Adsorption Of Phosphorus From Biomass And Release Of Endogenous Phosphorus Under Different Environmental Conditions

Phosphorus is the key element of eutrophication, when its concentration in water excess a level, the eutrophication would happened in water body, as a matter of fact, the water was polluted, and ultimately affect the development of economy and society. Therefore, to remove phosphate has great difference.In this study, rice straw were used as raw materials to prepare biochar by pyrolysis. Phosphorus removal from aqueous via adsorption by biochar and modified biochar and endogenous phosphorus release from biochar under different environmental conditions were investigated, so as to find a new way for phosphorus wastewater treating and recycling utilization of crop straw. The main research results are as follows:(1) The characteristics of the adsorption of phosphorus by biochar was studied in phosphorus solution, and results are as follows: The experimental data of the adsorption process of phosphorus fits the pseudo first-order kinetics model. Combined with the result of intra-particle diffusion shows that the speed of phosphorus adsorption onto RC500 mainly controlled by surface adsorption and intra-particle adsorption. The experimental data of adsorption process of phosphorus fits Langmuir and Freundlich isotherm equations. Through Langmuir, the theoretical monolayer saturation capacity for P is 8649.8749mg/kg. p H has a significant influence on adsorption of phosphorus onto RC500. When the p H value less than 5, the adsorption quantity increased with the increase of p H; and when p H value exceed 5, the adsorption quantity decreased with the increase of p H. Among coexistence anions, Cl- has a little effect on phosphorus adsorption, but NO3- and SO42- results the adsorption quantity reduced.(2) The characteristic of the adsorption of phosphorus by Fe-RC500 was studied in phosphorus solution, and results are as follows: The experimental data of the adsorption process of phosphorus fits the pseudo second-order kinetics model. Analysis of combined with the result of intra-particle diffusion shows that the speed of phosphorus adsorption onto Fe-RC500 mainly controlled by surface adsorption and intra-particle adsorption. The experimental data of adsorption process of phosphorus fits Langmuir isotherm equations. Through Langmuir, the theoretical monolayer saturation capacity for P is 36860.5821mg/kg and 22497.7235 mg/kg. p H has a significant influence on adsorption of phosphorus onto RC500. When the p H value less than 9, the adsorption quantity increased with the increase of p H; and when p H value between 9 and 11, the adsorption quantity decreased with the increase of p H. Coexistence anions affects the adsorption quantity of phosphorus onto Fe-RC500 slightly.(3) The release characteristic of the endogenous phosphorus was studied, and the result shows as follows: The release of endogenous phosphorus fits the pseudo first-order kinetics model, and the correlation coefficient R2 is 0.9360. p H value have significant effects on the release of endogenous phosphorus. Among coexistence anions, Cl- affects the release quantity slightly, however when NO3- and SO42- exists, biochar endogenous phosphorus release quantity increased obviously.