Waste X-ray radiographic films contain an appreciable amount of silver (Ag) that can be recovered and reprocessed. Most of the existing methods of Ag recovery from waste radiographic films are expensive and harmful to the environment. In this study, the extraction of Ag from waste radiographic films was done using oxalic acid solution heated at 90–100 °C. XRD and SEM results reveal that the recovered residue contains pure metallic Ag spherical microparticles. According to the response surface methodology (RSM) based on three-level, three-factorial Box-Behnken design, the optimized stripping conditions are oxalic acid concentration of 9.97% w/v, extraction temperature of 99.51 °C, and extraction time of 16.62 min. The predicted and actual % Ag recovery are of 94.94 and 90.07%, respectively. Reusability study confirms that the oxalic acid solution can be reused for several runs of Ag extraction. Initial Ag recovery of ~68.9% decreased to ~28.2% after 4 cycles of reusing the extraction solution.

废X射线照相胶片包含可回收和再处理的相当数量的银（Ag）。从废射线照相胶片中回收银的大多数现有方法昂贵且对环境有害。在这项研究中，使用加热在90–100°C的草酸溶液从废射线照相胶片中提取银。XRD和SEM结果表明，回收的残留物中含有纯金属Ag球形微粒。根据基于三级三因素Box-Behnken设计的响应面方法（RSM），最佳的反萃条件为草酸浓度为9.97％w / v，萃取温度为99.51°C，萃取时间为16.62分钟 预计的和实际的Ag回收率分别为94.94和90.07％。可重复使用性研究证实，草酸溶液可重复用于多次银提取。在重复使用提取溶液的4个循环后，最初的〜68.9％的Ag回收率降低至〜28.2％。