocatalytic activity compared with the other photocatlysts, and it can be used five times without loss of its photocatalytic activity.

A hydrothermal method was used to prepare CdS nanoparticles, and a photoassisted deposition method was used to prepare 0.5 wt% In2O3/CdS, 0.5 wt% Pt/CdS and 0.5 wt% Pt, In2O3/CdS nanoparticles. Different techniques, such as UV–Vis, XPS, TEM, XRD, PL and BET surface area, were used to characterize the prepared materials. The results reveal that the doping of Pt, In2O3 on the surface of CdS nanoparticles plays an important role in the control electron-hole recombination rate. The photocatalytic performance of CdS, 0.5 wt% In2O3/CdS, 0.5 wt% Pt/CdS, and 0.5 wt% Pt, In2O3/CdS nanoparticles was studied by measuring their photocatalytic oxidation of malachite green dye under visible light. Photocatalytic parameters such as the type of doped materials, photocatalyst dosage and photocatalytic stability were also studied. The photocatalytic activity of CdS is lower than that of doped cadmium sulphide nanoparticles. This can be attributed to the fact that the addition of Pt or In2O3 or both In2O3 and Pt to CdS nanoparticles decreases the electron-hole recombination rate or alternatively due to the transfer of electrons between the doped metal and CdS nanoparticles.

This research reports, for the first time, the eco-friendly green synthesis of zinc oxide nanoparticles (ZnO NPs) using Ziziphus jujuba leaves extract assisted by microwave irradiation. Eco-friendly prepared ZnO NPs were characterized by different techniques, and the results confirmed the formation of hexagonal wurtzite ZnO nanoparticles with different particle sizes. The prepared ZnO NPs were then used for the adsorption and removal of two different azo dyes; methyl orange (MO), and methylene blue (MB), as well as toxic Pb(II) ions, from a model solution and real samples. The influence of experimental conditions was explored; ZnO NPs mass, contact time, solution pH, solution ionic strength, and solution temperature, and the results showed that most of the MB, MO, and Pb(II) could be removed from the model solution within a few minutes, at ambient conditions. The experimental removal capacities of 5.21, 2.57, and 596 mg of MO, MB, and Pb(II) per gram of microwave-assisted green ZnO NPs (MWG ZnO NPs), respectively, were obtained. The removal of the MB, MO, and Pb(II) using ZnO NPs was studied kinetically and thermodynamically, and the results showed that the experimental data were best fitted using the pseudo-second-order kinetic models, with rate constants of 0.165, 0.364, 247 × 10–6, for the MO, MB, and Pb(II), respectively. The thermodynamics study showed that the process was spontaneous, with an exothermic nature. Finally, the prepared ZnO NPs were used for the removal of MB, MO, and Pb(II) in real wastewater samples, and high removal efficiency was presented. The regeneration and reusability were explored, and the results revealed the applicability of using the MWG ZnO NPs for the removal of MB, MO, and Pb(II) for five consecutive cycles.

The present work is aimed to fabricate a new set of composite materials containing conducting poly(azomethine-ether) reinforced with single-walled carbon nanotubes in the form of single-walled carbon nanotube/poly(azomethine-ether)1–5 for excellent enhanced thermal as well as conducting behavior of poly(azomethine-ether). Single-walled carbon nanotubes of variable loading have been embedded into conducting poly(azomethine-ether) using in situ polymerization technique. Before attempting the polymerization, 1,3-thiazole established poly(azomethine-ether) and its conformable monomers have been prepared and their chemical structures have been correlated by spectral analyses. Furthermore, ηinh and Mw values for poly(azomethine-ether) were found 0.89 dL g−1 and 39723.6, respectively. The fabricated single-walled carbon nanotube/poly(azomethine-ether)1–5 composites were specified and characterized by wide-angle X-ray diffraction patterns, Fourier transform infrared spectroscopy, thermal behavior, scannin...

