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Journal of Dispersion Science and Technology
ISSN: 0193-2691 (Print) 1532-2351 (Online) Journal homepage: http://www.tandfonline.com/loi/ldis20
The performance test of fatty acid methyl ester sulfonates and application in the dishwashing liquid detergent
Xiu-mei Tai, Jin-yu Song, Zhi-ping Du, Xiaoying Liu, Tianzhuang Wang &
Guoyong Wang
To cite this article: Xiu-mei Tai, Jin-yu Song, Zhi-ping Du, Xiaoying Liu, Tianzhuang Wang &
Guoyong Wang (2018): The performance test of fatty acid methyl ester sulfonates and application in the dishwashing liquid detergent, Journal of Dispersion Science and Technology, DOI:
10.1080/01932691.2017.1409633
To link to this article: https://doi.org/10.1080/01932691.2017.1409633
Published online: 22 Jan 2018.
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https://doi.org/10.1080/01932691.2017.1409633
The performance test of fatty acid methyl ester sulfonates and application in the dishwashing liquid detergent
Xiu-mei Taia, Jin-yu Songb, Zhi-ping Dua,c, Xiaoying Liua, Tianzhuang Wanga, and Guoyong Wanga
aChina Research Institute of Daily Chemical Industry, Taiyuan, Shanxi, China; bDepartment of Pharmaceutical Engineering, Shanxi Pharmaceutical Vocational College, Taiyuan, Shanxi, China; cResources and Environment Engineering Research Institute, Shanxi University, Taiyuan, Shanxi, China
ABSTRACT
Hydrolytic stability, foaming power and foam stability, calcium soap dispersing ability and stability in hard water of fatty acid methyl ester sulfonate (MES) were measured by potentiometric titration, Ross-Miles foam instrument, improved acid titration and turbidimetric test, respectively. The dishwashing detergent formulations containing MES were designed and stability and detergency of dishwashing detergents have been tested. The results showed that when storage temperature was 45°C, MES in pH 4.5 ∼ 9 was stable, disodium α-sulfonated fatty acid esters content increased at pH 10, hydrolysis rate was accelerated; foaming power of MES was lower than sodium linear alkyl benzene sulfonate (LAS) and the foam stability was equivalent to that of LAS; MES showed very excellent calcium soap dispersing ability, calcium soap dispersing amount of MES was 2.5 g calcium soap /1 g MES and LAS was 0.34 g /1 g LAS;
differential stability of MES in hard water was 542, and LAS was 322; the performance test results of dishwashing detergent products partially substituted LAS by MES can both meet the requirements of the Chinese national standard.
GRAPHICAL ABSTRACT
ARTICLE HISTORY Received 1 November 2017 Accepted 22 November 2017 KEYWORDS
Calcium soap dispersing ability; dishwashing detergent; fatty acid methyl ester sulfonate; hydrolytic stability
1. Introduction
With the rapid depletion of oil resources and improvements of people’s awareness to environmental protection, green, environmental compatibility surfactants from renewable resources have become one of the development directions of surfactant technology in recent years. Fatty acid methyl ester sulfonate (MES) was prepared from natural renewable materials, such as coconut oil, palm oil and other oil, which was directly sulfonated by sulfur trioxide (SO3) and neutralized.[1–3] MES had very excellent biodegradability, good resistance to hard water, good detergency, low irritation and good compatibility.[4,5] Therefore, MES has been recog- nized as a promising, cheap and efficient surfactant and the third representative surfactant to replace sodium linear alkyl benzene sulfonate (LAS) in the world. Generally, MES was
used in calcium soap dispersant, powder detergent, tableware detergent, shampoo and soap, industrial light and heavy duty liquid detergent, and so on. However, owing to the high krafft point of MES, MES is usually applied in combination with LAS and AES in liquid detergent formulations to improve the stability of the product,[6,7] to some extent, which limited the large scale application. In this paper, physical and chemical properties of MES were studied. According to the surfactant mixed principle and special detergent preparation technology, dishwashing detergent formulations were developed using MES/LAS mixture as the main surfactant. The properties of dishwashing detergent were tested. This research will provide theoretical and practical support for the application of MES in detergent products.
none defined
CONTACT Xiu-mei Tai [email protected] China Research Institute of Daily Chemical Industry, 34 Wenyuan Street, Taiyuan 030006, China.
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ldis.
