The role of dibutyl phthalate_Kain Industrial Additive

Background and overview^[1][2]

Since the industrialization of polyvinyl chloride in the mid-20th century, the production of phthalic acid compounds as the main plasticizer has developed rapidly, and the current global output is more than 20 million tons. Due to its large amount of addition and no chemical connection with resin, it has been widely entered into the environment along with plastic product waste. What needs to be pointed out in particular is that since the early 1960s, my country’s agricultural production began to use plastic films in large quantities. By the end of the 1970s, the use of agricultural films in my country had reached the highest level in the world in both quantity and area.

The extensive use of agricultural film has led to a large accumulation of residual film in the soil, which together with urban waste and sewage constitute a source of plasticizer pollution entering the farm ecosystem. In the past, people have always thought that dibutyl phthalate compound is safe and non-toxic, but recent research shows that it can cause apoptosis of rat spermatogenic cells, cause endocrine, immune, and nervous system abnormalities, and has embryotoxicity. It is a hormone-like endocrine interfering compounds. Both the United States and my country’s environmental testing stations have listed dibutyl phthalate as a priority organic pollutant to be controlled in the environment.

Dibutyl phthalate (DBP) is an excellent plasticizer. Due to its relatively low price and good processability, it is widely used at home and abroad. Dibutyl phthalate has good solubility for a variety of resins and has the characteristics of light color, good electrical properties, low volatility, low odor and low temperature resistance. Dibutyl phthalate is an ideal plasticizer for nitrocellulose, cellulose acetate, polyvinyl chloride, etc. It has good softening effect and excellent stability, adhesion, flex resistance and waterproofness. In addition, dibutyl phthalate is also used in the manufacture of chemical products such as paints, adhesives, artificial fibers, printing inks, safety glass, dyes, pesticides, perfume solvents and fabric lubricants.

However, dibutyl phthalate can cause functional changes in the central nervous system and peripheral nervous system, and then further cause changes in their tissues; it has hepatotropism, can cause mild sensitization, and has moderate accumulation. It has mild stimulating effect and is a suspected endocrine disruptor. At present, many countries such as the United States and the European Union have explicitly banned or restricted the use of dibutyl phthalate. my country also encourages the use of other chemicals to replace the toxic and harmful dibutyl phthalate in daily chemical products.

Dibutyl phthalate

Preparation ^[2]

Extraction of dibutyl phthalate from marine coccolithophore

Step 1. Prepare the ethyl acetate phase extract of marine coccolithophore: first extract with ethanol solution to obtain ethanol extract, then perform extraction treatment with ethyl acetate as the extractant, combine the extracts, and concentrate under reduced pressure to obtain Marine coccolithophore ethyl acetate phase extract;

Grow the marine coccolithophore to a stable phase, harvest, and freeze-dry to obtain 19.3740g of marine coccolithophore algae powder. Extract with 75% ethanol to obtain 5.1247g of ethanol extract. Add an equal volume of ethyl acetate and water, repeatedly extracted, collected the ethyl acetate phase, combined, and concentrated to dryness under reduced pressure to obtain 4.2357g of the ethyl acetate phase extract of marine coccolithophore;

Step 2. Preparation of primary crude dibutyl phthalate by reversed-phase silica gel column chromatography: chromatograph the obtained ethyl acetate phase extract of marine coccolithophore on a reversed-phase silica gel column, collect, detect, combine, Concentrate to dryness under reduced pressure to obtain a crude product of dibutyl phthalate;

After dissolving 4.2357g of marine coccolithophore ethyl acetate phase extract with an appropriate amount of analytically pure methanol, perform reverse-phase silica gel (180g) column chromatography; sequentially use water, a mass fraction of 25% methanol solution, and a mass fraction of It is a 50% methanol solution, with a mass fraction of 75% methanol solution, methanol elution, each gradient elution is 1.5L, the flow rate is controlled to 30mL/min, collect 1 tube for every 200mL, spin evaporate, and preliminarily analyze the effluent with TLC , combine the palmitic acid high-concentration flow segments, and concentrate to dryness under reduced pressure to obtain a crude product of dibutyl phthalate;

Step 3: Preparation of the secondary crude dibutyl phthalate product by chromatography on Sephadex LH-20 Sephadex gel column: The primary crude dibutyl phthalate product is chromatographed on Sephadex LH-20 Sephadex gel column. Collect, detect, combine, and concentrate to dryness under reduced pressure to obtain the secondary crude product of dibutyl phthalate;

