Electroreduction of Oxygen on Ruthenium Phthalocyanine in Alkaline Media

The effect of oxygen (O2)-delignified pine kraft pulp pretreatment by high-purity, thermostable, and alkaline-tolerant xylanases on elemental chlorine free (ECF) bleaching of O2-delignification kraft pulp was studied. The study found that xylanase pretreatment preserved the intrinsic viscosity and yield of O2-delignified pulp while causing about 7% of delignification with high delignification selectivity. The xylanases with high purity, higher thermostability (75°C~80°C) in highly alkaline media (pH 8.0~9.5) could be applied on an industrial scale. Pulp pretreatment by the high-purity, thermostable, and alkaline tolerant xylanases could improve pulp brightness or reduce the chlorine dioxide (ClO2) consumption. In a D0ED1D2 bleaching sequence using the same amount of ClO2, the xylanase-pretreated pulp obtained a higher brightness (88.2% vs. 89.7% ISO) at the enzyme dose of 2 U/g pulp; or for the same brightness as control (88.2% ISO), the ClO2 dosage in the D0 stage was reduced by 27%, which represents a 16% savings in total ClO2 used for bleaching.

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Chemical Transformations of Waxes during Mechanochemical Treatment of Peat in Aqueous Alkaline Media

Химия в интересах устойчивого развития ◽

10.15372/khur20170208 ◽

2017 ◽

Keyword(s):

Mechanochemical Treatment ◽

Alkaline Media ◽

Chemical Transformations

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Enhanced catalytic activity of low-Pt content nanocatalysts supported on hollow carbon spheres for the ORR in alkaline media

MRS Advances ◽

10.1557/adv.2020.370 ◽

2020 ◽

Vol 5 (57-58) ◽

pp. 2961-2972

Author(s):

P.C. Meléndez-González ◽

E. Garza-Duran ◽

J.C. Martínez-Loyola ◽

P. Quintana-Owen ◽

I.L. Alonso-Lemus ◽

...

Keyword(s):

Catalytic Activity ◽

Anion Exchange ◽

Average Particle Size ◽

Synthesis Method ◽

Alkaline Media ◽

High Catalytic Activity ◽

Average Particle ◽

Carbon Spheres ◽

Hollow Carbon ◽

Hollow Carbon Spheres

In this work, low-Pt content nanocatalysts (≈ 5 wt. %) supported on Hollow Carbon Spheres (HCS) were synthesized by two routes: i) colloidal conventional polyol, and ii) surfactant-free Bromide Anion Exchange (BAE). The nanocatalysts were labelled as Pt/HCS-P and Pt/HCS-B for polyol and BAE, respectively. The physicochemical characterization of the nanocatalysts showed that by following both methods, a good control of chemical composition was achieved, obtaining in addition well dispersed nanoparticles of less than 3 nm TEM average particle size (d) on the HCS. Pt/HCS-B contained more Pt0 species than Pt/HCS-P, an effect of the synthesis method. In addition, the structure of the HCS remains more ordered after BAE synthesis, compared to polyol. Regarding the catalytic activity for the Oxygen Reduction Reaction (ORR) in 0.5 M KOH, Pt/HCS-P and Pt/HCS-B showed a similar performance in terms of current density (j) at 0.9 V vs. RHE than the benchmark commercial 20 wt. % Pt/C. However, Pt/HCS-P and Pt/HCS-B demonstrated a 6 and 5-fold increase in mass catalytic activity compared to Pt/C, respectively. A positive effect of the high specific surface area of the HCS and its interactions with metal nanoparticles and electrolyte, which promoted the mass transfer, increased the performance of Pt/HCS-P and Pt/HCS-B. The high catalytic activity showed by Pt/HCS-B and Pt/HCS-P for the ORR, even with a low-Pt content, make them promising cathode nanocatalysts for Anion Exchange Membrane Fuel Cells (AEMFC).

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The Role of Cations and Electrolyte pH in the Hydrogen Evolution Reaction on Au in Alkaline Media

10.29363/nanoge.ecocat.2020.006 ◽

2020 ◽

Author(s):

Akansha Goyal ◽

Marc T.M. Koper

Keyword(s):

Hydrogen Evolution ◽

Hydrogen Evolution Reaction ◽

Alkaline Media ◽

Electrolyte Ph

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VDM LC-NICKEL 99.2

Alloy Digest ◽

10.31399/asm.ad.ni0502 ◽

1996 ◽

Vol 45 (3) ◽

Keyword(s):

Corrosion Resistance ◽

Physical Properties ◽

Surface Treatment ◽

Carbon Content ◽

Tensile Properties ◽

Heat Treating ◽

Alkaline Media ◽

Excellent Corrosion Resistance

Abstract VDM LC-Nickel 99.2 is unalloyed nickel which offers excellent corrosion resistance in many alkaline media. The metal also has good mechanical, magnetic, and magnetostrictive properties. It has a reduced carbon content to avoid graphitization at temperatures above 570 deg F (300 deg C). This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-502. Producer or source: VDM Technologies Corporation.

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Spectrophotometric study of the acid-base and optical properties of the 5-bromo and 5-chloro derivatives of 2-(2-pyridylazo)-5-(diethylamino)phenol (BrPADAP, ClPADAP) and their complexation equilibria with zinc(II) ions

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19822676 ◽

1982 ◽

Vol 47 (10) ◽

pp. 2676-2691 ◽

Cited By ~ 6

Author(s):

Miroslav Macka ◽

Vlastimil Kubáň

Keyword(s):

Equilibrium Constants ◽

Spectrophotometric Study ◽

Graphical Analysis ◽

Alkaline Media ◽

Acid Base ◽

Ethanol Medium ◽

Triton X ◽

Mixed Water ◽

Derivatives Of

The optical and acid-base characteristics of BrPADAP and ClPADAP were studied in mixed water-ethanol and water-DMF media and in 10% ethanol medium in the presence of cationic, anionic and nonionic tensides. The composition, optical characteristics, molar absorption coefficients and equilibrium constants of the ML and ML2 complexes with zinc(II) ions were found by graphical analysis and numerical interpretation of the absorbance curves by the modified SQUAD-G program. Optimal conditions were found for the spectrophotometric determination of Zn(II) in the presence of 0.1% Triton X-100 or 1% Brij 35 in alkaline media with pH = 6.5-10. BrPADAP and ClPADAP are the most sensitive reagents (ε = 1.3-1.6 . 105 mmol-1 cm2 at 557 and 560 nm, respectively) for the determination of zinc with high colour contrast of the reaction (Δλ = 104 nm) and selectivity similar to that for the other N-heterocyclic azodyes (PAN, PAR, etc.).

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Kinetic salt effects in the hydrolysis of ethyl malonate, methyl glutarate and ethyl adipate semiesters

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19862781 ◽

1986 ◽

Vol 51 (12) ◽

pp. 2781-2785 ◽

Cited By ~ 1

Author(s):

M. Martín Herrera ◽

J. J. Maraver Puig ◽

F. Sánchez Burgos

Keyword(s):

Salt Effect ◽

Alkaline Media ◽

Salt Effects ◽

Coulombic Interaction ◽

Hydroxide Ion ◽

Ethyl Malonate ◽

Hydrolysis Of

A study is made on the kinetic salt effect on the reaction of hydrolysis of several charged esters in alkaline media. The results are interpreted on the basis of the coulombic interaction, the salting in of hydroxide ion and a third component depending on size of the substrate.

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