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Thursday 25 June 2015

Barium chloride test for sulphate in water

Procedure to test sulphate in water using barium chloride.


METHOD: Turbidimetric Method.


PRINCIPLE : Sulfate ion is precipitated in a hydrochloric acid medium with barium chloride to form barium sulfate crystals of uniform size.


Minimum detectable conc. Approximately 1mg so4 /L
REAGENTS          :
  •  Conditioning Reagent : Mix 50 ml glycerol with solution Containing 30ml conc. HCl, 300ml distilled water, 100 ml 95% ethyl or isopropyl alcohol and 75gm NaCl( Sodium Chloride). 
  • Barium Chloride (BaCl2) : Crystals 20-30 mesh.


INTERFERENCE:     Silica more than 500 ppm will interfere. Colour and Suspended matter in large amount will interfere.


PROCEDURE : Measure 100 ml sample(Take distilled if necessary) add 5 ml of conditioning reagent. Add spoonful of BaCl2 crystals, Immediately stir for 1 min at constant speed. Take reading on spectrometer at wavelength 420 nm(use charcoal treatment for coloured samples


CALCULATION:                                                mg SO4 x 1000
mg/l SO4 =                                                     ---------------------------
                                                                                 ml sample