Friday, February 25, 2011

CHEMICAL ANALYSIS OF WATER:

             An industrial laboratory should not in general attempt to analyse water for drinking purposes. Th egardness having been determined together with other data necessary for steam raising purposes the only other data required are suspended matter humic matter iron dissolved oxygen and in rare cases sulphuretted hydrogen.

            Suspended matter.Filter I Liter though tared filter papers dry at mon more than one hundred and five deg .C. and weigh .In natural waters the residue may contain fine sand or earthy matter. In softened waters there may be suspended calcium and magnesium salts which sometimes continue to percipitate for some hours after softening. In zeolite especially from certain friable types .  There may also be iron rust from water pipes and suspended humic matter from moorland waters .  Occasionally filamentous algae are present. Suspended matter is very objectionable in all syeing processes where the dyeing liquor is circulated through packages of fibrous material whether hank cake top or beam.  Humic acid is a nuisance in neutral dyeing as it is absorbed by animal fibres almost like a neutral dyeing buff coloured dye stuff. In one case when water contained much humic matter pale blues could be obtained only by dyeing some material intended for dark shades in the water to be used for the blue shade to remove the hmic matter.  Iron is responsible for the flattening of shades with iron sensitive dye stuffs.

Iron .
         The I Liter of wather from determination of suspended matter is evaporated to dryness. Add dilute hydrochloric acid evaporate to dryness ignite moisten with conc.  HCI stand fifteen minutes add water boil filter through iron free paper and determine by any the usual colorimetric methods.  The residue from filtration is ignited and treated in the above manner.

Microscopical Ecamination :
         Some information usually more interesting than useful can be given in Wallis Analytical Microscopy or the standard work by thorpe and others may be consulted.
FILAMENT FIBRES:
         IN This pure silk is grouped with all those artificial fibres which have as a common property a single filament formation which is structureless in comparison with the natural fibres.
TURE SILK :
           
      This is a protein fibre and may be regarded chemically as a simplification of the wool protein ,the fundamental protein is a long chain molecule in which the unit NH CH CO is repeated many times. The protein is based principally on glycine and alanine residues with some tyrosine but cystine is absent and there are no cross linkages of sulphur as in wool all the cross links are salt linkages.
      Structurlly sill is uniqe amongst natural fibres in that it dose not deem to have any surface dkin or cuticle unless indeed dilk gum itself is regarded as a kind of cuticle layer.  Silk is perhaps the least complicated both chemically and physically of the natural fibres.
     It is produced by the larva of the bombyx mori moth which extrudes the filament from twin spinnerets when making its cocoon .  The filament proper consisting of the protein fibre is coated with an alkali soluble variant of fibroin termed serecin .  In the undegummed state silk appears as twin filaments which are more or less stuck together by serecin .
      In the process of reeling the silk filament from the cocoon the outer and inner layers are discarded as waste.  These layers are characterised by irregularity in diameter and especially by irregularity in the thickness of the serecin layer.  Waste silk is also provided by pierced double or feeble cocoons and by damaged cocoons.  There are several recognised qualities of silk waste. In the working up of waste the silk is degummed and carded which tears it p into short lengths of a staple corresponding roughly with the range of wool staples the carded silk is then combed on principles not dissimilar to those used in wool combing various staple lengths or drafts being produced which are spun into yarns of a fineness corresponding to the draft. such yarns are generally known as schappe and are manufactured into pile fabrics or spun silk goods. They have their analogy in viscose staple fibre . Schappe silk is often only partly boiled off.

EFFLUENTS :

The detailed treatment of effluents is outside the scope of this book but it may be said that very few effluents from texitle works are fit to be turned into a river shilst certain types such as alkaline wool scouring liquors will not be accepted by many sewage works without prior treatment. In the normal treatment of sewage it is necessary to have a fairly neutral liquid . It is an advantage for a textile laboratory to have some understanding of the prooblem of the sewage chemist . A general reviw written from the textile laboratory point of view is given in garner industrial microscopy . The textile laboratory may be concerned in oxidising sulphide effluents or arranging that mutually reacting effluents sulphide and acid effluents do not enter the same drain or in previnting the unpleasant smell from some biological retting a drip feed of potassium permanganate into the drain . The most important problem likely to be encountered is in connection with wool sxouring effluents. Here the works is faced either with payment of a certain sum to the local corporation for the acid treatment of the effluent or with the acid treatment of the effluent in the works.