Silica cleaning

NP 4tOP Recycled paper sludge Recycled paper sludge Soxhlet dichloromethane, silica clean-up Soxhlet dichloromethane, silica clean-up 9.6- 35 9.6- 35 [24] [24]... 

NP River and estuarine sediment Soxhlet dichloromethane silica clean-up 108 4 15 ( = LOQ) [25]... 

NP Estuarine sediment Sonication methanol aminopropyl silica clean-up 82.8 5.4 21.5 [13]... 

Sample preparation Condition a 3 mL 40 p,m bonded silica Clean Screen SPE cartridge (Worldwide Monitoring) with 3 mL MeOH, 3 mL water, and 1 mL pH 3 phosphate buffer. 1 mL Plasma + 2 mL 10 mM phosphoric acid, mix, add to the SPE cartridge, air dry for 30 s, wash with 1 mL pH 3 phosphate buffer, wash with 1 mL MeOH, air dry for 30 s, elute with 3 mL 2% ammoniacal MeOH. Evaporate the eluate to dryness under a stream of nitrogen at 45°, reconstitute the residue in 50 p,L mobile phase, inject an aliquot. 

The silica discs tliat now hold the back-silvered mica samples are finally mounted into the SFA so that die cylinder axes are crossed and the clean mica surfaces are facing each other. 

Hydrated amorphous silica dissolves more rapidly than does the anhydrous amorphous silica. The solubility in neutral dilute aqueous salt solutions is only slighdy less than in pure water. The presence of dissolved salts increases the rate of dissolution in neutral solution. Trace amounts of impurities, especially aluminum or iron (24,25), cause a decrease in solubility. Acid cleaning of impure silica to remove metal ions increases its solubility. The dissolution of amorphous silica is significantly accelerated by hydroxyl ion at high pH values and by hydrofluoric acid at low pH values (1). Dissolution follows first-order kinetic behavior and is dependent on the equilibria shown in equations 2 and 3. Below a pH value of 9, the solubility of amorphous silica is independent of pH. Above pH 9, the solubility of amorphous silica increases because of increased ionization of monosilicic acid. 

Sugar Processing. Dispersants are used in the production of cane and beet sugar to increase the time between evaporator clean outs. Typical scales encountered include calcium sulfate, calcium oxalate, calcium carbonate, and silica. Dispersants are fed at various points in the process to prevent scale buildup, which would interfere with efficient heating of the vessels. Only certain dispersants, conforming to food additive regulations, can be used, since a small amount of the dispersant may be adsorbed on the sugar crystals. 

Microwave extraction realized at 120 °C for 30 min with Hexane -Acetone (3 2 V/V) as the extraction solvent was identified as the most effective extraction procedure for isolation of TPH from biotic matrices. The aim of this research is to develop a silica gel and alumina fractionation procedure for plant sample extraction. Column chromatography with two solvents (chloroform and hexane dichloromethane) as a mobile phase were used for clean-up of extract. In this research the efficiency of recovery received from chloroform as a mobile phase. 

Silica [7631-86-9 (colloidal)-, 112945-52-5 (fumed)]. Purification of silica for high technology applications uses isopiestic vapour distillation from cone volatile acids and is absorbed in high purity water. The impurities remain behind. Preliminary cleaning to remove surface contaminants uses dip etching in HF or a mixture of HCl, H2O2 and deionised water [Phelan and Powell Analyst 109 1299 1984],... 

Resin-based TSK-GEL PW columns are durable to alkaline conditions, which cannot be used with silica-based columns. Such durability facilitates separations with basic eluents and allows the use of alkaline cleaning reagents. 

Figure 13.11 shows the chromatogram obtained for a surface water sample spiked with various chorophenoxy acids at a level of 0.5 p.g 1 under the same conditions as previously and after enrichment on a Cjg column and clean-up on silica SPE cartridges. 

In addition, H2 is extremely sensitive to spark initiation, and can cause premature detons when ammo is being handled, is in-tube during launch, or is being steam-cleaned for reloading, purposes. A parallel reaction involves the release of NH3, which can combine with metals such as Cu in the presence of nitrates to form such extremely shock sensitive compds as tetramino cupric nitrate (Ref 17). To obviate these effects, desiccants such as silica gel may be added to the extent of 0.5% (Ref 12)... 

The type of membrane cleaning required depends on both the type and degree of fouling experienced, but typically it is either organic (bacterial slimes, natural organics, or process foulants and nutrients) or inorganic (silica, carbonate, sulfate, or phosphate deposits). 

Perhaps the most important waterside problems relate to the likelihood of boiler surface deposits and their control. High concentrations of caustic or salines only occur if porous deposits are present. It is much better to remove the cause of deposition problems than to try to manage their effects, and modem iron and silica transport polymers, together with improved cleaning protocols, have done much to limit deposition in large boilers. 

When silica levels increase, hydroxide alkalinity measurements become increasingly important to ensure maximum silica solubilization and the reduction of risk of silica deposition. This is especially so for coil boilers because, more than any other boiler type, the use of hydroxide is critical in keeping the waterside surface of the coiled tube clean and deposit free. 

Crude Chromatographic Cleaning (in sequence) on 6 g sodium sulfate/sand 3 g 1 N NaOH on silica 12 g fluorisil in 50 ml CH2CI2... 

Liver Addition of water to sample followed by homogenization extraction with benzene, clean-up on silica column and HPLC GC/ECD No data No data Demeter and Heyndrickx 1979... 

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