Correlative roles of silica as a blowing aid and a Pb(II) adsorbent for natural rubber composite foams

Abstract

The present work aimed to study two correlative behaviors of rubber composites and rubber composite foams filled with SiO2 that affect the cure characteristics and the adsorption capacity of Pb(II) from an aqueous solution; these behaviors have never been reported before as a conjoint analysis. A two-stage curing technique was used to vulcanize the rubber samples. The effect of NaHCO3 as well as SiO2 content on the cure characteristics, physical properties, and Pb(II) adsorptivity of the rubber compounds was examined. The addition of SiO2 had a more pronounced effect on the cure characteristics and crosslinking density of rubber compounds than that of NaHCO3. Changes in t90, CRI, and crosslinking density as a function of SiO2 loading played an important role in the foaming behavior of the rubber samples. The SiO2 addition in the rubber compounds enhanced the blowing efficiency, which facilitated the adsorption of Pb(II). The adsorption mechanism for the samples containing SiO2 was mainly based on electrostatic attraction, as evidenced by a shifting wavenumber for the silanol functional group and as observed in FTIR results. The experimental results showed promising potential for the utilization of rubber filled with SiO2 for Pb(II) removal beyond its service lifetime.