In this research, strontium titanate ( $$\hbox {SrTiO}_{3})$$ nanoparticles were synthesised using an ultrasonic method, then were doped with Pt using a photo-assisted deposition method to form $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ nanoparticles. $$\hbox {SrTiO}_{3}$$ and $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ nanoparticles were characterized by XRD, XPS, TEM, BET surface area UV–Vis and PL techniques in order to explore their chemical and physical properties. The visible light irradiation photocatalytic performances of $$\hbox {SrTiO}_{3}$$ nanoparticles and $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ nanoparticles for photocatalytic oxidation of cyclohexane was investigated, and the results revealed that platinum was doped onto the $$\hbox {SrTiO}_{3}$$ nanoparticles surfaces as metallic platinum, and the weight percent of doped platinum greatly affected the band gap, and the 1.5 wt% $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ nanoparticles showed the highest photocatalytic activity due to the low band gap. The stability of the $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ nanoparticles for the photocatalytic oxidation of cyclohexane was examined and the results revealed that the $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ nanoparticles could be used five times without losing their efficiency. TEM images of $$\hbox {SrTiO}_{3 }$$ (A) and 1.5 wt% $$\hbox {Pt}/\hbox {SrTiO}_{3}$$ (B) nanoparticles, which showed that $$\hbox {SrTiO}_{3}$$ is a spherical nanoparticle (A) and that platinum was doped as dots (B).

The removal of different non-steroidal anti-inflammatory drugs (NSAIDs); Ibuprofen (IBU), Ketoprofen (KETO), Naproxen (NAP) and Diclofenac sodium salt (DIC); from an aqueous model and real solution using high surface area graphene (HSANGs) were investigated. The characterization showed the presence of graphene as over layered nanoplatelets with an average thickness of 5.0 nm and high specific surface area of 677.5 m2 g− 1. The effects of different factors, which affect the removal process were studied and optimized for efficient removal, and most of the KETO, NAP, DIC, and IBU could be removed within few minutes using 10.0 mg HSANGs at ambient temperature, and the adsorption capacities for KETO, NAP, DIC, and IBU were 16.6 mg/g, 17.8 mg/g, 19.3 mg/g, and 11.9 mg/g at 296 K; respectively. The removal of KETO, NAP, DIC, and IBU by HSANGs was studied kinetically and thermodynamically. The results showed that the removal was mainly a pseudo-second-order process, spontaneous, and entropy driving, due to the negative Gibbs free energy, positive entropy and the positive enthalpy values.

Montmorillonite nanoclay surface modified with octadecylamine (ODA nanoclay) was used to study the adsorptive removal of Orange G dye (OG dye) from model and real water samples. ODA nanoclay was characterized using different techniques and the results showed that ODA nanoclay has plate-like layered transparent structure, and the calculated BET specific surface area was found to be 16.38 m2 g− 1. Adsorption study showed that ODA nanoclay could remove most of the OG dye within few minutes, with adsorption capacity of 39.4 mg/g at ambient conditions. The results showed also that the interaction of the OG dye with the ODA nanoclay was electrostatic in nature and greatly depends on the pH of the solution. The adsorptive removal of OG dye on ODA nanoclay was explored kinetically and thermodynamically, and the results revealed the suitability of the pseudo-second-order kinetic model for describing the adsorption process compared with other kinetic model. Also, the adsorption process was spontaneous, endothermic in nature, and positive entropy change indicated the increase in the degree of freedom at the solid-liquid interface. The applicability of the ODA nanoclay for the adsorption of OG dye was explored using six different environmental water samples collected from different origin, and the results revealed the high efficiency of the proposed nanoclay.

Humic acid (HA)- and levulinic acid (LA)-coated magnetic Fe3O4 nanoparticles were prepared and subsequently characterized using scanning electron microscopy, X-ray diffraction spectroscopy, Fourier transformer infrared spectroscopy, thermogravimetric analysis, particle size distribution analysis, and zeta-potential analysis. These magnetic nanoparticles were used for ciprofloxacin adsorption from aqueous solutions. Non-linear Langmuir and Freundlich adsorption isotherm models were used to explain the adsorption equilibria. The Langmuir adsorption capacities (q(m)) were 101.93 mg/g for HA-coated Fe3O4 and 53.76 mg/g for LA-coated Fe3O4. The appropriate contact times were 40 min for HA-coated Fe3O4 and 60 min for LA-coated Fe3O4. The adsorption rates and mechanisms were determined using pseudo-first-order and pseudo-second-order kinetic models. After the adsorption studies, the loaded nanoparticles were used for desorption studies, and their desorption kinetics were investigated. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Natural organic polymer; chitin, was physically mixed with magnetite nanoparticles and the well-known adsorbent; multiwalled carbon nanotubes (MWCNTs), in order to enhance its adsorption ability and obtain magnetic nanocomposite. Morphological, chemical and physical properties of the prepared chitin/magnetite/MWCNTs (CMM) were investigated using various characterization techniques. The TEM revealed that MWCNTs and magnetite nanoparticles were homogenously dispersed over the chitin surface. Also, the prepared CMM magnetic nanocomposite showed higher surface area and significant magnetic properties compared with the natural chitin. Removal of Cr(VI) by CMM magnetic nanocomposite was explored, and it was found that significant enhancement in the %Cr(VI) removed by increasing the removal time, CMM mass, and by decreasing the temperature of solution, were observed. Moreover, Cr(VI) removal was explored kinetically and thermodynamically, and the results showed that pseudo-second-order kinetic model was the most appropriate model for describing the removal process, and the removal was spontaneous, exothermic, and accompanied with a decrease in the degree of randomness. Finally, the results showed the significant enhancement of the removal ability of natural chitin upon its modification and the preparation of the CMM magnetic nanocomposite, which is a potential and promising adsorbent for environmental remediation.

