First, the topic background:

Under the current problem of saving the earth, low carbon has become the theme of life. No matter work, study or life, no matter work, school or family, low carbon needs everyone to learn and practice. Environmental protection and low carbon is the most fundamental starting point of this topic. It has been found that 80% of the carbon dioxide emissions of polyester shirts are produced in the process of cleaning and drying. If the shirt is pure cotton, the ratio is even better. So, for the sake of environmental protection, please wash less clothes. For environmental protection, please choose washing powder carefully. Choosing the right washing powder can not only reduce the emission of carbon dioxide, but also save time, water and electricity, reduce the discharge of wastewater and be beneficial to health.

Washing powder is a common washing product in every family. At present, there are many kinds of washing powder on the market, and the prices are also different. When consumers buy washing powder, they are generally concerned about detergency. Therefore, various manufacturers advertise in advertisements, and all kinds of washing powder advertisements dazzle consumers and they don't know which one to choose. For example, "Bibo, a more cost-effective choice", "White cat, quickly dissolve dry and solid stains", "Jieba, go deep into fiber to remove stains, and decontaminate from the inside out" and "Tide, no stains" in the advertisement of washing powder ... Is the efficacy of washing powder really as good as advertised? In addition, most of the current washing powders are marked with the words "phosphorus-free" and "environmental protection". Is that so? In view of these two points, we compared the basic performance and decontamination ability of washing powder currently on the market, and explored whether it contains phosphorus and the determination of phosphorus content.

Second, the preparation and planning of the research.

Nine students, Yao Zhihui, Li Yaoxing, Peng Weishun, Jiang, Cheng Jingyi, Mai Yanting and Huang Sirong, chose this topic. They set up their own research group. In order to make the investigation and research orderly, the students held a preparatory meeting, initially established the research direction, and set out to draw up a specific research plan:

Team members: Yao Zhihui, Li Yaoxing, Peng Weishun, Jiang, Cheng Jingyi, Mai Yanting and Huang Sirong.

Division of tasks:

(1) Team leader: Yao Zhihui.

(2) Looking for information: members of the whole group.

(3) Investigation and interview: members of the whole group.

(4) Experimental operation: members of the whole group.

(5) Photography: Huang Sirong.

(6) Writing report: Yao Zhihui, Huang Zihong, Chen Wensen,

First, explore the decontamination ability of washing powder.

(a), activity query method:

Under the guidance of the teacher, we surf the Internet and read the materials, and determined the following research methods:

1. Go online or go to the library to inquire about the domestic manufacturers, brands, varieties, types and basic performance of washing powder.

2. Visit five supermarkets to learn about the varieties, types, prices and marketing information of washing powder, especially the brands that are common in advertisements and have a large market share.

3. Visit classmates, school teachers and nearby residents to understand the basic situation of using washing powder, sort the frequently used washing powder brands, and get the top 6 washing powder brands with market share.

Firstly, the domestic manufacturers, brands, varieties, models, basic performance and phosphorus-free of washing powder were inquired. Then we visited several shopping malls and learned about the market sales information of washing powder, and learned that the sales of washing powder such as Libai, Langqi, Tide and Secret were better. I visited nearly 30 residents and asked them about the basic situation of using washing powder. Some people choose to buy washing powder according to the price, while others choose to buy washing powder according to the selling points of brand advertisements. However, we sorted the brands of common washing powder and got the top six brands in market share, namely Libai washing powder, White Cat washing powder, Langqi washing powder, Jieba washing powder, Secret washing powder and Tide washing powder.

Table 1 General Household Washing Powder Brand Questionnaire (Reference Table)

No. Reasons for Respondents to Choose Common Washing Powder Brands

1 Zhou Hao Li Bai washing powder is cheap.

Jie Chen Ba washing powder has good decontamination ability.

3 Chen Wensen Libai Washing Powder Advertising Selling Point

Four selling points of Peng Weishun's mysterious washing powder advertisement

Jianyunqi Tide washing powder is cheap and has good decontamination ability.

6 Clock Kaixiang White Cat Washing Powder None

7 Huang Sirong Chao brand washing powder is cheap

8 Yuan Junfeng Langqi washing powder is cheap

9 Li Bilang washing powder advertising selling point

10 Huang Zihong Tide washing powder is cheap.

…… …… …… ……

4. Compare the basic properties of 10 kinds of washing powder.

Eight members of the research team were asked to bring a household washing powder and compare the basic performance of the top six washing powders according to their brands. Basic performance comparison items include:

Weight: measure the actual weight of washing powder and compare it with the weight marked on its package to determine whether there is a weight shortage.

