Polyurethane foam helps recycling of pesticides and waste oil

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In the treatment of the three wastes, polyurethane foam is currently mainly used in the recovery of pesticides and waste oil. It can be made into oil-absorbing material to absorb waste oil and recycle it.

If polyurethane foam is used as a material for absorbing heavy oil, the foam is firstly soaked in a solution of 100 parts of acrylonitrile, butadiene copolymer, 150 parts of CaC03, and 100 parts of water, and then rolled and dried. Put the treated foam into heavy oil, after 8s, the oil absorption is 19.19/g; if it is absorbed by cloth, it is only 9.59/g. Using lipophilic flexible polyurethane foam to recycle waste oil on the sea surface, the recovery rate can reach 90%. The method of use is mop type, which is to make the lipophilic foam into various mop shapes, and hang it on both sides and the stern of the oil suction boat; there is also a transmission belt type, which is to make the lipophilic foam into a similar transmission belt, and install it on the oil suction boat, one end of the transmission belt Stretching out to the surface of the sea, when the ship is driving, the foam is dragged across the sea, thereby absorbing the waste oil, and then the foam that has absorbed the oil is squeezed, the waste oil is recycled, and the foam is reused. Belt-type foams are generally continuous oil-absorbing-squeezing. At the same time, the size of the foam cells can be used, and the oil to be absorbed can also be selectively absorbed. The large pores absorb heavy oil, and the small pores absorb light oil. It can also be squeezed and recycled separately during extrusion, which is very convenient. With good effect, every kilogram of polyester lipophilic polyurethane foam can absorb 53kg of oil.

Oily sewage can absorb oil through the treatment of polyurethane foam, and the absorption capacity can be 20 times the weight of the foam, and then compress the foam to recover the oil. If the polyurethane foam is treated with a hydrophobic and lipophilic agent, the oil can be separated from the oily water. Natural rubber hexane solution is a good hydrophobic and lipophilic agent. Soak polyurethane foam in 4% natural rubber hexane solution for 3 hours, dry it at 93°C, and then compress it to 7% of its original volume. 6g of this foam can absorb 8g of water and 222g of oil.

Polyurethane foam can be made into various selective adsorbents to absorb toxic substances in wastewater. For example, polyurethane foam with ≥100 cells/cm3 made of more than 0.5% surfactant, with more than 90% open cells, can be used as petroleum ether, benzene, xylene, chloroform, carbon tetrachloride, carbon disulfide, etc. adsorption material. A reticular polyurethane foam can selectively absorb phenols from petroleum fractions (with other chemical solutions), which can not only separate and recover phenols, but also remove phenols discharged into rivers or other waste water, so as to reduce pollution . Polyether polyurethane foam was used to remove phenol in heptane (C7H16) solution, and the result was that 50% to 80% of phenol could be removed. If vegetable activated carbon was used, only 45% could be removed. White clay and porous alumina are ineffective.

Polyurethane foam can also be used for the treatment of pesticide sewage, and can recover pesticides from industrial or agricultural sewage. For example, the recovery rate of DDT compounds can reach more than 90%. The particles or powder of polyurethane foam can also be used as bioflotation agent for wastewater treatment. The resulting polyurethane foam can be used for mercury spill removal by mixing polyurethane prepolymer with sulfur.