Mostafa Y. Nassar

A novel synthetic route for magnesium aluminate (MgAl2O4) nanoparticles using sol–gel auto combustion method and their photocatalytic properties

In this paper a novel and inexpensive route for the preparation of spinel magnesium aluminate nanoparticles (MgAl2O4) is proposed. Magnesium aluminate photocatalyst was synthesized via sol-gel auto combustion method using oxalic acid, urea, and citric acid fuels at 350°C. Subsequently, the burnt samples were calcined at different temperatures. The pure spinel MgAl2O4 with average crystallite size 27.7, 14.6 and 15.65nm was obtained at 800°C calcinations using the aforementioned fuels, respectively. The obtained samples were characterized by powder X-ray diffraction, Fourier transform infrared, UV-Vis spectroscopy, transmission electron microscope, scanning electron microscope. The photo catalytic activity of MgAl2O4 product was studied by performing the decomposition of Reactive Red Me 4BL dye under UV illumination or sunlight irradiation. The dye considerably photocatalytically degraded by 90.0% and 95.45% under UV and sunlight irradiation, respectively, within ca. 5h with pseudo first order rate constants of 5.85×10(-3) and 8.38×10(-3)min(-1), respectively.

Cobalt ferrite nanoparticles via a template-free hydrothermal route as an efficient nano-adsorbent for potential textile dye removal

We have reported herein the preparation of a pure cobalt ferrite (CoFe2O4) nanostructure, as an efficient nano-adsorbent, via a template-free hydrothermal and post thermal conversion route. We prepared micro-spherical particles of a cobalt carbonate/iron carbonate (CoCO3/FeCO3) composite precursor using the hydrothermal reaction of cobalt sulfate, iron sulfate, ascorbic acid, and ammonium carbonate at 140 °C for 3 h. Various parameters influencing the hydrothermal reaction have been studied. Thermal decomposition of the carbonate composite precursors prepared using different Co2+ : Fe2+ molar ratios generated various impure products. However, the CoCO3/FeCO3 composite precursor synthesized employing a 0.4Co2+ : 0.6Fe2+ molar ratio produced a pure spinel CoFe2O4 nanostructure with an average crystallite size of 9.5–21.6 nm on calcination in the temperature range of 400–600 °C for 2 h. The products were identified using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HR-TEM), nitrogen physical adsorption (BET), zeta potential and thermal analysis. The as-prepared spinel CoFe2O4 product showed a high adsorption capacity (91.7 mg g−1) toward Reactive Red 195 (RR195) dye in 20 min. The adsorption results fitted well the pseudo-second-order kinetics and could be well described by the Langmuir isotherm model. The RR195 dye adsorption was spontaneous, exothermic, and a physisorption process, implied from the calculated thermodynamic constants: ΔG0 (from −0.022 to −0.711 kJ mol−1), and ΔH0 (−7.55 kJ mol−1). It is concluded that the suggested CoFe2O4 nanostructure can be employed as an efficient nano-adsorbent for the removal of RR195 textile dye from aqueous solutions.

Hydrothermal tuning of the morphology and particle size of hydrozincite nanoparticles using different counterions to produce nanosized ZnO as an efficient adsorbent for textile dye removal

The current study aimed to investigate the effect of counterions on hydrothermally synthesized hydrozincite (zinc hydroxide carbonate), which was thermally converted to generate ZnO nanostructures, which are an efficient nanoadsorbent for the removal of Reactive Black 5 (RB5) dye from wastewater. Hydrozincite nanospheres and flower-like structures were hydrothermally prepared using various zinc salts (sulfate, acetate, and nitrate) and ammonium carbonate in a molar ratio of 1:3, respectively, at 120 °C for 3 h. The morphology and crystallite size of the hydrozincite precursor were effectively controlled via the parameters of the hydrothermal reaction. Interestingly, sulfate was the optimum counterion, as zinc sulfate salt produced pure hydrozincite nanospheres with the smallest crystallite size (∼13.57 nm), which were consequently thermally decomposed at 400 °C for 1 h to produce pure nanosized ZnO (∼10 nm). The compositions of the as-synthesized products were determined by means of FT-IR, FE-SEM, HR-TEM, XRD, zeta potential, BET, and thermal analyses. An adsorption study showed a much higher adsorption capacity (80.9 mg g−1) of the as-prepared ZnO nanoparticles toward RB5 dye. The adsorption of RB5 dye followed pseudo-second-order kinetics. In addition, the equilibrium adsorption of RB5 dye was best described by a Langmuir isotherm model and the calculated thermodynamic parameters, ΔG0 (from −4.027 to −7.533 kJ mol−1), ΔH0 (30.798 kJ mol−1), and Ea (29.105 kJ mol−1), indicate the spontaneous, endothermic, and physisorptive nature of the adsorption process.

