粘土-生物炭复合改性材料对底泥磷释放控制研究
- Control effect of clay-biochar composite modified material on phosphorus release from sediment
- 摘要：本研究以凹凸棒土和生物炭为载体，通过组分调整及活性金属负载，制备了镧铝负载的粘土-生物炭复合锁磷材料(La/Al@AB).通过微观表征、物相组成识别以及化学分析等分析了改性前后材料的表面形貌和理化性质变化特征.开展批次吸附与原位模拟实验,研究了La/Al@AB对水体磷的吸附性能及其对底泥磷释放的影响. 利用高分辨孔隙水采样装置(HR-Peeper)、薄膜扩撒梯度(DGT)以及磷形态分级提取等技术探讨了改性材料对底泥磷的释放机理及控制效果.结果表明, La/Al@AB对磷的饱和吸附量约为28.32mg/g，可在5h达到平衡.底泥原柱样模拟培养实验结果表明，锁磷材料添加后上覆水及底泥间隙水中磷含量显著下降，并伴随底泥有效磷通量的减少.磷形态实验表明，添加La/Al@AB后不稳定的活性磷(Mobile-P)不断向稳定惰性的Ca-P和Res-P转变.处理组在表层0-2cm相较于空白组Mobile-P含量分别降低了77.61%(1倍添加量)和87.93%(2倍添加量). 该粘土-生物炭复合改性材料磷吸附量高，较单一粘土材料对磷的吸附效果更佳，较市售常见锁磷剂经济成本大幅降低，在湖泊水体除磷和底泥内源磷控制方面具有广阔的前景.
- Abstract：Abstract: In this study, clay-biochar composite phosphate-locking material (La/Al@AB) supported by lanthanum-aluminum was prepared by means of composition adjustment and active metal loading using attapulgite and biochar as carrier. The surface morphology and physicochemical properties of the materials before and after modification were analyzed by microscopic characterization, phase composition identification and chemical analysis. Batch adsorption and in-situ simulation experiments were carried out to study the adsorption performance of La/Al@AB on phosphorus in water and its effect on phosphorus release from sediment. The mechanism and control effect of modified materials on phosphorus release from sediment were discussed by using high-resolution pore water sampling device (HR-Peeper), diffusive gradients in thin-films (DGT), grading extraction of phosphorus forms and other technologies. The results showed that the saturation adsorption capacity of La/Al@AB is about 28.32mg/g, and can reach the equilibrium at 5h. The results of simulated culture experiment of sediment samples showed that the phosphorus content of overlying water and sediment pore water decreased significantly after the addition of phosphorus locking materials, and the effective phosphorus flux of sediment decreased. The phosphorus morphology experiment showed that the unstable active phosphorus (Mobile-P) was continuously transformed into stable and inert Ca-P and Res-P after the addition of La/Al@AB. Compared with the blank group, the Mobile-P content in the surface 0-2cm was reduced by 77.61%(1 times the addition amount) and 87.93%(2 times the addition amount), respectively. The clay-biochar composite modified material has higher phosphorus adsorption capacity, better phosphorus adsorption effect than a single clay material, and significantly lower economic cost than common phosphorus locking agents on the market. It has broad prospects for phosphorus removal in lake water and phosphorus control in sediment.
