Critical water system used for decomposition and debromination of waste printed circuit board (PCBs) has two disadvantages: low value-added oil phase products and halfway debromination at low temperature condition. In this study, critical water-alcohol composite medium was found to be a promising method to surmount these disadvantages. Critical water-ethanol (CWE) and critical water-methanol (CWM) were selected as the composite medium. The temperature of CWE and CWM had a significant effect on the oil phase composition. At low temperature CWE/CWM of 300 °C, 4-(1-methylethyl)-phenol with high concentration could be recovered. CWM of 400 °C was beneficial to the generation of ether compounds and high level of anisole could be obtained, while 450 °C was beneficial to the generation of high level of multi-alkyl substituted phenol derivatives or benzene derivatives such as p-xylene. Br-free oil phase products could be obtained when the temperature of CWE/CWM ≥300 °C. Different oil phase products with high level of chemicals or chemical intermediates could be obtained by controlling the reaction conditions of CWE/CWM. It is believed that the additional value of the oil phase products derived from waste PCBs can be greatly improved by this new process.

中文翻译：

---

关键水醇复合介质在处理废印刷电路板上的应用：油相产品的特性和脱溴

用于废印刷电路板（PCB）分解和脱溴的关键水系统有两个缺点：低附加值的油相产品和低温条件下的半脱溴。在这项研究中，关键的水-醇复合介质被发现是克服这些缺点的一种有前途的方法。选择临界水乙醇（CWE）和临界水甲醇（CWM）作为复合介质。CWE和CWM的温度对油相组成具有显着影响。在300℃的低温CWE / CWM下，可以回收高浓度的4-（1-甲基乙基）-苯酚。400°C的CWM有利于醚化合物的生成，并且可以获得高含量的苯甲醚，450°C有利于生成高含量的多烷基取代的苯酚衍生物或苯衍生物（例如对二甲苯）。当CWE / CWM的温度≥300°C时，可以获得无溴的油相产物。通过控制CWE / CWM的反应条件，可以获得具有高水平化学物质或化学中间体的不同油相产物。相信通过这种新工艺可以大大提高废PCB产生的油相产品的附加价值。