Tall Oil Soap Research Articles

Esterification of crude tall oil catalyzed by Beta zeolite

In softwood Kraft pulping process, fatty/resin acids (extractives) react with the white liquor and are saponified, producing Tall Oil Soap (TOS). TOS can be converted back to the respective fatty/resin acids, generating Crude Tall Oil (CTO). In this work, TOS was converted into CTO according to standard methods, producing residual lignin and an aqueous phase as co-products. Then, CTO was esterified in the presence of Beta zeolites with different Si/Al ratios and particle sizes in rotary Teflon-lined stainless-steel autoclave. Compared to esterification of oleic and palmitic acids, esterification of CTO is a slow process, with conversions limited to no more than 83 % after 6 h at 393 K. Smaller particles (0.26 μm) and lower Si/Al ratio (15) showed greater conversion. This may be associated with a higher strength of Brønsted acid sites (due to lower Si/Al ratio) but also with an improved diffusion of reactants/products within zeolite micro- and mesopores (due to the relatively smaller particle size). The esterification product was mainly composed of esters of fatty acids, such as dimethyl 4-isopropyloctanedioate, methyl elaidate and methyl palmitate. Esters of resin acids (methyl abietate and dehydroabietate), phthalic acids, as well as paraffins are also present, but probably in lower concentrations.

Effect of resin and fatty acids on sodium salt fouling

The evaporation of black liquor is an important, energy intensive unit operation in the kraft chemical recovery process. Between 50 and 85% dry solids, black liquor evaporators are susceptible to heavy sodium salt fouling leading to reduced heat transfer efficiency and in extreme cases, plugging. Recent mill experiences indicate that the addition of small amounts of resin and fatty acids containing streams (tall oil soap, tall oil, tall oil brine) to the concentrators can reduce sodium salt fouling. The underlying mechanism for this is unknown, which limits broader application and control. In this work we use model solutions of sodium salts in a bench-top scaling setup to investigate the impact of resin and fatty acids on sodium salt fouling. The results show that low concentrations of abietic acid and oleic acid can inhibit sodium salt fouling during nucleation and in the presence of a stable crystal population.

Process development for tall oil lignin production

The aim of this work was to study the production and characterization of tall oil lignin (TOL) from tall oil soap (TOS) of the kraft pulping process following a new process (i.e., LignoTall). Also, the properties of the TOL and kraft lignin (KL) produced via LignoForce technology were compared. Although TOL and KL were generated from the same black liquor and softwood species, they had remarkably different characteristics, confirming the impact of the production methods on the physicochemical properties of the isolated lignin. TOL had higher molecular weight, O/C elemental ratio, sulfur content, and carboxylate-OH content but lower methoxy group content than did KL. The high sulfur group content (7.3%) of TOL can be very useful for the vulcanization process. Moreover, the high carboxylate-OH content of TOL (0.56 mmol/g) is desirable for its utilization in epoxy resin production.

Sodium salt scaling in black liquor evaporators and the effects of the addition of tall oil brine

AbstractSodium salt scaling, i. e. the formation of doubles salts comprised of sodium, carbonate and sulphate on the heat transfer surfaces, is a common problem that occurs during black liquor evaporation. In this study, experimental results are presented that provide new insights into the formation and composition of such scales and how they are influenced by the addition of tall oil brine. It was found that increased content of sodium carbonate and sodium sulphate in the black liquor increased scaling, while the ratio between carbonate and sulphate had a lesser influence than reported in other studies. Black liquor created loose clay-like scales comprised of aggregated crystals and black liquor, whereas salt solutions created hard mineral-like scales. The scales formed by both the black liquor and the salt solution showed a tendency to fall off during formation after primary nucleation. It was also found that both tall oil soap and alkalized tall oil brine could inhibit the formation of scales. The inhibition effect is stronger if adding the soap or brine just before scaling starts, but also depends on the amount added, the sodium carbonate and sodium sulphate content in the liquor as well as other factors.

