Alkali in Bleach Baths Containing Hydrogen Peroxide

AATCC 98-2016 pdf free.Alkali in Bleach Baths Containing Hydrogen Peroxide.
2.1 A weighed specimen of the bleachbath is titrated with a standardized solution of sulfuric acid to a Phenol Red endpoint, or to the pH range 6.8-8.4 on a pHmeter. The total alkali，expressed as %NaOH, is calculated based on the weightof the bath.
3. Terminology
3.1 bleaching, n.—elimination of unwanted coloring matter from a substrate by oxidative or reductive chemical treatment.
4.Safety Precautions
NOTE: These safety precautions arefor information purposes only.The safetyprecautions are ancillary to the testingprocedures and are not intended to be allinclusive. It is the user’s responsibility touse safe and proper techniques in han-dling materials in this test method. Manu-facturers MUST be consulted for specificdetails such as material safety data sheetsand other manufacturer’s recommenda-tions. All OSHA standards and rulesmust also be consulted and followed.4.1 Good laboratory practices shouldbe followed. Wear safety glasses in all laboratory areas.
4.2 All chemicals should be handledwith care. Sulfuric acid is corrosive.
When preparing the dilute solutions frompure or concentrated reagents, use chemi-
cal goggles or face shield,imperviousgloves，and an impervious apron.CAU-TION: Always add acid to water.
4.3 An eyewash/safety shower shouldbe located nearby and a high efficiencyparticulate respirator with organic vaporcartridge and full facepieceshould bereadily available for emergency use.
4.4 Exposure to chemicals used in thisprocedure must be controlled at or below
levels set by governmental authorities(e.g.，Occupational Safety and Health
Administration’s [OSHA] permissible exposure limits [PEL] as found in 29 CFR
1910.1000; see web site: www.osha.govfor latest version). In addition, the Ameri-
can Conference of Governmental Industrial Hygienists (ACGIH)Threshold
Limit Values (TLVs) comprised of timeweighted averages (TLV-TWA),short
term exposure limits (TLV-STEL) andceiling limits (TLV-C) are recommended
as a general guide for air contaminant ex-posure which should be met (see 10.1).
5.Apparatus and Materials
5.1 Potassium acid phthalate (CH,O,K),ACS Reagent.
5.2 Phenol Red (phenol-sulfonphthalein),or 0.06% solution thereof， if a pH meteris not used as an alternative.
5.3 Methanol(CH OH) (not needed if0.06% Phenol Red solution is available).
5.4 Sulfuric acid (0.1N) (H,SOA),ACSReagent,95-98%，or 0.1N (see 6.1 and10.2).
6.1Weigh 20.4080±0.0002 g potas-sium acid phthalate (National Bureau of Standards sample No.84) and dissolve itin approximately 100 mL deionized wa-ter in a 250 mL beaker.Transfer the solution to a 1 L volumetric flask, and rinsethe beaker 5 times with deionized water,adding the rinses to the volumetric flask.Dilute to mark with deionized water.6.1.4 Using a volumetric pipette, trans-fer 25 mL of the potassium acid phthalatesolution into a 250 mL Erlenmeyer flask.Add 5 drops of 0.06%Phenol Red indicator solution，and titrate with the sodiumhydroxide solution to a greenish-yellowend-point，or to pH 7.6 ± 0.8 if using a pH meter to detect the endpoint.
6.1.8.3 Re-standardizetheadjustedsulfuric acid solution using 6.1.6and6.1.7.
6.2 If the indicator solution is preparedin-lab, preparation of 0.06% Phenoi Redindicator solution (see 10.2).
6.2.1 Weigh 1.0±0.1 g Phenol Red anddissolve it in 833 mL methanol.
6.2.2 Add 833 mL deionized water.6.2.3 Cover the solution and stir with amagnetic stirrer until the solution is com-pletely clear.
7.Procedure
7.1 Measure 20 ± 1 mL deionized wa-ter into a 250 mL beaker,and add 2-3drops of Phenol Red indicator solution. Ifa pH meter is used to detect the end-point,do not add Phenol Red indicatorsolution.
7.2 Weigh a 10 ±0.01 g specimen fromthe bleach bath. Add the specimen to thebeaker and mix (see 10.3).
7.3 Titrate the contents of the beakerwith 0.1N sulfuric acid to a greenish-yel-low end-point, or to pH 7.6 ±0.8 if usinga pH meter to detect the end-point.
7.4 Record the number of the 0.1N sul-furic acid used to the nearest 0.1 mL.AATCC 98 pdf download.Alkali in Bleach Baths Containing Hydrogen Peroxide