RU2744382C1 - Method of producing soap from black liquors of sulphate production - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing secondary products from spent liquors after cooking predominantly hardwood. Method of producing soap from black liquors of sulphate production of wood species, including addition of surfactants to black liquor. In black liquor with density of 1.02–1.12 g/cm³ and temperature of 20–25 °C is sequentially introduced aqueous solutions of cationic surfactant (CS) of octadecyldimethylbenzylammonium chloride of formula {C₁₈H₃₇(CH₃)₂(CH₂C₆H₅)N}Cl and a nonionic surfactant (NS) of oxyethylated monoalkylphenol based on propylene trimers of formula C₉H₁₉C₆H₄O(C₂H₄O)₆H at a ratio of black liquor:CS:NS 1:0.0001:0.0009–1:0.0002:0.0008, wherein sulphate soap is separated by settling black liquor for 4–10 hours and at temperature of 20–25 °C.

EFFECT: invention enables to obtain sulphate soaps at low temperatures from unpaired black liquors after cooking predominantly hardwood with high content of unsaponifiable substances in the obtained sulphate soap with biologically active substances based on β-sitosterol with simultaneous simplification of black liquor processing technology and reduction of energy consumption.

1 cl, 1 tbl, 1 ex

Description

The invention relates to the pulp and paper industry, and in particular to a method for producing sulphate soap (SM) from spent liquors from cooking deciduous or a mixture of deciduous and coniferous wood. The resulting product (CM) contains an increased amount of unsaponifiable substances, including valuable biologically active substances, including β-sitosterol used in the cosmetic industry as a biologically active additive and emulsifier.

Obtaining black liquor in the process of wood delignification includes the operations of taking it from the boiler, separating it from cellulose, separating sulphate soap and evaporating to a density required for the chemical recovery process. These operations successfully combine the interests of the main pulp production and the production of by-products. At the same time, the extraction of sulphate soap from the liquor is not only an economically feasible operation, but also meets the task of improving the process of evaporation of liquor in multi-shell apparatus and subsequent combustion. In the process of kraft pulping, under the influence of cooking liquor reagents, resin and fatty acids are saponified and pass into the liquor in the form of sodium salts. The release of sulphate soap from liquors is determined by the course of the processes of salting out and settling of the salted out substance. The technological parameters of the process that determine the process of separating sulphate soap are the density of black liquor, the duration of its settling and the temperature of the process. The composition of crude sulphate soap is a mixture of resin and fatty acids, unsaponifiables, lignin and other dyes. The output of sulfate soap per 1 ton of cellulose is 70-75 kg. The low extractability of sulphate soap leads to the formation of deposits in evaporation plants, an increase in foaming on paper machines, and a deterioration in the treatment of industrial wastewater.

Known methods of producing sulphate soap (SM) by settling black liquor in the buffer tanks of evaporation stations, followed by the separation of sulphate soap formed on the surface. The completeness of the separation of soap from lye depends on the solubility (concentration) of the soap, settling time, temperature, dry matter content in black liquors [Bogomolov B.D. and others. Processing of sulfate and sulfite liquors. - M. Forest Industry, 1989. - p. 56-77]. The sedimentation processes using flotation with continuous aeration with air, with the addition of activated sludge, in the presence of coagulating additives, leads to accelerated separation of sulfate soap, but does not allow it to be completely removed from black liquor. All these methods of obtaining take place at elevated temperatures [Bogomolov B.D. and others. Processing of sulfate and sulfite liquors. - M. Forest Industry, 1989. - p. 56-77, New handbook of chemist and technologist. Raw materials and products of the industry of organic and inorganic substances. Part II. - SPb .: Professional, 2003 .-- p. 708-709]. The disadvantages of these methods include the low efficiency of the settling process and the loss of sulphate soap, high energy consumption, expensive equipment and insufficient environmental safety of the resulting product (SM), the complexity of preparation and the cost of additives used (for example, activated sludge).

