[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 and 0.71 mg·g, 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.