Ultralight aerogel based on molecular-modified poly(m-phenylenediamine) crosslinking with polyvinyl alcohol/graphene oxide for flow adsorption

Abstract

Poly(m-phenylenediamine) is an excellent adsorbent material. Nevertheless, it is difficult to recover and can even generate secondary pollution due to its powder-like form. Aerogels, monolithic three-dimensional structured materials, that are ultralight and have porous properties are efficient at adsorbing contaminants from water and can solve these problems. Here, we synthesized an aerogel based on molecular-modified poly(m-phenylenediamine) (mPmPD) crosslinking with polyvinyl alcohol (PVA) and graphene oxide (GO) (GO/mPmPD/PVA). Of note is that 3-aminophenylboronic acid was introduced into the polymer structure to induce a crosslinking reaction between boric acid units and PVA to constrain poly(m-phenylenediamine) in the aerogel. The GO/mPmPD/PVA aerogel shows stable mechanical properties in aqueous solution and an effective adsorption capacity for Ag(I); the maximum Ag(I) adsorption capacity is 917.41 mg g⁻¹. The mechanism of Ag(I) adsorption and reduction was clarified in that Ag(I) chelated with imine units, and a redox reaction occured between Ag(I) and the benzenoid amine units. Furthermore, the GO/mPmPD/PVA aerogel also shows excellent adsorption ability toward methyl orange and Congo red dyes. This GO/mPmPD/PVA aerogel shows enormous potential for application to silver recovery and dye removal due to its low cost, effective adsorption capacity and facile separation with aqueous solution.