The study of the adsorption equilibria of naphthalene onto graphene nanoplatelet supported MIL-101 composite material (GNP/MIL-101) has been conducted. In the experimental context of this study, firstly GNP/MIL-101 was synthesized by applying hydrothermal method and characterized via FTIR, XRD, SEM, TEM and surface area analyses. The effects of GNP/MIL-101 amount, temperature and initial naphthalene concentration on the adsorption process have been investigated. Results show that the maximum removal of naphthalene was obtained as about 93% by 0.075 g GNP/MIL-101 at 298 K. The isothermal data were fitted to linear and non-linear Langmuir, Freundlich, and Temkin adsorption isotherm models and the kinetic data were fitted to Elovich and other kinetic models. Adsorption depended on initial naphthalene concentration at investigated various temperatures (298, 308, 318 K) significantly. The temperature dependence of adsorption process is associated with the changes in several thermodynamic parameters such as standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°).

This study demonstrates the adsorption experiments of toxic dyes malachite green (MG) and Rhodamine B (RB) on Fe3O4-loaded activated carbon (AC). AC, which is known to be a high-capacity adsorbent, was aimed to be easily separated from aqueous media by loading it with Fe3O4. Fe3O4-loaded AC was prepared by the coprecipitation method and named magnetic activated carbon (M-AC), and the produced M-AC was characterized by x-ray diffraction (XRD), thermogravimetric analysis (TGA), and pHpzc analyses. MG and RB adsorption by the M-AC was performed separately by batch technique and the effects of adsorbent amount, solution pH, and initial dye concentration on the adsorption were explored. Maximum removal efficiencies were found to be 96.11% for MG and 98.54% for RB, and the Langmuir isotherm model was the most fitted isotherm model for the adsorption. The kinetic and thermodynamic studies showed that the adsorption proceeded via the pseudo-second-order kinetic model and endothermic in-nature for both dyes.

A novel form of sodalite was synthesized from muscovite (M.SD) as low-cost softening material for both Ca 2+ and Mg2+ ions from real groundwater in batch and column studies. The sodalite sample showed significant surface area (105 m2/g) and ion exchange capacity (87.3 meq/100 g) which qualifies it strong for softening applications. The incorporation of the M.SD as a fixed bed in column system at a fixed thickness of 4 cm and flow rates of 5 mL/min resulted in removal percentages of 90.5% and 92.2% for Ca2+ and Mg2+, respectively at pH 7.6. Considering the real concentrations of the ions (Ca2+ (233 mg/L) and Mg2+ (114 mg/L)), the M.SD bed has the ability to reduce their concentrations according to the recommended limits (75 mg/L for Ca2+ and 50 mg/L for Mg2+). These conditions resulted in purification of about 8.1 L and 8.7 L with breakthrough intervals of 1380 min and 1440 min; and saturation interval more than 1620 min for Ca2+ and Mg2+, respectively. The M.SD columns' performances were described considering the assumption of the Thomas model, Adams–Bohart model, and Yoon–Nelson model. The batch studies demonstrate the uptake of both Ca2+ and Mg2+ ions according to the Pseudo-First order kinetics and Langmuir equilibrium behaviour. Considering the values of Gaussian energies (0.77 KJ/mol (Ca2+) and 1.36 KJ/mol (Mg2+)), the uptake of these ions occurred by homogenous reactions of monolayer form and physical nature. The thermodynamic studies declared the spontaneous properties of the reactions and their exothermic properties.

