Surfactants for the production of softwood kraft pulp cooking additives

Surfactant as a cooking additive can be used to reduce the surface tension between the liquid and the wood chips, and promote the complete wetting of the wood chips. This will help the rapid penetration and diffusion of the liquid medicine, accelerate the speed of the wood chips delignification, and improve the speed of the wood chips. The resin acts to reduce the Kappa number of the pulp and the amount of slag, improving the quality of the pulp.

US NA/CO Chemicals has studied various types of surfactants in the laboratory, such as ethoxylated nonylphenol, ethoxylated alcohols, sodium alkylbenzene sulfonates, alkanolamines, and sulfonated naphthalenes as cooking additives. Experiments were conducted on the cooking of softwood and reference was made to the cooking without additives. Softwood sulphate cooking conditions: total alkali consumption 15% -18%, degree of sulfuration 30%, H factor 1800, cooking maximum temperature 17 °C, liquid ratio 3.5:1, holding time 60 min, additive dosage 0.1% (for dry wood chips Weight calculation). The results showed that among the various additives selected, ethoxylated alcohol was the most suitable for softwood. The Kappa number without additives and 0.1% ethoxylated alcohol for the cooking of softwood kraft was 30 and 26.1 respectively. 2.8% and 1.5% respectively, the resin content in the pulp was 0.132% and 0.099% respectively, and the residual active alkali content in the black liquor was 4.5 g/l and 6.1 g/l, respectively. This result confirms that the surfactant can increase the permeation and dispersion speed of the cooking liquor into the internal structure of the wood chips, thereby improving the homogeneity of cooking, lower Kappa number of the obtained pulp, and lower content of screening residue and resin, and black The residual active alkali content in the liquid is higher. In the case of fixed pulp Kappa, pulp yield can be increased by 0.5%-0.8%.

The addition of various types of surfactants as cooking additives has different effects on the wood kraft pulping, which is mainly attributed to the different types of extracts contained in the wood raw materials. Therefore, it is necessary to choose according to the wood species. Appropriate surfactants can achieve satisfactory pulping results.