Preparation of core–shell structured CaCO 3 microspheres as rapid and recyclable adsorbent for anionic dyes

Core–shell structured CaCO3 microspheres (MSs) were prepared by a facile, one-pot method at room temperature. The adsorbent dosage and adsorption time of the obtained CaCO3 MSs were investigated. The results suggest that these CaCO3 MSs can rapidly and efficiently remove 99–100% of anionic dyes within the first 2 min. The obtained CaCO3 MSs have a high Brunauer–Emmett–Teller surface area (211.77 m2 g−1). In addition, the maximum adsorption capacity of the obtained CaCO3 MSs towards Congo red was 99.6 mg g−1. We also found that the core–shell structured CaCO3 MSs have a high recycling capability for removing dyes from water. Our results demonstrate that the prepared core–shell structured CaCO3 MSs can be used as an ideal, rapid, efficient and recyclable adsorbent to remove dyes from aqueous solution.