Halloysite (HS) nanoclay was used for the environmental treatment of desalination brine water discharge via the adsorptive removal of selected heavy metals ions, zinc, iron, nickel, and copper, as well as salinity. Different techniques were used for the characterization of the HS nanoclay and it was found that HS nanoclay exists as transparent hollow nanotubes with high surface area. The study showed that most of the heavy metal ions could be removed successfully using the HS nanoclay in a few minutes, at normal conditions. The adsorptive removal of zinc, iron, nickel, and copper, as well as salinity on HS nanoclay was explored kinetically. It was concluded that the pseudo-second-order kinetic model was able to describe the remediation process. In addition, it was found that most of the heavy metals and salinity were removed from the desalination plant outfall brine discharge and the final concentrations were lower than those in the control and standard samples.

Contamination of drinking or irrigation water with pathogenic bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), is a major global health problem. Nanomaterials have been of growing interest owing to their promising properties as antimicrobial agents. In this study, in situ oxidative polymerization of pyrrole with silver nitrate was employed to obtain nanocomposites materials containing different percentages of single wall carbon nanotubes (CNT0–60/PPy/AgNPs). The reaction proceeds smoothly at room temperature and the silver content was about 80 wt% of composite. The morphology of composites was determined by transmission electron microscope (TEM) to indicate the formation of core–shell structure in which AgNPs as core and PPy–CNT as shell with observed homogeneity in the nanocomposites. The samples were also characterized by ATR-FTIR, XRD, and TGA. CNT0–60/PPy/AgNPs materials were used for bacterial removal from water. The bacterial removal was evaluated using the column filter method. The results indicated that the removal percentage of E. coli ranged from 87.5% to 95% using CNT0–20/PPy/AgNPs. The data obtained in this study indicated that CNT60/PPy/AgNPs nanocomposite was found to be effective towards E. coli with 100% removal, whereas PPy/AgNPs obtained in this work was specific for the complete removal of S. aureus (100%).

Three series of polyethylene glycol–carbon nanotube nanocomposites in the form of PEG/CNTa–e, PEG/f-CNT.Oxia–e, and PEG/CNT.C18a–e have been fabricated using a dissolution stirring ultra-sonication method. The compounds were then characterized using different characterization techniques, including FT-IR, XRD, and TEM. The FT-IR and XRD data provided clear evidence of the CNTs functionalization as well as the composite formation. The FT-IR spectral data of the functionalized MWCNTs were slightly changed due to the introduction of PEG groups on their surfaces. The TEM images indicated that the nanotubes were homogenously distributed and embedded within the PEG polymer matrix. A flat glassy carbon electrode was modified with GCE/PEG-f-CNToxd nanocomposites (NCs) to obtain a sensor for L-glutathione (GSH), which was seen to exhibit improved sensitivity, low detection limit, large dynamic range, short response time, and good stability, whereby the calibration plot (at +0.5 V) was linear (r2: 0.9957) in the 0.1 nM to 1.0 mM GSH concentration range, the detection limit was as low as 0.026 nM, and the sensitivity was 17.4 μA μM−1 cm−2. To the best of our knowledge, this is the first report on the determination of GSH using such a modified GCE/PEG-f-CNTs by an I–V approach. The GCE/PEG-f-CNT was applied for the selective determination of GSH in spiked rabbit serum samples and achieved acceptable results.

Fe/N/C catalysts are very active for the oxygen reduction reaction (ORR); however, the nature of the active site(s) is not fully understood. In this work, we study the performance of different types of N/C and Fe/N/C catalysts for the ORR, and the effect of the addition of NaCN. Phthalocyanine and graphene have been studied as model metal-free catalysts for the ORR. Fe-phthalocyanine (FePhcy), Fe-phthalocyanine dispersed in graphene (FePhcy/G) and Fe/N/G, have been used as model Fe-containing catalysts. FePhcy and FePhcy/G only contain Fe atoms coordinated to 4 nitrogen atoms. On the other hand, different species such as Fe-Nx and Fe3C coexist in Fe/N/G. In addition, C C ensembles are present in the graphene present in FePhcy/G and Fe/N/G. The ORR activity is characteristic of each catalyst, being the highest for the catalysts containing FeN4 ensembles. The addition of CN− results in the selective poisoning of the Fe-containing sites but it does not suppress the ORR activity of the Graphene containing samples. In-situ infrared spectroscopy studies during the ORR reveal that CN− poisoning of the Fe sites is reversible, desorbing at potentials less positive than ca. 600 mV. As a consequence, the ORR activity of the Fe-containing sites is recovered gradually.

