Abstract Zinc aluminum layered double hydroxides (LDH) with Zn/Al molar ratios of 2 and 3 were synthesized by general (Zn 2G -Al, Zn 3G -Al) and modified (Zn 2M -Al, Zn 3M -Al) urea hydrolysis methods. The effects of time, pH, selectivity and initial phosphorous concentration were investigated on phosphate uptake by synthesized LDH in a simulated soil solution. Moreover, phosphate desorption from studied LDH was evaluated. Based on the results, nitrate containing Zn-Al LDH were synthesized by both methods. However, the presence of carbonate ion in the interlayer space of Zn 3G -Al was recorded. The kinetics experiments indicated that the pseudo-second order model well described phosphate uptake on all LDH. The lowest uptake (1.09 mmol g − 1 ) was observed for Zn 3G -Al likely due to Zn/Al molar ratio, the presence of carbonate in the interlayer space and incomplete phosphate intercalation mechanism. Phosphate adsorption isotherms of LDH were in agreement with Freundlich model. Although phosphate uptake decreased in the presence of other anions, the highest selectivity especially in the pure nitrate containing LDH were measured for phosphate anion. Phosphate uptake declined with increasing the pH from 6 to 8. The amounts of phosphate desorption from prepared LDH were between 23.2 and 36.3% suggesting that synthesized LDH may have potential to be used as a slow release phosphate fertilizer in soils.

中文翻译：

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两种方法合成的Zn-Al LDH对磷酸盐在模拟土壤溶液中的吸附和解吸比较

摘要 采用一般(Zn 2G -Al, Zn 3G -Al)和改性(Zn 2M -Al, Zn 3M -Al)尿素水解法合成了Zn/Al摩尔比为2和3的锌铝层状双氢氧化物(LDH)。 . 在模拟土壤溶液中研究了时间、pH、选择性和初始磷浓度对合成 LDH 吸收磷酸盐的影响。此外，评估了从研究的 LDH 中解吸的磷酸盐。基于这些结果，两种方法都合成了含有 Zn-Al LDH 的硝酸盐。然而，记录到 Zn 3G -Al 的层间空间中存在碳酸根离子。动力学实验表明，伪二级模型很好地描述了所有 LDH 对磷酸盐的吸收。由于 Zn/Al 摩尔比，观察到 Zn 3G -Al 的最低吸收 (1.09 mmol g - 1 )，层间空间存在碳酸盐和不完全的磷酸盐插层机制。LDH的磷酸盐吸附等温线与Freundlich模型一致。尽管在其他阴离子的存在下磷酸盐的吸收降低，但对磷酸盐阴离子的选择性最高，尤其是在含有 LDH 的纯硝酸盐中。随着 pH 从 6 增加到 8，磷酸盐吸收率下降。从制备的 LDH 中解吸磷酸盐的量在 23.2% 和 36.3% 之间，表明合成的 LDH 可能具有用作土壤中缓释磷肥的潜力。磷酸根阴离子的选择性最高，尤其是在含有 LDH 的纯硝酸盐中。随着 pH 从 6 增加到 8，磷酸盐吸收率下降。从制备的 LDH 中解吸磷酸盐的量在 23.2% 到 36.3% 之间，表明合成的 LDH 可能具有用作土壤中缓释磷肥的潜力。磷酸根阴离子的选择性最高，尤其是在含有 LDH 的纯硝酸盐中。随着 pH 从 6 增加到 8，磷酸盐吸收率下降。从制备的 LDH 中解吸磷酸盐的量在 23.2% 到 36.3% 之间，表明合成的 LDH 可能具有用作土壤中缓释磷肥的潜力。