Teflon feed preparation

Several liters of the wastewater to be used as feed to the columns were spiked with 238pu to a concentration of about 4 pCi/L. The pH was re-adjusted to the original 8.3 using dilute NaOH. This solution was pumped with an Eldex Model E-120-S precision metering pump through a 1.0 pm pore size Teflon Millipore filter and then to the bottom of a column prepared as in the previous paragraph. The effluent from the top of the column was collected in plastic tubes with an HBI Model LC 200 fraction collector. Each tube collected one pore volume of effluent. Six flow rates were used to determine the rates of adsorption 0.5, 1, 2, 3, 4, and 5 ml/min. At least five consecutive pore volumes were collected for each flow rate to ensure steady state concentrations of plutonium in the effluent. The effluent concentration, C, was compared with the influent concentration, Co. 

The urethane-doped POC bioelastomers were prepared as follows in the first step, citric acid and 1,8-octanediol were bulk polymerized at 140 °C at the molar ratio of 1 1.1 for achieving POC prepolymers in the second step, the POC prepolymers were dissolved in 1,4-dioxane to form a 3% (wt/wt) solution, and reacted with HDI with stannous octoate as catalyst (0.1%wt) at 55 °C for preparing urethane-doped POC prepolymers at different feeding ratios of 1 0.6, 1 0.9 and 1 1.2 (POC prepolymer/HDI) in the third step, the urethane-doped POC prepolymers were cast into a Teflon mould and allowed to dry with a laminar airflow until all the solvents were evaporated, and then were further maintained in an oven at 80 °C to obtain the cured urethane-doped POC bioelastomers. Tg of the bioelastomers ranged from 0.64 to 5.20 °C. The urethane-doped POC bioelastomers with higher isocyanate content exhibited faster degradation rates, and their mass losses were lower than 16% after 2 months in phosphate buffer solutions. 

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