Filter paper, properties

Nonwood fibers are used in relatively small volumes. Examples of nonwood pulps and products include cotton Enters for writing paper and filters, bagasse for cormgated media, esparto for filter paper, or Manila hemp for tea bags. Synthetic pulps which are based on such materials as glass (qv) and polyolefins also are used (see Olefin polymers). These pulps are relatively expensive and usually are used in blends with wood pulps where they contribute a property such as tear resistance, stiffness, or wet strength which is needed to meet a specific product requirement. 

Black smoke (BS) is a particulate measure that typically contains at least 50% respirable particulates smaller than 4.5 mm in aerodynamic diameter, sampled by the British smokeshade (BS) method. The reflectance of light is measured by the darkness of the stain caused by particulates on a white filter paper. The result of BS sampling depends on the density of the stain and the optical properties of the particulates. Because the method is based on reflectance from elemental carbon, its use is recommended in areas where coal smoke from domestic fires is the dominant component of ambient particulates. 

Interactions in Solid-Surface Luminescence Temperature Variation. Solid-surface luminescence analysis, especially solid-surface RTF, is being used more extensively in organic trace analysis than in the past because of its simplicity, selectivity, and sensitivity (,1,2). However, the interactions needed for strong luminescence signals are not well understood. In order to understand some of the interactions in solid-surface luminescence we recently developed a method for the determination of room-temperature fluorescence and phosphorescence quantum yields for compounds adsorbed on solid surfaces (27). In addition, we have been investigating the RTF and RTF properties of the anion of p-aminobenzoic acid adsorbed on sodium acetate as a model system. Sodium acetate and the anion of p-aminobenzoic acid have essentially no luminescence impurities. Also, the overall system is somewhat easier to study than compounds adsorbed on other surfaces, such as filter paper, because sodium acetate is more simple chemically. 

The RPIA technology has been enhanced in the Stratus CS system by utilization of a dendrimer-antibody complex in which the analyte-specific capture antibody is covalenty coupled onto a dendrimer. The test packs in the Stratus CS system include dendrimer-capture antibody complex reagent, the alkaline phosphatase labeled antibody conjugate reagent, the substrate-wash reagent and a piece of glass fiber filter paper as the solid phase. Preparation and unique properties associated with these dendrimer-coupled antibody complexes are described below. 

Hydral-cellulose, (Q Hl0Os)4 H20, mw 666.58. May be prepd by digesting cellulose, such as filter paper, with a solution of H 20 2 until completely disintegrated. On evaporation, a white substance is obtained which resembles oxycellulose in its properties. When treated with 10% aqueous NaOH, 33% of it dissolves, leaving a residue resembling cellulose... 

Owing to their liquid nature at room temperature, essential oils are called as such. They should not be confused with fixed oils or fatty oils, which are composed of a naturally occurring mixture of lipids which may not necessarily be volatile. Therefore, essential oils differ entirely both in chemical and in physical properties from fatty oils. Essential oil evaporates completely when dropped on filter paper however, fixed oil leaves a permanent stain which does not evaporate even when heated. 

Preparation of Plastic Sulphur. Heat sulphur until it boils and pour it out in a thin stream into a crystallizer with cold water. Extract the solid substance from the water and dry it between sheets of filter paper. Test the ductility of the sulphur and its solubility in chloroform. Keep part of the sulphur for the next lesson and again study its physical properties. What molecules does plastic sulphur consist of ... 

The components of mixtures can be separated from one another by taking advantage of differences in the components physical properties. A mixture of solids and liquids, for example, can be separated using filter paper through which the liquids pass but the solids do not. This is how coffee is often made the caffeine and flavor molecules in the hot water pass through the filter and into the coffee pot while the solid coffee grounds remain behind. This method of separating a solid-liquid mixture is called filtration and is a common technique used by chemists. 

Although ordinary filter papers can be used, special papers are manufactured for PC. They are highly purified (especially from metal contaminants) and are manufactured under controlled conditions so that such properties as porosity, thickness, and arrangement of cellulose fibers are reproducible from batch to batch. A single paper, Whatman No. 1 or its equivalent, is satisfactory for most separations. The theoretical aspects related to PC have been summarized by Stewart.17... 

---