Integrating lewis acid/base pairs and hydroxyfunctional groups into porous biochar fiber for enhanced iodine adsorption

Nuclear energy, though clean and efficient, poses environmental challenges, especially with the treatment of contaminated water containing dangerous radioactive substances like iodine. The adsorption method is considered a simple and effective method for treating radioactive waste. This study synthesized boron-carbon-nitrogen (B-C-N) co-doped porous biochar fiber using three low-cost and green raw materials: boric acid, NaHCO3, and casein, for efficient and selective adsorption of iodine. The active sites of porous biochar fiber are the lewis acid/base pairs (B-N) and hydroxyfunctional (C-OH) groups for enhanced iodine (I2) adsorption. Furthermore, the experimental data exhibits a stronger correlation with the pseudo-first-order model, suggesting that physisorption is the primary mechanism governing the adsorption of iodine onto the adsorbent. Moreover, the Freundlich isotherm is highly appropriate for characterizing iodine adsorption on biochar, owing to the abundance of adsorption sites within its porous structure, particularly at the Lewis acid/base pairs and C-OH groups, which markedly enhance the adsorption capacity. Overall, these findings emphasize the potential of B-C-N co-doped ultra-thin porous fiber biochar in effectively reducing the presence of radioactive iodine (I2) and demonstrate its prospects in addressing environmental challenges related to radioactive pollution.