Pseudo Reaction Rate Research Articles

Photocatalytic performance of novel zinc ferrite/copper sulfide composites for the degradation of Rhodamine B dye from wastewater using visible spectrum

Novel synthesis of composites of zinc ferrite ZnFe2O4 and copper sulfide CuS (ZnFe@CuS) was done by hydrothermal strategy and their photocatalytic performance was studied by degradation of Rhodamine B (RhB) dye. Relevant techniques of characterization have been utilized to characterize the prepared samples. Structural investigation revealed formation of composite and increment in crystallite size from 24 nm to 64 nm. Morphological study revealed the formation of cubic shaped to random shaped particles with increase in composite percentage. Similarly, emission at 412 nm with slight shift and decrease in peak intensity in PL spectra was also observed. At last, photocatalytic study revealed highest degradation efficiency (93%) for ZnFe@CuS 25% sample followed by first order pseudo reaction rate with reaction constant k 0.04060 min−1. It was observed that ZnFe@CuS 25% is environment friendly, photostable, and anti-photo corrosion with excellent reusability. These results suggest that composite ZnFe@CuS can be employed as a photocatalyst without producing secondary pollution that will further have positive impact on overall environment.

Simple synthesis of WO3 based activated carbon co-doped CuS composites for photocatalytic applications

This research work reports the simple synthesis of pure tungsten trioxide (WO3), its doping series with activated carbon (AC) in addition to pure copper sulfide (CuS). Then, WO3 based AC was co-doped with CuS composites, prepared through the facile hydrothermal method. The photocatalytic activity for the degradation of Aspirin is reported here. The percentage of CuS was varied as 10% and 15% in the 2% AC doped WO3 sample. X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transforms infrared (FTIR) spectroscopy, photoluminescence spectroscopy and ultraviolet–visible (UV–vis) spectroscopy techniques have been used to characterized the prepared samples. Photocatalytic performance was investigated for the time period of 150 min for degradation of the Aspirin drug. Here in this research, Aspirin has been used as a as a model organic pollutant. The photocatalytic study revealed that WO3 based AC co-doped 15% CuS have the highest degradation efficiency (97%) following by first-order pseudo reaction rate. It is observed that the same sample is photo-stable, anti-photo corrosive and has been proved to be environmental friendly. This is also reusable after many cycles of activity. These results suggested that 15% CuS composite can be utilized as a photo-catalyst for the degradation of pharmaceutical pollutants without causing any other secondary pollutant.

Kinetic Studies on an Algal Biofilm Reactor for Raw Sewage Water Treatment

AbstractA packed‐bed algae biofilm reactor was developed using porous and nonporous dual packings. The biofilm was cultivated on reticulated polyurethane foam cubes. The nonporous glass Raschig rings were taken as bed support that helps to remove generated gas from the system. The effect of variables such as column length‐to‐diameter ratio, catalyst cube dimension, and feed flow rate on the treatment of sewage water was studied. The reaction kinetics indicates that the nutrients uptake rate is dependent on both pore and film diffusion. The kinetics of uptake of nutrients follows a pseudo first‐order reaction. From the pseudo reaction rate constant, Thiele modulus and effectiveness factor were calculated and a kinetic model equation for fractional nutrient uptake was developed in terms of operating variables. The model can predict the reaction rate with low deviation. The results obtained may be valuable for large‐scale treatment of sewage water.

Decomposition of acetic acid by advanced oxidation processes

Decomposition of acetic acid, known as a non-degradable organic compound, was conducted for several advanced oxidation processes such as TiO2-UV-H2O2, Fe2+-H2O2-UV, UV-H2O2 and TiO2-UV system. Acetic acid was efficiency decomposed within 120 minutes of UV radiation under the initial concentration of 500 ppm. The initial chemical oxygen demands (COD cr ) tended to increase as H2O2 was added in most reactions. However, the initial COD cr was not increased as H2O2 was consumed for the oxidation of iron salt in the photo-Fenton oxidation process. COD cr and concentration of acetic acid rapidly decreased as the mole ratio of hydrogen peroxide increased owing to rapid decomposition of the reactant at the beginning of reaction. All reactions show first order pseudo reaction rate. The COD cr removal rate and the decomposition efficiency of acetic acid were fastest in the UV-H2O2 process.

