Nanocasting fabrication of ordered mesoporous phenol–formaldehyde resins with various structures and their adsorption performances for basic organic compounds

Abstract

Highly ordered mesoporous carbonaceous phenol–formaldehyde resins with two-dimensionally (2-D) hexagonal and 3-D bicontinuous cubic mesostructures have been successfully prepared by a simple nanocasting process. We adopted a low-molecular-weight resol as a precursor and mesoporous silica materials SBA-15 and KIT-6 as the hard templates. The resol precursor can be readily infiltrated into the mesochannels of the silica templates and converted to rigid 3-D zeolite-like resin skeletons under a simple heat treatment of 200–500°C without any catalyst. Several factors influencing the mesostructural replication, including the symmetry and texture of the hard templates, the structure and loading amount of the precursor, and the thermopolymerization temperature, are systematically investigated. The results show that better mesopore connectivity, higher thermopolymerization temperature and proper loading amount of the thermosetting resol precursor are essential for faithful mesostructural replication. The structural, textural and framework properties of the ordered mesoporous replicas are fully characterized. It is manifested that the replicas are composed of highly cross-linked phenolic resin frameworks. These mesoporous phenolic resin replicas have high surface areas (up to 1600m2/g) and large pore volume (up to 1.12cm3/g) and uniform mesopore size (3–4nm). When used as adsorbents, the ordered mesoporous carbonaceous phenolic resins exhibit excellent performances for removing toxic basic organic compounds from waste-water, with fast adsorption kinetics, high adsorption affinity and large adsorption capacities.