Heterocyclic cationic Gemini surfactants for efficient antibacterial, dispersion and fixation

Gemini surfactants are highly demanded worldwide due to their promising applications in paper, medical hygiene, and textile. However, the design of Gemini surfactant integrated with biosafety and multi-functionality has been considered a long-standing demand for environmental protection and industry cost. Hence, three kinds of heterocyclic cationic Gemini surfactants (C 12 -2 P-C 12 , P C 4 H 5 N, C 4 H 9 NO, C 3 H 4 N 2 ) with different hydrophilic groups were synthesized and employed to enhance antibacterial, dispersion, and fixation in leather processing. Their surface activity was measured by a series of analytical and testing methods, including the surface tension (γ cmc ), wettability and emulsifying ability. The results showed that the surface activity of the Gemini surfactants were followed the order of C 12 -2 C 4 H 5 N-C 12 (γ cmc =28.65 mN/m)< C 12 -2 C 4 H 9 NO-C 12 (γ cmc =25.85 mN/m)< C 12 -2 C 3 H 4 N 2 -C 12 (γ cmc =23.31 mN/m). Their antibacterial activities were assessed by means of Staphylococcus aureus . C 12 -2 C 3 H 4 N 2 -C 12 obtained a superior antibacterial rate (~100%) owing to its high charge density. And compared with the traditional soaking programs (JFC and commercial fungicides), the sheepskins treated by C 12 -2 P-C 12 exhibited favorable antibacterial properties and fiber dispersion . Among them, the protein content in the soaking solution containing C 12 -2 C 3 H 4 N 2 -C 12 increased notably by 68.0 μg/mL in contrast to the traditional soaking solution (23.8 μg/mL), indicating that C 12 -2 C 3 H 4 N 2 -C 12 has the best effect for fiber dispersion. For dyeing processing, the color fastness of the sheepskin treated by C 12 -2 C 3 H 4 N 2 -C 12 could be improved from level 4 to level 4–5 compared to the commercial dye-fixing agent. And it led to significant changes of the dye concentration in waste liquid (from 1.1 g/L for comprasion to 0.1 g/L for C 12 -2 C 3 H 4 N 2 -C 12 ), which may be imposed on the possibilities of the sustainable development of leather processing.