The removal of antibiotic amoxicillin (AA) from aqueous solution was investigated using magnetically modified graphene nanoplatelets (M-GNPs). M-GNPs were prepared by mixing GNPs with freshly prepared magnetite nanopartilcles, and characterized using TEM, and XRD. The characterization results revealed the homogenous distribution of the magnetite nanopartilcles over the surface of transparent platelet-like graphene platlets. The M-GNPs proved to possess superior adsorption capacity compared with the pristine GNPs and the magnetite nanopartilces. The effects of different operational parameters which affect the removal process were explored; adsorbent amounts, contact time, initial pH, temperature, and the initial concentration of AA. The results showed the great affinity of the M-GNPs toward the AA and the maximum adsorption capacity was found to be 14.10 mg g −1 . The adsorption mechanism of AA by the M-GNPs involved π–π stacking and electrostatic interaction. The adsorption was studied kinetically and thermodynamically, and was found to mainly follow pseudo-second-order kinetic model, and was spontaneous and exothermic in nature.

Graphene-like (G), multiwalled carbon nanotubes (CNTs) and active carbon (AC) have been used as carbon matrix for the synthesis of Fe/N/C catalysts for the oxygen reduction reaction. A thorough physicochemical characterization of the electrocatalysts, including X-ray photoelectronic and X-ray absorption spectroscopies, reveal that the formation of Fe/Nx ensembles is favored when the graphene-like or the CNTs are used as the carbon matrix. As a result, the catalyst prepared with the graphene matrix (Fe/N/G) records the highest activity for the ORR in the series of 3.1 A g −1 at 0.9 V. This very high ORR activity positions these catalysts as a realistic alternative to replace Pt/C cathodes in alkaline fuel cells. Moreover, using graphene as the carbon matrix endows the catalyst with very high stability during the ORR showing stable catalytic performance for the ORR even after being subjected to severe treatments of 3000 cycles up to 1.4 V. In situ IRRA spectra demonstrate that such a high stability for the ORR relates to the excellent resistance against corrosion of the graphene-based catalyst.

In the present work, a green method has been developed to fabricate a novel nanocatalyst by the coupling of silver nanoparticles (Ag-NPs) onto δ-FeOOH and urea-formaldehyde polymer (PUF) using microwave irradiation heating process for the production AgNPs@δ-FeOOH/PUF. Several FT-IR functional groups as C O, C N, C N, C O and Fe-O were characterized in the assembled AgNPs@δ-FeOOH/PUF. The XRD diffraction peaks of silver nanparicles are well-matched to the cubic crystal structure of AgNPs to refer to a cubic crystal structure of AgNPs. The XPS analysis of AgNPs(0.5 wt %)@δ-FeOOH/PUF nanocatalyst confirmed the presence of Ag, N, O, C and Fe elements. The TEM image and histogram for particle size distribution of AgNPs@δ-FeOOH/PUF nanocatalyst showed the appearance of spherical particles on the surface of PUF with average size 10 nm. Moreover, AgNPs(0.5 %wt)@δ-FeOOH/PUF nanocatalyst exhibited brilliant efficiency in the catalytic hydrogenation of two selected azo dyes, methyl orange (MO) and congo red (CR) with high TOF in different loading contents of AgNPs/CP as 0.818 and 0.436 s−1, respectively. In addition, AgNPs@δ-FeOOH/PUF nanocatalyst showed good reusability as well as highly activity for reduction conversion of MO and CR into 100 to 89 %, respectively in few minutes after five cycles. The AgNPs@δ-FeOOH/PUF nanocatalyst with high TOF may be potential candidate as a workable and efficient nanocatalyst in treatment of environmental samples such as sea water (degradation efficiency percent is 80.62 % for MO and 81.51 % for CR).

