BS EN 890:2012 pdf download – Chemicals used for treatment of water intended for human consumption – Iron (III) sulfate solution
5.1.2.1General
5.1.2.1.1 Mix the contents of each container to be sampled by shaking the container, by rolling it or by rocking ifrom side to side, taking care not to damage the container or spill any of the liquid.
5.1.2.1.2 lf the design of the container is such (for example, a narrow-necked bottle) that it is impracticable touse a sampling implement, take a sample by pouring after the contents have been thoroughly mixed. otherwise,proceed as described in 5.1.2.3.
5.1.2.1.3 Examine the surface of the liquid. If there are signs of surface contamination, take samples from thesurface as described in 5.1.2.2.Otherwise, take samples as described in 5.1.2.3.
5.1.2.2Surface sampling
Take a sample using a suitable ladle.Lower the ladle into the liquid until the rim is just below the surface, so thatthe surface layer runs into it. Withdraw the ladle just before i flls completely and allow any liquid adhering to theladle to drain off. lf necessary， repeat this operation so that, when the other selected containers have beensampled in a similar manner, the total volume of sample required for subsequent analysis is obtained.
5.1.2.3 Bottom sampling
Take a sample using an open sampling tube, or a bottom-valve sampling tube, suited to the size of container andthe viscosity of the liquid.
When using an open sampling tube,close it at the top and then lower the bottom end to the bottom of thecontainer. Open the tube and move it rapidly so that the bottom of the tube traverses the bottom of the containerbefore the tube is filled. Close the tube, withdraw it from the container and allow any liquid adhering at the outsideof the tube to drain off.
When using a bottom-valve sampling tube, close the valve before lowering the tube into the container and thenproceed in a similar manner to that when using an open sampling tube.
5.1.3 Sampling from tanks and tankers
From each access point, take samples as follows:
a) from the surface of the liquid, using a ladle as described in 5.1.2.2;
b) from the bottom of the tank or tanker， using a sampling tube as described in 5.1.2.3 or using speciallydesigned bottom-sampling apparatus;
c)from one or more positions,depending on the overall depth, between the bottom and the surface using a
weighted sampling can.
5.2Analyses
5.2.1 Main product
lron (ll) sulfate is determined as Fe (Il) contents in the test sample.Fe (ll) content is determined as the differencebetween total iron content and Fe (ll) content (see B.1 ).
5.2.2lmpurities
5.2.2.1 Manganese
The manganese content shall be determined by flame atomic absorption spectrometry (FAAS)(see B.2)
5.2.2.2 Iron (II) ( Fe (II))
The Fe (II) content is expressed as C (II) (see B.1.2.5.3).
5.2.2.3 Insoluble matters
The percentage mass fraction of the insoluble matters shall be determined in accordance with the method
described in B.3.
5.2.2.4 Free acid
The free acid shall be determined in accordance with the method described in B.4.
5.2.3 Chemical parameters
5.2.3.1 Preparation of sample solution
5.2.3.1.1 General
Oxidation and wet digestion is used to bring the samples into a stable solution.
5.2.3.1.2 Principle
Oxidation with hydrogen peroxide (H 2 O 2 ) followed by digestion with hydrochloric acid (HCl).
5.2.3.1.3 Reagents
All reagents shall be of a recognized analytical grade and the water used shall conform to the grade 3 specified in
EN ISO 3696.
5.2.3.1.3.1 Hydrochloric acid (HCl), solution, mass fraction 30 %.
5.2.3.1.3.2 Hydrogen peroxide (H 2 O 2 ), solution, mass fraction 30 %.
5.2.3.1.4 Apparatus
Ordinary laboratory apparatus and glassware together with the following.
5.2.3.1.4.1 Analytical balance.
5.2.3.1.4.2 Graduated cylinder, capacity 50 ml.
5.2.3.1.4.3 Round flask with reflux condenser.
5.2.3.1.4.4 Hot plate.
5.2.3.1.4.5 Volumetric flask, capacity 200 ml.
5.2.3.1.5 Procedure Dissolve with 20 ml of water 20,0 g of the iron solution. Add 5 ml hydrogen peroxide solution (5.2.3.1.3.2) to iron (III)-samples. After adding 50 ml hydrochloric acid (5.2.3.1.3.1) boil the solution for 15 min by using a reflux condenser (5.2.3.1.4.3). Cool down the solution, transfer to a 200 ml volumetric flask (5.2.3.1.4.5) and fill up to the mark with water. This is the sample solution.