Cranfield Water Science Institute, Vincent Building, Cranfield University, Bedfordshire MK43 0AL, UK; Dept. Biol. Chem. Eng., National Institute of Applied Sciences and Technology (INSAT), University of Carthage (, Tunisia).
Chemical Engineering Department, Barcelona Research Center for Multiscale Science and Engineering Escola d'Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya (UPC)-BarcelonaTECH, C/ Eduard Maristany 10-14, Campus Diagonal-Besòs, 08930 Barcelona, Spain.
Sci Total Environ. 2020 Aug 20;731:139002. doi: 10.1016/j.scitotenv.2020.139002. Epub 2020 Apr 26.
The sorption of phosphate by K-zeolites synthesized from fly ash (FA) by hydrothermal conversion is investigated in this study. The aim is the synthesis of Ca bearing K-zeolites to recover phosphate from urban and industrial wastewater effluents. The loaded zeolites are considered as a by-products rich in essential nutrients such K and P (KP1) with a potential use as slow release fertilizer. A number of synthesis conditions (temperature, KOH-solution/FA ratio, KOH concentration, and activation time) were applied on two FA samples (FA-TE and FA-LB) with similar glass content but different content of crystalline phases, to optimize the synthesis of a zeolitic sorbent suitable for the subsequent phosphate uptake. Merlinoite and W rich zeolitic products synthesized from FA-LB and FA-TE were found to have sorption properties for phosphate removal. A maximum phosphate sorption capacity of 250 mgP-PO/g and 142 mgP-PO/g for the zeolitic products selected (KP1-LB and KP1-TE, respectively) was achieved. The dominant phosphate sorption mechanism, in the pH range (6-9) of treated wastewater effluents, indicated that sorption proceeds via a diffusion-controlled process involving phosphate ions coupled with calcium supply dissolution from K-zeolitic products and subsequent formation of brushite (CaHPO 2HO(s)). The phosphate loaded sorbent containing a relatively soluble phosphate mineral is appropriate for its use as a synthetic slow release fertilizer. The simultaneous valorisation of fly ash waste and the P recovery from treated wastewaters effluents, (a nutrient with scarce natural resources and low supply) by obtaining a product with high potential for land restoration and agriculture will contribute to develop one example of circularity.
本研究考察了由粉煤灰（FA）通过水热转化合成的钾沸石对磷酸盐的吸附。目的是合成含 Ca 的钾沸石，以从城市和工业废水废水中回收磷酸盐。负载的沸石被认为是一种富含必需营养元素（如 K 和 P）的副产物（KP1），具有作为缓释肥料的潜在用途。在两种 FA 样品（FA-TE 和 FA-LB）上应用了多种合成条件（温度、KOH 溶液/FA 比、KOH 浓度和活化时间），以优化适合随后吸收磷酸盐的沸石吸附剂的合成。发现从 FA-LB 和 FA-TE 合成的 Merlinoite 和富含 W 的沸石产物具有去除磷酸盐的吸附性能。所选沸石产物（分别为 KP1-LB 和 KP1-TE）的最大磷酸盐吸附容量为 250mgP-PO/g 和 142mgP-PO/g。在处理废水废水中的 pH 范围（6-9）下，主要的磷酸盐吸附机制表明，吸附是通过涉及与钙供应溶解耦合的扩散控制过程进行的，钙供应溶解来自 K-沸石产物，随后形成二水合磷酸氢钙（CaHPO 2HO(s)）。负载磷酸盐的吸附剂含有相对可溶性的磷酸盐矿物，适合用作合成缓释肥料。通过获得一种具有高土地恢复和农业潜力的产品，同时对粉煤灰废物进行增值和从处理后的废水废水中回收磷（一种具有稀缺自然资源和低供应的营养物质），将有助于开发一种循环利用的范例。
