For improving the dispersion of iron oxide yellow pigments (FeOOH) in organic solvents, a layer of silica was coated on the surface of FeOOH, and then further modified by silane coupling agent, as a heterogeneous coating was formed on the surface of FeOOH. The modified FeOOH was characterized by TEM, XRD, IR, XPS, TG-DTA, and zeta potential. The dispersibility of modified FeOOH under different conditions was also studied. After coating and modification, a coating layer about 5 nm was formed on the surface of FeOOH. XRD results showed that sodium silicate and KH560 modified did not change crystal structure of FeOOH, even the SiO₂ coating layer existed in amorphous form. The FeOOH was bound with SiO₂ and silane coupling agent by chemical bond, based on the IR and XPS analysis. The heat resistance of FeOOH was slightly improved after coating. When the amount of SiO₂ modified in surface coating was 8% of the mass of FeOOH, the modification time range from 1 to 1.5 h, temperature was between 60°C and 80°C, the pH value was 7–8, and the dispersibility of FeOOH in water was significantly improved. The zeta potential test showed that the surface of FeOOH/SiO₂ was negative, and its dispersibility in water was improved because the absolute value of zeta potential increased. The dispersibility of FeOOH/SiO₂ was related to the structure of coupling agent. After modification with KH560, the dispersion rate increased from 14.49% to 88.0%, which improved the dispersibility in organic solvents.

中文翻译：

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包覆氧化铁黄颜料的表面改性和结构分析以提高在有机溶剂中的分散性

为改善氧化铁黄颜料（FeOOH）在有机溶剂中的分散性，在FeOOH表面包覆一层二氧化硅，然后用硅烷偶联剂进一步改性，在FeOOH表面形成异质涂层。改性的 FeOOH 通过 TEM、XRD、IR、XPS、TG-DTA 和 zeta 电位进行表征。还研究了改性 FeOOH 在不同条件下的分散性。经过包覆和改性后，在FeOOH表面形成了约5nm的包覆层。XRD结果表明，硅酸钠和KH560改性没有改变FeOOH的晶体结构，即使SiO ₂涂层以非晶形式存在。FeOOH 与 SiO ₂结合和硅烷偶联剂通过化学键，基于 IR 和 XPS 分析。涂覆后FeOOH的耐热性略有提高。当表面涂层中SiO ₂改性量为FeOOH质量的8%时，改性时间为1～1.5 h，温度为60～80℃，pH值为7～8， FeOOH在水中的分散性显着提高。zeta电位测试表明FeOOH/SiO ₂表面为负值，由于zeta电位绝对值增加，其在水中的分散性提高。FeOOH/SiO ₂的分散性与偶联剂的结构有关。用KH560改性后，分散率从14.49%提高到88.0%，提高了在有机溶剂中的分散性。