Fixed-bed column system for Cd2+ uptake from aqueous solution by sodium- and thiourea-modified clinoptilolite-rich tuff
Two kinds of clinoptilolite-rich tuffs from the state of Sonora (Mexico), previously treated with NaCl solution and then modified with thiourea, were investigated to remove Cd2+ from aqueous solution in a fixed-bed column system. Experiments were conducted with a 30 mg L-1 Cd2+ solution at a pH valu...
| Veröffentlicht in: | Environmental technology. - 1993. - 41(2020), 7 vom: 13. März, Seite 832-841 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2020
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| Zugriff auf das übergeordnete Werk: | Environmental technology |
| Schlagworte: | Journal Article Cadmium bed-depth-service-time dynamic-system thiourea zeolites Water Pollutants, Chemical 00BH33GNGH clinoptilolite 12173-10-3 mehr... |
| Zusammenfassung: | Two kinds of clinoptilolite-rich tuffs from the state of Sonora (Mexico), previously treated with NaCl solution and then modified with thiourea, were investigated to remove Cd2+ from aqueous solution in a fixed-bed column system. Experiments were conducted with a 30 mg L-1 Cd2+ solution at a pH value of 5 and three-bed heights of sodium- and thiourea-modified clinoptilolite-rich tuffs. The experimental data were examined with the bed depth service time model (BDST), the Thomas model, and a mass balance approach. According to the BDST model, the dynamic sorption capacity (No) for the thiourea-modified clinoptilolite-rich tuff was 0.0357 Kg L-1. This value corresponded to 1.2 times higher than that for sodium-modified clinoptilolite-rich tuff (0.0287 Kg L-1). The experimental data obtained for sodium- modified clinoptilolite-rich tuff (ZSGNa) with 3 cm of bed height, fitted to the Thomas model, with R2 = 0.9679 and Cd sorption capacity of 35.4 mg g-1, while for the thiourea-modified clinoptilolite-rich tuff (ZSGThio) with 4.5 cm of bed height, was 36.52 mg g-1 with R2 = 0.9368. The parameters calculated with the mass balance model describe a favourable process where the system with ZSGThio (6 cm bed height) had the best performance for sorption capacity up to the breakthrough point, qb = 22.35 mg g-1. The zeolite modified with thiourea exhibited higher capacity in Cd2+ removal than the one modified with NaCl, in the column with 6 cm of bed height. To investigate the mechanisms of removal of Cd2+ by the modified zeolites, Na⁺ was measured to determine the milliequivalents of cadmium removed |
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| Beschreibung: | Date Completed 20.02.2020 Date Revised 20.02.2020 published: Print-Electronic Citation Status MEDLINE |
| ISSN: | 1479-487X |
| DOI: | 10.1080/09593330.2018.1511754 |