© 2017 Taylor & Francis
2. Experimental 2.1. Materials
Fatty acid methyl ester sulfonate (MES, commercial, 35 wt.%, Zouping Fuhai technology development Co., Ltd.); potassium hydroxide (AR, Tianjin chemical reagent 3 plant); 95% ethanol (AR, Beijing chemical plant); hydrochloric acid (AR, Taiyuan chemical fertilizer plant); sodium oleate (AR, Shanghai Aladdin biochemical Technologies Co., Ltd.); anhydrous magnesium sulfate (MgSO4) and anhydrous calcium chloride (CaCl2) (AR, Tianjin Tianda chemical reagent plant); sodium citrate (AR, Jiangsu Wu Jiang Donghao fine chemical Co., Ltd.); sodium linear alkyl benzene sulfonate (LAS) (commer- cial, Nanjing Alkylbenzene factory); fatty alcohol polyoxyethy- lene ether, fatty alcohol polyoxyethylene ether sulfate (commercial, Zhejiang Jilida chemical Co., Ltd.); alkyl polygly- coside (commercial, Shanghai fine chemical Co., Ltd); all products were used without further purification; deionized water (18.2 MΩ) was used for all experiments.
2.2. Apparatus
Automatic potentiometric titration ZDJ-2D, Beijing Xianqu Weifeng technology development company; PHS-3C pH detector, Shanghai precision scientific instrument Co., Leici instrument factory; Ross-Miles foam meter, China research institute of daily chemical industry.
3. Physical and chemical properties measurements of MES
3.1. Hydrolysis resistance
20% MES aqueous solutions of pH 4.5, 7, 8, 9 and 10 were pre- pared and stored in an oven at (45 �2)°C for different time.
The content of disodium α-sulfonated fatty acid esters (DS) was tested under different storage time. About 0.5 g (accurate to 0.001 g) sample, 10 mL ethanol and 90 mL water were taken in a 150 mL beaker, was heated up to 60 ∼ 70°C in water bath until the system is homogeneous, then the system was cooled to room temperature. A certain amount of analyzed solution was put in automatic potentiometric titration table, the electrodes was immersed in the solution with stirring, 0.5 mol/L hydro- chloric acid solution was added drop by drop to adjust pH 2.60 �0.10. 0.1 mol/L potassium hydroxide standard solution was used as titration agent to measure the content of Ds. The titration curve is shown in Figure 1a, and the titration potential differential diagram is shown in Figure 1b. The potential abrupt points 1 was caused by sodium fatty acid sulfonate, and the potential abrupt points 2 was caused by excess hydrochloric acid and fatty acid methyl ester sulfonic acid.
The content of disodium α-sulfonated fatty acid esters (DS) W2 was calculated according to the equation 1 (eq1):
W2%¼c2�M� ðV3 V2Þ 10�m2
½1�
The results are represented by arithmetic averages to four significant digits.
Where:
M: Molar mass of surfactant, g/mol;
V2: The amount of standard solution for potassium hydroxide at the first abrupt point, mL;
V3: The amount of standard solution of potassium hydrox- ide at second abrupt points, mL;
c2: Standard solution concentration of potassium hydrox- ide, mol/L;
m2: mass of surfactant, g.
3.2. Foaming measurement
Hard water was prepared according to the following method, 0.37 g MgSO4 and 0.50 g CaCl2 were fully dissolved in 5000 mL distilled water.
Firstly, Ross-Miles foam instrument was heated to 40 �1°C. 2.5 g sample was weighted to the 1 L beaker and 1000 mL 150 mg/kg hard water was added into the beaker with stirring. Then, the test solution was put into 40 �1°C water bath kettle for 30 min. 200 mL test solution was used to wash and wet the Ross-Miles foam instrument. The test solution was put into the Ross-Miles foam instrument to the 50 mL scale, another 200 mL test solution which was placed in the separat- ing funnel was flowed down from the above and center of Ross-Miles foam instrument immediately. After the test sol- ution was flowed over from separating funnel, the power height was writed down, the power height of 5 min and 10 minute was also wrote down. Every sample was measured at least 2 times, the last power result was obtained according to the error within the scope of the permit average, the last results held until it is integer.
Figure 1. Potentiometric titration curve of disodium α-sulfonated fatty acid esters in MES (a), potentiometric titration differential curve of DS in MES (b).
