Effect Of KBr Research Articles

A highly efficient, green, and straightforward approach for 2,5-diformylfuran synthesis from carbohydrates using carbonized sugarcane bagasse and KBr

2,5-Diformylfuran (DFF) is an important chemical that is utilized to synthesize several valuable chemicals. Direct preparation of DFF from plentiful and inexpensive carbohydrates in a one-pot approach is highly desired. Here, we report the development of a heterogeneous sulfonated amorphous carbon-derived sugarcane bagasse combined with KBr as a catalyst system to convert fructose to DFF in a short time and high yield in DMSO. Several reaction conditions, such as the effect of metal bromide, the effect of KBr and carbon-based solid acid catalyst loading, the effect of temperature, the effect of solvent, the effect of substrate, reusability test, and scale-up synthesis, have been investigated. The optimized yield of DFF was 90 ± 3% at 140 °C in DMSO solvent for 5 h. The approach has several outstanding features, including high chemo-selectivity, high yield, low cost, and recyclable catalyst.

Electrochemical Performance of Potassium Bromate Active Electrolyte for Laser-Induced KBr-Graphene Supercapacitor Electrodes

In this paper, we have reported a low-concentration active electrolyte of KBrO3 for the supercapacitor’s application. The electrochemical processes were carried out in two concentrations of KBrO3 with 0.2 and 0.4 M. Additionally, we have reported a novel strategy for doping graphene during its fabrication process with a potassium bromide (KBr) solution. The chemical doping of graphene with KBr improved the electrochemical properties of graphene used as supercapacitors. HRTEM images confirmed the multi-layer graphene obtained by CO2 laser based on polyimide. The effect of KBr on the graphene lattice has been studied using Raman spectroscopy. The two electrodes of graphene and KBr-doped graphene were subjected to the electrochemical properties study as a supercapacitor by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge techniques. The results exhibited the successful method of graphene doping and the stability of using KBrO3 as a suitable electrolyte for electrochemical processes with this lower molarity. The specific capacitance of the pristine graphene capacitor in 0.2 M of KBrO3 was 33 Fg−1, while this value increased up to 70 Fg−1 for KBr-doped graphene in 0.4 M of KBrO3. The specific capacity in mAhg−1 has also increased twofold. The results exhibited the possibility of using KBrO3 as an electrolyte. The supercapacitor performance almost showed good stability in the life cycle.

Effects of KBr and KI on Photocatalytic Degradation of Dye W-7G with Nano-TiO2 as Catalyst

To investigate the influence of inorganic salt on the photocatalytic degradation, the effects of KBr and KI at various concentrations and pH values on the photocatalytic degradation of dye W-7G using nanoscaled titanium dioxide as photocatalyst in a bubbling fluidized bed photocatalytic reactor (BFBPR) were studied. The results indicated that the degradation apparent rate constant ( K app ) of the system with KI was clearly higher than that with KBr under acidic or alkaline conditions. And the maximum value of K app (0.01127) appeared at the KI concentration of 0.075 g L-1 with a pH value of 9.37, meaning the highest degradation efficiency. Furthermore, the possible mechanism of photocatalytic degradation of W-7G in the presence of KBr and KI was proposed, which could provide a theoretical support for the further study of inorganic salt effects on the photocatalytic degradation of dyes.

Effect of KBr on the FTIR Spectra of NO3−LDHs (Layered Double Hydroxides)

Abstract Anion exchange of NO3−LDH with Br− of KBr, which leads to the formation of Br−LDH and NO3−-doped KBr, was found to occur during the preparation of KBr pellets for FTIR measurement, and the obtained spectra were composed of characteristic features of NO3− bands in NO3−LDH and in NO3−-doped KBr mixed in variable proportions depending on pellet preparation conditions.