From the prior art, a method is known for producing SM from black liquor according to the international patent application WO 2008/092005 (07/31/2008) IPC C11B 13/00 (2006.01), selected by the applicant as the closest analogue. This method consists in adding to the black liquor a separation aid selected from the group consisting of alkyl alcohol alkoxylates of the formula RO [(CH ₂ CHCH ₃ O) _x (CH ₂ CH ₂ O) _y ] M and combinations thereof. The amount of tall oil soap in the preliminary experiment (ie, when no separating agent was added) was about 47.6 kg (105 lb) tall oil soap per ton of pulp produced. During the experiment using the separating additive, the yield increased to about 97.5 kg (215 lb) tall oil soap per ton of pulp produced. After the stage of separation of the liquor from the pulp, the black liquor obtained in the process of delignification of wood was subjected to an evaporation process in order to concentrate it and treated with the declared additives. The concentration in the black liquor of the additives used was in the range of 0.25 ppm-250 ppm. The separation of soap from the lye took place in the process of settling. The duration of the settling process was 6 hours. The separation of soap from black liquor was carried out with a skimmer. The resulting soap was processed into tall oil fatty acids. Despite the fact that the described method of obtaining increases the yield of sulfate soap, it is not entirely satisfactory. The disadvantages of this method include the presence of an energy-intensive additional stage of concentration of liquors by evaporation and the release of sulfate soap at an elevated temperature (87 ° C), in addition, sulfate soap is used only for the processing of fatty acids, valuable unsaponifiable substances present in sulfate soap, in addition to fatty acids, go to waste production.

The objective of the proposed invention is to eliminate these disadvantages, namely to obtain sulphate soap at low temperatures from unboiled black liquors after cooking mainly deciduous wood with an increased content of unsaponifiable substances in the obtained sulphate soap with biologically active substances based on β-sitosterol, while simplifying the technology of processing black liquor and lower energy costs.

The problem is solved by the fact that in the method of producing soap from black liquors of sulphate production of wood species, including the addition of surfactants to black liquor, and in black liquor after cooking mainly hardwood with a density of 1.02-1.12 g / cm ³ and a temperature of 20-25 ° C, aqueous solutions of a cationic surfactant (CSAS) octadecyldimethylbenzylammonium chloride of the formula {C ₁₈ H ₃₇ (CH ₃ ) ₂ (CH ₂ C ₆ H ₅ ) N} Cl and a nonionic surfactant are sequentially introduced (NSAID) oxyethylated monoalkylphenol based on propylene trimers of the formula C ₉ H ₁₉ C ₆ H ₄ O (C ₂ H ₄ O) ₆ H at a ratio of black liquor: CSA: NSAID 1: 0.0001: 0.0009-1: 0, 0002: 0.0008. Sulphate soap settling is carried out within 4-10 hours.

The essential features of the proposed method is an inseparable set of features specified in the claims of claim 1. There are known cationic type additives separately used for flocculation of dispersions and a nonionic surfactant used in technical detergents to effectively reduce the surface tension at the interface. In the claimed solution, the additives perform both their function and in a combination of the declared cationic and nonionic surfactants at these ratios, when they are sequentially introduced into the liquor in combination with other features mentioned above, they achieve a simplified, cheaper, less energy-intensive method of obtaining from waste black liquors from sulphate cellulose production of sulphate soap wood with a high content of unsaponifiable substances, including a biologically active product - β-sitosterol. Based on this, it can be concluded that the differences in the declared decision are significant.

The raw material is used black liquor after cooking hardwood or a mixture of hardwood and softwood pulp and paper production; surfactants (surfactants), previously purified from impurities by extraction in a known manner: cationic surfactant - an aqueous solution of octadecyldimethylbenzylammonium chloride of the formula {C ₁₈ H ₃₇ (CH ₃ ) ₂ (CH ₂ C ₆ H ₅ ) N} Cl ( CSA) and a nonionic surfactant - oxyethylated monoalkylphenol based on propylene trimers of the formula C ₉ H ₁₉ C ₆ H ₄ O (C ₂ H ₄ O) ₆ H (non-surfactant). The problem is solved by sequential introduction of surfactants into the black liquor solution.

Example

In a solution of black liquor obtained after delignification of wood, with a density of 1.02-1.12 g / cm ³ , located in a settling tank, a pre-purified addition of a cationic surfactant octadecyldimethylbenzylammonium chloride of the formula {C ₁₈ H ₃₇ (CH ₃ ) ₂ (CH ₂ C ₆ H ₅ ) N} Cl and further nonionic surfactant oxyethylated monoalkylphenol based on propylene trimers of the formula C ₉ H ₁₉ C ₆ H ₄ O (C ₂ H ₄ O) ₆ H Additives are introduced at the ratio of black liquor: CSAS: NSAS = 1: 0.0001: 0.0009-1: 0.0002: 0.0008. Black liquor settles for 4-10 hours at a temperature of 20-25 ° C. Then sulphate soap is separated from the surface of the black liquor by any suitable method, for example using a skimmer, and dehydrated to a moisture content of 50%. The output of sulphate soap is 55-80%, depending on the resinousness of the wood raw material. As a result, sulfate soap is obtained with a content of unsaponifiable substances of 18.2-28.8%, determined in accordance with GOST 50482-93, including β-sitosterol (BP) 4.1-8.5%. The resulting sulfate soap is used to isolate sterols in a known way [New reference book of a chemist and technologist. Raw materials and products of the industry of organic and inorganic substances. Part II. - SPb .: Professional, 2003. - p. 713]. The analysis of the isolated biological-active product from sulfate soap, carried out by gas-liquid chromatography, showed a high content of β-sitosterol in it of 80%. The product with this degree of purity can be used as a component of cosmetic emulsions.