A controlled, template-free, and hydrothermal synthesis route to sphere-like α-Fe2O3 nanostructures for textile dye removal

Iron carbonate nanospheres were synthesized via hydrothermal treatment of aqueous solutions of iron sulfate, ascorbic acid and ammonium carbonate with a molar ratio of 1:1:3, respectively, at 140 °C for 1.5 h. Pure α-Fe2O3 nanoparticles with an average crystallite size of 10.5–32 nm were produced by thermal decomposition of FeCO3 at 400–600 °C for 2 h. The compositions of the products were identified by means of XRD, FE-SEM, HR-TEM, FT-IR, BET, zeta potential and thermal analysis. The adsorption properties of α-Fe2O3 were evaluated using reactive red 195 (RR195) dye. Various parameters influencing the adsorption process were investigated, using a batch technique. The results show that α-Fe2O3 nanoparticles show good adsorption capacity and the dye removal percentage reaches about 98.77% in 10 min. Plus, increasing the surface area of the α-Fe2O3 nanoparticles from 107.7 to 165.6 m2 g−1 increases the adsorption capacity from 4.7 to 20.5 mg g−1. Moreover, the adsorption data fit the Langmuir isotherm model well and the thermodynamic parameters exhibited an endothermic and spontaneous nature for the adsorption of RR195 dye on the hematite adsorbent.

Facile controllable hydrothermal route for a porous CoMn2O4 nanostructure: synthesis, characterization, and textile dye removal from aqueous media

We herein report the synthesis of a pure sphere-like spinel CoMn2O4 nanostructure using a facile and surfactant-free hydrothermal approach followed by a thermal decomposition of the as-prepared CoCO3/MnCO3 composite precursor. Various factors affecting the hydrothermal reaction of cobalt chloride, manganese chloride, and ammonium hydrogen carbonate have been investigated to synthesize a pure CoCO3/MnCO3 composite precursor. Calcination of the CoCO3/MnCO3 composite (synthesized using 0.4Co2+:0.6Mn2+ molar ratio) at 550 °C for 1 h gave the pure sphere-like spinel CoMn2O4 nanostructure product (∼16 nm), but the other carbonate composites (synthesized using other molar ratios) did not generate pure spinel CoMn2O4 on calcination. The as-prepared products were identified employing XRD, FT-IR, TEM, EDS, FE-SEM, zeta potential, TG, and BET analyses. The as-prepared spinel CoMn2O4 product showed high adsorption capacity (132 mg g−1) for the removal of Reactive Black 5 (RB5) dye from aqueous media. The pseudo-second-order kinetics and Langmuir isotherm models described well the experimental adsorption results. The adsorption of RB5 dye on the as-prepared adsorbent is an endothermic, spontaneous, and physisorption process according to the calculated thermodynamic constants: ΔH0 (22.144 kJ mol−1), ΔG0 (from −4.321 to −6.990 kJ mol−1), and Ea (20.916 kJ mol−1), respectively. The as-prepared spinel CoMn2O4 adsorbent showed high stability, reusability, and high adsorption capacity implying its efficiency in removing the RB5 textile dye from aqueous media.

Tunable auto-combustion preparation of TiO2 nanostructures as efficient adsorbents for the removal of an anionic textile dye

We have developed a new route for the synthesis of pure TiO2 nanostructures via a facile auto-combustion method followed by heat treatment. We have tuned the produced phases, morphologies, and crystallite sizes of the nano-sized TiO2 products through an auto-combustion method employing different fuels and various fuel-to-oxidant equivalence ratios, Φc. The as-synthesized products were analyzed by means of FE-SEM, FT-IR, XRD, TEM, BET, and thermal analyses. Interestingly, urea fuel at Φc = 1 generated a pure anatase TiO2 phase (U1) having almost the smallest crystallite size (11.9 nm) and the highest adsorption capacity (135 mg g−1) for the removal of Reactive Red 195 (RR195) dye from aqueous solutions. Moreover, the adsorption data could be described well using the pseudo-second-order kinetic and Langmuir isotherm models. Based on the calculated thermodynamic parameters: ΔH0 (1.343 kJ mol−1), ΔG0 (from −4.630 to −5.031 kJ mol−1), and Ea (18.46 kJ mol−1), the adsorption of RR195 dye on the as-prepared TiO2 nano-adsorbent is an endothermic, spontaneous, and physisorption process, respectively. Moreover, the as-prepared TiO2 adsorbent is a promising candidate for the removal of RR195 textile dye from aqueous media based on its reusability, high stability, and high adsorption capacity.