Color: color reflects the composition quality and processing quality of washing powder to a certain extent. Washing powder should be white and cannot be mixed with yellow powder or black powder.

Particle size: Particle size refers to the index of particle size and uniformity (including fine powder) of washing powder. Particle size will affect the solubility of washing powder. Washing powder with uniform particles has the same dissolution speed, which is beneficial to the washing efficiency of washing powder.

PH value: Washing powder is generally weakly alkaline, and alkalinity has certain influence on washing effect. Generally speaking, the stronger the alkalinity, the higher the detergency, but at the same time, the damage to clothes will also increase.

We collected six kinds of washing powders used by students in our class, and compared their basic performances. First of all, we compare the six kinds of washing powder from the aspect of color, because the color can reflect the composition quality and processing quality of washing powder to a certain extent, and the washing powder should be white and cannot be mixed with yellow powder or black powder. Then we compare the particle sizes of six kinds of washing powder. Particle size is an index of particle size and uniformity of washing powder, and particle size will affect the solubility of washing powder. Washing powder with uniform particles has the same dissolution speed, which is beneficial to the washing efficiency of washing powder. Then, we pour 1 teaspoon of all kinds of washing powder into a beaker with the same amount of water at the same time, and slowly stir it for 50 times to observe the dissolution rate of six kinds of washing powder. Then, we measured the pH of six kinds of washing solutions, and the alkalinity had a certain influence on the washing effect. Generally speaking, the stronger the alkalinity, the better the detergency, but at the same time, the damage to clothes will also increase. After the washing powder in each washing liquid is completely dissolved, dip a small amount of washing liquid into the PH test paper with a glass rod, and compare the color displayed on each test paper with the standard colorimetric card. The basic properties of various washing powders are obtained. Upon completion, the following results are obtained:

(Dissolve and prepare washing powder)

Table 2 Comparison Table of Basic Properties of Various Washing Powder

Brand factory

Jiabiao

heavy

(gram) price

style

(meta) color

Zec

wheat

Generation of pH value (pH value)

Date shelf life

Mysterious Shanghai Unilever 1700 24.5 white is good, even 10 ○.

Libai Libai Group 1550 15.5 White is not detailed but unified.

Tide Unilever 1550 9.9m white, thin and even 10 ○.

Jieba Shanghai Kao 1800 25.5m White is not detailed but unified.

White Cat Shanghai White Cat Bai Jinglian10.

Langqi Guangzhou Langqi White is not detailed but unified 9000.

Mysterious washing powder Jieba washing powder Langqi washing powder

Libai Washing Powder Tide Washing Powder White Cat Washing Powder

2. Comparative test of detergency of six common washing powders

After that, the decontamination ability of these six washing powders was compared. Because the detergency of washing powder is an important index to measure the practicality of washing powder, it is also a problem that consumers are generally concerned about. Because it is impossible to evaluate the detergency subjectively, a comparative test is needed to verify the explanation.

First of all, we made the material of dirty cloth and imitated the common stains in daily life:

1, making dirty cloth material

Cloth material cotton gauze, cotton cloth

Method for make dyed cloth

Mix the dyed cloth, ink, cooking oil, soy sauce and cola, drop the dye on the cloth and dry it.

Coke will stain the cloth. Coke will drip coke on the cloth and then dry it.

Soy sauce stains the cloth, and soy sauce drips soy sauce on the cloth to dry.

Dye the cloth block with ink, drop ink on the cloth, and dry it.

Hot sauce stains the cloth, and hot sauce drips hot sauce on the cloth to dry.

Coke stains, hot sauce stains, blue ink stains, soy sauce stains

Experiment 1 comparison of detergency of various washing powders on dry cotton cloth in cold water

2. Experimental operation

First, we made a dry rag with cotton cloth and undiluted cola, soy sauce, ink, Chili sauce and cooking oil.

(2) Then, prepare various laundry detergents with cold water, put them into dry-burnt stained cloth, let them stand and soak for 2 minutes, and then rub the stained cloth by hand for 30 times. After comparison, it is concluded that all kinds of laundry detergents have good detergency to dry coke stains.

(3) After that, prepare all kinds of laundry detergent with cold water, put in dry edible oil stain cloth, let it stand and soak for 2 minutes, and then rub the stain cloth by hand for 30 times. After comparison, it is concluded that all kinds of laundry detergents have good detergency on dry edible oil stains.

