Nghiên cứu xây dựng hệ chất hoạt động bề mặt bền nhiệt ứng dụng trong công nghệ sản xuất chất tạo bọt chữa cháy TT TIENG ANH

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY NGUYEN THI NGOAN RESEARCH ON BUILDING HEAT-RESISTANT SURFACTANTS S

MINISTRY OF EDUCATION

AND TRAINING

VIETNAM ACADEMY OF AND TECHNOLOGY

GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY

NGUYEN THI NGOAN

RESEARCH ON BUILDING HEAT-RESISTANT

SURFACTANTS SYSTEM APPLIED IN FIRE FIGHTING

FOAM PRODUCTION TECHNOLOGY

Major: Chemical engineering Code : 9.52.03.01

SUMMARY OF CHEMICAL DOCTORAL THESIS

HA NOI – 2021

This thesis was completed at Graduate University of Science and Technology – Vietnam Academy of Science and Technology

Hardcopy of the thesis can be found at:

- Library of Graduate University of Science and Technology

- National Library of Vietnam

INTRODUCTION

1 The acceptability of the thesis

Fire is a threat to humans The consequences, damage to people and property caused by fire and explosion are enormous Fire can happen anywhere and in all fields Water is used to extinguish forest fires, house fires, boat fires… Today, it is still the primary fire extinguishing agent with good cooling and low cost However, water is ineffective against burning gasoline, oil, or other flammable liquids because water has a greater density than these fuels Fire derived from liquid fuels is characterized by a fast-burning rate, a long time, and a risk of strong thermal radiation, which can lead to serious damage to the surrounding environment Therefore, the research and manufacture of effective fire extinguishing agents and quick extinguishers are important

Nowadays, fire fighting foam has been produced into many types to meet each purpose of fire fighting Fire-fighting foaming agents are used to extinguish fires and prevent re-burns in fuel fires With fast, popular fire-fighting properties, fire-fighting foam is currently the most widely used on the market

In our country, the research and production of fire fighting foam products are limited, mainly imported Special, a product line of aqueous film-forming foam (AFFF) and alcohol - resistant aqueous film-forming foam concentrate (AR-AFFF) Therefore, it is necessary to research and manufacture fire fighting foam products to meet the needs of using and actively produce domestically Therefore, the implementation of the thesis

topic "Research on building heat-resistant surfactants system applied in fire

fighting foam production technology" is topical has scientific and

meaningful meaning in practice

2 The research objectives of the thesis

- Building heat-resistant surfactants system from some surfactants, suitable for the high-temperature conditions and characteristics of each fire object;

- Optimization of the built-in heat-resistant surfactant system, applied

in the production of aqueous film-forming foam (AFFF) and resistant aqueous film-forming foam (AR-AFFF), meets TCVN;

alcohol Evaluate the applicability of some siliconalcohol containing compounds to improve fire suppression efficiency for aqueous film-forming foam AFFF

3 The main research contents of the thesis

- The study analyzes, evaluates, and selects surfactants suitable to the harsh conditions of the fire (high temperature, powerful heat radiation, long burning time ) to improve fire extinguishing efficiency;

- Study physical and chemical properties, compatibility, and heat stability;

- Research to optimize the mixing ratio of surfactants suitable for the AFFF and AR-AFFF fire extinguishing foam and the lowest surface tension;

- Research on using surfactants with some silicon compounds to improve the fire extinguishing efficiency of the AFFF

CHAPTER 1 OVERVIEW

The overview consists of four main parts: Part 1 overview of the fire fighting foaming agent: general introduction about AFFF and AR-AFFF foam Part 2 studies, learns about the composition of fire fighting foam the and application of some silicon-containing compounds in fire fighting foam Part 3 introduces the role and principle of extinguishing foam Part 4 presents the research situation of foaming agents in the world and Vietnam

CHAPTER 2 EXPERIMENT AND METHODOLOGY

2.1 Chemical and equipment

2.2 Evaluation and analysis method

2.2.1 Method for determining the chemical and physical properties of the fire fighting foam

Determine the parameters:

- Interfacial tension, surface tension and spreading coefficient, viscosity, expansion and 50 % drainage time, pH, and freezing temperature

2.2.2 Method of determining the stability of the foam

The technique using two syringes used to create foam and to assess foam stability

2.2.3 Method for determining compatibility and heat resistance

Compliance and heat stability were investigated by isothermal incubation at 150°C for 8 hours Observe the turbidity, measure the surface tension and the pH of those solutions

2.2.4 Experimental planning method and optimization

Design matrix of experimental plans according to Box - Hunter model The optimal composition and concentration of a surfactant system are determined when the surface tension reaches the minimum value

2.3.5 Test method

Evaluate the fire extinguishing effect of foam solution fabricated according to TCVN - 7278: 2003 standard