Sulphate soap purified from sterols goes for processing to obtain tall products in a known way [New reference book of a chemist and technologist. Raw materials and products of the industry of organic and inorganic substances. Part II. - SPb .: Professional, 2003 .-- p. 709-712]. After the extraction of sterols, tallow products of higher quality and purity are obtained, with an increased yield and with the further possibility of isolating fatty acids, see table. As a result, by this method, due to the complex separation of substances, a product with a low amount of waste is obtained.

The method has been tested in laboratory conditions. Below are examples of its implementation.

Example 1.

A) In 500 ml of black liquor for hardwood cooking with a density of 1.02 g / cm ^3, 1% aqueous solution of CSAS in an amount of 5 ml is introduced while stirring black liquor, and then, without stopping stirring, a 1% solution of NSAS in an amount 45 ml. subjected to settling for 5 hours at a temperature of 22 ° C. From 500 ml of black liquor, 0.7 g of CM was obtained, which is 56%, the amount of unsaponifiables in the composition of the obtained CM is 0.15 g (20.5%), the remaining substances are 0.55 g (79.5%), and is isolated in in the form of white needle-like crystals BP 0.04 g (5.6% as soap).

B) Into 500 ml of black liquor for hardwood cooking with a density of 1.02 g / cm ^3, 1% aqueous solution of surfactant in an amount of 10 ml is introduced while stirring black liquor, and then, without stopping stirring, a 1% solution of nonionic surfactant is introduced in an amount 40 ml. The ratio of black liquor: KSAV: NSAS is 1: 0.0002: 0.0008. Black liquor is subjected to settling for 5 hours at a temperature of 22 ° C. From 500 ml of black liquor, 0.69 g of CM was obtained, which is 55%, the amount of unsaponifiables in the composition of the obtained CM is 0.14 g (20.4%), the remaining substances are 0.55 g (79.6%), and is isolated in the form of white needle-like crystals BP 0.038 g (5.5% as soap).

A qualitative analysis of the obtained sulfate soap revealed an increased content of unsaponifiables with an increased content of a biologically active product based on β-sitosterol. The data are shown in the table.

It can be seen from the table that only the declared additives of surfactants introduced into black liquor obtained from cooking wood predominantly of deciduous species at a liquor density of 1.02-1.12 in the presented range of black liquor: surfactant ratios, settling time 4-10 hours and temperature in the range of 20-25 ° C provide the tasks described above. It can be seen from the table that the best indicators (extraction efficiency 77 ± 3%, the highest content in sulfate soap - unsaponifiable substances 28.7% and biologically active substance - β-sitosterol 12.0%) of the obtained product correspond to sulfate soap isolated from black liquor after cooking hardwood with a density of 1.12 g / cm3, settling time 5 hours, liquor temperature 22 ° C.

In the prototype, the method for producing sulfate soap has a significant disadvantage in that it consists of additional energy-intensive stages of concentration and evaporation of black liquor to a dry matter content of 29.3%, as well as the process of settling sulfate soap is carried out at a temperature of 87 ° C. In addition, the method for producing sulfate soap presented in the prototype will make it possible to obtain from it only tall oil with the release of fatty acids. The advantage of the claimed solution is the production of sulphate soap from unevaporated liquors at low temperatures. Moreover, the resulting product contains an increased amount of unsaponifiable substances, including β-sitosterol. All these qualities also have economic advantages in comparison with the prototype.

Claims (2)

1. A method of producing soap from black liquor of sulphate production of wood species, including the addition of surfactants to black liquor, characterized in that in black liquor with a density of 1.02-1.12 g / cm ³ and a temperature of 20-25 ° C sequentially injected aqueous solutions of cationic surfactant (CSAS) octadecyldimethylbenzylammonium chloride of the formula {С ₁₈ Н ₃₇ (СН ₃ ) ₂ (СН ₂ С ₆ Н ₅ ) N} Cl and nonionic surfactant (NSAS) oxyethylated monoalkylphenol based on trimers propylene of the formula C ₉ H ₁₉ C ₆ H ₄ O (C ₂ H ₄ O) ₆ N at a ratio of black liquor: CSAS: NSAS 1: 0.0001: 0.0009-1: 0.0002: 0.0008, while sulphate soap is isolated by settling black liquor for 4-10 hours and at a temperature of 20-25 ° C. 2. The method according to claim. 1, in which black liquor is taken from cooking predominantly hardwood.