Site-specific Binding Affinities within the H2B Tail Domain Indicate Specific Effects of Lysine Acetylation

Acetylation of specific lysines within the core histone tail domains plays a critical role in regulating chromatin-based activities. However, the structures and interactions of the tail domains and the molecular mechanisms by which acetylation directly alters chromatin structures are not well understood. To address these issues we developed a chemical method to quantitatively determine binding affinities of specific regions within the individual tail domains in model chromatin complexes. Examinations of specific sites within the H2B tail domain indicate that this tail contains distinct structural elements and binds within nucleosomes with affinities that would reduce the activity of tail-binding proteins 10-50-fold from that deduced from peptide binding studies. Moreover, we find that mutations mimicking lysine acetylation do not cause a global weakening of tail-DNA interactions but rather the results suggest that acetylation leads to a much more subtle and specific alteration in tail interactions than has been assumed. In addition, we provide evidence that acetylation at specific sites in the tail is not additive with several events resulting in similar, localized changes in tail binding.

Rapid and Quantitative Displacement of Poly(ethylene oxide) from MnPS3 and Other Layered Hosts

The reaction of tetraethylammonium salt with the nanocomposites K0.2(C2H4O)2.3M0.9PS3 (M = Mn, Cd) under ambient conditions results in the rapid and quantitative displacement of the polymer and alkali metal to form the alkylammonium intercalate. Solid reactants and products, characterized using XRD, TGA, IR, gel permeation chromatography, and elemental analyses, show that these displacement reactions go to completion with no polymer degradation after initial formation of the nanocomposite. Pseudoreaction rates (0.0−7.8 min-1) are obtained using temporal XRD studies for different cations, concentrations, and polymer molecular weights. Reaction rates increase for lower polymer molecular weights, and a strong rate dependence is observed for alkylammonium concentration. Displacement from the MPS3 host occurs very slowly, or only to a limited extent, for tetramethylammonium, tetrapropylammonium, and tetrabutylammonium salts. A reaction mechanism is proposed from observed trends. Rapid displacement is also repo...

Diffusional behaviour of immobilised glucose oxidase

AbstractGlucose oxidase immobilised on Amberlite CG‐50 by glutaraldehyde technique, was used to study the behaviour of immobilised enzyme reactor with respect to diffusional restrictions. The film diffusion effects were observed by assaying the performance of column reactors of different diameters, 1.0, 1.5 and 2.0 cm and each packed with two catalyst weights of 1.0 and 1.5 g to give different bed depths. The columns were packed with bulk catalyst preparation of approximately 118 μm average size and the substrate feed rate through them was varied from 5 to 50 ml min−1. The conversions increased for the same values of space times with factors that increase the linear velocity of feed and thus decrease the film thickness. Internal pore diffusional resistances could be satisfactorily described by Thiele analysis. The diffusional restriction was minimum when the largest effectiveness factor of 0.94 was obtained with the particles in the size range of 56–65 μm, the value of pseudo reaction rate constant (K') in this range was 34.7 cm3 g−1 cat.min−1. The results of the analysis of the experimental work achieved a good fit to the predicted curve well.

Pseudo reaction rate in the ac response of an electrolytic cell

When theoretical impedance-frequency “data” calculated from an exact small-signal ac solution of the transport equations for an unsupported intrinsic-conduction situation are fitted to an appropriate equivalent circuit using nonlinear complex least squares, one finds that a non-zero apparent charge transfer resistance is necessary for a good fit even when charges of one sign are taken completely blocked at the electrodes and those of opposite sign are taken as completely unblocked. Normally, one would expect no reaction resistance under these conditions. This effect only occurs when positive and negative charges have different mobilities and may be ascribed to ambipolar drag of one set of charges on the other set. Here we demonstrate the effect and derive approximate relations to be used in data analysis which should allow an accurate estimate of the true reaction rate to be obtained when it is not too large. The practical limit to the maximum reaction rate which can be derived from experimental impedance data for the present situation is shown to depend on both a diffusion coefficient and the Debye length.

Pseudo reaction rate in the AC response of an electrolytic cell

When theoretical impedance-frequency “data” calculated from an exact small-signal ac solution of the transport equations for an unsupported intrinsic-conduction situation are fitted to an appropriate equivalent circuit using nonlinear complex least squares, one finds that a non-zero apparent charge transfer resistance is necessary for a good fit even when charges of one sign are taken completely blocked at the electrodes and those of opposite sign are taken as completely unblocked. Normally, one would expect no reaction resistance under these conditions. This effect only occurs when positive and negative charges have different mobilities and may be ascribed to ambipolar drag of one set of charges on the other set. Here we demonstrate the effect and derive approximate relations to be used in data analysis which should allow an accurate estimate of the true reaction rate to be obtained when it is not too large. The practical limit to the maximum reaction rate which can be derived from experimental impedance data for the present situation is shown to depend on both a diffusion coefficient and the Debye length.