Tall oil production from black liquor: Challenges and opportunities

Abstract Tall oil is an important by-product of Kraft pulping processes. One possibility to improve the economic feasibility of Kraft pulp mills is to consider tall oil production from their wasted tall oil soaps. This review paper describes the current technology practiced to produce tall oil from the black liquor of Kraft pulping processes. Moreover, alternative processes to separate tall oil soap from black liquor, produce tall oil from the separated soap, purify tall oil, and to produce value-added products from tall oil are reviewed. The main perspectives and challenges associated with each process are comprehensively described. Currently, soap is separated from black liquor via decantation. To improve the efficiency of this separation, the application of neutral soluble colloids in dilute black liquor reported to be promising. Tall oil soap is converted to crude tall oil in the acidulation process via treating with sulfuric acid. However, the use of sulfuric acid forms calcium sulfate as a by-product of the process. The replacement of sulfuric acid with a sodium sesquisulfate solution is beneficial for decreasing the direct use of sulfuric acid in the tall oil production process. Crude tall oil can be used without purification as fuel. Its purification and subsequent reaction with methanol can lead to biodiesel production. However, this process may be complicated to implement in industry. The production of valuable lignin-based products from the tall oil production process may have benefits for the mills as these processes can be fully integrated into the Kraft pulping and tall oil production processes.

Microwave-Assisted Esterification of Tall Oil Fatty Acids with Methanol Using Lignin-Based Solid Catalyst

During alkaline pulping significant amounts of lignin, carbohydrates (mostly hemicelluloses), and extractives (tall oil soap and turpentine) are removed from wood feedstock. In this study, the catalytic esterification of fatty acids in tall oil with methanol to produce fatty acid methyl esters under microwave irradiation was performed at 100 °C for 10–60 min. A novel heterogeneous acid catalyst tested for this purpose was synthesized from the hardwood alkali lignin that was precipitated by acidification from the black liquor from soda-AQ pulping. The comparative reaction data were obtained by using other solid catalysts, Amberlyst 15, and p-toluenesulfonic acid. The results showed the highest esterification yields of 93, 88, and 80% with the p-toluenesulfonic acid, lignin-based, and Amberlyst 15 catalysts, respectively, at 100 °C with a reaction time of 60 min, and the corresponding yield without catalyst was 20%. It was also observed that the lignin-based catalyst could be easily recovered and reused wit...

Pyrolysis of crude tall oil-derived products

Crude tall oil (CTO) soap, purified and neutralised CTO, and neutralised distilled tall oil (DTO) were pyrolysed (at 750ºC for 20 s) by pyrolysis gas chromatography with mass-selective and flame ionisation detection (Py-GC/MSD and FID) to clarify their thermochemical behaviour. In each case, the pyrolysates were characteristically dependent on the feedstock, and a wide range of volatile aliphatic and aromatic compounds with some chemically bound oxygen formed. The CTO soap pyrolysate was typically composed of initial extractives-type compounds together with a significant amount of unsaturated aliphatic hydrocarbons and aromatics, whereas the DTO pyrolysate contained mostly just unsaturated aliphatic hydrocarbons and aromatics. These data are of importance when considering the suitability of various extractives-derived resources for producing bioliquids and chemicals.

Extraction of phytosterols from tall oil soap using selected organic solvents

AbstractTall oil soap as a waste product of the sulphate cellulose production process was treated by single-stage liquid-liquid extraction. The aim of this study was to compare yields of health beneficial matters contained in tall oil soap when several extraction solvents, recommended in literature, were used. Hexane, 1-methyl-4-(1-methylethenyl)-cyclohexene, 2-methylpropan-1-ol, hexan-1-ol, 4-methylpentan-2-one, 2-methoxy-2-methylpropane, and butyl ethanoate were tested. For hydrocarbons it was necessary to add a de-emulsifier into the system, which limits the formation of foams and stable emulsions. The highest yields of total phytosterols (78 %) and especially of β-sitosterol (100 %) were reached when butyl ethanoate was used. However, it was necessary to adjust pH of the treated raw material to approximately 7. The highest yields for feed where pH was not adjusted were obtained with 2-methylpropan-1-ol: 67 % of total sterols and 89 % of β-sitosterol. Disadvantages of most of the tested solvents included the formation of the undesirable solid interphase which could not be removed, partial solubility of the solvents in the water phase, their high boiling point and/or instability. These disadvantages prevent the use of these solvents in industrial applications; they also complicate the treatment of tall oil soap by liquid-liquid extraction or the regeneration of the used organic solvent.

