Particles, hydrolysis product, surface

Uniform submicron particles cannot be obtained by hydrolysis of concentrated Ti(OR)4 solutions, as the increase of concentration results in agglomeration of the hydrolysis product, these agglomerates cannot be redispersed. Agglomeration is a result ofthe sticking together ofthe particles in the course of Brown movement, which can be overcome electrostatically (it assumes introduction in the solution of electrolyte ions) or sterically by introduction of surface active components, which should be able to diffuse from solution and bind with the surface of the particle by physical adsorption. To prevent ag-... 

Size and Surface Area of Hydrolysis Product Particles... 

Hydration of HPP. All factors mentioned above affect the T i value, showing the change in the state of water to be the result of a change in the composition of the water and the surface properties of the disperse phase. Aluminium hydrolysis products are mostly particles of Al(OH)3 with aluminium hydroxyl complexes adsorbed on them, so the change in T can be associated with an altered nature and number of hydrophilic centres. It has been shown5,6 that in all cases the spin-spin relaxation time of water protons decreases with increasing OH/A1 ratio in the coagulant molecule. This is an evidence of increased hydration of particles surface in this direction. 

Surface Activation. Acid Activation. Acid treatment of cellulose and hemicelluloses generally leads to hydrolysis to monosaccharides, which can subsequently dehydrate and condense to form furan-type compounds such as furfural and its 5-hydroxymethyl adduct. Further reactions lead to polymeric materials of dark color as well as to monomers such as levulinic acid, formic acid, and angelica lactones. Various condensation and solvolysis reactions also accompany the acid treatment of lignin 123). The hydrolysis, dehydration, and condensation reactions have been used to explain formation of covalent bonds between surfaces (85), increase in water resistance (85, 124), and weakening of wood (75) in nonconventional plywood or particle board production. However, very little factual information is available on how far, in terms of the consecutive reactions mentioned, and in what direction, in terms of the parallel reactions mentioned, does the surface of lignocellulosic materials actually change... 

Radioactive tracers adsorb not only on solid container surfaces and precipitates but on any kind of solid material suspended or in contact with the solution. Dust, cellulose fibers, glass fragments, organic materials, etc., are examples of substances that readily adsorb radioactive tracers from solution. If the solution contains large molecules as, for example, polymeric metal hydrolysis products, these also tend to adsorb trace elem ts. In addition to sorption, the presence of such material in the solution can lead to the phenomenon of radiocolloid formation, which is the attachment of radionuclides to semicolloidal aggregates in solution. If the solution is kept at sufficiently low pH and extremely free from foreign particles, sorption and radiocolloid formation are usually avoided as major problems. 

Figure 3. Variation of the specific surface Figure 4. Pore size distribution of the areas of the hydrolysis products after se- nano-particles heated at 200 C. The...

Water and Waste Water Treatment. PAG products are used in water treatment for removal of suspended soHds (turbidity) and other contaminants such as natural organic matter from surface waters. Microorganisms and colloidal particles of silt and clay are stabilized by surface electrostatic charges preventing the particles from coalescing. Historically, alum (aluminum sulfate hydrate) was used to neutralize these charges by surface adsorption of Al cations formed upon hydrolysis of the alum. Since 1983 PAG has been sold as an alum replacement in the treatment of natural water for U.S. municipal and industrial use. 

CDU in pure form is a white powder. It is made slowly available to the soil solution by nature of its limited solubihty in water. Once in the soil solution, nitrogen from CDU is made available to the plant through a combination of hydrolysis and microbial decomposition. As with any CRE which is dependent on microbial action, the mineralization of CDU is temperature dependent. Product particle size has a significant effect on CDU nitrogen release rate. Smaller particles mineralize more rapidly because of the larger surface contact with the soil solution and the microbial environment. The rate of nitrogen release is also affected by pH because CDU degrades more rapidly in acidic soils. 

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