改性牡蛎壳对低磷浓度水体的净化性能研究

Study on purification performance of modified oyster shell for low phosphorus concentration water

为寻求经济、高效的生态浮床除磷基质,以牡蛎壳为对象,通过等温吸附、吸附动力学和吸附剂投加量影响实验对比研究了经不同温度热处理的改性牡蛎壳对低磷浓度水体的吸附性能。结果表明:相比Langmuir方程,Freundlich方程能更好地模拟天然及改性牡蛎壳对总磷的等温吸附行为;相对于伪一级动力学和Elovich方程,牡蛎壳对总磷的吸附动力学过程与伪二级动力学方程更为吻合。热处理温度对总磷的吸附效果产生明显影响,650℃改性牡蛎壳的吸附性能最优。牡蛎壳投加量对总磷去除效果影响也较为显著,当投加量增至20g/L时,天然牡蛎壳、250℃改性牡蛎壳、500℃改性牡蛎壳、650℃改性牡蛎壳的总磷去除率分别可达到51.27%、62.50%、88.27%和99.69%。当投加量为8g/L时,650℃改性牡蛎壳对总磷的去除率已高达90%左右。总体而言,650℃改性牡蛎壳的总磷吸附效果最好,可优先选为生态浮床除磷基质。

Oyster shell was modified via oxygen-limited heating treatment to improve its TP adsorption effeciency for use as a substrate of ecological floating bed.Isothermal adsorption and kinetic experiments were conducted to compare the adsorption performances of the modified oyster shells.The effect of adsorbent dosing on TP removal performance was also studied.The results showed that Freundlich model was better to predict the isothermal experimental data for raw oyster shell and the modified oyster shells than Langmuir model.The pseudo-secondary kinetic model could better simulate the adsorption kinetic data than the pseudo-first kinetic model and Elovich model as well.The heating treatment temperature was found to have a significant effect on the ability for TP removal,and the 650℃-treated oyster shell showed the best performance.The effect of oyster shell dosage on TP removal was also significant.With the increase of the adsorbent dosage to 20 g/L,TP removal efficiency for the raw oyster shell,250℃-treated oyster shell,500 ℃-treated oyster shell and 650 ℃-treated oyster shell could reach 51.27%,62.50%,88.27% and 99.69%,respectively.When the adsorbent dosing was 8 g/L,the removal efficiency of 650 ℃-treated oyster shell had reached to 90%.Thus,650℃-treated oyster shell could be chosen as the most preferred substrate for ecological floating raft.