In this research work, for the first time, the biopolymer chitin was modified chemically through activation followed by covalent linking to 8-hydroxyquinoline, and was then modified magnetically with the magnetic nanomaterial magnetite to produce magnetic chitin 8-quinolyl ether (C8QE). The prepared C8QE was studied by scanning electron microscopy, transmission electron microscopy, attenuated total reflection Fourier transform IR spectroscopy, and surface area analysis for characterization of the morphological structure, functional groups, and surface area of the magnetic C8QE solid, and also for its use as an adsorbent for removal of cadmium ions from contaminated water. The experimental results indicate the uniform and homogeneous formation of magnetic C8QE. The effects of the C8QE mass, adsorption time, ionic strength, solution pH, and temperature on Cd(II) ion removal by C8QE were studied. The optimum removal capacity of C8QE was about 119.9 mg Cd(II)/g with 20 mL of 100 mg L−1 cadmium solution and 15.0 mg C8QE within 10.0 min at pH 7.0 and 298 K. Cd(II) ion removal by C8QE was studied kinetically as well as thermodynamically, and the findings showed the suitability of the pseudo-second-order kinetic model for the removal process and the electrostatic, exothermic, and chemical nature and the spontaneity of the removal process. Moreover, C8QE could be used four consecutive times for the efficient removal of Cd(II) ions with high efficiency. Finally, the applicability of C8QE for removal of Cd(II) ions in different water samples was explored, and solid C8QE showed great potential for eliminating Cd(II) ions from water.

Exfoliated kaolinite sheets/cellulose fibres nanocomposite (EXK/CF) was synthesised as a novel hybrid of materials of enhanced surface area and adsorption capacities for inorganic—selenate [Se(VI)] and selenite [Se(IV)]—and organic selenium pollutants—selenomethionine (SeMt). The adsorption reactions of the addressed selenium forms followed pseudo-first-order as a kinetic model and Langmuir as an isotherm model. The fitting results and the calculated Gaussian energies—Se (VI) at 2.0 KJ/mol, Se (IV) at 2.2 KJ/mol, and SeMt at 1.7 KJ/mol—suggested physisorption uptake in a monolayer and homogeneous form. The theoretical maximum selenium uptake capacity (qmax) for Se (VI), Se (IV), and SeMt was 137.5 mg/g, 161.4 mg/g, and 95.4 mg/g, respectively. The thermodynamic investigation verified spontaneous and exothermic properties of the selenium uptake reactions by the EXK/CF composite.

It is very important to purify and remediate the environment by removing the heavy metals such as bismuth. Herein, Na-ilerite nanoclay was prepared and then treated to produce SiO2 pillared ilerite. For exploring the morphological structure, functional groups, and surface area of the ilerite before and after pillaring, different characterization techniques were used; scanning electron microscope (SEM), X-Ray diffraction (XRD), FT-IR, and surface area analysis solid. The prepared pillared ilerite nanoclay was used as an adsorbent for removing Bi(III) from model solution, and environmental samples. The characterization results indicates the pillaring of the ilerite nanoclay, and the great enhancement in the specific surface area of the ilerite upon pillaring from 45.0 m2 g−1 to 582 m2 g−1. The effects of pillared ilerite nanoclay mass, adsorption time, solution pH, ionic strength, and temperature on the removal of Bi(III) had been explored. The optimum removal capacity of pillared ilerite obtained was about 139.9 mg Bi(III)/g using 0.02 L of 100 mg L−1 Bi(III) solution, and pillared ilerite 5.0 mg within 60.0 min, at pH 2.0, and 298 K. Bi(III) ions removal by pillared ilerite was studied kinetically as well as thermodynamically, and the findings showed the pseudo-second-order kinetic model suitability, electrostatic, endothermic, chemical, and spontaneity nature of the removal process. Moreover, pillared ilerite nanoclay could be used for three consecutive times for the efficient removal of Bi(III) with high efficiency. Finally, the pillared ilerite nanoclay applicability for removal of Bi(III) in different spiked Red Sea water, waste water, and tap water sample was investigated and the pillared ilerite nanoclay showed a great potential application to removing Bi(III) from the environment.

