Abstract Surfactant residues in foam forming are related to the circulation of surfactant in the foaming process, but they may also affect the properties of the foam-formed product. In this work, residues of an anionic surfactant, sodium dodecyl sulphate (SDS), in foam-formed products were studied. Two different methods were applied for the determination of SDS: ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) and solvent extraction spectrophotometry. The dry matter content of the sample before the drying step has a significant effect on the SDS residue. Another factor that has a significant effect on the SDS residues is the amount of precipitated dodecyl sulphate (DS). It was found that SDS does not degrade in the drying phase and will remain in the salt form in the final product. SDS residue decreased when the temperature of the fibre suspension was increased. Theoretical values for SDS residues were estimated from the original surfactant concentration and the amount of water remaining in the product before the drying phase. When all the surfactant was in soluble form, measured SDS residues were close to the theoretical values, which indicates that SDS was not permanently adsorbed onto softwood cellulose fibres.

中文翻译：

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泡沫形成的纤维素基产品的十二烷基硫酸钠 (SDS) 残留分析

摘要 发泡过程中的表面活性剂残留与发泡过程中表面活性剂的循环有关，但也可能影响发泡产品的性能。在这项工作中，研究了泡沫形成产品中阴离子表面活性剂十二烷基硫酸钠 (SDS) 的残留物。两种不同的方法用于测定 SDS：ICP-OES（电感耦合等离子体发射光谱）和溶剂萃取分光光度法。干燥步骤前样品的干物质含量对 SDS 残留有显着影响。另一个对 SDS 残留有显着影响的因素是沉淀的十二烷基硫酸盐 (DS) 的量。发现 SDS 在干燥阶段不会降解，并且会以盐的形式保留在最终产品中。当纤维悬浮液的温度升高时，SDS 残留量减少。SDS 残留的理论值是根据原始表面活性剂浓度和干燥阶段之前产品中剩余的水量估算的。当所有表面活性剂均为可溶形式时，测得的 SDS 残留量接近理论值，这表明 SDS 不会永久吸附在软木纤维素纤维上。