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Main Title: Quantification and isotherm modelling of competitive phosphate and silicate adsorption onto micro-sized granular ferric hydroxide
Author(s): Hilbrandt, Inga
Lehmann, Vito
Zietzschmann, Frederik
Ruhl, Aki Sebastian
Jekel, Martin
Type: Article
Language Code: en
Abstract: Adsorption onto ferric hydroxide is a known method to reach very low residual phosphate concentrations. Silicate is omnipresent in surface and industrial waters and reduces the adsorption capacity of ferric hydroxides. The present article focusses on the influences of silicate concentration and contact time on the adsorption of phosphate to a micro-sized iron hydroxide adsorbent (μGFH) and fits adsorption data to multi-component adsorption isotherms. In Berlin drinking water (DOC of approx. 4 mg L−1) at pH 7.0, loadings of 24 mg g−1 P (with 3 mg L−1 initial PO43−–P) and 17 mg L−1 Si (with 9 mg L−1 initial Si) were reached. In deionized water, phosphate shows a high percentage of reversible bonds to μGFH while silicate adsorption is not reversible probably due to polymerization. Depending on the initial silicate concentration, phosphate loadings are reduced by 27, 33 and 47% (for equilibrium concentrations of 1.5 mg L−1) for 9, 14 and 22 mg L−1 Si respectively. Out of eight tested multi-component adsorption models, the Extended Freundlich Model Isotherm (EFMI) describes the simultaneous adsorption of phosphate and silicate best. Thus, providing the means to predict and control phosphate removal. Longer contact times of the adsorbent with silicate prior to addition of phosphate reduce phosphate adsorption significantly. Compared to 7 days of contact with silicate (c0 = 10 mg L−1) prior to phosphate (c0 = 3 mg L−1) addition, 28 and 56 days reduce the μGFH capacity for phosphate by 21 and 43%, respectively.
Issue Date: 30-Jul-2019
Date Available: 11-Sep-2019
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Subject(s): micro-sized ferric hydroxide
silicate adsorption
Sponsor/Funder: DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berlin
BMBF, 02WIL1389, AdsFilt: Entfernung anorganischer Wasserschadstoffe durch neuartige Hybridprozesse mit Adsorption und Filtration (Deutsch-Israelische Wassertechnologie-Kooperation)
Journal Title: RSC Advances
Publisher: RSC Publishing
Publisher Place: London
Volume: 9
Issue: 41
Publisher DOI: 10.1039/C9RA04865K
Page Start: 23642
Page End: 23651
EISSN: 2046-2069
Appears in Collections:FG Wasserreinhaltung » Publications

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