LHHW/RSM reaction rate modeling for Co-Mn/SiO2 nanocatalyst in Fishcher-Tropsch synthesis.

This study aims to assess the kinetics of Fischer-Tropsch (FT) reaction over the cobalt-manganese nanoparticles supported by silica oxide. Nanoparticles were synthesized by the thermal decomposition method using "[Co(NH3)4CO3]MnO4" complex and characterized by XRD, TEM, and BET techniques. The kinetics of the process were evaluated using a combination of Langmuir-Hinshelwood-Hougen-Watson (LHHW) and response surface methodology. Correlation factors of 0.9902 and 0.962 were obtained for the response surface method (RSM) and LHHW, respectively. The two methods were in good agreement, and the results showed that the rate-determining step was the reaction of the adsorbed methylene with the adsorbed hydrogen atom, and only carbon monoxide molecules were the most active species on the catalyst surface. A temperature of 502.53 K and a CO partial pressure of 2.76 bar are proposed as the optimal conditions by RSM analysis. The activation energy of CO consumption reaction was estimated to be 61.06 kJ/mol.

Enhanced photocatalytic performance of UiO-66-NH2/TiO2 composite for dye degradation.

In this study, the performance of TiO2, ZnO, UiO-66-NH2 and UiO-66-NH2/TiO2 nanoparticles was investigated. They apply as photocatalysts for the destruction of organic reactive red dye 120 (RR120) under UV light. In order to determine the optimal conditions, effects of different catalysts and initial dye concentration, H2O2 content and catalyst loading parameters were examined. Taguchi-designed experimental method was used to obtain optimal test conditions. The physical and chemical properties of synthetic photocatalysts were investigated by SEM, XRD, EDX, BET and DRS. SEM images show that the globular particles of titania are well placed on the surface of the metal-organic framework (MOF). XRD and EDX analyses also confirmed the presence of titania in the synthesised UiO-66-NH2/TiO2 photocatalyst. Optimal values of H2O2, pH, the amount of catalyst, the dye concentration and the type of available photocatalyst to remove the RR120 dye, were obtained by 80 µl/l, 3 mg/l, 5 mg/l and 20 mg/l, UiO-66-NH2/TiO2 catalyst, respectively. The required time for complete removal of RR120 dye under detection limit of 0.136 mg/l in optimal conditions was 10 min. The RR120 photocatalytic degradation followed the first-order kinetic equation according to the Langmuir-Hinshelwood model (kapp = 0.407 min-1). The result of optimisation showed the 20 wt% of the titania on MOF (UiO-66-NH2) photocatalyst can be used in advanced oxidation processes, and it can be used as a suitable option for cleaning coloured effluent.

A new nickel-based co-crystal complex electrocatalyst amplified by NiO dope Pt nanostructure hybrid; a highly sensitive approach for determination of cysteamine in the presence of serotonin.

A highly sensitive electrocatalytic sensor was designed and fabricated by the incorporation of NiO dope Pt nanostructure hybrid (NiO-Pt-H) as conductive mediator, bis (1,10 phenanthroline) (1,10-phenanthroline-5,6-dione) nickel(II) hexafluorophosphate (B,1,10,P,1,10, PDNiPF6), and electrocatalyst into carbon paste electrode (CPE) matrix for the determination of cysteamine. The NiO-Pt-H was synthesized by one-pot synthesis strategy and characterized by XRD, elemental mapping analysis (MAP), and FESEM methods. The characterization data, which confirmed good purity and spherical shape with a diameter of ⁓ 30.64 nm for the synthesized NiO-Pt-H. NiO-Pt-H/B,1,10, P,1,10, PDNiPF6/CPE, showed an excellent catalytic activity and was used as a powerful tool for the determination of cysteamine in the presence of serotonin. The NiO-Pt-H/B,1,10, P,1,10, PDNiPF6/CPE was able to solve the overlap problem of the two drug signals and was used for the determination of cysteamine and serotonin in concentration ranges of 0.003-200 µM and 0.5-260 µM with detection limits of 0.5 nM and 0.1 µM, using square wave voltammetric method, respectively. The NiO-Pt-H/B,1,10,P,1,10,PDNiPF6/CPE showed a high-performance ability for the determination of cysteamine and serotonin in the drug and pharmaceutical serum samples with the recovery data of 98.1-103.06%.

Simultaneous voltammetric determination of glutathione, doxorubicin and tyrosine based on the electrocatalytic effect of a nickel(II) complex and of Pt:Co nanoparticles as a conductive mediator.

Glutathione (GSH) is an important tripeptide that plays an important role in preventing damage to reactive oxygen species. An electrochemical assay was fabricated for this purpose by modification of a carbon paste electrode (CPE) with bis(1,10-phenanthroline)(1,10-phenanthroline-5,6-dione)nickel(II) hexafluorophosphate (BPPDNi) as new electro-catalyst and Pt:Co nanoparticle (Pt:CO-NPs) as highly conductive mediator. The analyses were performed at a scan rate of 10 mV/s and at a pH value of 7.4. The BPPDNi/Pt:CO-NPs/CPE showed a high sensitivity and good selectivity for electro-catalytic determination of glutathione (GSH) in nano-molar concentration range. In addition, the BPPDNi/Pt:CO-NPs/CPE was used for the determination of glutathione in the presence of doxorubicin (DOX) and tyrosine (Tyr) with three separated oxidation signals ~160 mV, ~385 mV and ~790 mV vs. Ag/AgCl/KClsat, respectively. The peak currents of the square wave voltammetric analyses were linearly dependent on glutathione, doxorubicin and tyrosine concentrations in the respective ranges of 0.001-450, 0.5-300 and 1.0-650 µM, with detection limits of 0.5 nM, 0.1 µM and 0.6 µM, respectively. Graphical abstract The first analytical sensor for simultaneous determination of glutathione, doxorubicin and tyrosine.

