Iron phosphate, Fe2 (HPO4)3*4H2O, is synthesized at ambient temperature, using the inorganic sol–gel method coupled to the microwave route. The experimental conditions for the gelling of Fe (III)-H3PO4 system are previously defined. Potentiometric Time Titration (PTT) and Potentiometric Mass Titration (PMT) investigate the acid–base surface chemistry of obtained phosphate. Variations of surface charge with the contact time, Q a function of T, are examined for time contact varying in the range 0–72 h. The mass suspensions used for this purpose are 0.75, 1.25 and 2.5 g L−1. The point of zero charge (PZC) and isoelectric point (IEP) are defined using the derivative method examining the variations $$\frac{{{\text{dpH}}}}{{{\text{d}}t}} = f\left( {{\text{pH}}} \right)$$ , at lower contact time. A shift is observed for PZC and IEP towards low values that are found to be 2.2 ± 0.2 and 1.8 ± 0.1, respectively. In acidic conditions, the surface charge behavior of synthesized phosphate is dominated by $$\overline{{ > {\text{POH}}}}$$ group which pKa = 2.45 ± 0.15. Q against T titration method is performed for synthesized Fe2 (HPO4)3*4H2O in NaCl electrolytes. The maximal surface charge (Q) is achieved at the low solid suspension. Hence, for m = 0.75 g L−1, Q value of 50 coulombs is carried at μ = 0.1 and pH around 12, while charge value around 22 coulombs is reached in the pH range: 3–10. The effect of activation time, Q and pH on sodium insertion in iron phosphate, were fully evaluated. To determine the optimal conditions of the studied process, mathematical models are used develop response surfaces in order to characterize the most significant sodium interactions according to the variation of the pH, Q, the contact time and the contents of the synthesized material.

中文翻译：

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无定形磷酸铁的统计优化：无机溶胶-凝胶合成-钠电位插入

磷酸铁 Fe2 (HPO4)3*4H2O，是在环境温度下合成的，使用无机溶胶-凝胶法结合微波路线。Fe (III)-H3PO4 系统胶凝的实验条件是先前定义的。电位时间滴定 (PTT) 和电位质量滴定 (PMT) 研究所得磷酸盐的酸碱表面化学。检查表面电荷随接触时间的变化，Q 是 T 的函数，用于在 0-72 小时范围内变化的时间接触。用于此目的的质量悬浮液为 0.75、1.25 和 2.5 g L-1。零电荷点 (PZC) 和等电点 (IEP) 使用微分方法定义，检查变化 $$\frac{{{\text{dpH}}}}{{{\text{d}}t}} = f\left( {{\text{pH}}} \right)$$ ，接触时间较短。观察到 PZC 和 IEP 向低值移动，发现分别为 2.2 ± 0.2 和 1.8 ± 0.1。在酸性条件下，合成磷酸盐的表面电荷行为由 $$\overline{{ > {\text{POH}}}}$$ 基团控制，pKa = 2.45 ± 0.15。对 NaCl 电解质中合成的 Fe2 (HPO4)3*4H2O 进行 Q 对 T 滴定法。在低固体悬浮液中实现最大表面电荷 (Q)。因此，对于 m = 0.75 g L-1，50 库仑的 Q 值在 μ = 0.1 和 pH 值约为 12 时进行，而在 pH 值范围内达到约 22 库仑的电荷值：3-10。充分评估了活化时间、Q 和 pH 值对磷酸铁中钠插入的影响。为了确定研究过程的最佳条件，