The phosphoric acid activated biochar adsorbent is recognized as a good candidate for application in efficient disposal of uranium-containing nuclear wastewaters. However, the production of high-efficiency biochars with typical characteristics of large specific surface area, hierarchically porous structure and abundant adsorption group remains a challenge. In this work, we report a new hydrogelation-carbonization technique to facilely produce phosphorus-doped biochar from pomelo peel and meantime provide new sights into the interaction mechanism of phosphoric acid groups with uranium ion. An i...