Synthesis and application of ion-imprinted polymer nanoparticles for the determination of nickel ions.

Novel Ni(II) ion-imprinted polymers (Ni-IIP) nanoparticles were prepared by using Ni(II) ion-1,5-diphenyl carbazide (DPC) complex as the template molecule and methacrylic acid, ethylene glycol dimethacrylate (EGDMA) and 2,2'-azobisisobutyronitrile (AIBN) as the functional monomer, cross-linker and the radical initiator, respectively. The synthesized polymer particles were characterized physically and morphologically by using infrared spectroscopy (IR), thermo gravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopic (SEM) techniques. Some parameters such as pH, weight of the polymer, adsorption time, elution time, eluent type and eluent volume which affects the efficiency of the polymer were studied. The preconcentration factor, relative standard deviation, and limit of detection of the method were found to be 100, 1.9%, and 0.002 µg mL(-1), respectively. The prepared ion-imprinted polymer particles have an increased selectivity toward Ni(II) ions over a range of competing metal ions with the same charge and similar ionic radius. The method was applied to the determination of nickel in tomato and some water samples.

Interaction of two new mixed ligand copper(II) complexes with DNA probed by thermodynamic and spectroscopic studies.

The DNA binding behavior of [Cu(4,7-dmp)(phen-dione)Cl]Cl (1) and [Cu(2,9-dmp)(phen-dione)Cl]Cl (2) where dmp and phen-dion stand for dimethyl-1,10-phenanthroline and 1,10-phenanthroline-5,6-dion, respectively, was studied with a series of techniques including Viscometry, UV-Vis absorption, circular dichroism and fluorescence spectroscopy. Cytotoxicity effect was also investigated. Thermodynamic parameters, enthalpy and entropy changes were calculated according to Van't Hoff equation, which indicated that both reactions are predominantly enthalpically driven. However, these two complexes show different behavior in fluorescence, circular dichroism and viscometry methods which indicate the Cu(II) complexes interact with calf-thymus DNA by different mode of binding. These have further been verified by competition studies using Hoechst as a distinct groove binder. All these results indicate that these two complexes (1) and (2) interact with CT-DNA via groove binding and partially intercalative mode, respectively and the binding affinity of the complex 1 is higher than that of complex 2. Finally, our findings suggest that the type of ligands and structure of complexes have marked effect on the binding affinity of complexes involving CT-DNA. Also, these new complexes showed excellent antitumor activity against human T lymphocyte carcinoma-Jurkat cell line.

DNA binding, DNA cleavage and cytotoxicity studies of a new water soluble copper(II) complex: the effect of ligand shape on the mode of binding.

The interaction of native calf thymus DNA (CT-DNA) with [Cu(ph(2)phen)(phen-dione)Cl]Cl was studied at physiological pH by spectrophotometric, spectrofluorometric, circular dichroism, and viscometric techniques. Considerable hypochromicity and red shift are observed in the UV absorption band of the Cu complex. Binding constants (K(b)) of DNA with the complex were calculated at different temperatures. Thermodynamic parameters, enthalpy and entropy changes were calculated according to Van't Hoff equation, which indicated that reaction is predominantly enthalpically driven. All these results indicate that Cu(II) complex interacts with CT-DNA via intercalative mode. Also, this new complex induced cleavage in pUC18 plasmid DNA as indicated in gel electrophoresis and showed excellent antitumor activity against K562 (human chronic myeloid leukemia) and human T lymphocyte carcinoma-Jurkat cell lines.

DNA binding, DNA cleavage, and cytotoxicity studies of two new copper (II) complexes.

The DNA binding behavior of [Cu(phen)(phen-dione)Cl]Cl (1) and [Cu(bpy)(phen-dione)Cl]Cl (2) was studied with a series of techniques including UV-vis absorption, circular dichroism spectroscopy, and viscometric methods. Cytotoxicity effect and DNA unwinding properties were also investigated. The results indicate that the Cu(II) complexes interact with calf-thymus DNA by both partially intercalative and hydrogen binding. These findings have been further substantiated by the determination of intrinsic binding constants spectrophotometrically, 12.5 × 10(5) and 5 × 10(5) for 1 and 2, respectively. Our findings suggest that the type of ligands and structure of complexes have marked effect on the binding affinity of complexes involving CT-DNA. Circular dichroism results show that complex 1 causes considerable increase in base stacking of DNA, whereas 2 decreases the base stacking, which is related to more extended aromatic area of 1,10-phenanthroline in 1 rather than bipyridine in 2. Slow decrease in DNA viscosity indicates partially intercalative binding in addition to hydrogen binding on the surface of DNA. The second binding mode was also confirmed by additional tests: interaction in denaturation condition and acidic pH. Also, these new complexes induced cleavage in pUC18 plasmid DNA as indicated in gel electrophoresis and showed excellent antitumor activity against K562 (human chronic myeloid leukemia) cells.