Diabetes is one of the fastest growing diseases worldwide that can lead to dangerous complications. Therefore, the demand for the development of optimal glucose sensors has increased for diabetes disease management. In this study, a non-enzymatic glucose sensor based on a reduced graphene oxide and nickel oxide (rGO/NiO) nanocomposite was developed. This novel rGO/NiO nanocomposite was synthesized using a facile and rapid green economic microwave-assisted hydrothermal method in the absence and presence of organic/reducing agents and subcritical water, respectively. The morphology and composition of the as-prepared rGO/NiO nanocomposite were characterized via X-ray diffraction, Fourier transform infrared, energy-dispersive X-ray spectrometry, and field emission scanning electron microscopy. The electrochemical performance of the rGO/NiO-modified electrode was examined by cyclic and square wave voltammetric techniques under optimal conditions. The results indicated that the developed rGO/NiO electrode exhibited a good performance toward glucose detection in 0.1 M NaOH alkaline solution with two linear electrochemical responses to glucose ranging from 20 μM to 80μM and from 1mM to 15 mM. Moreover, the detection limit was 19.35 μM ([S/N] = 3). The fabricated sensor was also investigated for the detection of glucose in the presence of common interfering species. Thus, the sensor exhibited good sensitivity and selectivity and was repeatable, stable, and economical for non-enzymatic glucose detection. Additionally, the proposed sensor was successfully applied for glucose detection in human serum samples with satisfactory recoveries.

Pieces of glass as solid wastes were recycled in the synthesis of highly order MCM-41 that decorated by green fabricated Co3O4 nanoparticles using the green extract of green tea leaves forming novel green nano-composite. The synthetic Co3O4/MCM-41 exhibit high surface area, low bandgap energy (1.63 eV), and typical spherical morphology decorated by Co3O4 nanoparticles. The composite was evaluated as green photocatalyst in effective oxidation of methyl parathion pesticide in the presence of a visible light source. The degradation results revealed complete removal of 50 mg/L and 100 mg/L after 60 min and 90 min, respectively using 0.25 of the catalyst at pH 8. The detection of the TOC in the treated methyl parathion solution gives strong indications about the formation of organic intermediate compounds during the oxidation steps. The main detected intermediate compound are C6H5OH(NO2), C6H5OH, (CH3O)3P(S), C6H4(OH)2, C6H3(OH)3, C6H4(NH2)OP(O)(OCH3)2, (CH3O)2P(O)OH, (CH2)2C(OH)OH(CHO)OC(O), and HO2C(CH2)2C(O)CHO. The detected intermediate compounds converted into SO42−, PO43−, NO3−, and CO2 under the extensive photocatalytic of them over Co3O4/MCM-41. The oxidizing species trapping test verified the controlling of the methyl parathion degradation pathway by the hydroxyl radicals. Finally, the composite showed significant reusability properties and applied five times in the oxidation of methyl parathion with considerable degradation percentages.

The antibiotic wastes in environment are very dangerous for human being because of the spread of epidemics due to increasing of the antibiotic-resistant bacteria. For reducing the proliferation of these bacteria, an environmental-friendly, cheap and non-toxic adsorbent, chitosan-grafted SiO2/Fe3O4, was developed in this study. The chitosan-grafted SiO2/Fe3O4 (Chi-SiO2/Fe3O4) nanoparticles were prepared and characterised by different physical and chemical techniques such as X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption-desorption isotherms (BET), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and zeta-potential analysis. The prepared nanoparticles were used for ciprofloxacin (CPX) adsorption from water. The nonlinear Langmuir and Freundlich isotherms were applied to experimental data. And Langmuir isotherm showed the best fit. The nonlinear pseudo-first-order and pseudo-second-order kinetic models and Weber-Morris intraparticle diffusion model were applied to kinetic data. The adsorption process followed the pseudo-second-order kinetic model. And the rate-limiting step was intraparticle diffusion step. The most suitable eluent for CPX desorption was determined as phosphate buffer solution rather than ethanol, and NaCl solution. It desorbed the 100% of CPX solution in 5 h.

Metal organic frameworks are widely used as adsorbent materials in recent years. In this study, the most prepared metal organic framework MIL-101 was prepared by hydrothermal method and featured magnetic property using co-precipitation method Fe3O4. Then, the prepared composite (MIL-101/Fe3O4) was first characterized using XRD, FTIR, SEM-EDS, and surface area analysis, then was used for the adsorptive removal of the most used antibiotic, ciprofloxacin (CIP). The effect of different adsorption variables which may affect the removal of CIP by MIL-101/Fe3O4 was investigated, as well as their adsorbent quantity, initial CIP concentration, pH, temperature, and contact time. The non-linear Langmuir and Freundlich isotherm were applied to experimental data. It was observed that rising solution temperature decreases adsorption efficiency, as the maximum adsorption uptake value was 63.28 mg g(-1) at 298 K and 22.93 mg g(-1) at 313 K, indicating the exothermic nature of the adsorption. The adsorption was studied kinetically and found to follow the pseudo-second-order kinetic model. The desorption of CIP from the MIL-101/Fe3O4 was investigated using three different eluents, and the results showed that phosphate-buffered solution was the most effective desorption eluent.

