In-situ synthesis of graphene-based polymer and metal carbonate ternary composite for selective separation of dyes from their mixture

Abstract

Developing quick and effective techniques for the selective removal of organic pollutants from waste streams remains a challenge in environmental research. This study prepared a novel PPy@rGO/CaCO3 (PRC) composite by functionalizing graphene, calcium carbonate and pyrrole using a facile one-pot fabrication method, avoiding tedious multistep reactions. The prepared PRC composite was coated onto the surface of silica (PRC@silica) and melamine sponge (PRC@sponge) to effectively remove organic pollutants. The as-synthesized PRC@sponge and PRC@silica were used for removing methylene blue (MB), brilliant green (BG) dyes. As-prepared PRC@silica and PRC@sponge adsorbed 99.5% and 99.4% of MB in 25 min. The results showed that the as-prepared PRC materials exhibited high dye adsorption capacity compared with only CaCO3, PPy and rGO because they provided more interaction sites. PRC demonstrated remarkable selectivity for the adsorption of cationic dye (BG) from a mixture with anionic dye [acid orange II (AO II)] with excellent adsorption efficiency up to 94.79%. Thus, the prepared adsorbent exhibited selectivity for the removal of cationic dyes MB and BG. PRC@silica and PRC@sponge sustained up to 10 consecutive cycles without losing their adsorption efficiencies (85.7% and 85.43%, respectively). The adsorption process followed the Langmuir adsorption isotherm and the pseudo-second order kinetic model with R2 value of 0.996 and 1, respectively. The finding of this study provides a new insight for the mass production of synthesized PRC composites for different applications in sustainable chemistry, including the selective purification of organic pollutants from waste streams.