Surfactant-assisted enzymatic hydrolysis was used to extract the flavor compounds from piper nigrum L. The extraction conditions were optimized through orthogonal and single-factor experiments. The extracted piperine content, measured with High-Performance Liquid Chromatography (HPLC) and UV spectrophotometric, was used as experimental index. The optimized conditions were as follows: the amount of cellulase, neutral protease and surfactant (sodium stearoyl lactylate) addition was 0.08%, 0.1% and 0.4% (w/w) respectively. The solid-liquid ratio was 1:5 (g/mL), the enzymolysis temperature and time were 60°C and 4 h, and the granularity was less than 10 mesh. Under these conditions, the content of the extracted piperine was 4.54% (UV spectrophotometric) and 4.42% (HPLC), respectively. Meanwhile, the mechanisms of the enzymatic reaction, as well as the role of the surfactant in enzymatic hydrolysis process were discussed.

Introduction Gemini surfactant has two lipophilic tail groups and hydrophilic head groups 1. Due to the unique chemical structure, gemini surfactant tends to form rather rich array of self-assembled structures in aqueous solution, including spherical micelle, ellipsoidal micelle, rodlike micelle, layered micelle, linear micelle, a membrane, vesicle, liquid crystals, sponge and other morphologies, and has better performance, such as low critical micelle concentration CMC , high thermal stability, strong wettability, adhesion ability, and high surface reduction efficiency, etc 2 6. In recent years, cationic gemini surfactants especially gemini quaternary ammonium surfactants, which have shown enormous potential applications in various fields, covering detergents, cosmetics, textile dyeing, biotechnology, the pharmaceutical industry, food industry and the petroleum industry, have attracted wide attention from researchers 6 8. Studies have shown that a gemini surfactant molecule with the requested properties to specific applications is possible to obtain by structure modification, such as changing its component, hydrophobic chain, counterion, spacer group length, spacer group softness and introducing specific functional groups 9 13. At present, some studies

The discharge of industrial phenol pollutants causes great harm to the natural environment and human health. In this study, phenol removal from water was studied via the adsorption of Na–montmorillonite (Na–Mt) modified by a series of Gemini quaternary ammonium surfactants with different counterions [(C11H23CONH(CH2)2N+ (CH3)2(CH2)2 N+(CH3)2 (CH2)2NHCOC11H23·2Y−, Y = CH3CO3−, C6H5COO− and Br−, 12–2–12·2Y−]. The results of the phenol adsorption indicated that MMt–12–2–12·2Br−, MMt–12–2–12·2CH3CO3− and MMt–12–2–12·2C6H5COO− reached the optimum adsorption capacity, which was 115.110 mg/g, 100.834 mg/g and 99.985 mg/g, respectively, under the conditions of the saturated intercalation concentration at 2.0 times that of the cation exchange capacity (CEC) of the original Na–Mt, 0.04 g of adsorbent and a pH = 10. The adsorption kinetics of all adsorption processes were in good agreement with the pseudo-second-order kinetics model, and the adsorption isotherm was better modeled by Freundlich isotherm. Thermodynamic parameters revealed that the adsorption of phenol was a physical, spontaneous and exothermic process. The results also showed that the counterions of the surfactant had a certain influence on the adsorption performance of MMt for phenol, especially the rigid structure, hydrophobicity, and hydration of the counterions.

The series of gemini amine-oxide surfactants with the formula CnH2n+1CONH(CH2)2N+O–(CH3)–(CH2)3–(CH3)N+O– (CH2)2NHCOCnH2n+1 (n = 11, 13, 15, and 17) have been synthesized, and their pH-stimuli responsive behavior in aqueous solution has been studied.

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