Antimicrobial activity of cotton fabric pretreated by microwave plasma and dyed with onion skin and onion pulp extractions

Abstract

Onion has been extracted to obtain colour compound for dyeing cotton fabric and the antimicrobial property of dyed fabric studied. The fabric is first desiccated with ethanol and then pretreated with low-temperature microwave plasma for 4 s with oxygen pressure of 0.2 Torr and power of 800 W. Thereafter, the plasma-treated samples are grafted for 10, 30, 60 min at 70ºC with onion skin and onion pulp extractions. The best inhibition zone of anti Staphylococcus aureus is found to be 1.1-0.8 cm by 10 min grafting time of onion skin extraction and 0.7-0.5 cm by 30 min grafting time of onion pulp extraction. The samples with 10 and 30 min grafting of both onion skin and onion pulp show anti S. aureus ability even after 5 times test washing, but both the samples lost their anti S. aureus property with 60 min grafting. The FTIR-ATR spectrum of dyed cotton fabric shows flavonoids’ functional peak at 1624 cm⁻¹ of onion skin that provides cotton fabric brown colour with wash fastness rating of 4.