A facile Pechini sol–gel synthesis of TiO2/Zn2TiO2/ZnO/C nanocomposite: an efficient catalyst for the photocatalytic degradation of Orange G textile dye

We have developed an efficient route for the synthesis of TiO2/Zn2TiO2/ZnO/C nanocomposites through a Pechini sol–gel method followed by heat treatment at 550 °C for 30 min. The produced phases and their crystallite sizes have been controlled by varying the Ti4+:Zn2+ molar ratios. FE-SEM, FT-IR, XRD, TEM, diffuse reflectance spectroscopy (DRS) and thermal analysis techniques were utilized for characterization of the as-prepared products. The photocatalytic activity of the products was investigated. Superior activity was observed for the TiO2/Zn2TiO2/ZnO/C nanocomposite for the photocatalytic degradation of Orange G dye (OG) under sunlight and UV illumination with ca. 100% degradation in 50 and 120 min, respectively. The kinetic studies showed that the observed first-order rate constant (kobs) was 113.48 × 10−3 and 29.46 × 10−3 min−1 for the photocatalytic degradation under sunlight and UV irradiation, respectively. The results also showed the stability and reusability of the as-prepared nanocomposite and its applicability for the removal of OG textile dye from aqueous media.

Synthesis and characterization of a ZnMn2O4 nanostructure as a chemical nanosensor: a facile and new approach for colorimetric determination of omeprazole and lansoprazole drugs

We have developed a facile method for preparation of ZnMn2O4 nanostructures via an auto-combustion method using various fuels: urea, glycine and L-alanine. The type of fuel and pH of the combustion media have a significant effect on the combustion products. Glycine fuel generated spinel ZnMn2O4 on combustion, and calcination of the sample produced pure spinel ZnMn2O4 nanoparticles with an average crystallite size of 19 nm. Whereas, other fuels generated multiphase compounds on combustion. The products were elucidated by means of XRD, FE-SEM, EDS, TEM, FT-IR, and UV-Vis diffuse reflectance spectra. The as-fabricated product was applied to construct a novel chemical nanosensor for the determination of omeprazole and lansoprazole drugs. Different factors influencing the colorimetric determination of the drugs were examined such as contact time, temperature, initial drug concentration, and ZnMn2O4 dose. The proposed chemical nanosensor revealed high sensitivity, low detection limit, and a relatively wide linear range (0.80–8.0 and 0.80–8.8 μg mL−1 at λmax 454 nm for omeprazole and lansoprazole, respectively).

Design and synthesis of new thiobarbituric acid metal complexes as potent protease inhibitors: spectral characterization, thermal analysis and DFT calculations

Five novel metal complexes of thiobarbituric acid (TBAH) have been prepared with the general formulae: [Ti(TBA)2(H2O)2]Cl2·2H2O, [Pd(TBA)2]·4H2O, Na[Ag(TBA)2(H2O)2]·4H2O, [Hg(TBA)2(H2O)2] and [Ce(TBA)2(H2O)3]SO4·H2O. The complexes have been fully characterized employing physicochemical and diverse spectroscopic techniques (IR, UV–Vis, mass and 1H NMR) as well as thermal analysis. Elemental analyses and spectroscopic data have showed that the stoichiometries of all complexes were 1:2. Thermal analysis measurements indicated that the complexes have good thermal stability. Density functional theory calculations were carried out at the B3LYP levels of theory with a double basis set, LANL2DZ basis set for titanium, palladium, cerium atoms, or LANL2MB basis set for silver, mercury atoms and 6-31+G(d,p) basis set for the other atoms. The optimized geometry of the ligand and its complexes was obtained based on the optimized structures. The ligand and its metal complexes act as protease inhibitors and repressed their enzymatic activity significantly.

Cylindrical-design, dehydration and sorption properties of easily synthesized magnesium phospho-silicate nanopowder

ABSTRACT Nanoparticles of magnesium phosphosilicate (MgPSi) with enhanced sorption properties have successfully synthesized using (NH4)2HPO4 as precipitating media. Structure, morphology, and dehydration changes of the synthesized nanopowder were detected using differential thermal analysis (DTA)–thermal gravimetric analysis, scanning electron microscopy (SEM), X-ray powder diffraction, Fourier transform infrared, and X-ray fluorescence. Studies appeared that, the MgPSi have semicrystalline stain with diameter of ∼40 nm. SEM image indicated that MgPSi particles were distributed as nanoclumps of cotton-wool morphology after heating up to 400°C. The order and activation energy of main dehydration processes were estimated from DTA-thermogram. Evaluation of MgPSi as new adsorbent was investigated for Cu2+, Ni2+, and Co2+ through a batch technique. MgPSi nanopowder was fabricated into adsorption surface by pressing into cylindrical beads. The kinetic adsorption of Cu2+, Ni2+, and Co2+ onto MgPSi can be qualified by a pseudo-second-order model very well. The adsorption of Cu2+, Ni2+, and Co2+ onto MgPSi is strongly relying on pH and also temperature. The adsorption isotherms are fitted well by Freundlich model. This cylindrical layout make it has an excellent physical stability, soft to handle and provided a pathway to fulfill the target of adsorption and recycling ability than the powder form.