After dissolving the crude product of the ethyl acetate phase extract of marine coccolithophore with an appropriate amount of methanol, put it on a SephadexL columnH-20, use methanol as the eluent for elution, control the flow rate to 12-13S/drop, use an automatic collector to collect each fraction, collect one tube every 30 minutes, initially analyze the effluent with TLC, and combine the fractions from 80 to 90 tubes , concentrated to dryness under reduced pressure to obtain the secondary crude product of dibutyl phthalate;

Step 4. Preparation of the primary product of dibutyl phthalate by reversed-phase silica gel column chromatography: perform chromatography on the obtained secondary crude product of dibutyl phthalate using a reversed-phase silica gel column, collect, detect, combine, and reduce pressure Concentrate to dryness to obtain a fine product of dibutyl phthalate;

The secondary crude product of dibutyl phthalate was eluted with a methanol water gradient with a mass fraction of 30%, 40%, 50%, 60%, and 70%, and finally was eluted with methanol for reversed-phase silica gel column layer Analysis, each gradient elutes 300mL, the flow rate is controlled to 5mL/min, rotary evaporation, preliminary analysis of the effluent with TLC, combine the dibutyl phthalate high concentration flow segments, and concentrate to dryness under reduced pressure to obtain dibutyl phthalate A fine product;

Step 5. Preparation of the secondary fine product of dibutyl phthalate by normal phase silica gel column chromatography: perform chromatography on the obtained primary fine product of dibutyl phthalate using a normal phase silica gel column, collect, detect, combine, and reduce pressure Concentrate to dryness to obtain the secondary fine product of dibutyl phthalate;

Put the primary product of dibutyl phthalate through normal phase silica gel column chromatography, mix the sample with silica gel powder, saturate the silica gel with petroleum ether and load it into the column. After the sample is loaded on the column, use petroleum ether and acetone system to elute. Petroleum ether The volume ratio to acetone is 200:1. Collect the fractions and concentrate to dryness under reduced pressure to obtain the secondary fine product of dibutyl phthalate;

Step 6. Preparation of pure dibutyl phthalate by PTLC: Perform PTLC on the obtained secondary fine product of dibutyl phthalate, spotting, unfolding, scraping, sample recovery, and storing at -20°C to obtain phthalic acid Pure dibutyl ester;

Put the secondary fine product of dibutyl phthalate through PTLC to finally obtain dibutyl phthalate: use a high-efficiency thin layer chromatography plate, in a developing solvent with a volume ratio of: petroleum ether: ethyl acetate = 80:1 Expand, develop color at the front and rear ends, scrape the middle part with a razor blade, combine, dissolve with methanol, centrifuge at high speed, collect the supernatant, concentrate to dryness under reduced pressure, and finally obtain dibutyl phthalate.

Wastewater treatment

Step 1. Add alkali solution to the organic wastewater containing high concentration dibutyl phthalate to adjust its pH to alkaline. After stirring for a period of time, let it stand and separate into layers. The upper layer contains high concentration dibutyl phthalate. The oil phase of butyl ester, the lower layer is an aqueous phase solution containing dibutyl phthalate and other organic substances;

Step 2, recycling the upper oil phase;

Step 3. The lower aqueous phase solution is subjected to hydrogen peroxide (H2O2, or hydrogen peroxide)-wet oxidation treatment: first use acid to adjust the pH of the lower aqueous phase solution to 3 to 4, then add hydrogen peroxide, and wait for a certain period of time. React under temperature and pressure for 1 to 1.5 hours. After the reaction is completed, use alkali to adjust the pH of the reaction residue to 7 to 9 and discharge it harmlessly.

Main reference materials

[1] Cheng Guisun, & Liu Xiaoyang. (1986). Microbial degradation of plasticizer dibutyl phthalate. Environmental Science (6), 27-29.

[2] Tu Jianfeng, Deng Lin, Wu Feng, & Deng Nansheng. (2005). Photodegradation of dibutyl phthalate in iron (Ⅲ)-oxalate complex system. Water Treatment Technology, 31(3 ), 39-42.

[3] Zhang Qianlong. (2007). Effects of dibutyl phthalate on lifespan, SOD and MDA of Drosophila melanogaster. 2007 Shanghai International Symposium on Public Health.