Semi-interpenetrating polymer network microspheres with superior dimensional stability as multifunctional antibacterial adsorbent materials

Wastewater containing positively-charged toxins and pathogenic bacteria can cause high environmental danger which seriously threatens human health. Fixed-bed column has emerged as a practical technique for water remediation owing to its simple operation, high efficiency and cost-effective implementation. However, how to prepare adsorbents with adequate dimensional stability, high adsorption capability and antibacterial property remains an open question. Herein, semi-interpenetrating network (Semi-IPN) microspheres were prepared by combining poly (ether sulfone) with poly (acrylic acid) (PAA) hydrogels via electrospraying technique coupled with subsequent in-situ cross-linking polymerization. Then, Ag nanoparticles were immobilized on the PAA hydrogels to endow the microspheres with antibacterial property. The as-prepared multifunctional microspheres exhibited superior dimensional stability. The compressive stress of the microspheres reached up to 17.90 MPa (with a strain of 60%), which was over 400-fold larger than that of the PAA hydrogels. The swelling ratio of the microspheres under pH 10 was 1.75 g/g and declined by 90.17% compared to that of the PAA hydrogels. Furthermore, the column filled with the microspheres showed ultrahigh removal ratios for positively-charged toxins (98.03%, 99.57%, 99.42% and 98.21% for methylene blue, Cu2+, Cd2+ and Pb2+, respectively) and robust bacterial killing efficiency (100% for either Escherichia coll. or Staphylococcus aureus). Overall, we present a method on developing promising multifunctional hydrogel microspheres with enhanced antibacterial activities as well as adsorbent with higher adsorption capacities. We envision that the proposed multifunctional microspheres could overcome the limitations facing the fixed-bed column and be applied for treatment of water polluted by positively-charged toxins and pathogenic bacteria.