Organo-inorganic hybrid IPN sourced porous carbons and their lead decontamination perspectives

Abstract

The present communication is about generation of porous carbons through sacrificial template route, from organo-inorganic hybrid interpenetrating polymer networks (IPN's) and their use as a remediation tool for the removal of lead ions from contaminated water. The hybrid IPN's between phenol-formaldehyde (PF) polymer and silica were formed through sequential IPN formation route, in which, silica network was formed first through sol-gel process involving tetraethoxysilane (TEOS) dispersed in phenolic resin followed by thermal crosslinking of the later. The resulting PF/SiO2 IPNs were transformed to C/SiO2 composites through carbonization at 1000 °C under inert atmosphere with silica contents ranging from 10 to 70 %. The silica phase was sacrificed through hydrogen fluoride (HF) leaching to obtain porous carbons, which were further chemically activated with KOH. The derived porous carbons had hierarchical open pore geometry with majority of the pores belonging to the meso category. The carbons were employed to scavenge lead (Pb2+) ions from aqueous effluents and a maximum uptake of 177.3 mg of Pb2+ ions per gram of the adsorbent, was achieved with the present carbons. The adsorption was studied with standard adsorption models, such as Langmuir and Freundlich, of which a better compliance with Langmuir model was noted. Adsorption between the PFSiC carbons and Pb2+ ions obeyed second order kinetics.