Immobilized AgZnO photocatalyst in Poly(acrylic acid) matrix synthesized in water suspension and their photocatalytic activity A. B. Jasso-Salcedo a , D. Meimaroglou b , M. Camargo b , S. Hoppe b , F. Pla b and V. A. Escobar-Barrios a a IPICYT, San Luis Potosí, S.L.P., Mexico, vladimir.escobar@ipicyt.edu.mx, b CNRS-Université de Lorraine, Nancy, France, sandrine.hoppe@univ-lorraine.fr ABSTRACT Silver modified ZnO particles (1% wt. Ag/ZnO), using UV light, were immobilized on a 3D network of crosslinked poly(acrylic acid) through ester linkages using GLYMO as coupling agent. Water based free radical polymerization was used for synthesis of Ag/ZnO-poly(acrylic acid) composites with 5 to 11% wt. content of photocatalyst, homogeneously dispersed as verified by SEM analysis. The Ag/ZnO- poly(acrylic acid) composites showed a higher thermal stability compared with pure poly(acrylic acid). The photocatalytic activity for bisphenol-A degradation was lower for the Ag/ZnO-poly(acrylic acid) composites (~50%) in comparison with the pure Ag/ZnO (>70%), but remained fairly constant after at least two consecutive reuse cycles. Keywords: Ag/ZnO, Polymeric Composite, Photocatalysis, Bisphenol-A, Water Treatment. 1 BACKGROUND Zinc oxide (ZnO) is a photocatalyst with an adequate efficiency for photodegradation of dyes and several organic molecules in aqueous solution [1,2]. However, this efficiency must be improved for photocatalysis under visible light. In this sense, the modification of ZnO with silver nanoparticles (AgNPs) reduces the photocorrosion [3], improves the absorption of visible light [4,5] and increases the photocatalytic activity [3-6] in comparison to pure ZnO. The role of AgNPs is to increase the half-life time of the primary (excited electrons and holes, e * -h + ) and secondary active species (free radicals, i.e.  OH), thus inducing a positive effect on the photocatalytic behavior of ZnO. In spite of a series of specific Ag/ZnO advantages (e.g., decreased charge-carriers recombination rate, photostabillity, low cost and non-toxicity), its application in pilot scale systems has not yet been exploited. This is mainly attributed to difficulties related to the photocatalyst recovery and the UV/visible light sorption efficiency. Homogeneous dispersion and immobilization of the photocatalyst within a matrix may affect favorably the reactive sites availability, surface area for contact, quantum yield and diffusion processes. A recent application includes the immobilization of photocatalysts (e.g., TiO 2 ) into polymeric matrices for the degradation of dyes in aqueous solutions. Among the most commonly used polymeric matrices are polyaniline [7, 8], polystyrene [9], acrylates [10, 11] and polypyrrole [12]. In order for a matrix to be suitable for photocatalytic water treatment under UV/visible light irradiation, in batch or continuous reactors, it must be hydrophilic, transparent, photochemically stable and mechanically resistant. Acrylic polymers are hydrogels that allow effective water transport for contact with the target pollutants due to their hydrophilicity and high wettability (i.e., display a capacity to absorb large amounts of water with respect to their own weight). In addition, they are generally colorless and visually transparent which allows the penetration of light into the matrix. Accordingly, in the present work, a silver modified ZnO photocatalyst is synthesized and immobilized in a poly(acrylic acid) (PAA) polymer matrix for the degradation of bisphenol-A in water. 2 EXPERIMENTAL 2.1 Ag/ZnO preparation The functionalization procedure of ZnO (VP AdNano ZnO 20 DW, Degussa Co.) using 1% wt. of stabilized silver nanoparticles (CITD-Peñoles Mexico) and the coupling agent GLYMO (Dynasylan ®) is described in Figure 1. 2.2 Synthesis of Ag/ZnO-PAA composite The Ag/ZnO-GLYMO photocatalyst was vigorously dispersed in de-ionized water using ultrasound (1 h) under vacuum to remove oxygen. The degased suspensions (5 to11% wt., 22.5 mL) Figure 1. Flow diagram of the ZnO functionalization procedure. NSTI-Nanotech 2014, www.nsti.org, ISBN 978-1-4822-5826-4 Vol. 1, 2014 416