Folding filter paper

Some training in origami is de rigueur for chemists. It seems that the regular filter paper fold is inefficient, since very little of the paper is exposed. The idea here is to flute or corrugate the paper, increasing the surface area in contact with your filtrate. You ll have to do this several times to get good at it. 

After shaking the soil suspension in the extraction bottle, a tube of filter-paper folded about the centre to form a V with the open ends uppermost is inserted into the bottle. Clear filtrate collects inside the paper tube and aliquots are removed with a pipette. 

Assemble a filtration system consisting of a ring stand, a funnel rack (or two small rings), two clean long-stem funnels, and two beakers or flasks to catch the filtrate. Obtain two pieces of Whatman 40 filter paper, fold, and place into the funnels, moistening with a little distilled water so they adhere to the funnel walls (Figure 3.8). Label the funnels to coincide with the labels on your beakers. 

Preparation of dry sample. Transfer two 35g portions of the sample to two 2j4 inch glass funnels, each funnel having a filter paper folded and inserted in it. With the aid of suction, wash the Hg fulminate with enough 95% ethyl alcohol to remove most of the water. Place the filter paper holding the Hg fulminate in a small evaporating dish and dry in a sealed unit electric oven or a steam oven at 40°C—50°C to constant weight... 

Cleaning of Mercury. Mercury used in nitrometer detns can be sufficiently purified by touching its surface with several pieces of filter paper (in order to remove sulfuric acid), followed by filtration either thru several layers of filter paper, folded in a glass funnel and perforated at the bottom with several pin holes (Ref 2), or thru special filters, such as described in Ref 5... 

Quantitative. The acidity is estimated as follows 25 grams of the product are made into a paste with 30 c.c. of water and titrated, with shaking, with N/10-caustic soda solution until a drop of the starch suspension, when placed on a filter-paper folded several times so as to absorb the water, is no longer coloured red by tincture of litmus. The acidity is expressed in c.c. of decinormal alkali per 100 grains of starch. 

Hunt [340] has described a simple method of filtering soil extracts that eliminates the need for filter funnels and receivers. It therefore reduces the risk of contamination and speeds up the procedure. It also offers a convenient means of obtaining filtrates in the field for subsequent analysis. After shaking the soil suspension in the extraction bottle, a tube of filter paper folded about the centre to form a V with the open ends uppermost is inserted into the bottle. Clear filtrate collects inside the paper tube and aliquots are removed with a pipette. 

How to Use Filter Paper. Fold a circle of filter paper in half and then into quarters. Open it so that it becomes cone-shaped. Roughly tear off one corner. Place the filter paper in a funnel and fill it with water. Let the water run through until there is no air in the stem, then stop the flow with your finger. Now add the liquid mixture to be filtered. The presence of liquid rather than air in the stem makes the other liquid, that is, the mixture, pour through more quickly. 

Preparation of fluted filter paper. Fold the filter paper into halves and again into quarters. Open the half sheet as shown in Figure 8(o), and fold edges 1, 2 and 2, 3 on to 2, 4, thus producing the new folds 2, 5 and 2, 6 as shown in Figure 8(6). Do not crease... 

For quantitative work, 20-cm wide plates are normally used. As the development chamber should be lined on all four sides in this case, the sheets of filter paper folded as described above can be cut at the folds with a sharp knife unless a suitably large guillotine is available. In the latter case, the 58 x 58 cm sheets can be marked out with a lead pencil and cut into six strips just under 10 cm wide or three ca. 19.6 cm wide. 

Chill the contents of the flask in an ice-bath when the desired product coumarin gets separated. Filter it in a Buchner funnel, wash with a little spray of cold water, drain well and dry it in filter paper folds. 

The filtration of any solution through the ordinary conical funnel may be hastened considerably by the use of a fluted filter-paper, instead of one folded into quarters in the usual way. The folding of a fluted paper may be learnt far more readily by a demonstration in the laboratory than by any written description. 

Proper procedure for filtering solids using filter paper. The filter paper circle in (a) is folded in half (b), and folded in half again (c). The filter paper is parted (d), and a small corner is torn off (e). The filter paper is opened up into a cone and placed in the funnel (f). Note that the torn corner is placed to the outside. 

