Abstract In this paper, we used the semiconducting and lightfastness properties of synthetic and mineral arsenic sulfide pigments to study their stability by means of electrochemical and microfadometric techniques. A combination of these techniques shows that in the early stage of the degradation process, amorphous arsenic sulfides are more stable than both crystalline forms, while upon longer exposure time, amorphous pigments will fade more than both mineral pigments, making it less suitable. While the stability study was carried out on unbound pigments, the influence of the organic binder on the relative degradation of the arsenic sulfide pigments was investigated through a multi-analytical approach on pigment/binder mock-up paint samples. For this purpose, the formation of arsenic trioxide was assessed by micro Fourier transform infrared (μ-FTIR) spectroscopy while the influence of the binder on the formation of sulfates was studied by means of synchrotron radiation X-ray near edge structure (μ-XANES). Both techniques elucidate a higher stability of all pigments in gum arabic while the use of egg yolk as binder leads to the most degradation, most likely due to its sulfur-rich composition. In the context of the degradation of arsenic sulfide pigments, other binders such as animal glue, egg white or linseed oil show an intermediate impact.

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通过光谱和电化学技术评估硫化砷颜料的稳定性和结合介质对其降解的影响

摘要 在本文中，我们利用合成和矿物硫化砷颜料的半导体和耐光性，通过电化学和显微技术研究了它们的稳定性。这些技术的组合表明，在降解过程的早期阶段，无定形硫化砷比两种结晶形式更稳定，而在更长的暴露时间后，无定形颜料比两种矿物颜料褪色得更多，使其不太适用。在对未结合颜料进行稳定性研究的同时，通过对颜料/粘合剂模型涂料样品的多分析方法研究了有机粘合剂对硫化砷颜料相对降解的影响。以此目的，通过微傅立叶变换红外（μ-FTIR）光谱评估三氧化二砷的形成，而通过同步辐射X射线近边缘结构（μ-XANES）研究粘合剂对硫酸盐形成的影响。这两种技术都阐明了阿拉伯树胶中所有颜料的更高稳定性，而使用蛋黄作为粘合剂导致降解最多，这很可能是由于其富含硫的成分。在硫化砷颜料降解的背景下，其他粘合剂如动物胶、蛋清或亚麻籽油显示出中等影响。这两种技术都阐明了阿拉伯树胶中所有颜料的更高稳定性，而使用蛋黄作为粘合剂导致降解最多，这很可能是由于其富含硫的成分。在硫化砷颜料降解的背景下，其他粘合剂如动物胶、蛋清或亚麻籽油显示出中等影响。这两种技术都阐明了阿拉伯树胶中所有颜料的更高稳定性，而使用蛋黄作为粘合剂导致降解最多，这很可能是由于其富含硫的成分。在硫化砷颜料降解的背景下，其他粘合剂如动物胶、蛋清或亚麻籽油显示出中等影响。