Abstract: Laboratory tests were organized by adopting coded orthogonal test design.Based upon effects of mass concentration of each components (AES,AEO₉ and NaOH) in the cleaning agent as well as the operating temperature,via linear regression,effects of all single factor items,interaction items as well as all square items were studied.The P value of the regression results showed that z₂ (AEO₉ mass concentration) is the most important one,followed by z₁ (AES mass concentration),z₁′ (the square of AES mass concentration),z₄ (temperature),z₁z₂,z₂z₄ and z₃z₄ (the interaction between NaOH mass concentration and temperature).Since all interaction items and square items influence the cleaning performance via single items,the sequence of importance is AEO₉ mass concentration,AES mass concentration,temperature and NaOH mass concentration.The optimization of the regression equation indicated that the optimized conditions are:AES 4.0 g·L^-1,AEO₉ 6.9 g·L^-1,NaOH 12.8 g·L^-1,and temperature 35.5 ℃,and the predicted cleaning time is about 5 s.

Key words: cleaning agent, waste PET bottled, coded orthogonal design, linear regression