Original article Improvement of washing properties of liquid laundry detergents by modification with N-hexadecyl-N,N- dimethyl-3-ammonio-1-propanesulfonate sulfobetaine Tomasz Kalak 1 , Krzysztof Ga ˛sior 2 , Daria Wieczorek 2 and Ryszard Cierpiszewski 1 Abstract Detergency of commercial liquid detergents before and after modification with SB3C16 (5%, m/m) sulfobetaine (N- hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate) was examined using colorimetric analysis based on a CIELab system. The EMPA 101 standard cotton fabric soiled with carbon black and olive oil was used in washing tests under the following experimental conditions: the concentration of liquid laundry detergents 1.25–50 g/L, 30 min washing cycle, water hardness 5.35 mval/L, 40  C, 200rpm. Results of physicochemical analysis of color, form, odor, pH, viscosity, density and content of anionic surfactants in detergents, as well as construction parameters of tested cotton fabrics, showed compliance with the requirements of standards and manufacturers’ declarations. The studies revealed that increasing the concentration of laundry detergent solutions caused a gradual increase in foaming power and detergency. Modification with SB3C16 positively improved washing ability and the maximum values were achieved at 23.7% (m-L1, 50 g/L) and 37% (m-L2, 40–45 g/L), respectively. Detergency efficiency was improved by 6.86% (m-L1) and 10.72% (m-L2) on average. EMPA 101 fabrics before and after washing were subjected to microscopic observations, which showed no serious damage to the fibers, but only slight loosening of individual fibers. In summary, the results clearly indicate that SB3C16 sulfobetaine favorably improves washing performance and can be successfully used in liquid laundry detergents due to its good surface properties. Keywords detergency quality, liquid laundry detergents, surfactants, zwitterionic sulfobetaine SB3C16, colorimetric analysis Currently, many liquid laundry detergents have been offered in the household chemistry sector. The demand for these products is increasing due to good washing properties and environmentally friendly ingre- dients. The most important are surfactants, which are used as emulsifiers and as wetting, suspending, solubi- lizing, and stabilizing substances due to their amphiphi- lic properties. The most commonly used are anionic, nonionic, and cationic compounds. However, another group of surfactants, such as amphoteric ones, deserves attention and can be successfully used as an additive to liquid detergents. For comparison, they are generally 1 Department of Industrial Products and Packaging Quality, Institute of Quality Science, Poznan ´ University of Economics and Business, Poznan ´, Poland 2 Department of Technology and Instrumental Analysis, Institute of Quality Science, Poznan ´ University of Economics and Business, Poznan ´, Poland Corresponding author: Tomasz Kalak, Department of Industrial Products and Packaging Quality, Institute of Quality Science, Poznan ´ University of Economics and Business, Niepodleglos ´ci 10, 61-875 Poznan ´, Poland. Email: tomasz.kalak@ue.poznan.pl Textile Research Journal 0(00) 1–15 ! The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/0040517520934161 journals.sagepub.com/home/trj