Performance of Fast and Slow Phosphorus Release from Nano-Bone Char

The study investigates the release of phosphorus (P) from nano-bone char (Nano-BC), which could be a potential P-soil fertilizer. The study evaluated the performance of P releasing from Nano-BC compared to the originated bone char (BC) which was prepared under pyrolysis temperature 650oC. BC and Nano-BC were characterized by elemental composition, X-ray diffraction (XRD), surface areas, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM), showing the physicochemical properties differences.The P-fast release was determined after 24 hours under different conditions (pH, ionic strength, and coexisting of anion species), while the P-slow release was after 21 days. The performance of P-fast release from Nano-BC was higher than from BC, acidic conditions were more suitable with the privilege for Nano-BC. Higher ionic strength gave the lowest P-releasing amounts for both materials (0.47 to 0.51 mg/g for BC and 0.61 to 0.62 mg/g for Nano-BC). The coexisting SO4= anion encouraged the rapid release of P from Nano- BC (8.65 mg/g) than those for Cl- and NO3 anions. For the slow release experiments, Nano-BC gave higher P- release than BC withpH ranging from 4.25 to 9.39 for Nano-BC and 4.75 to 9.75 for BC. The pseudo-second-order kinetic model was correlated quite to the release of ortho-P (R2 = 0.894, and 0.901 for BC, Nano-BC, respectively) and this indicated the chemical nature of the release process of ortho- P. The results could suggest the privilege of using Nano-BC as a soil P fertilizer.