A novel adsorbent, Fe3O4/activated carbon/chitosan (MACC: Magnetic activated carbon/chitosan) was prepared by a simple coprecipitation method. MACC was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), and surface area analysis. MACC adsorption ability was tested for three commonly used hazardous antibiotics: ciprofloxacin, erythromycin, and amoxicillin. Langmuir isotherm model and pseudo second order kinetic model were best fitted with experimental results. Superior uptake values were found with using MACC; 90.10, 178.57 and 52631 mg/g were calculated as the theoretical adsorption capacity (g,n) using Langmuir isotherm for ciprofloxacin, erythromycin, and amoxicillin, respectively. Finally, MACC is considered as a promising magnetically separable efficient adsorbent for antibiotics removal. (C) 2017 Elsevier B.V. All rights reserved.

Drilling efficiency depends on several dynamic factors and challenges. Horizontal drilling well design is critical to maximizing production and reservoir contact particularly cases in which several fluid engineering aspects affect drilling. Challenges increase when transitioning from horizontal to extended-reach drilling (ERD); however, minimizing metal-metal or metal-formation friction is vital. This paper presents a detailed study of laboratory testing of a range of lubricants and software simulation models of a true drilling environment to minimize friction. For nearly a decade, efforts to reduce friction have focused on engineering the lubricant only without taking into consideration additional factors that could help diminish friction. The challenges of drilling reservoirs are numerous; however, the availability of intelligent software allows for replication of the actual conditions precisely enough to design and drill wells with minimum friction, while taking into account the numerous aspects affecting success. A detailed laboratory study that included software simulation was conducted to create a true ERD environment model with the goal of creating a plan to reduce friction; thus, improve production. During one of the ERD intelligent projects, the service company team successfully simulated a scenario showing how the drilling fluid behaves under downhole conditions. Taken into consideration were temperature and pressure, the effect of tripping pressures on the equivalent static density (ESD), the effect of drilling parameters on equivalent circulating density (ECD), and the effect of lubricants on performance of different types of fluid design. A comprehensive study of all the parameters was completed, and their effect on drilling performance was determined. Both laboratory-prepared fluids and field fluids were further studied for high-pressure/high-temperature (HP/HT) rheology, lubricity, tripping pressure calculations, and ECD predictions to identify any gaps. Both data sets were consistent, allowing for excellent predictions for the fluid performance when well geometry is known. A wide range of lubricants, both solid and liquid, and their effects were studied as well as the effect of using ester-based oil to formulate nonaqueous synthetic fluid. The study was extended to include both clay-based and clay-free invert emulsion fluids (IEF), including variable concentrations of ester-based fluid at different oil/water ratios and with different types of lubricants to present a comprehensive overview of all aspects of lubricity.

Chemical modification of MWCNTs via oxidation followed by side wall functionalization using polyethylene glycol (PEG) and octadecylamine (ODA); separately, was studied. Different characterization techniques such as FTIR spectrometry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and solubility in different solvents were performed for the oxidized MWCNTs, MWCNTs–PEG and MWCNTs–ODA. The characterization techniques proved the presence of the functional groups on the MWCNT surface. Thermal gravimetric analysis revealed that nearly 16% (by weight) of the MWCNTs were functionalized with PEG and 39% (by weight) was functionalized with ODA.

Modelling of catalytic ammonia oxidation reactor for nitric oxide production in nitric acid plant over gauzes of Pt/Rh catalyst was the subject of current study. Viscosity, mass transfer and kinetic equations were used for the gas mixture feeding the reactor, partial pressure and mole fraction of ammonia was essential, also wire diameter was considered to detect platinum losses during oxidation operation. In order to investigate the performance of catalytic oxidation reactor, ordinary equation for determining of conversion yields of ammonia to nitric oxide was solved in mathematical model numerically. Variations of conversion with inlet mixture temperature, mixture concentration, inlet pressure and gauze temperature during cycle were investigated. Platinum losses rate as platinum oxide (PtO2) was studied with gauzes surface temperature by using numerical solution of the mathematical model. Modelling results were compared with an industrial reactor data. Comparing industrial data for all studied variables with those obtained by using mathematical model have shown the higher degree of accuracy of the model to predict the operating values with minimum deviation.