分子筛吸附法脱除废水中的聚丙烯酰胺

聚丙烯酰胺(PAM)用于油田驱油产生大量难处理的含聚废水。以分子筛为吸附剂处理含聚废水,研究分子筛类型(Y、Beta和ZSM-5,H型和Na型)和物化性质对其吸附PAM性能的影响,并测定吸附等温线。结果表明,吸附性能顺序为Beta>Y>ZSM-5,H型优于Na型。H-Beta对PAM的吸附来自分子筛中阳离子与PAM中阴离子的静电作用,Si—O和Al—OH与PAM中酰胺基的氢键作用。H-Beta开放的通道结构,较高的介孔比例和表面积,较强的酸性和良好的酸中心可接近性使其具有优异的吸附性能。SiO2/Al2O3=26的H-Beta对浓度为200 mg/L的PAM溶液,PAM脱除率可达95.2%。在低PAM平衡浓度时,PAM在H-Beta上的吸附符合Langmuir单层吸附特征,饱和吸附量达70.2 mg/g,在高浓度区域则由于PAM疏水缔合作用加强呈现多层吸附。

Removal of polyacrylamide from wastewater by adsorption of molecular sieves

Extensive usage of polyacrylamide (PAM) in oil field results in significant quantities of wastewater containing PAM. Herein, molecular sieves were used to adsorb the PAM in wastewater. The effects of type and physiochemical properties of molecular sieves on the adsorption performance were investigated, moreover, the adsorption isotherm was measured. The results show that the adsorption performance follows the order of Beta>Y>ZSM-5 and H-type is more active than Na-type. PAM can be effectively adsorbed on H-Beta through electrostatic attraction between cations in molecular sieve and anions of PAM, as well as H-bonding between Si—O and Al—OH groups of molecular sieve and amide groups of PAM. H-Beta exhibits excellent adsorption performance due to its opening channel, high mesopore proportion and surface area, strong acidity and accessible acid sites. H-Beta with SiO2/Al2O3 of 26 can remove 95.2% of PAM in water with PAM concentration of 200 mg/L. In low PAM balance concentration, the adsorption isotherm of PAM over H-Beta is consistent with Langmuir model and the saturation adsorption capacity reaches 70.2 mg/g, whereas in high concentration regime, multiple layers adsorption occurs due to the enhancement of hydrophobic associations of PAM.