Facilitization filtration

Although the trend in the viscosity of the system tended to decrease, which facilitated filtration, a gel occasionally appeared during the filtration and a polarisation layer was always formed. The first line (1-5 h) of Figure 4 is based on an assay in which the filtration started after a reaction time of 1.5 hours, when there were still polymers and the viscosity of the system was high. A sharp decrease in the permeate flux was obtained because a gel appeared among the hollow fibers, as did a polarisation layer. The second line (4-11 h) of Figure 4 is from an assay in which the filtration started after a reaction time of 4.5 hours, when there were no polymers and the viscosity of the system was low. In this experiment no sharp decrease in the permeate flux was obtained and no gel appeared between the hollow fibers. Only the appearance of the polarisation layer was responsible for the decrease of the flux from 250 mL/h (initial flux) to almost 200 mL/h. 

The diatomaceous earth retains various substances, such as pigments, by adsorption, which simplifies subsequent purification and at the same time facilitates filtration by preventing the filter from clogging. 

Th[Fe(CN)6] and asbestos (the latter is added to facilitate filtration of the gelatinous precipitate). Wash with a little cold water. Treat the ppt. on the filter paper with dilute NaOH solution acidify the alkaline extract with dilute HC1 and add a few drops of FeCl3 solution. 

The addition of filter paper pulp or a Whatman filtration accelerator will facilitate filtration. 

Kragl et al.100 described the retention of diaminopropyl-type metallodendrimers bearing palladium phosphine complexes on ultra- or nanofiltration membranes and their use as catalysts for allylic substitution in a continuously operating chemical membrane reactor. Their results demonstrated a viable procedure for catalyst recovery, because these metallodendrimers acting as catalyst supports offered an advantage in that the intrinsic viscosity of the solution is smaller, facilitating filtration. 

The o-benzoyl benzoic acid is prepared by mixing phthalic anhydride with an excess of benzene and adding to an amount of aluminum chloride equimolar to the anhydride used. This mixture is maintained at a temperature of 35° C. in a lead lined kettle, jacketed for steam heating, for about half an hour. The temperature is then slowly raised to the boiling point of benzene and maintained until hydrochloric arid is no longer evolved. Benzene is removed by distillation with steam, the o-benzoyl benzoic arid dried and converted to anthraquinone by treatment with 95 to 98 per cent sulfuric acid at a temperature of from 110° to 150° C. for three-quarters to one hour. The anthraquinone thus fomied is recovered from the concentrated sulfuric acid by careful dilution of the acid with water or treatment with steam to obtain large crystals to facilitate filtration, removal of acid, and washing. 

An optimal solid support should (i) be mechanically robust (ii) be stable to variation in temperatures (iii) have reagent-accessible sites (iv) show acceptable loadings (v) present acceptable bead sizes, if applicable, when required, facilitating filtration (vi) be stable in diverse media, and in the case of being used in biochemical assays (vii) show biocompatibility and swelling in aqueous buffers. 

Precious metal catalysts are usually shipped back to the catalyst suppliers to recover the expensive metal from the spent catalysts. For hygiene and regulatory reasons the spent catalyst must be washed thoroughly to remove toxic organic products. To get the best results for metal recovery, spent catalysts should not contain inorganic products (e. g. materials to facilitate filtration such as Tonsil or Hyflo) or large amounts of water. 

An important difference between the batch and the continuous mode of precipitation is the available reaction time. Different standing times are normally used in batch procedures to ensure the completeness of the precipitation reaction or/and the form of the precipitate to facilitate filtration and minimize contamination. Standing times of IS min to a few hours are typical, occasionally with elevated temperatures. Such procedures are obviously not feasible in continuous on-line precipitation systems where reaction times are typically in the range of a few seconds to a few tens of seconds. Quantitative recovery of analyte through precipitate collection is therefore not likely unless the precipitation (or coprecipitation) process is extremely fast. 

The precipitate is separated by filtration, or as a heavy sludge by decantation, and packed for disposal. Some gelatinous hydroxides are difficult to filter. In such cases, heating the mixture close to 100 °C or stirring with diatomaceous earth, approximately 1 to 2 times the weight of the precipitate, often facilitates filtration. 

In a typical process for the preparation of a liquid epoxy resin, a mixture of bisphenol A and epichlorhydrin (about 1 4 molar) is heated to about 60°C with stirring. Solid sodium hydroxide (2 mole per mole bisphenol A) is added slowly at such a rate that the reaction mixture remains neutral. The reaction is exothermic and cooling is applied to keep the temperature at 60°C. Excess of epichlorhydrin is then removed by distillation under reduced pressure. The residue consists of epoxy resin mixed with sodium chloride. The latter is filtered off, toluene having been added to the mixture in order to facilitate filtration. The toluene is removed by distillation under reduced pressure and then the resin is heated at 150°C/5 mm Hg to remove traces of volatile matter. This last step is important since the presence of volatiles may lead to bubble formation when the resin is subsequently used. Finally, the resin is clarified by passage through a fine filter. 

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