Raffinate coal tar pitch-derived micro/mesoporous carbon foams for removal of Cadmium ions

A novel type of laminar micro/mesoporous carbon foams were prepared from co-pyrolysis of raffinate coal tar pitch from low temperature coal tar, urea and ammonium citrate. The effects of additives, activation temperature, and carbonization time on the chemical composition, and morphology structure of micro/mesoporous carbon foams were systematically investigated, and the formation mechanism of micro/mesoporous carbon foams were revealed. The specific surface area of obtained micro/mesoporous carbon foam (MCFAC-CM-2–1000) was the 671.1 m2∙g−1. The adsorption properties of materials for heavy metal cadmium ions (Cd (II)) in aqueous solution were studied. A systematic investigation of the effect of different conditions (e.g., contact time, pH, and initial metal ion concentration) on the adsorption of Cd(Ⅱ) was conducted. The maximum Cd(Ⅱ) adsorption capacity by MCFAC-CM-2–1000 was 151.73 mg/g at 318 K. The adsorption equilibrium of heavy metal Cd (II) was in agreement with the Langmuir isothermal model and the quasi second-order model, the adsorption process was spontaneous. Analytical experiments showed that MCFAC-CM-2–1000 had a good stability and strong regeneration. Therefore, MCFAC-CM-2–1000 presents remarkable adsorption capability, excellent recoverability, demonstrating its potential as a promising adsorbent for water purification. This work offers a new alternative to transform harmful coal tar pitch waste into an effective adsorbent for cadmium removal. © 2022 Elsevier B.V.