(4) After that, prepare various laundry detergents with cold water, add dry soy sauce stains, let stand and soak for 2 minutes, and then rub the stained cloth by hand for 30 times each. After comparison, it is concluded that White Cat Laundry Liquid and Tide Laundry Liquid have better detergency to dry soy sauce stains, while Libai Laundry Liquid, Langqi Laundry Liquid and Jieba Laundry Liquid have average detergency to dry soy sauce stains, while the secret laundry liquid has poor detergency to dry soy sauce stains.

⑤ After that, prepare all kinds of laundry detergents with cold water, put dry ink stains into them respectively, and let them stand and soak for 2 minutes. Then, rub each stained cloth 30 times by hand. After comparison, it is concluded that Libai Laundry Liquid, Jieba Laundry Liquid and Tide Laundry Liquid have average detergency on dry ink stains, while the secret laundry liquid has poor detergency on dry ink stains.

⑥ Then prepare all kinds of laundry detergents with cold water, put the dyed cloth stained with dried Chili sauce into it, let it stand and soak for 2 minutes, and then rub the dyed cloth by hand for 30 times each. After comparison, it is concluded that Libai laundry detergent and Tide laundry detergent have good detergency on dried Chili sauce stains, while White Cat laundry detergent and Jieba laundry detergent have average detergency on dried Chili sauce stains, while secret laundry detergent and Langqi laundry detergent have poor detergency on dried Chili sauce stains.

3. Experimental results:

Table 3 Comparison of decontamination effects of cotton gauze

Weather: sunny room temperature: 24℃ water temperature: 18℃

Scrub the stained cloth with washing powder solution.

Sample pollution type

Mixed stains cola stains soy sauce stains ink stains hot sauce stains

Libai washing powder has dim spots, no spots, dim spots, dim spots and weak spots.

White cat washing powder has light stains, light stains, obvious stains and dim stains.

Langqi washing powder has dim stains on the same page, with obvious stains on it and obvious stains on it.

Jieba washing powder has a faint stain, just like before, a dim stain, a dim stain.

Tide washing powder has a faint stain, same as above, a faint stain, a faint stain.

Secret washing powder has obvious stains, same as above, obvious stains, obvious stains, obvious stains.

After summing up, it is concluded that Libai, Baimao and Tide washing powder have good decontamination ability on cotton gauze in cold water. However, Langqi, Jieba and Mimi washing powder have poor decontamination ability to cotton gauze in cold water.

Experiment 2 Comparison of detergency of various washing powders on dry stained cotton cloth in warm water at 40℃

1, experimental steps: (same as above)

2. Experimental results:

Table 4 (Fabric: Cotton Gauze)

Weather: sunny room temperature: 22℃ water temperature: 40℃

Sample pollution type

Mixed stains cola stains soy sauce stains ink stains hot sauce stains

Libai washing powder has dark stains, no stains, dark stains, dark stains and dark stains.

White cat washing powder has light stains, no stains, dim stains, obvious stains and dim stains.

Langqi washing powder has dim stains, no stains, dim stains, obvious stains, obvious stains.

Jieba washing powder has light stains, no stains, light stains, dim stains and dim stains.

Tide washing powder has light stains, no stains, light stains, dim stains and dim stains.

Secret washing powder has dim stains, no stains, dim stains, obvious stains, obvious stains.

It is concluded that Libai, Jieba and Tide washing powder have good decontamination ability on cotton gauze in warm water. However, Langqi, White Cat and secret washing powder have poor decontamination ability to cotton gauze in warm water.

Experiment 3 Comparison of detergency of various washing powders on dry cotton cloth in cold water

1, experimental steps: (same as above)

Scrub dyed cloth

2. Experimental results:

Table 5 (Fabric: Cotton Fabric)

Weather: sunny room temperature: 23℃ water temperature: 17℃

Sample pollution type

Mixed stains cola stains soy sauce stains ink stains hot sauce stains

Libai washing powder has dark marks, no stains, dark stains, dark stains and dark stains.

White cat washing powder has light stains, no stains, light stains, dim stains, dim stains.

Langqi washing powder has dark marks, no stains, dark stains, obvious stains, obvious stains.

Jieba washing powder has dark marks, no stains, dark stains, dark stains and dark stains.

Tide washing powder has light stains, no stains, light stains, dim stains and dim stains.