Comparative Study of Jhamarkotra Soap Emulsion and Tall Oil Soap Emulsion as Flotation Collectors

Soaps of mixed fatty acid origin or soap-light diesel oil (LDO) emulsion are used as collectors in the froth flotation of salt type minerals (for example – apatite, fluorite, dolomite, etc.). Detergents are sometimes used along with soaps to reduce the consumption of soap and also to improve the process efficiency. In the present investigations effect of different reagent regimes on flotation of a siliceous phosphate ore was studied. Flotation tests were carried out using mixed fatty acid soap and tall oil. Both the reagents were used as emulsions with light diesel oil in the ratio of 1:1.2. Tests were also carried out with promoters (Alfa Olefin Sulfonate [AOS], Linear Alkyl Benzene Sulfonate [LABS] and Urea) along with these reagents to evaluate the process efficiency. While AOS and LABS are detergents, urea is a polar non electrolyte reagent known to act as hydrotrope. It is noted that mixed fatty acid soap-LDO emulsion (SL emulsion) shows better process efficiency than tall oil-LDO emulsion (TL emulsion). The highest recoveries (>90%) were achieved when mixed fatty acid was used in conjunction with promoters. The experiments with promoters yielded higher recoveries rather than mixed fatty acid or tall oil used alone.

Quantitative determination of fatty and resin acids in Kraft black liquors as their trimethylsilyl derivatives by gas chromatography

Tall oil soap is an important byproduct of the Kraft pulping process used at papermaking facilities. Tall oil soap is comprised primarily of the sodium salts of unsaturated fatty acids and a variety of resin acids. These can be recovered from spent black liquor and sold as a feedstock for specialty chemicals manufacture. The ability to monitor the removal of soap from liquor at various stages of the recovery process is of extreme importance to the recovery operation. This paper describes a new procedure which has been developed for the analysis of residual tall oil components in black liquors. In this method, the liquor is extracted with methyl tert.-butyl ether (MTBE) under highly alkaline conditions. The extracted components are converted to their trimethylsilyl derivatives, and then analyzed by GC with on-column injection. Quantitation is performed through comparison to an internal standard. This new procedure provides many important advantages over the wet chemical method routinely used for monitoring residual soap levels. These include a more simplified extraction and analysis procedure, an increase in method precision, and detailed quantitative information regarding the type and distribution of components.

98/02826 Liquid-phase thermal treatment of tall oil soap into hydrocarbon fuels: Oasmaa, A. et al. Dev. Thermochem. Biomass Convers., 1997, 1, 696–710

98/02826 Liquid-phase thermal treatment of tall oil soap into hydrocarbon fuels: Oasmaa, A. et al. Dev. Thermochem. Biomass Convers., 1997, 1, 696–710

Fatty and Resinic Acids Extraction from Crude Tall Oil

Abstract The separation of fatty and resinic acidic fractions from crude tall-oil soap solutions with n-heptane by the technique of dissociation extraction is discussed. The theory of the overall process is supported by a systematic study developed to cover the high selectivity demonstrated in the differential solubility and the aptness between fatty and diterpenic acids to both liquids phases. To study the main factors affecting those liquid-liquid extraction systems and the amphiphilic behavior of such molecules involved, sodium salts aqueous solutions of crude tall oil and synthetic mixtures as molecular acidic models were used.

Tall oil soap skimming—the state of the art

AbstractThis paper calls attention to the increased interest in tall oil production within the past 5 years and the simultaneous increase in the market price of tall oil. It points out that tall oil has grown from a relatively unknown product to a well established commodity of considerable commercial importance, which has given kraft pulp mills a renewed interest in soap skimming. This paper also covers the state of the art in soap skimming.

Comparative value of fatty acids and resin acids of tall oil in soaps

SummaryA study has been made of the detergency and foaming power of soaps made from a typical acid‐refined American tall oil. Sodium soap of tall oil, straight tall oil fatty‐acid soap, and straight tall oil resin‐acid soap were evaluated. The effect of fatty acid‐resin acid ratio was determined by using mixtures of those soaps. Sodium rosinate, sodium oleate, and mixtures of these soaps were used as comparison standards. Curves plotted show wash‐test data and foaming values as functions of the ratio of fatty soap to resin soap.The data indicate in terms of detergency: a) tall oil soap has a higher value than sodium rosinate; b) sodium oleate is better than tall oil fatty‐acid soap, but the latter is approximately equivalent to soaps from various unsaturated vegetable oils; c) both tall oil resin‐acid soap and rosin soap have low detergency on cotton; d) the detergency of most mixtures of tall oil fatty‐acid and resin‐acid soaps at lower concentrations is greater than would be predicted from the individual soaps, indicating a synergistic effect.As a rough approximation, tall oil soap without unsaponifiables is equivalent to a corresponding mixture of sodium oleate and sodium rosinate. The presence of unsaponifiables lowers both detergency and foaming. Tall oil soap is somewhat less sensitive to hard water than sodium oleate.Significant differences between detergencies of soaps, and especially between soap mixtures, are obscured when launderometer tests are run at moderate soap concentrations. These differences are readily detected at lower concentrations.