[Characteristics of Phosphorus Adsorption in Aqueous Solution by Si-modified Peanut Shell Biochar]

In this work, a novel sodium silicate-modified peanut shell biochar(Si-PSB) was synthesized and used as phosphorus adsorbents. Compared with unmodified biochar(PSB), the adsorption capacity of Si-PSBs increased significantly. The adsorption capacity of 8% sodium silicate solution modified biochar(8%Si-PSB) was 3.9 times higher than that of PSB. The biochar was characterized using scanning electron microscopy(SEM), Fourier transformed infrared(FTIR), and X-ray diffraction(XRD), which confirmed that silica was present on the surface of 8%Si-PSB. The introduction of silica improved the reaction activity of biochar's own metal ions by affecting the morphology of calcium carbonate. The 8%Si-PSB had a good adsorption effect on phosphorus in both acid and alkali environments. Phosphorus adsorption by 8%Si-PSB and PSB was described well by the pseudo-second-order model, and the adsorption capacity after equilibrium fluctuated between 2.79 mg·g^-1 and 0.71 mg·g^-1, respectively. Further, the isothermal adsorption experimental data fitted well to the Langmuir model. The presence of humic acid in the solution inhibited the adsorption of phosphorus by the 8%Si-PSB and PSB. The 8%Si-PSB, as a new low-cost phosphorus removal material, can improve the utilization of metal ions in peanut shell itself.