Secret washing powder has obvious stains, no stains, obvious stains, obvious stains, obvious stains.

After summing up, it is concluded that Libai, Jieba, Baimao and Tide washing powder have good decontamination ability for cotton clothes in cold water. However, Langqi and Mimi washing powder have poor decontamination ability to cotton clothes and fabrics in cold water.

Record the data of dissolved washing powder

According to the results of repeated experimental research, clothes can be decontaminated as long as they are stained with various washing powders. However, when clothes are washed with cold water to dry stains, the detergency of various washing powders will be different. Finally, it is concluded that Tide washing powder has better real detergency, which is consistent with the advertisement, and its price is among all kinds of washing powders. However, the real decontamination ability of secret washing powder is poor, which is inconsistent with its advertising description, and the price is higher than that of ordinary washing powder.

Three. Detection and content determination of phosphorus in washing powder

At present, most washing powder packages are marked with the words "phosphorus-free". In order to confirm whether the washing powder contains phosphorus or not, we consulted a lot of materials under the guidance of the teacher and chose the detection and content determination methods.

The data show that washing powder contains many raw materials: surfactant, bleaching agent, anti-redeposition agent, fluorescent whitening agent, essence and so on. Among various components, phosphorus-containing component is the chief culprit of water eutrophication. After phosphorus-containing wastewater is injected into rivers, lakes and seas, it will cause abnormal reproduction of cyanobacteria and green algae, slow down the water flow, make the water turbid, and lead to the death of aquatic organisms and the deterioration of drinking water sources. At present, 30-40% of the world's water bodies are in different degrees of eutrophication. If people drink phosphorus-containing water, its residual poison will accumulate in the human body for a long time, which will seriously affect people's health to some extent. Therefore, it is necessary to detect the phosphorus content in washing powder by chemical method. We found the following methods for qualitative and quantitative determination of phosphorus:

1. Qualitative determination of sodium tripolyphosphate in washing powder.

Through our online investigation, we know that a phosphorus component used in washing powder is sodium tripolyphosphate (Na5P3O 10), and its main function is to chemically react with stains on clothes, thus generating stain suspension for laundry. The suspension is spherical, columnar or flaky, which can be carefully observed with a magnifying glass. In order to preliminarily determine whether various brands contain phosphorus. We conducted the following experiments:

(1). First, we weigh 2g of various washing powders and dissolve them in 250ml distilled water. Dissolve.

(2) Pour a spoonful of pure milk into each washing powder solution, stir and fuse, and the solution will appear suspended matter after standing.

The results of three repeated experiments are as follows:

cleanser

Mystery of suspended matter

Washing powder tide

Washing powder jieba

Washing powder langqi

Washing powder white cat

Washing powder is white.

cleanser

The amount of suspended solids in milk is large, small, small, small, small, small.

The content of suspended solids in edible oil is very big, big, big, big, big.

Suspended matter after mixing wet washing powder solution with edible oil

6 The order of mixed samples of washing powder and milk is as follows:

Li Bai, the white cat of Langqi, was relieved by the mysterious tide.

The mixed samples of washing powder solution and edible oil in 6 are, from left to right:

Li Bai, the white cat of Langqi, was relieved by the mysterious tide.

Mysterious washing powder, Tide washing powder and Jieba washing powder have more suspended substances. However, the suspended solids in Langqi washing powder, White Cat washing powder and Libai washing powder solution are less. Through this experiment, we speculate that all kinds of washing powder contain phosphorus, which is not consistent with phosphorus-free packaging, but the content is different.

2. Quantitative determination of sodium tripolyphosphate in washing powder:

(1), experimental principle:

The principle of volumetric determination of sodium tripolyphosphate in washing powder is that sodium tripolyphosphate is decomposed into orthophosphoric acid in acidic medium, and the PH value of the solution is adjusted to 3 ~ 4. At this time, orthophosphoric acid is stored in the solution in the form of dihydrogen phosphate. Then titrate the PH value of the solution to 8 ~ 10 with alkaline standard solution to convert dihydrogen phosphate into monohydrogen phosphate. The content of sodium tripolyphosphate in washing powder can be determined indirectly by titration.

The reaction equation is as follows:

na5p 3 o 10+5 HNO 3+2H2O = 5 nano 3+3 h3po 4

H3PO4+NaOH=NaH2PO4+H2O

NaH2PO4+NaOH=Na2HPO4+H2O

(2) Experimental steps:

① Prepare 0.5mol/L sodium hydroxide standard solution. Weigh 5g NaOH solid with an electronic balance, add water to dissolve it, and adjust the volume to 250mL.