2 X.-M. TAI ET AL.
3.3. Calcium soap dispersing power
0.5 wt.% sodium oleate solution was prepared and kept in 40°C for 24 h. The oleate solution and the measured MES solution were mixed, and a certain volume of 1000 ppm CaCl2 solution was added into the mixture. After the mixture was placed at 40°C for 1 ∼ 1.5 h, the calcium soap sediments would float on top. The calcium soap in the low solution was titrated by hydrochloric acid standard solution using bromocresol green as an indicator. As a result, the amount of calcium soap which can be dispersed with 1 g surfactant is called calcium soap dispersing power.
3.4. Stability in hard water
Three water solutions with different hardness and a certain concentration of surfactant solution were prepared, respect- ively. 15 colorimetric tubes were divided into three groups, 5 colorimetric tubes in each group. The different amount surfactant solutions were added in the every colorimetric tube of each group. Three kinds of hard water solutions were added to 50 mL scale mark in the three groups. the tube plugs were sticked, then the tubes were slowly turned up and down to avoid bubble producing by one time per second, this courses were repeated for ten times. The 15 tested tubes were placed in 20 �2°C for 1 ∼ 2 h. The solution appearances were observed to assess the surfactant stability in hard water, clear, milky, opacity, a small amount of precipitation, precipitation means 5 points, 4 points, 3 points, 2 points, respectively. If the stability of calcium salts increases with temperature, tests are carried out at 50 �2°C and observed at this temperature.
The average stability of the 15 tubes was evaluated, and the scores of 5 tubes in each group were averaged to evaluate the differential stability.
3.5. Application performance
MES was applied into the dishwashing detergent, the formulation was followed as Table 1.
3.5.1. Storage stability
Thermal storage stability: the sample was placed in (40 �2)°C oven for 24 h, then the sample was taken out to return to room temperature, and the difference between the original sample and the treated sample was observed whether it has stratification phenomenon.
Freeze thaw stability: the sample was placed in ( 18 �2)°C refrigerating chamber for 24 h, then the sample was taken out to return to room temperature, and the difference between the original sample and the treated sample was observed whether it has stratification phenomenon.
3.5.2. Detergency testing
Detergency testing of dishwashing detergent was measured referring to GB 9985-2000. The detergency of the prepared dishwashing detergent was evaluated by comparison the washed dishes numbers with standard dishwashing detergents and the prepared dishwashing detergent, when there were half foam residued.
4. Results and discussion
4.1. Physical and chemical properties of MES 4.1.1. Hydrolysis resistance of MES
The hydrolysis stability of 20 wt.% MES solution at different pH and different time was tested, as shown in Table 2. MES solutions were sealed in glass bottles. It can be seen that when pH was larger than 4.5 and less than 9, MES samples stored for 40 d at (45 �2)°C were not obviously hydrolyzed. When pH was more than 10, the hydrolysis phenomenon began to occur.
With the increase of storage days, the content of disodium α-sulfonated fatty acid esters gradually increased, which was basically consistent with the results reported in the literature.[8]
4.1.2. Foaming properties of MES
Foaming power is one of the important performances of surfactant. Figure 2 is foam height of 0.25 wt.% MES and 0.25 wt.% LAS at 0 min and 5 min, it can be seen that foaming power of MES is lower than LAS, and the two surfactants have good foam stability. For MES, it is more suitable for low foam detergent formulations.[9]
4.1.3. Calcium soap dispersing power of MES
Solid particles dispersed in liquid were easily aggregated to and were precipated. The surfactant can disperse the solid chunks particles into small particles without being sinked. It is called calcium soap dispersing power.[10] Figure 3 were the disperse diagrams of calcium soap of MES (Figure 3a) and LAS (Figure 3b) in the different concentration surfactant solution.
LAS was taken as the contrast sample, the samples were put in (40 �2)°C for 1.5 h. It can be seen that with the increase of surfactant concentration, calcium soap dispersing power was better and better. 2.5 g calcium soap can be dispersed by 1 g MES while 0.34 g calcium soap can only be dispersed by 1 g LAS. So, MES has better dispersing ability. This is mainly because MES may generate calcium ion flocculation like LAS, but MES has a methyl ester close to its sulfonic acid and can prevent MES calcium salt precipitation. The meta- stable micelles were formed between MES and calcium ion,
Table 1. Formulations of dishwashing liquid detergent.
