Cluster defects in gibbsite nanoplates grown at acidic to neutral pH

Nanoscale ◽  
2021 ◽  
Author(s):  
Sebastian Mergelsberg ◽  
Mateusz Dembowski ◽  
Mark E Bowden ◽  
Trent R Graham ◽  
Micah P Prange ◽  
...  
Keyword(s):  
Growth Mechanism ◽  
Industrial Applications ◽  
Mineral Phase ◽  
Neutral Ph ◽  
Wide Ph Range ◽  
Ph Range

Gibbsite [α-Al(OH)3] is the solubility limiting phase for aluminum across a wide pH range, and it is a common mineral phase with many industrial applications. But the growth mechanism of...

ZIF‐8 MOF Encapsulated Co‐porphyrin, an Efficient Electrocatalyst for Water Oxidation in a Wide pH Range: Works Better at Neutral pH

ChemCatChem ◽  
2020 ◽  
Vol 12 (21) ◽  
pp. 5430-5438 ◽  
Author(s):  
Subhabrata Mukhopadhyay ◽  
Olivia Basu ◽  
Samar K. Das
Keyword(s):  
Water Oxidation ◽  
Neutral Ph ◽  
Wide Ph Range ◽  
Ph Range

scholarly journals pH-Dependent Gelation of a Stiff Anionic Polysaccharide in the Presence of Metal Ions

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 868 ◽  
Author(s):  
Andrey V. Shibaev ◽  
Dmitry A. Muravlev ◽  
Aleksandra K. Muravleva ◽  
Vladimir V. Matveev ◽  
Anatoly E. Chalykh ◽  
...  
Keyword(s):  
Metal Ions ◽  
Freeze Fracture ◽  
Industrial Applications ◽  
Cross Linking ◽  
Chromium Ions ◽  
Transmission Electron ◽  
Wide Range ◽  
Carboxylic Groups ◽  
Wide Ph Range ◽  
Ph Range

Cross-linking of polysaccharides by metal ions provides polymer gels highly required by industrial applications. In this article, we study the rheological properties and microstructure of solutions of a stiff anionic polysaccharide xanthan cross-linked by chromium (III) ions, and we demonstrate that their properties are highly sensitive to the preparation pH. Stable gels are obtained in a wide range of pH from 2.4 to 7.8. The maximum elastic modulus is observed for the gels made at pH 6.3, and by freeze-fracture transmission electron microscopy it is shown that they are characterized by the most dense network structure. However, out of this pH interval, no gelation is observed. At low pH (< 2.4) it is due to high protonation of carboxylic groups of xanthan preventing their interaction with chromium ions, and to the disappearance of oligomeric ions, which are effective in cross-linking. At high pH (> 7.8) the absence of gelation is caused by the transformation of reactive chromium ions into insoluble chromium hydroxide. At the same time, for the gels initially formed at pH 6.3, subsequent change of pH to strongly acidic (1.4) or basic (8.9) medium does not affect appreciably their properties, meaning that chromium cross-links are stable once they are formed. These observations open a reliable route to produce polysaccharide gels with required mechanical properties in a wide pH range where they initially cannot be prepared. It is also shown that the increase of pH to 6.3 of the initially ungelled solution prepared at pH 1.5 results in gelation. This effect offers a facile way for delayed gelation of polysaccharides, which is especially required by oil industry.

Effect of media pH on the growth of Entomopathogenic Fungi isolated from different rhizosphere soils

2017 ◽  
Vol 6 (03) ◽  
pp. 5325 ◽  
Author(s):  
Chandra K.N.P. Teja* ◽  
S. J. Rahman
Keyword(s):  
Insect Pests ◽  
Abiotic Factors ◽  
Industrial Applications ◽  
Fungal Species ◽  
Biomass Growth ◽  
Wide Ph Range ◽  
Field Efficacy ◽  
The Media ◽  
Ph Range ◽  
Ph Variations

Many Entompathgenic fungal species are of agricultural importance as safe alternatives for chemical insecticides in controlling the various insect pests of crops. pH is one of the abiotic factors influencing the activity of these fungi in both laboratory survival and field efficacy. The effect of pH of the media on the biomass growth of seven locally isolated Entomopathogenic fungal isolates was evaluated in the present study. The isolates in general had a wide pH range for their growth but had maximum biomass at low pH of 4 or 5 and least biomass growth at higher basic pH. Variations in growth among isolates were also noticed. The importance of our findings was discussed in the light of the agricultural as well as industrial applications of these fungi.

