The removal of uranium using novel temperature sensitive urea-formaldehyde resin: adsorption and fast regeneration

A novel adsorbent of temperature sensitive urea-formaldehyde (TS-UF) resin was synthesized by base/acid two-step synthetic strategy with low formaldehyde/urea mole ratio of 0.8. The sorption kinetics of TS-UF resin obeys the pseudo-second-order model, and the adsorption is an endothermic process. The Langmuir model can well describe the sorption isotherms, through which the Q_max is calculated to be 99.2 mg/g for uranium (VI) at pH 6.0 and T = 298 K. The characterized results show that the functional groups -NH- and -CH₂OH in TS-UF resin have been involved in uranium sorption via chemical interaction. The temperature sensitive property of TS-UF resin significantly accelerates the regeneration of TS-UF resin, which can be fast regenerated within 15 min at its low critical solution temperature 333 K and exhibits high removal efficiency of uranium (VI) (>90%) over 5 cycles. Therefore, TS-UF resin can be as a promising sorbent for the uranium (VI) removal from wastewater due to its low-cost, easy-fabrication, high-efficiency and fast regeneration. This work can not only boost the exploration of novel adsorbent materials, but also promote the investigations of the regeneration and reusability of adsorbents.