Evaluation of Hypochlorite Concentration in Household Bleaches as Colour Removal Agent on Coloured Cotton Fabrics

Abstract

Bleaches are known to remove stains from fabric. This study evaluates chlorine-based household bleaches as effective fabric colour removal agents and was conducted in the Chemistry and Textile laboratories of the Federal University of Agriculture, Abeokuta using experimental design. Five common household bleaches were collected from markets in study areas. The concentrations of Sodium hypochlorite in each bleach sample as indicated by the manufacturer were: A (3.85%), B (3.5%), C (not available), D (4.3%) and E (5.3%). To confirm the concentration of sodium hypochlorite in each bleach sample, Redox titration was conducted. One-minute Spot Test was used to determine the time taken for each bleach sample to remove colour (black, brown, navy blue, purple and army-green) from fabrics samples and similar test conducted with pure sodium hypochlorite (7.21% Chlorine) as control. The L*a*b* values for fabric colour change were obtained from images of the fabric samples using Fiji-Image J and Corel Photo-Paint 17. The laboratory analysis and evaluation revealed the concentration of hypochlorite in the bleaches samples as A: 0.36% (3.56 g/dm3), B: 3.5% (34.00g/dm3), C: 1.15% (11.48g/dm3), D: 4.29% (42.92g/dm3), and E: 0.06% (0.57g/dm3); therefore, established the information on bleaches B and D product package. The average time (seconds) to remove colour from fabric samples by bleach samples were A- 80.37; B- 19.60; C- 30.36; D- 20.10; E- no vivid colour change after 120.00 sec while colour change was obtained 7.00 sec by the control. Furthermore, Image J analysis and L*a*b* values show colour changes on fabric samples with Bleach B ((x ̅= 75.74) and D ((x) ̅= 61.22) most effective in colour removals. In conclusion, Chlorine base household bleaches containing above 1.0% V/v hypochlorite are suitable colour removal agents on coloured fabrics and not stain removals only. Consumers must be careful how to handle Chlorine household bleaches and coloured fabrics