Calcium oxalate/calcium silicate hydrate (Ca-Ox/C-S-H) from blast furnace slag for the highly efficient removal of Pb2+ and Cd2+ from water. Issue 5 (October 2021)

• Record Type: Journal Article
• Authors: Le, Quynh T.N.; Vivas, Eleazer L.; Cho, Kuk
• Is Part Of: Journal of environmental chemical engineering. Volume 9:Issue 5(2021)
• Publication Date: 2021-10
• Subjects: Lead -- Cadmium -- Sorption -- Ion exchange -- Calcium oxalate -- Calcium silicate hydrate; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2021.106287
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: Heavy metal pollution of water is a global environmental concern which necessitates viable remediation through the exploration of highly effective adsorbents. Based on the affinity between oxalate and heavy metal, we synthesized a novel calcium oxalate/calcium silicate hydrate (Ca-Ox/C-S-H) adsorbent from blast furnace slag (BFS) by a facile oxalic acid/NaOH treatment. The BFS-derived Ca-Ox/C-S-H exhibited superior maximum uptake capacities for Pb 2+ (2117 mg g −1 ) and Cd 2+ (1083 mg g −1 ). The removal mechanism involves ion exchange, and adsorption kinetics showed an equilibration time of 10 min for Pb 2+ at a solid-to-liquid ratio of 1.0 g L −1, in agreement with both the pseudo-first- and pseudo-second-order reaction kinetics models. The adsorption isotherms of Ca-Ox/C-S-H for both metal ions also fitted the Sips model well. Ca-Ox/C-S-H showed high selectivity toward Pb 2+ among various heavy metals and coexisting ions in water, and demonstrated high retention of adsorption capacity after being recycled up to four times. These results support the use of BFS-derived Ca-Ox/C-S-H as an efficient and economical Pb 2+ and Cd 2+ adsorbent. Graphical Abstract: ga1 Highlights: Ca-Ox/C-S-H is prepared from slag for the first time. Ca-Ox/C-S-H has uptake capacities of 2117 mg g −1 for Pb 2+ and 1083 mg g −1 for Cd 2+ . Ca-Ox/C-S-H exhibits rapid uptake kinetics, reaching equilibrium within 10 min for Pb 2+ . Ca-Ox/C-S-H has a high distribution coefficient of 5.6 × 10 5 mL g −1 for Pb 2+ . Ca-Ox/C-S-H is reusable, maintaining high uptake capacities after several cycles.