Effect of Graphite on Copper Bioleaching from Waste Printed Circuit Boards

Abstract

The efficient extraction of copper as a valuable metal from waste printed circuit boards (WPCBs) is currently attracting growing interest. Here, we systematically investigated the impact of bacteria on the efficiency of copper leaching from WPCBs, and evaluated the effect of graphite on bioleaching performance. The HQ0211 bacteria culture containing Acidithiobacillus ferrooxidans, Ferroplasma acidiphilum, and Leptospirillum ferriphilum enhanced Cu-leaching performance in either ferric sulfate and sulfuric acid leaching, so a final leaching of up to 76.2% was recorded after 5 days. With the addition of graphite, the percentage of copper leaching could be increased to 80.5%. Single-factor experiments confirmed the compatibility of graphite with the HQ0211 culture, and identified the optimal pulp density of WPCBs, the initial pH, and the graphite content to be 2% (w/v), 1.6, and 2.5 g/L, respectively.

Leaching of Copper from Waste-Printed Circuit Boards (PCBs) in Sulfate Medium Using Cupric Ion and Oxygen

“…Leaching processes of PCBs have been examined using hydrogen peroxide (H 2 O 2 ) [11][12][13][14], ammonia solution [10,[14][15][16], HNO 3 [16][17][18], halogen [16,17,19,20], glycine [12,13], and ionic liquid [21]. Bacterial leaching processes of PCBs have also been reported as environment-benign processes, where Phanerochaete chrysosporium [22], Acidithiobacillus ferrooxidans [23], Leptospirillum ferriphilum or its mixed culture Metals 2021, 11, 1369 2 of 11 with Acidithiobacillus ferrooxidans [24][25][26], and Frankia sp. [27] were used for Cu leaching.…”

Bioleaching of Typical Electronic Waste—Printed Circuit Boards (WPCBs): A Short Review

“…In the case of sphalerite, graphite has been found to influence microbial populations [ 82 ]. Tong et al [ 83 ] investigated the effect of graphite on leaching behavior of WPCBs. In the absence of graphite, the copper leaching rate was 90% after 5 days.…”