Adsorption performance and mechanism of waste paper-derived phosphorus-rich carbon for separation of uranium from radioactive wastewater

Abstract

The use of household waste-derived materials for wastewater treatment has double environmental benefit due to the availability of simultaneous disposal of household waste and wastewater. In this work, we report the facile production of phosphorus-rich carbon from waste paper as a potential adsorbent for the disposal of uranium (VI)-containing nuclear wastewater. A simple phosphoric acid activation-carbonization strategy is developed to effectively transform waste paper into carbon. The phosphorus content of the obtained carbon reaches 8.55 at% and large pores with sizes ranging from 2 to 100 nm are observed. Batch and column adsorption experiments verify that waste paper-derived carbon can efficiently adsorb uranium (VI) from aqueous solution under weakly acidic conditions. The maximum amount of uranium adsorption on the carbon attains 492 mg g−1 at pH 4.6, and adsorption of uranium (VI) on the carbon quickly reaches the equilibrium within 20 minutes. The distribution coefficient of uranium (VI) on waste paper-derived carbon is as high as 128 L g−1. The carbon can be reused for five times with uranium (VI) adsorption efficiencies above 89% and can be used for dynamic adsorption of uranium (VI) in a fix-bed column. Kinetics, thermodynamics and DFT calculations reveal a surface complexation mechanism between uranium (VI) ion and ionized phosphoric acid group. Moreover, to avoid the generation of secondary polluted water during the treatment of uranium-containing nuclear wastewater, a water-saving method is developed for the adsorption preparation and a water-free combustion method is employed for the disposal of uranium-containing spent adsorbent instead of recycling. This study demonstrates the good application potential of household waste-derived materials in wastewater treatment and provides more clues for the amalgamation of multifold subjects.