The objective of this study is to assess the effectiveness of three vanadium-substituted polyoxomolybdates, [PMo₁₁VO₄₀]⁴⁻, [PMo₁₀V₂O₄₀]⁵⁻, and [PMo₉V₃O₄₀]⁶⁻, for the removal of methylene blue dye (MB) from aqueous solutions. The materials were synthesized and initially characterized by Fourier transform infrared spectroscopy (FTIR) to confirm purity. Then the effect of several experimental factors, such as contact time (0–55 min), adsorbent dose (0.003–0.2 g), initial dye concentration (2–35 mg/L), as well as pH (1–10) and temperature (293–313 K) of the reaction, were investigated in order to identify the optimum conditions for each parameter. Accordingly, MB concentrations were recorded before and after adsorption using an ultraviolet–visible spectrophotometer (UV–Vis) at 664 nm. Hence, the synthesized compounds, which are all negatively charged, showed high removal efficiency towards the cationic dye. Optimized results for 25 mg/L methylene blue exhibited a contact time of only 10 min for [PMo₁₁VO₄₀]⁴⁻ and [PMo₁₀V₂O₄₀]⁵⁻while only 5 min for [PMo₉V₃O₄₀]⁶⁻. For [PMo₉V₃O₄₀]⁶⁻, the percentage of removal decreases from 92.70 to 78.20% with increasing pH showing the suitability of acid pH.

本研究的目的是评估三种钒取代的多氧钼酸盐 [PMo ₁₁ VO ₄₀ ] ⁴⁻、[PMo ₁₀ V ₂ O ₄₀ ] ⁵⁻和 [PMo ₉ V ₃ O ₄₀ ] ⁶⁻的有效性，用于从水溶液中去除亚甲蓝染料 (MB)。合成材料并通过傅里叶变换红外光谱 (FTIR) 初步表征以确认纯度。然后是几个实验因素的影响，例如接触时间（0-55 分钟）、吸附剂剂量（0.003-0.2 克）、初始染料浓度（2-35 毫克/升）以及 pH（1-10）和对反应温度 (293–313 K) 进行了研究，以确定每个参数的最佳条件。因此，使用紫外-可见分光光度计 (UV-Vis) 在 664 nm 处记录吸附前后的 MB 浓度。因此，合成的化合物均带负电荷，对阳离子染料显示出高去除效率。25 mg/L 亚甲蓝的优化结果显示 [PMo₁₁ VO ₄₀ ] ⁴⁻和 [PMo ₁₀ V ₂ O ₄₀ ] ⁵⁻而 [PMo ₉ V ₃ O ₄₀ ] ⁶⁻仅需要 5 分钟。对于 [PMo ₉ V ₃ O ₄₀ ] ^6-，随着 pH 值的增加，去除率从 92.70% 下降到 78.20%，表明酸性 pH 值的适用性。