Summary Recovery of uranium from concentrated brine rejection from a small seawater reverse osmosis plant in Thailand using four types of the amidoxime adsorbents was experimentally performed. Adsorbents were directly submerged in continuously flowing discharged brine concentrate. Studied adsorbents were amidoximated polymer gel prepared from gamma irradiation, amidoximated polymer gel prepared from UV radiation curing, amidoximated polyacrylonitrile fibers, and chromic‐acid‐treated low‐density polyethylene fibers grafted with amidoxime functional group using gamma radiation. Uranium concentration in brine concentrate and input seawater was analyzed to be 4.8 and 3.1 ppb, respectively. Gel adsorbent synthesized by gamma irradiation exhibited the highest uranium loading capacity of 1.39 mg/g‐ad with 20 000 L/h rejected brine flow‐rate after 6 weeks of soaking. The estimated uranium recovery cost is 406.81 USD/kg uranium. If the adsorption capacity was increased to 2 mg/g‐ad, the projected cost was reduced to 338.95 USD/kg. Under this land‐based recovery scheme, no work is performed in an open ocean environment, thus, ensuring safety and reducing cost and time, especially the costs associated with ships, personnel, and diesel fuel to bring the materials to the ocean and back to the shore. The present study demonstrates that direct uranium recovery from discharged brine concentrate is possible using amidoxime‐based adsorbents developed to study uranium extraction from natural seawater. This should pave the way for further experimental studies in larger seawater reverse osmosis (SWRO) plants for the possible future energy source. A proposed large‐scale, yet very simple, deployment strategy at a hypothetical SWRO plant is also presented. Novelty statement Successful uranium adsorption by directly submerging adsorbents in continuously flowing discharged brine concentrate from seawater reverse osmosis plant Mooring and recovery costs largely eliminated because of land‐based deployment Highest uranium uptake capacity of 1.39 mg/g adsorbent after 6 weeks of soaking

Controlled Release Urea Fertilizers-based hydrogels matrices was synthesized by graft copolymerization of acrylamide onto the rice straw cellulose backbones in the presence of silica fillers using simultaneous graft copolymerization by gamma irradiation as initiator. Evidence of the silica presence on grafted cellulose was obtained from FTIR. X-ray diffraction analysis showed that the crystalline was reduced through silica fillers added. The effect of silica content on grafting efficiency, gel fraction, Young modulus, swelling degree, and urea loading were examined. It was found that grafting efficiency and gel fraction decrease with increasing silica added inversely with Young modulus. Water swelling and loading urea fertilizers into hydrogels matrices were conducted and the results showed that swelling degree and urea fertilizers loading increased first and then decreased with increasing silica added. The effect of the silica fillers had implications in the mechanism of controlled release urea fertilizers that diffusion-controlled mechanism became dominant, which attributed to the decreasing of urea diffusion coefficient.

Recycling process of waste cotton fabrics into value added products is still limited. Cotton fabrics are made of cotton fiber, which is a high cellulose source and it can be converted into microcrystalline cellulose (MCC). In this research, MCC was prepared by dissociation of waste cotton fabric using gamma irradiation with various radiation doses in dried phase and in wet phase by 35 % H2O2 solution. The properties of the prepared MCC were investigated and compared with standard Avicel PH101 MCC. The results from FTIR spectra and X-ray diffraction patterns show that the obtained MCC has typical similarity to commercial MCC. X-ray diffraction analysis showed that the crystallinity percentage (%Cr) was increased while crystallite size was decreased through gamma irradiation. At the same dose, degree of polymerization (DP) and solubility in water in dried phase, i.e. 135; 5.46 % were higher than wet phase irradiation i.e. 123; 4.38 %. Degree of polymerization and solubility in water decreases with increasing total irradiation dose. The investigated physicochemical properties of the obtained MCC conform to the European Pharmacopoeia requirements. The results indicated that waste cotton fabrics have a great potential as a low cost MCC raw material and can lead to many applications.

Polyethylene terephthalate (PETE) fibers are used as a reinforcing agent to enhance concrete strength as well as to shield against thermal neutrons. This study increased the stability of PETE fibers in a strong alkali solution characteristic of concrete (pH = 12) using low-dose gamma radiation to induce crosslinking of the polymer chains. Results indicated that gamma ray dose of only 30 kGy resulted in the highest molecular weight, tensile strength and degree of crystallinity of PETE fibers with size 1.3 D. The surface topology using SEM micrography were also evaluated. An accelerated age testing revealed that these radiation-treated fibers will maintain their mechanical strength in concrete for up to at least 60 months. Thermal neutron attenuation test of fiber-reinforced concrete (FRC) indicated that the degree of thermal neutron shielding increased with increasing PETE fiber content, and that at 0.3% fiber content, FRC exhibited the highest thermal neutron attenuation of about 60% compared to unreinforced concrete. Therefore, these FRCs can readily be utilized as an effective neutron shielding material for nuclear and radiation applications to enhance radiation safety.

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