Unconventional mesoporous single crystalline NiO by synergistically controlled evaporation and hydrolysis

Mesoporous single-crystal NiO was synthesized by controlling metal ion hydrolysis and solvent evaporation rates, exhibiting excellent electrochemical activities.

Microtubule Templated Synthesis of Inorganic Nanomaterials

Protein microtubules (MTs) have been used as templates for the biomimetic synthesis of metal oxide, metal sulfide, and metallic nanomaterials. These materials were coated onto MTs via three distinct synthetic pathways: metal ion hydrolysis which yielded iron oxide or zinc oxide-coated microtubules, metal ion/sulfide co-precipitation which yielded zinc sulfide coated MTs, and metal ion reduction which yielded gold-coated MTs. The growth process of metal oxide coating involves heterogeneous nucleation on the MT surface and produces even, microcrystalline films. Metal sulfide and metal coating initially involves the formation of nanoparticle arrays that decorate the MT surface and can eventually lead to either semi- or fully continuous coatings.

Effect of colloids on radionuclide migration for performance assessment of HLW disposal in Japan

Colloidal effect is one of the major factors to enhance the migration of radionuclides in groundwater. The experimental and theoretical studies of colloid mobility and colloid-facilitated radionuclide transport for the performance assessment of high-level radioactive waste (HLW) geological disposal is presented in this paper. The major aims of the study are (1) to study the filtration effect on colloids by the engineered barrier system, (2) to study bentonite colloid generation by erosion of the engineered barrier system, and (3) to calculate radionuclide migration with groundwater colloids through fractured rock systems. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Hydrolyzing metal salts as coagulants

Aluminium and ferric salts are widely used as coagulants in water and wastewater treatment. They are effective in removing a broad range of impurities from water, including colloidal particles and dissolved organic substances. Their mode of action is broadly understood in terms of essentially two mechanisms: charge neutralization of negatively charged colloids by cationic hydrolysis products and incorporation of impurities in an amorphous precipitate of metal hydroxide. The relative importance of these two mechanisms depends on many factors, especially pH and coagulant dosage. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Extraction and separation of metal cations in solution by supported liquid membrane using lasalocid A as carrier

Flat-sheet-supported liquid membranes incorporating lasalocid A (a natural ionophore), were previously shown to be permeable to metal cations (Cd2+ and Zn2+) against a proton gradient (DpH), which is the driving force of the process [1]. This transport process has been extended to other metal species such as Pb2+, Na+, and Ag+ and also to the case where two metal species compete for transport. A higher transport flux for Pb2+ as compared to Cd2+ and Zn2+ is observed and partly explained by a higher rate of interfacial complexation owing to the smaller hydration shell of this species. This effect is confirmed by the data obtained with Ag+. However, the size of the metal cation in relation to its hydration shell does not appear as the major parameter to take into account for an estimate of the trans-membrane transport efficiency, as the Na+ ions escape to this behavior, which has been considered until now as a general trend for metal cation ionophores. Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation. Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved

Hydrolysis of the thorium(IV) ion in sodium nitrate medium

The hydrolysis of the thorium(IV) ion in sodium nitrate medium was studied by the emf method at 25 °C. The data show that the extent of the thorium hydrolysis depends both on the concentration of thorium and the sodium nitrate medium. Thus, at a definite pH, the extent of the hydrolysis of thorium increases with increasing its concentration, but decreases with increasing concentration and the hydration energy of the medium ions. The stability constants of complexes Th2(OH)26+, Th3(OH)57+, and Th6(OH)159+ also slightly differ going from one concentration of sodium nitrate to another. The observed effect of the medium is in agreement with the linear free energy relationship proposed for the metal ion hydrolysis.