| Nitrogen and phosphorus removal is important to prevent eutrophication, the traditional methods are physical methods, chemical methods and biological methods. Although biological methods is low-cost, the operational stability is poor and affected by external environment greatly. The adsorption method has the advantages of high efficiency, fast, simple operation, no second-pollution. while because nitrogen and phosphorus resources can be recycled, it is being widely attention around the world.In the thesis research, low-cost and easy-get bamboo charcoal were soaked with Mg Cl2,Fe Cl3 as well as the two mixed solution to modify, and then adsorb ammonia nitrogen and phosphorus, study the best modified condition, the adsorptive performance, kinetic and isothermal adsorption model. While the modified bamboo charcoal were analyzed to explore the mechanism of ammonia nitrogen and phosphorus adsorption. The following conclusions were drawn:①The BC modified by soaking Mg Cl2 and Fe Cl3 solutions improved adsorption ability of ammonia nitrogen significantly, and FMBC was more effective than MBC or FBC. The order of best modified bamboo charcoal adsorbing ammonia nitrogen was: BC < MBC < FBC < FMBC.② The specific surface area sizes of bamboo charcoal were:BC > MBC > FBC > FMBC. after modified, the BET surface area, micro-pore surface area, total pore volume decreased, but the average pore size increased. The internal pore structure arrangement became uneven and irregular. Analysis of FTIR implied that the bamboo charcoal have similar chemical groups, such as-OH, C=C, C-C, C=O, C-H, O-H, C-O, RC = CR and HC = CH bond.③ The curves of MBC, FBC and FMBC adsorption of ammonia nitrogen changing with time are similar, which reached adsorption equilibrium all after 24 h. The adsorption processes were all fitting to pseudo-second-order kinetic models, which showed the adsorption of ammonia nitrogen was mainly chemical adsorption. MBC and FBC adsorption processes fitted well with the Langmuir isotherm, FMBC adsorption process fitted well with the Freundlich isotherm. The adsorption of MBC and FBC on ammonia were single molecular layer adsorption, while FMBC were non uniform multiple molecular layer adsorption, and adsorb easily.④ When the ammonia nitrogen and phosphorus coexistence, adsorption capacity of MBC and FMBC on ammonia are more than adsorb separately, the adsorption of FBC on ammonia decreased. MBC, FBC, FMBC adsorption capacity of phosphate were well. The ammonia adsorption of MBC and FMBC were best when NH4-N and PO43--P molar ratio is 1:1 in the initial solution. Analysis of XRD after modified bamboo charcoal adsorbed ammonia and phosphorus found that precipitate compounds Mg NH4PO4·H2O, Mg3(PO4)2, Fe(PO3)3, Fe3(PO4)2 attached to the surface and inner pores of modified bamboo charcoal.⑤ After adsorption of ammonia nitrogen and phosphorus, the MBC, FBC, FMBC have a good performance in desorption. The iron, magnesium were attached firmly on the modified bamboo charcoal, not fall off easily. it showed the modified bamboo charcoal can regenerate. |