Sample No.
w/%
MES LAS AEO9 AES C12∼14APG Na3C6H5O7 H2O
1# 6.0 2.0 2.5 3.0 2.5 0.5 ∼100
2# 8.0 / 2.5 3.0 2.5 0.5 ∼100
Table 2. Disodium α-sulfonated fatty acid esters (DS) content in MES at (45 �2)°C, different pH and different times.
Items
DS (%)
0 d 10 d 20 d 30 d 40 d
pH 4.5 2.58 2.48 2.71 2.61 2.55
pH 7.0 2.61 2.70 2.65 2.59 2.60
pH 8.0 2.60 2.55 2.73 2.51 2.47
pH 9.0 2.68 2.68 2.66 2.56 2.78
pH 10.0 2.62 3.52 5.71 6.75 8.23
calcium ion was aggregated around micelles and was not directly combined with MES, so MES has very excellent calcium soap dispersing power.[11–13]
4.1.4. Stability of MES in hard water
Surfactant molecules can react with calcium and magnesium ions in water to form insoluble calcium salts and magnesium salts, which greatly reduced the detergency of surfactants.
The stability of surfactant in hard water is one of the main affecting factors for its application.[7] 5 wt.% LAS and MES solutions were placed at (20 �2)°C for 1 h. The differential stability results of MES and LAS at 120 ppm, 180 ppm, 240 ppm hard water are shown in Table 3. The differential stab- ility level is classified into 5, 555 is the best and 111 is the worst.
It can be seen that the differential stability of MES was better than that of LAS according to the scores at different hard water.
MES has very good ability of resisting hard water.
4.2. Application performance test of MES
MES from natural fats and oils was easy to be degraded. It was of great significance to apply MES into the dishwashing deter- gent, whether from requirements of energy saving and emission reduction, or from green and environmental protection.
4.2.1. Stability of dishwashing detergents
Stability was an important indicator of product performance, and good stability meant long shelf life for goods. Table 4
showed the stability of different formulas. It can be seen that two samples exhibited good thermal, cold, and freeze thaw stability. The products were placed for 6 months, no floccu- lation, stratification phenomenon was observed. It was proved that the prepared dishwashing detergents had good stability.
4.2.2. Detergency of dishwashing detergents
The two prepared dishwashing detergents can wash 5 plates, while the standard dishwashing detergent can wash 4 plates, it was proved that the prepared dishwashing detergents had higher detergency than the standard dishwashing detergent.
However, as we know, MES has lower foam height than LAS, so, it was unfair using foam method to evaluated the detergency of dishwashing detergents containing MES. If the decontamination was evaluated using the deoiling rate, maybe better detergency would be obtained for the dishwash- ing detergent containing MES.
5. Conclusion
1. When pH was larger than 4.5 and less than 9, MES samples stored for 40 d at (45 �2)°C were stable and not obviously hydrolyzed. When pH was more than 10, the hydrolysis phenomenon began to occur, which showed that the con- tent of disodium α-sulfonated fatty acid esters increases gradually.
2. Foaming power of MES was worse than that of LAS, and the foam stability is basically the same as that of LAS.
3. 1 g MES can disperse 2.5 g calcium soap, while 1 g LAS can only disperse 0.34 g calcium soap. MES is obviously better than LAS for dispersing calcium soap.
4. Differential stability of MES in hard water is 542, whereas differential stability of LAS in hard water is 322, so, stability of MES in hard water is obviously better than that of LAS.
5. The two prepared dishwashing detergents containing MES have very excellent stability and detergency performance.
Funding
This research was supported by the state key research and development project (2017YFB0308704) and Natural Science Found of Shanxi Province (No. 2014011014-1).
Figure 3. MES and LAS calcium soap dispersing power, (a) MES, from left to right: 10 g, 5 g, 2.5 g, 2 g calcium soap/g MES; (b) LAS, from left to right: 5 g, 1 g, 0.5 g, 0.25 g calcium soap/g LAS.
Table 3. Stability of MES and LAS in different hard water.
Item
MES LAS
Score
Differential
stability level Score
Differential stability level
S1 25 5 18 3
S2 22 4 12 2
S3 7 2 7 2
Differential stability 542 322
Table 4. Stability of dishwashing liquid detergent containing MES.
Sample No. 1# 2#
Thermal S S
Cold C and T C and T
Freeze S S
Note: Stable: S; Clear and transparent: C and T.
Figure 2. foam performance of LAS and MES.
4 X.-M. TAI ET AL.
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