Polarographic and spectrophotometric behaviour of some N-p-phenyl substituted benzamidines

1991 ◽  
Vol 56 (12) ◽  
pp. 2791-2799 ◽  
Author(s):  
Juan A. Squella ◽  
Luis J. Nuñez-Vergara ◽  
Hernan Rodríguez ◽  
Amelia Márquez ◽  
Jose M. Rodríguez-Mellado ◽  
...  
Keyword(s):  
Spectrophotometric Study ◽  
Absorption Bands ◽  
Electrochemical Parameters ◽  
Wide Ph Range ◽  
Group A ◽  
Substituent Constants ◽  
Ph Range ◽  
The Waves

Five N-p-phenyl substituted benzamidines were studied by DC and DP polarography in a wide pH range. Coulometric results show that the overall processes are four-electron reductions. Logarithmic analysis of the waves indicate that the process are irreversible. The influence of the pH on the polarographic parameters was also studied. A UV spectrophotometric study was performed in the pH range 2-13. In basic media some variations in the absorption bands were observed due to the dissociation of the amidine group. A determination of the pK values was made by deconvolution of the spectra. Correlations of both the electrochemical parameters and spectrophotometric pK values with the Hammett substituent constants were obtained.

High degradation efficiency of sulfamethazine with the dual-reaction-center Fe-Mn-SiO2 Fenton-like nanocatalyst in a wide pH range

2021 ◽  
Author(s):  
Manoj Kumar Panjwani ◽  
Qing Wang ◽  
Yueming Ma ◽  
Yuxuan Lin ◽  
Feng Xiao ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Reaction Center ◽  
Degradation Efficiency ◽  
Heterogeneous Fenton ◽  
Wide Ph Range ◽  
Ph Range

The development of a heterogeneous Fenton-like catalyst, possessing high degradation efficiency in a wide pH range, is crucial for wastewater treatment. The Fe-Mn-SiO2 catalyst was designed, and prepared by a...

scholarly journals Defect-Rich Heterogeneous MoS2/rGO/NiS Nanocomposite for Efficient pH-Universal Hydrogen Evolution

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 662 ◽  
Author(s):  
Guangsheng Liu ◽  
Kunyapat Thummavichai ◽  
Xuefeng Lv ◽  
Wenting Chen ◽  
Tingjun Lin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Reduced Graphene ◽  
Heterogeneous Interfaces ◽  
Wide Ph Range ◽  
Ph Range ◽  
A Current ◽  
Poor Stability

Molybdenum disulfide (MoS2) has been universally demonstrated to be an effective electrocatalytic catalyst for hydrogen evolution reaction (HER). However, the low conductivity, few active sites and poor stability of MoS2-based electrocatalysts hinder its hydrogen evolution performance in a wide pH range. The introduction of other metal phases and carbon materials can create rich interfaces and defects to enhance the activity and stability of the catalyst. Herein, a new defect-rich heterogeneous ternary nanocomposite consisted of MoS2, NiS and reduced graphene oxide (rGO) are synthesized using ultrathin αNi(OH)2 nanowires as the nickel source. The MoS2/rGO/NiS-5 of optimal formulation in 0.5 M H2SO4, 1.0 M KOH and 1.0 M PBS only requires 152, 169 and 209 mV of overpotential to achieve a current density of 10 mA cm−2 (denoted as η10), respectively. The excellent HER performance of the MoS2/rGO/NiS-5 electrocatalyst can be ascribed to the synergistic effect of abundant heterogeneous interfaces in MoS2/rGO/NiS, expanded interlayer spacings, and the addition of high conductivity graphene oxide. The method reported here can provide a new idea for catalyst with Ni-Mo heterojunction, pH-universal and inexpensive hydrogen evolution reaction electrocatalyst.

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