Process analysis and optimization for the ionic interactions of quaternary ammonium salts with nylon 66 fibers using statistical experimental design

A 24 response surface central composite design was successfully formulated using statistical software to establish the optimum process conditions for developing durable antimicrobial nylon 66 fibers through interactions with two different types of quaternary ammonium salts (QASs) namely cetylpyridinium chloride (CPC) and benzyldimethylhexadecyl ammonium chloride (BDHAC). The treatment conditions such as pH, temperature, concentration and time were studied for % exhaustion and thoroughly analyzed by analysis of variance (ANOVA) statistical concept. Appropriate predictable empirical models were developed incorporating interaction effects of all variables and then optimized. The significance of the mathematical model developed was ascertained using Microsoft Excel regression (solver) analysis module. The theoretical optimum conditions for 100% exhaustion were found to be pH 10.83, temperature 79 °C, concentration 1.63% omf and time 57 min for CPC and those for BDHAC were 10.75, 85 °C, 1.85% omf and 77 min, respectively. However, at the optimum conditions, maximum % exhaustion of 97.32% for CPC and 94.56% for BDHAC was achieved experimentally.