Ruwoldt Jost, Handiso Berhane, Øksnes Dalheim Marianne, Solberg Amalie, Simon Sébastien, Syverud Kristin
RISE PFI AS, Høgskoleringen 6B, NO-7094 Trondheim, Norway.
Ugelstad Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway.
Langmuir. 2024 Mar 12;40(10):5409-5419. doi: 10.1021/acs.langmuir.3c03950. Epub 2024 Feb 29.
In this paper, the potential of esterified Kraft lignin as a novel oil-soluble surfactant was examined. The lignin was chemically modified by esterification with lauric or stearic acid, making it soluble in solvents such as toluene or -decane. Adsorption at the oil-water interface was then studied by the Du Noüy ring-method. The oil-soluble lignin behaved similar to water-soluble lignin surfactants, both the qualitative and quantitative progression of interfacial tension. Modeling revealed a surface excess of 7.5-9.0 × 10 mol/m, area per molecule of 185-222 Å, and a diffusion coefficient within the range 10 to 10 m/s; all of which are in line with existing literature on water-soluble lignosulfonates. The data further suggested that the pendant alkyl chains were extended well into the paraffinic solvent. At last, bottle tests showed that the oil-soluble lignin was able to stabilize oil-in-water emulsions. The emulsion stability was affected by the concentration of lignin or NaCl as well as the oil phase composition. Aromatic oils exhibited lower emulsion stability in comparison to the aliphatic oil. In conclusion, a new type of surfactant was synthesized and studied, which may contribute to developing green surfactants and novel approaches to valorize technical lignin.
本文研究了酯化硫酸盐木质素作为一种新型油溶性表面活性剂的潜力。通过用月桂酸或硬脂酸进行酯化反应对木质素进行化学改性，使其可溶于甲苯或癸烷等溶剂。然后采用杜诺伊环法研究其在油水界面的吸附情况。油溶性木质素的行为与水溶性木质素表面活性剂相似，界面张力的定性和定量变化趋势相同。模型显示表面过剩量为7.5 - 9.0×10⁻⁶ mol/m²，每分子面积为185 - 222 Ų，扩散系数在10⁻¹⁰至10⁻⁹ m²/s范围内；所有这些都与关于水溶性木质素磺酸盐的现有文献一致。数据进一步表明，侧链烷基很好地伸展到石蜡溶剂中。最后，瓶试表明油溶性木质素能够稳定水包油乳液。乳液稳定性受木质素或氯化钠浓度以及油相组成的影响。与脂肪族油相比，芳香族油表现出较低的乳液稳定性。总之，合成并研究了一种新型表面活性剂，这可能有助于开发绿色表面活性剂以及实现工业木质素增值的新方法。