2.3 Experimental

The general research process for manufacturing the firefighting foaming agent system is as follows:

2.3.1 Manufacture of aqueous film-forming foam

2.3.2 Dispersion of silicon compounds in AFFF foam

2.3.3 Manufacture of alcohol-resistant aqueous film-forming foam

of mixtures of surfactants

3 Optimized mixing of surfactants

4 Study the

selection of additives

CHAPTER 3 RESULTS AND DISCUSSION

3.1 Aqueous film-forming foam AFFF

3.1.1 Study and selection of surfactants

Table 3.1: Results of investigating the expansion

and half-life of hydrocarbon surfactants

(times)

50 % drainage time (minute: seconds)

1 Branched alkyl benzene

5 Nonylphenol ethoxylates (NPE) 5.5 4:11

6 Lauryl hydoxysulfo betaine

Selection of hydrocarbon surfactants: Alkyl polyglucosides (APG),

Nonylphenol ethoxylates (NPE), and Lauryl hydoxysulfo betaine (LHSB)

with the parameters of expansion 5 times greater and 50 % drainage time of

more than 4 minutes

1 1,5 2 2,5 3 3,5 4

14 14,5

15 15,5

16 16,5

17

SCBM (mN/m) SCBM liên diện (mN/m)

Figure 3.1 The effect of the DCF concentration on the

surface tension of the water

Table 3.2: Expansion and 50 % drainage time of solution DuPont™

DuPont™ Capstone® fluorosurfactant 1440 (DCF) is suitable for

researching the manufacture of aqueous film-forming foam

Figure 3.2: Graph showing surface tension of surfactants by concentration The results in figure 3.2 showed that hydrocarbon surfactants are capable of reducing the surface tension of water to about 28 - 33 mN/m Meanwhile, fluorinated surfactants reduce water surface tension about 15-

16 mN /m lower than hydrocarbon surfactants On the other hand, DCF is heat stable under high-temperature conditions because it contains C-F bonds Therefore, DCF is selected as the main ingredient in the fire fighting foam formulation

3.1.2 Determination of compatibility and heat resistance of mixtures of surfactants

From the results of evaluating the compatibility and heat stability of a

mixture of 2, 3, and 4 surfactants, it is found that the system of 4 substances

is capable of reducing the surface tension of the system to a low value The

changes in pH and surface tension after the annealing are not significantly

changed, indicating that the system is thermally stable The ratio of DCF:

APG: LHSB: NPE studied was 1: 3: 2: 1

Table 3.10 Investigating the expansion, 50 % drainage time

of the surfactant system

(times)

50 % drainage time (minute: seconds)

3.1.3 Optimizing of the surfactants system

The regressive equation corresponds to the emirical variables:

Ŷ = 42.81 – 5.324*10-2

Z1 – 8.279*10-2Z2 – 0.1118*Z3 - 4.69*10-5Z1Z2 + 6.56*10-5Z1Z3 – 7.19*10-5 Z2Z3 + 2.423*10-4Z1

2

+ 2.07*10-4 Z2

Figure 3.4: Contour lines represent the value of σ according

to the concentration of surfactants

3.1.4 Research and selection of additives

The changes in pH and surface tension of the surfactant system when

having 5.0% butyl diglycol, 2.5% glycerin, 1.5% Ure and 1.0% HEC have a

slight change, indicating that the research material system is relatively

thermally stable Heat resistance will be studied more carefully by fire tests

according to Vietnamese standards

3.1.5 Study to investigate the mix order

Through experiments investigating the mixing order of surfactants, it

was found that bisexual surfactants such as LHSB should be added first

with the fluorinated surfactant then to the last nonion active substance

Table 3.20: The results of surveying the mixing order of the AFFF

Note: +++: the solution is completely clear and little foam forms

++-: the solution has many small bubbles -: the solution has a lot of foam, durable

Continue to study the additive composition, based on the parameters of

50 % drainage time, mixing time, and surface tension When changing the mixing order, the 50 % drainage time and surface tension of the surfactants system change not significantly But the stirring time changes, in the order

of mixing butyl diglycol, glycerin, hydroxyethyl cellulose, urea corresponds

to order 6; 7; 8; 9 for the shortest stir time is 29 minutes, so the order of mixing substances is as follows: Water; DCF; LHSB; NPE; APG; Butyldiglycol; Glycerin; HEC; Urea corresponds to mixing order 1; 2; 3; 4; 5; 6; 7; 8; 9

3.1.6 Examine the time and the speed of agitating

Table 3.24 Results of the time and the speed of agitating

Homogeneity

of solution

50 % drainage time (minute:

seconds)

Surface tension (mN/m)

