Highly promising recycled low-density polyethylene sheet adsorbents for uranium recovery from seawater

Amidoximated absorbers based on recycled low-density polyethylene (LDPE) sheets (food packaging bags, breast milk storage bags and grocery bags) for uranium recovery from seawater were investigated. Simultaneous irradiation grafting by gamma ray was performed. A 40-µm thick LDPE sheet submerged in the acrylonitrile (AN): methacrylic acid (MAA) solution of 60: 40 v/v% with the optimal gamma ray dose of 40 kGy showed the highest cografting degree of 85.28% and the highest amidoxime group density of 4.38 mol/kg. The field study was performed along the coastal area of the Gulf of Thailand. After 56 days of soaking, the highest adsorption capacity reached 1.79 g-U/kg-adsorbent. The reusability study for up to 6 cycles revealed about 20% of the adsorption capacity remaining in the last cycle. The study demonstrated that recycled LDPE sheets can be utilized as a substrate to synthesize uranium absorbers. It showed an acceptable uranium loading with good reusability in natural seawater environment. This method of reusing discarded LDPE sheets also helps alleviate environmental issues of non-degradable plastic wastes. Novel synthesis of amidoximated seawater uranium absorbers using recycled LDPE sheets. Highest adsorption capacity of 1.79 g-U/kg-adsorbent after 56 days of soaking. This method helps alleviate environmental issues of non-degradable plastic wastes. (author)