Peptization Ratio

Many attempts have been made to characterize the stabiUty of the colloidal state of asphalt at ordinary temperature on the basis of chemical analysis in generic groups. For example, a colloidal instabiUty index has been defined as the ratio of the sum of the amounts in asphaltenes and flocculants (saturated oils) to the sum of the amounts in peptizers (resins) and solvents (aromatic oils) (66) ... 

However, no rutile phase is shown even though the molar ratio of TENOH/TTIP increased up to 1.0(Fig. 1(b)). In addition, the anatase particles with a high degree of crystallinity are formed compared to the HNOs-peptized particles. It is thought that the existence of OH- groups in the peptized sols can enhance the growth of anatase particles. 

Total carbon and nitrogen were analyzed for the core sediments, the interstitial waters, and the peptized aqueous solutions the results are given in Table VIII. The ratios of Total C/Total N of the bulk composition, interstitial waters of the core sediments, and the average ratios of the peptized aqueous solutions are also summarized in Table VIII. 

Mixtures of Al and Mg chlorides at different ratios, total molarity 0.5, were added to ammonia solution, and the final pH was 9.5. The precipitate was aged for 5 h at room temperature and washed with water. It was peptized at 333K and washed by ultrafiltration. 

A mixed solution of Mg and Tcfiii) chlorides (molar ratio 2, 2.5, or 3) of total metal ion concentration 0.5 M was slowly titrated with 0.25 M ammonia to pH 9.5. The precipitate was aged for 2 h in the mother solution, then washed with water and peptized at 80°C for 1 d. 

Method B (Vacuum-sol method) A 0.96M aluminum nitrate solution was added to 50ml water glass solution until the Si/Al molar ratio was attained. The precipitate was collected by centrifugation and washed 7 times to remove the sodium ions. After washing, the precipitate was put into 200ml of water and then added a certain quantity of 0.94M nitric acid to peptize the precipitate to obtain the sol sample. The prepared sol was dried at room temperature in a vacuum box until it began to form the gel sample. The gels were also calcined at 550 C in air for 10 hours. The sol and solid samples produced by method B were defined as VSG samples [5]. 

The controlled formation of polymeric Pu(IV) is important to the sol-gel process for the production of spherical PUO2 particles. Ammonia is added to a nitric acid solution of Pu(IV) to precipitate Pu(OH)4, which is subsequently peptized at 50°C with dilute nitric acid to produce sols of 1 to 3 M Pu with a NOs /Pu ratio of 0.1 to 03. The sols, which remain stable over periods of a few months, are dispersed in a dehydrating organic solvent to form a gel, which is ignited to form spherical particles of PuOj [K2]. 

HaO/solid ratio used in the washing step, drying protocol, extrusion parameters (type and concentration of peptizing agents, solid/solution ratio and mixing time) and nitridation conditions. Because of the limited space available, this communication only reports the main effects brought by the adjustment of some of these parameters. 

Si02/Al203 (mol ratio 240) was mixed with peptized and neutralized Catapol AI2O3 at 2 1 sieve/Al203 wt. ratio, impregnated with solution of Zn, and Ni LHSV 0.5,0.69 MPa, 65.6 C gave C5+ olefins with 72.7% conversion and 77% selectivity to dimers after 40 h on stream Dimers 225 3 ns 0 f... 

The amount of asphaltenes precipitated from various solvents are summarized In Table 4. Figures 2-9 show that, In general. Increase in solvent/oil ratio Increases the amount of asphaltene precipitation and levels off after certain solvent/oil ratio. Addition of solvent to oil reduces concentration of resins (which act as peptizing agents for asphaltenes) in the oil resulting in asphaltene... 

In a later work of similar nature, Chatterjee etal. [170] prepared a boehmite sol from an aluminum salt. Boehmite particles were precipitated from an aluminum nitrate solution heated to 80 -90 C by addition of an ammonia solution into it. The precipitate was washed and peptized with glacial acetic acid to obtain a colloidal sol. The W/O emulsion was prepared by addition and dispersion of the sol (as the water phase) to an organic liquid, 1,1,1 trichloroethane (TCE) or n-heptane (the oil phase) containing 2-2.5 vol % of Span 80, a non-ionic surfactant. The volume ratio of water phase oil phase was about 1 4, and a suitable sol viscosity range was -10-20 mPa.s. The sol droplets were converted to gel droplets by addition of triethylamine (TEA), a base. The addition of TEA was monitored so that the pH of the system reached a value of 8-9 for completion of ion extraction for this purpose, the volume ratio of the sol to the base was adjusted at 1 0.4. The gel microspheres were washed with acetone and methanol, dried at 100°C and calcined up to 1200"C/1 h, when a-Al203 crystallized from transient alumina phases. The pathway, in brief, was boehmite —> y 5 —> 0 —> a-Al203. Under tailored conditions, it was possible to obtain hollow microspheres (Fig. 4.2). 

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