Semi-aromatic polyamide membrane incorporated with yolk-shell mesoporous hybrid nanospheres for ultrahigh permeability and improving comprehensive property

In this report, yolk-shell (YS) organic-inorganic hybrid nanospheres (YSHNs) with radially ordered mesopores were synthesized by a co-assembly strategy using 1,2-bis(triethoxysilyl)ethane and tetraethoxysilane as precursors, and cetyltrimethylammonium bromide as a soft template. Then, Silver nanoparticles (AgNPs) were uniformly embedded in the hollow cavities of the YSHNs. The semi-aromatic polyamide (SAP) based nanocomposite membrane was fabricated using 1,3,5-cyclohexane tricarbonyl chloride as an organic phase, meta-phenylene diamine as an aqueous phase, and the mesoporous YS hybrid nanospheres as nanoadditives by an interfacial polymerization approach. The results show that the YS nanospheres were successfully incorporated into the polyamide (PA) separation layer, and the membrane becomes very hydrophilic. The membrane incorporated with the aminated YS mesoporous nanospheres exhibits ultrahigh pure water permeability (PWP, 9.34 L m−2 h−1 bar−1) and comparable NaCl rejection (96.1%), which is dramatically higher than the membrane with common mesoporous nanospheres. It is because that the hollow cavity of the YS nanosphere further decreases the membrane resistance, and the aminated spherical surface improves the interfacial compatibility between the PA matrix and the YS nanospheres. Furthermore, the flexible YS hybrid structure and the mesoporous core could play an important buffering for avoiding the shell fracture under a high operation pressure. The chlorine resistance of the YS-nanosphere incorporated membrane is significantly improved compared to the pristine SAP membrane in a strong chlorination strength (5500 ppm h, pH = 5). The confined AgNPs in the YS mesostructure endow the membrane with a sustainable antibiofouling property. Moreover, the polylysine modification improves the membrane fouling resistance and performance stability.