Catalytically Active Monomer of Class Mu Glutathione Transferase from Rat

Although rat glutathione transferase M1-1 is crystallized as a homodimer (GST M1-1), we have generated monomers (GST M1) of the enzyme by adding potassium bromide to buffer solutions containing the wild-type enzyme and by introducing point mutations in the electrostatic region of the subunit interface. The wild-type enzyme was evaluated in 0.05 M MES (pH 6.5) containing up to 3 M KBr. We report that the addition of KBr greatly influences the monomer-dimer equilibrium of the wild-type enzyme and that at 3 M KBr GST M1 has a specific activity close to that of GST M1-1. Since the effect of KBr is likely due to charge screening at the subunit interface, the influence on the monomer-dimer equilibrium exerted by the amino acid residues in the electrostatic region of the interface (Arg77, Asp97, Glu100, Asn101) was investigated. Mutations introduced at positions 97, 100, and 101 promote monomerization, resulting in enzymes that exhibit a decreased weight average molecular weight in comparison to that of the wild-type enzyme. However, only mutations at position 97 result in enzymes that have catalytic activity in the monomeric form. The mutations introduced at positions 100 or 101 result in enzymes whose activity can be accounted for by the amount of dimeric enzyme present. Our results indicate that the electrostatic region of the interface is important in the monomer-dimer equilibrium of glutathione transferase and that, although GST M1-1 may be more active than GST M1, the dimer is not required for catalytic function.

Effect of KBr on the micellar properties of CTAB

The effect of KBr on the size, shape and microviscosity of CTAB micelles has been investigated by means of laser light scattering (LLS),1H NMR measurements and fluorescence probe. The data obtained from the various techniques are quantitatively in agreement. The Rh of micelles in 0.01 rnol · L−1 CTAB solution increases from 3.5 nm to 43 nm andR g increases to 89 nm with addition of KBr salt. In this process, both the microviscosity and molecular weight of micelles Mw have noticeable increases, too. The rod-like micelles are formed at 0.1 rnol · L1 KBr and the worm-like micelles are formed at above 0.2 rnol · L-1 KBr.

Effects of hydroxide ion, salts and temperature on the hydrolytic cleavage of ionized N-hydroxyphthalimide (NHPH) in the presence of cationic micelles

The effects of cetytrimethylammonium bromide (CTABr) micelles on pseudo first-order rate constants ( k obs) for the alkaline hydrolysis of N-hydroxyphthalimide (NHPH) have been studied at different NaOH and NaBr concentrations. Pseudo first-order rate constants were treated with a pseudo-phase ion-exchange model of micelles. The rate constants for micellar-mediated reactions are independent of NaBr concentration, while the binding constant of anionic NHPH with CTABr miceles decreases with increasing NaBr concentration. The rate of reaction in the micellar pseudo-phase is significantly smaller than that in the aqueous pseudo-phase. The effects of KBr and KCl concentration on k obs at constant CTABr and NaOH concentrations reveal that an increase in KBr or KCl concentration causes the expulsion of micellized anionic NHPH molecules (NHP M −) from the micellar pseudo-phase to the aqueous pseudo-phase. Bromide ions expel NHP M − more strongly than chloride ions.

Interaction of Bovine Serum Albumin with Detergent Cations

Abstract The binding isotherms of bovine serum albumin (BSA) with cationic detergents, decyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and tetradecyltrimethylammonium bromide have been determined at temperatures 8 and 25 °C for pH 6.8. The isotherms have also been determined at pH 3.0 and 25 °C. The effect of KBr on the binding of dodecyltrimethylammonium bromide to BSA has been examined at 25 °C for pH 6.8. The results obtained are as follows. (a) The average number of detergent cations bound, \barv, increased with the increase in the length of hydrocarbon chain, (b) the standard free energy changes −ΔG°, calculated from the intrinsic association constants K, were comparable with the cohesive energy change when one methylene group is transferred from the aqueous phase to the hydrocarbon environment on micellization, (c) values of \barv at pH 3.0 differ only slightly from those at pH 6.8 in a wider range of detergent concentration, and (d) the presence of the salt shifted the binding isotherms to the lower detergent concentrations. These results are discussed as regards the nature of micellization of detergents.