A new facile process to remove Br~- from waste printed circuit boards smelting ash: Thermodynamic analysis and process parameter optimization

摘要

Waste printed circuit boards smelting ash (WPCBs-SA) is generated by the smelting process of waste printed circuit boards (WPCBs), which contains valuable metals, such as copper (Cu), zinc (Zn), and sliver (Ag), and a large amount of harmful bromide (Br-). In this work, a facile sulfation roasting (SR) proposed for the removal of Br- from WPCBs-SA with high efficiency. The thermodynamic analysis is systemically investigated, and the results demonstrate that Br- in WPCBs-SA is converted into HBr or Br-2 comfortably below 564.8 K during the SR process. The influences of essential variables such as the ratio of sulfuric acid into smelting ash, roasting temperature and time are systematically investigated, and the variables are also optimized via response surface methodology (RSM). Under the optimized experimental conditions, the Br- removal efficiency reached up to 98.97%, and the values of the three variables were 0.8 g/g, 590.04 K and 123.25 min, respectively. The proposed RSM model equation shows a good correlation with the experimental data, with a correlation coefficient (R-2) of 96.05%. This work will be a new method to enrich the harmful elements of WPCBs-SA and reduce the potential environmental pollution of related hazardous wastes. (C) 2020 Elsevier Ltd. All rights reserved.