Comparative study of lac dye adsorption on cotton fibre surface modified by synthetic and natural polymers

Poly(ethyleneimine) (PEI) and bovine serum albumin (BSA) were investigated as pretreating agents for surface modification of the cotton fibres. The measurement of zeta potential was initially used to indicate the effectiveness of the pretreatment. It was found that the PEI largely developed the positive charge whereas the BSA slightly enhanced the positive charge on cotton fibres following a decrease in the pH. Adsorption studies of lac dye on these pretreated cotton fibres show that both PEI and BSA enhance adsorption capacity of lac dye on cotton fibres. The zeta potential results and adsorption studies reveal that the uptake of lac dye on treated cotton fibres occurs via electrostatic attractions between the anion of the dye and cationic segments on the treated cotton fibres. The wash fastness of the dyeing is slightly increased by pretreatment while light fastness is unaffected. (c) 2005 Elsevier Ltd. All rights reserved.