Wetsus, Centre of Excellence for Sustainable Water Technology, Leeuwarden, The Netherlands.
Environ Sci Technol. 2012 Sep 4;46(17):9638-45. doi: 10.1021/es302186k. Epub 2012 Aug 17.
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 akaganéite. The kinetics of the adsorption of NTMP onto GFH was predicted fairly well with two models that consider either combined film-pore or combined film-surface 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.
吸附去除阻垢剂为改善当前反渗透（RO）浓缩液处理工艺提供了一种有前途的方法，并使阻垢剂能够在 RO 脱盐过程中重复使用。本工作研究了膦酸盐阻垢剂亚氨基二（亚甲基膦酸）（NTMP）从 RO 膜浓缩液到主要由纤铁矿组成的颗粒状氢氧化铁（GFH）上的吸附和解吸。NTMP 在 GFH 上的吸附动力学可以通过两个模型很好地预测，这两个模型都认为联合膜孔或联合膜表面扩散是质量传递的主要机制。此外，还证明在 pH 值为 7.85 时，GFH 优先吸附硫酸盐。钙的存在导致平衡吸附等温线从朗缪尔型转变为弗伦德利希型，吸附容量大大增加。此外，钙还大大增加了吸附速率。GFH 可以用氢氧化钠溶液再生后重复使用，表明 NTMP 可以从 RO 浓缩液中回收。这项工作表明，GFH 是一种很有前途的吸附剂，可用于从 RO 膜浓缩液中去除和回收 NTMP 阻垢剂。
