聚乙烯醇包埋水化硅酸钙粉末制备薄片状材料用于处理含磷废水

Preparation of PVA entrapped CSH adsorbent sheets and used for treatment of phosphorus wastewater

采用聚乙烯醇(PVA)包埋固定水化硅酸钙(CSH)粉末,硝酸钠作为交联剂,制备片状除磷材料(PVA-CSH),解决粉状CSH易流失、易堵塞等实用性问题,同时尽量避免对CSH粉末吸附性能的影响。通过SEM和FTIR对材料进行表征,通过批量的静态实验研究材料对含磷废水的吸附行为,通过连续运行实验考察材料的实际应用性能。结果表明,PVA-CSH材料成多孔网状结构,包埋前后CSH基团种类不变;PVA的加入对CSH除磷的吸附速率会有一定的影响,但平衡吸附量基本不受影响,准二级动力学方程可用于描述吸附过程,吸附等温曲线符合Langmuir等温方程;连续柱实验中,同等条件下,CSH及PVA-CSH柱出水磷浓度超出0.5 mg·L^(-1)时,运行时长均为7 d左右,PVA-CSH柱出水COD浓度始终小于10 mg·L^(-1),NO_3^--N浓度始终小于2 mg·L^(-1),PVA-CSH柱出水浊度接近0 NTU显著优于CSH粉末。

Planar calcium silicate hydrate（ CSH） adsorbents were prepared using the polyvinyl alcohol（ PVA）embedding method,with sodium nitrate as crosslinking agent,to solve practical problems of powder CSH. These include easy loss,tendency for plugging,and so on; to avoid the negative influence of the adsorption properties of CSH. The embedded CSH adsorbent（ PVA-CSH） was characterized using SEM and FTIR. The adsorption of phosphorus from aqueous solution onto CSH and PVA-CSH was investigated using a static batch experiment. The practical application of CSH and PVA-CSH was researched by continuous experiment. The results showed that PVA-CSH had a porous net structure,and that the groups of CSH were unchanged before and after embedding.Adding PVA had some impact on the phosphorus adsorption rate,but the equilibrium adsorption capacity was unaffected. The adsorption fitted well with the pseudo-second-order kinetic model. The fitted isotherm equation for the adsorption accorded with the Langmuir adsorption model. The results of flowing column experiments showed that under the same conditions,when the effluent concentration of phosphorus exceeded 0. 5 mg·L^-1,the run time of filter columns of CSH and PVA-CSH were both about seven days. For the filter column with PVA-CSH,the effluent concentration of COD was always 〈10 mg·L^-1,the effluent concentration of NO3^--N was always 〈2 mg·L^-1,and the effluent turbidity was close to 0 NTU. These were significantly better than those with CSH powder.