40 minutes to create an AFFF fire fighting foaming agent

From the survey results, the formulation of aqueous film-forming foam

is presented in table 3.23

Table 3.23 The formula for making aqueous film-forming foam

1 DuPont™ Capstone® fluorosurfactant (DCF) 10.4

5 Hydroxyethyl cellulose (HEC) 1.0

Table 3.24: The properties of aqueous film-forming foam

5 Time to extinguish (seconds) 266 279 276

The results of determining the properties of the aqueous film-forming foam 0.5% meet the requirements according to TCVN 7278 - 1: 2003

3.2 Alcohol-resistant aqueous film-forming foam

3.2.1 Study and selection of surfactants

Investigating the expansion and 50% drainage time of the surfactants hydrocarbon with the concentration of 0.05% The obtained results are shown in the following table 3.25

Table 3.25: Expansion and 50% drainage time of the surfactants

hydrocarbon

(times)

50 % drainage time (seconds)

1 Branched alkyl benzene sulfonate 4.8 212

6 Nonylphenol ethoxylates 4.4 245

The results in table 3.25 show that, there are five surfactants: Sodium lauryl ether sunfat (SLES); Sodium lauryl sulfate (SLS); Alkylphenol ethoxylate (APE); Nonylphenol ethoxylates (NPE) và Lauryl hydoxysulfo betaine (LHSB) has satisfactory 50% drainage time and expansion

Selection of fluoroalkyl betaine (FB) to research and manufacture an alcohol-resistant aqueous film-forming foam Investigate the compatibility

of fluorinated surfactants and hydrocarbon surfactants in the ratios of 1:4, 1:3, 1:2, 1:1, 3:1, 2:1 with a total concentration of 0.2% in water incubated

at 150°C for 8 hours The results are as follows:

Table 3.24: Compatibility of the surfactant mixtures

Ratio

Mixture

Comment

FB : SLES transparent transparent transparent transparent transparent transparent

FB : SLS transparent transparent transparent transparent turbidity turbidity

FB : APE transparent transparent transparent transparent turbidity turbidity

FB : NPE transparent transparent transparent transparent transparent transparent

FB : LHSB turbidity turbidity turbidity turbidity turbidity turbidity

The mixtures were mixed with a total concentration of 0.2%

Through experiments found that the mixture FB: SLS; FB: APE and FB: LHSB after 8 hours of incubation shows that the solution is turbidity That indicates that the mixtures have poor compatibility and heat stability The mix of FB: SLES and FB: NPE was completely clear after 8 hours of incubation Therefore, the research team identified two surfactants: Sodium lauryl ether sulfate (SLES) and Nonylphenol ethoxylates (NPE) for the next study For alcohol-resistant foaming agents, it is extremely important to use

a combination of water-soluble, alcohol-insoluble, and fluorinated polymers Select partially fluorinated acrylic copolymer (PFAC) fluorinated polymer product - the ingredient that increases heat resistance, to conduct

research Investigating the change of surface tension according to the concentration of surfactants gives the results as shown in figure 3.6

Figure 3.6: The graph shows the surface tension of surfactants

according to concentration Hydrocarbon surfactants have higher surface tension than fluorinated surfactants, so in the construction of the dominant material system, the FB fluorinated surfactant is selected as the main ingredient

3.2.2 Determination of compatibility and heat resistance of mixtures of surfactants

From the results of evaluating the compatibility and heat stability of a mixture of 2, 3, and 4 surfactants, it is found that the system of 4 substances

is capable of reducing the surface tension of the system to a low value The changes in pH and surface tension after the annealing are not significantly changed, indicating that the system is thermally stable The ratio of FB : SLES : NPE : PFAC studied was 1 : 2 : 1 : 1

3.2.3 Optimizing of the surfactants system

The regressive equation corresponds to the emirical variables:

Figure 3.7: graph showing σ according to values of surfactant concentration

Figure 3.8: Contour lines represent the value of σ according

to the concentration of surfactants

The corresponding optimum concentration of surfactants is as follows::

FB = 111.21 ≈ 111 g/kg SLES = 226.8 ≈ 227 g/kg

NPE= 113.44 ≈ 113 g/kg PFAC = 105.78 ≈ 106 g/kg

The surface tension reached the smallest is σ = 17.56 mN/m

3.2.4 Research and selection of additives

Using the same additive composition as aqueous film-forming foam

applied to the research of alcohol-resistant foaming agent The results

showed that with the above optimal system and the concentration of

additives as 1.6% xanthan gum, 5% butyl diglycol, 3% glycerin, 2.5% urea,

1.2% HEC, the best heat resistance system

3.2.5 Study to investigate the mix order

Through experiments investigating the order of the assimilation of

partial surfactants, it was found that two fluorinated surfactants, FB and

PFAC, need to be assimilated first, then the SLES anion surfactant, and

finally the NPE nonion active surfactants