Filtering is accomplished by folding the filter paper into a cone, which is then placed in a long-stem funnel (Figure 8.6). A seal between the filter cone and the... 

A fluted filter is made by first folding a large circular filter paper in the 01 dinary way. It is then half opened out and the t vo quadrants folded towards the middle line (see a, Fig". 41), "This makes three creases with the hollows on the same side. TThe filter is now turned over and each section folded down the... 

The acid, without drying, is suspended in about 200 cc. of distilled water and with vigorous stirring, cautiously (Note 3) treated with 25 per cent sodium hydroxide solution until dissolved and the solution reacts neutral to litmus. The solution is then filtered through folded filter paper which should be free from soluble calcium salts, otherwise the filtrate will remain clouded by a suspension of the calcium salt. The clear, faintly yellow or colorless filtrate is then vigorously stirred and treated with 1.5 volumes of 95 per cent alcohol. Crystallization is induced by rubbing with a rod and then an additional volume of alcohol is added. The mixture should be allowed to cool to about 200 and stand for at least two hours to complete the precipitation of the salt, which is then filtered by suction and washed thoroughly with 85 per cent alcohol. The salt is then air-dried. The yield is 73-77 g. (38-40 per cent of the theoretical amount). 

The size of the filter paper selected for a particular operation is determined by the bulk of the precipitate, and not by the volume of the liquid to be filtered. The entire precipitate should occupy about a third of the capacity of the filter at the end of the filtration. The funnel should match the filter paper in size the folded paper should extend to within 1-2 cm of the top of the funnel, but never closer than 1 cm. 

Zirconium ( > 100 mg in ca /. M sulphuric acid solution). Add freshly prepared 10 per cent aqueous diammonium hydrogenphosphate solution in 50-100-fold excess. Dilute to 300 mL, boil for a few minutes, allow to digest on a water bath for 15-30 minutes and cool to about 60 °C. Filter through a quantitative filter paper, wash first with 150 mL of 1M sulphuric acid containing 2.5 g diammonium hydrogenphosphate and then with cold 5 per cent ammonium nitrate solution until the filtrate is sulphate-free. Dry the filter paper and precipitate at 110°C, place in a platinum crucible and carefully burn off the filter paper. Finally heat at 1000 °C for 1-3 hours and weigh as ZrP207 (Section 11.51). 

No. 41 or 541 filter paper. Wash the precipitate first with warm, dilute hydrochloric acid (approx. 0.5M), and then with hot water until free from chlorides. Pour the filtrate and washings into the original dish, evaporate to dryness on the steam bath, and heat in an air oven at 100-110 °C for 1 hour. Moisten the residue with 5 mL concentrated hydrochloric acid, add 75 mL water, warm to extract soluble salts, and filter through a fresh, but smaller, filter paper. Wash with warm dilute hydrochloric acid (approx. 0.1M), and finally with a little hot water. Fold up the moist filters, and place them in a weighed platinum crucible. Dry the paper with a small flame, char the paper, and burn off the carbon over a low flame take care that none of the fine powder is blown away. When all the carbon has been oxidised, cover the crucible, and heat for an hour at the full temperature of a Meker-type burner in order to complete the dehydration. Allow to cool in a desiccator, and weigh. Repeat the ignition, etc., until the weight is constant. 

Fick s law 592 Filter funnel 102 Filter papers 115 folding of, 116 incineration of, 120, 121 macerated, 450 quantitative, (T) 116 Filter pulp 450 Filtering crucibles 102 Filters, optical 661 Filtration 102, 106, 115 accelerated, 450 technique of, 116, 117 with filter papers, 116 with filtering crucibles, 117 Flame emission spectroscopy 779, 797 background correction, 795 elementary theory of, 780 D. of alkali metals by, 812... 

Electrolyte leakage. Tissue discs, prepared from potato tubers as described above, were incubated for 16 h at 25°C between wet filter papers. After incubation, the discs were shaken in 20 ml H2O for another 60 min. One ml of this extract was diluted 30-fold with water, and subjected to conductivity measurements using a HI 8788 apparatus (Hanna Instruments). An increase in conductivity indicates a leakage of electrolytes through lesions in the cell wall caused by enzyme action. Control samples were not incubated, they were shaken in water only. 

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