响应曲面优化改性沸石的制备及其对水中氨去除特性

Response Surface Optimization of the Preparation of Modified Zeolite and its Removal of Ammonia from Water

采用柠檬酸钠联合高温煅烧制备改性沸石,利用响应曲面法优化制备参数,通过批次吸附实验探究了改性沸石去除水中氨的特性及机理。结果表明:柠檬酸钠质量分数为2.24%,煅烧温度为395.72℃,煅烧时间为3.58 h条件下制备的改性沸石效果最佳;在投加量为10 g/L条件下处理20 mg/L氨,去除率达到80.21%,较天然沸石提高35.62%。SEM和BET表明改性后沸石孔径增大了1.48倍。吸附氨的最佳pH为6,阳离子共存对吸附氨的影响顺序为:K^(+)>Ca^(2+)>Mg^(2+)>Na^(+);拟二级动力学和Langmuir模型可更好地描述氨吸附过程,改性沸石循环5次后的氨去除率依然可达70.49%。本研究制备的改性沸石可作为吸附剂用于水中氨的高效去除。

The modified zeolite was prepared by sodium citrate combined with high-temperature calcination,the preparation parameters were optimized by the response surface method,and the characteristics and mechanism of the modified zeolite in the removing ammonia from water were explored through the batch adsorption experiments.The results showed that the modified zeolite has the best effect when the concentration of sodium citrate is 2.24%,the calcination temperature is 395.72℃,and the calcination time is 3.58 h.When the dosage of 10 g/L was used to treat 20 mg/L ammonia,the removal rate reached 80.21%,which was 35.62%higher than that of natural zeolite.The SEM and BET showed that the pore size of the modified zeolite increased by 1.48 times.The optimum pH for the adsorption of ammonia was 6,and the order of effect of cation coexistence on the adsorption of ammonia was:K^(+)>Ca^(2+)>Mg^(2+)>Na^(+).The pseudo-second-order kinetics and Langmuir models can better describe the ammonia adsorption process,and the modified zeolite was cycled 5 times,the ammonia removal rate can still reach 70.49%.The modified zeolite prepared in this study can be used as an adsorbent for the efficient removal of ammonia from the water.