(2) Weigh 2g of all kinds of washing powder in a 250mL iodine volumetric flask with an electronic balance. Add 50mLH2O, 250 ml 1: 10 HNO3, shake well, and then add some zeolite.

(3) Heat and boil the iodine flask of the asbestos net on the tripod for 20 minutes, then take it off and cool it to room temperature.

④ Add 3 drops of 0. 1% methyl orange reagent, and the solution turns red. Then add saturated NaOH solution drop by drop, and continue to shake until it is light yellow. Then carefully adjust it to light pink with 0.5mol/L HCl solution. Add 3 drops of phenolphthalein indicator into the iodine volumetric flask, and finally drop it to light pink with 0.5mol/LNaOH standard solution, and record the volume V of NaOH solution consumed.

na5p 3 o 10 = cv×368/(3× 1000)/m× 1000%

C-mass concentration of NaOH solution.

V—— the number of milliliters of standard sodium hydroxide solution consumed.

M- sample quality

Changes of solution before and after titration

(The result of three repetitions)

Sample m V Na5P3O 10% average Na5P3O 10%.

Secret washing powder1.2g1.1ml 33.73% 35.77%

2g12ml 36.80%

3 2g 12ml 36.80%

Jieba washing powder1.2g17m152.13% 48.04%

2g15ml 46.00%

3g15ml 46.00%

White cat washing powder1.2g7ml21.47% 22.67%

2 g 6 ml 18.40%

3 g 8 ml 24.53%

Tide washing powder1.2g7ml21.47% 20.44%

2g 5ml 15.33%

3 g 8 ml 24.53%

Libai washing powder1.2g3ml 9.20%12.27%

2g 5ml 15.33%

3 g 4 ml 12.27%

Langqi washing powder 1.2G8ml 24.53% 25.53%

2g, 8ml, 24.53%

3 g 9 ml 27.6%

The experimental results show that all the washing powder samples we sampled contain sodium tripolyphosphate, among which Jieba washing powder contains more phosphorus, while Libai washing powder contains the least phosphorus. The experimental results are basically consistent with our previous qualitative measurement results.

Thinking:

Sodium tripolyphosphate has the functions of removing calcium and magnesium ions from water, buffering, preventing dirt from reattaching, and improving the wettability and emulsification of detergent. At the same time, sodium tripolyphosphate has low toxicity and is easily decomposed into phosphate in sewage, which is the nutrient component of most organisms. In addition, it is cheap, easy to recycle and can be reused after recycling. Other substitutes such as zeolite are cheap. However, the removal efficiency of hard water ions is only 70% of that of sodium tripolyphosphate, and it has no ability to resist scaling and redeposition. If zeolite is compounded with more expensive additives, the cost of manufacturing detergent will not have any advantage. In addition, the content of organic surfactant, binder and dispersant in phosphorus-free detergent increases, which often leads to the increase of cost, resulting in a large number of organic substances discharged into the environment, which is very harmful to the environment. Therefore, from the comprehensive performance and price point of view, other substitutes can not be compared with sodium tripolyphosphate at present.

There are two ways to reduce the discharge of phosphorus into the environment: sewage treatment and controlling phosphorus pollution sources. The data show that the water quality in some countries where phosphorus is restricted and banned has not been improved. For example, in Japan, 1984 phosphorus-free washing powder accounts for 84%, and now it is basically phosphorus-free. However, the measurement results of phosphorus in its largest lake show that it is similar to that before phosphorus was banned in the late 1970s. On the contrary, some countries that have not banned phosphorus, such as the Netherlands and Sweden, have strengthened environmental protection and adopted tertiary treatment of sewage to maintain good water quality. Therefore, banning and limiting phosphorus is not the best way. By reforming detergent composition, changing agricultural production mode, adopting advanced wastewater treatment technology (such as phosphorus removal by precipitation) and using biological control technology, the discharge of phosphorus into the environment can be reduced.

Activity feeling: Through this exploration of washing powder, we uncovered the true essence of various washing powders in advertisements, solved the doubts about washing powder in everyone's hearts, and publicized our exploration results among students, so that everyone can have a clearer judgment when choosing washing powder in the future.

References: Zheng Jinding and Liu Volumetric Method for Rapid Determination of the Content J of Triphosphate in Washing Powder. Daily chemical industry, 199 1 (5): 38 ~ 39