Sulphate Soap Demulsifying with Addition of Non-Ionic Surfactant

Abstract

Biorefining based on comprehensive and advanced processing of wood raw materials with getting the products of a high added value and waste reduction is an innovative solution at the fast-growing market of the pulp and paper industry. Isolation of organic substances, which represent by-products in wood processing technology, from spent liquors is an urgent issue of biorefining. The current technology of sulphate soap extraction (which is a byproduct) from spent liquors is process complicated and energy-intensive. All this makes the sulphate soap extraction disadvantageous, despite the fact that the soap is a raw material for production of a wide range of products with a high added value: bioactive substances, tall oil, rosin, etc. This article presents the colloid-chemical properties of sulphate soap separated from black liquors of various wood species pulping. A method of sulfate soap extraction based on soap particles aggregation through addition of a demulsifier is proposed. It was found that with addition of non-ionic surfactant neonol AF 9-6 into the solution of sulphate soap, the molecularly dissolved part of the soap is significantly reduced, while the dispersed component of the presented system increases up to 98 %. As a result, deterioration of aggregative and sedimentation stability and, as a consequence, aggregation of soap particles are observed. A size quadruplication of soap particles was recorded with addition of demulsifier by the method of dynamic light scattering. This will allow to increase the sedimentation rate of sulfate soap in black liquor dozens of times and speed up its sedimentation. The proposed method can be the foundation of a High-Tech technology of by-product separation from production solutions of the pulp and paper enterprises.