Adsorption of Phosphonate Antiscalant from Reverse Osmosis Membrane Concentrate onto Granular Ferric Hydroxide

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• 作者：Luciaan Boels ; Karel J. Keesman ; Geert-Jan Witkamp
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：September 4, 2012
• 年：2012
• 卷：46
• 期：17
• 页码：9638-9645
• 全文大小：399K
• 年卷期：v.46,no.17(September 4, 2012)
• ISSN：1520-5851

文摘

Adsorptive removal of antiscalants offers a promising way to improve current reverse osmosis (RO) concentrate treatment processes and enables the reuse of the antiscalant in the RO desalination process. This work investigates the adsorption and desorption of the phosphonate antiscalant nitrilotris(methylenephosphonic acid) (NTMP) from RO membrane concentrate onto granular ferric hydroxide (GFH), a material that consists predominantly of akagan茅ite. The kinetics of the adsorption of NTMP onto GFH was predicted fairly well with two models that consider either combined film鈥損ore or combined film鈥搒urface diffusion as the main mechanism for mass transport. It is also demonstrated that NTMP is preferentially adsorbed over sulfate by GFH at pH 7.85. The presence of calcium causes a transformation in the equilibrium adsorption isotherm from a Langmuir type to a Freundlich type with much higher adsorption capacities. Furthermore, calcium also increases the rate of adsorption substantially. GFH is reusable after regeneration with sodium hydroxide solution, indicating that NTMP can be potentially recovered from the RO concentrate. This work shows that GFH is a promising adsorbent for the removal and recovery of NTMP antiscalant from RO membrane concentrates.