强化混凝消除水中全氟化合物

Elimination of perfluorinated compounds in water by enhanced coagulation

以十六烷基三甲基溴化铵(CTAB)有机改性膨润土作为助凝剂,采用聚合氯化铝(PAC)协同CTAB-膨润土进行强化混凝实验,对消除水中两类典型的全氟化合物全氟辛烷磺酸(PFOS)/全氟辛酸(PFOA)和浊度进行研究.考察了PAC和CTAB-膨润土投加量、p H值、原水浊度对PFOS/PFOA和浊度去除的影响.结果表明,经有机改性,实现了CTAB对膨润土的插层,增大了层间距,比表面积、阳离子交换容量、有机碳含量也得到较大提高.在PAC投加量为20mg/L、CTAB-膨润土投加量为30mg、p H6~7时,强化混凝去除效果分别达到76%、70%,PFOS/PFOA去除率随着CTAB-膨润土投加量的增大而增大.最佳p H值范围是6~7,混凝过程中Zeta电位在p H值为6.0时达到最大,p H值为7.0时接近于零.PFOS/PFOA的去除率随着原水浊度的增大而增大.

Bentonites organic modified by cetyltrimethyl ammonium bromide （CTAB） was used as coagulant aid. The elimination of PFOS/PFOA and turbidity in water by enhanced coagulation were studied with PAC and CTAB-bentonite. The effects of dosage of PAC and CTAB-bentonite, pH value, initial turbidity on the elimination of PFOS/PFOA were tested. The results showed that CTAB intercalated into bentonite increasing the layer space meanwhile, the specific surface area, cation exchange capacity and organic carbon content were greatly improved after organic modification. PFOS/PFOA removal efficiency reached 76% and 70% respectively by adding 20mg/L of PAC, 30mg of CTAB-bentonite and controlling the pH value among 6 and 7. The removal rates of PFOS/PFOA increased with the increasing dosages of CTAB-bentonite. The best range of pH values was 6~7. The Zeta potential reached the maximum at pH=6.0, while pH=7.0was close to zero in the coagulation process. The removal rates of PFOS/PFOA increased with the turbidity increasing in raw water.