Bioleaching of copper and nickel from mobile phone printed circuit board using Aspergillus fumigatus A2DS

The recovery of metals from electronic waste was investigated by using fungal strain Aspergillus fumigatus A2DS, isolated from the mining industry wastewater. Fifty-seven percent of copper and 32% of nickel were leached (analyzed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-OES)) by the organism after one-step leaching at a temperature of 30 °C (shaking condition for 7 days). Maximum % of copper and nickel were obtained at a pH of 6 (58.7% Cu and 32% Ni), the temperature of 40 °C (61.8% Cu and 27.07% Ni), a pulp density of 0.5% (62% Cu and 42.37% Ni), and inoculums of 1% (58% Cu and 32.29% Ni). The XRD pattern of PCB showed 77.6% of copper containing compounds. XRD analysis of the leachate residue showed only 23.2% Euchorite (ASCu₂H₇O₈) and 9.4% other copper containing compounds, indicating the leaching property of the fungus. HPLC analysis of the spent medium showed the presence of different acids like citric, succinic, and fumaric acid. The FTIR spectrum showed a decrease in carboxylic stretching in the leachate produced after bioleaching using spent medium. ICPOES of the leachate obtained using spent medium showed that 61% of the copper and 35% of nickel were leached out after seven days of incubation at shaking condition and 57% of copper and 32.8% of nickel at static condition confirming acidolysis property of the strain. A. fumigatus A2DS metal absorption and adsorption ability were observed using transmission electron microscopy (TEM) and scanning electron microscopy energy dispersive X-ray (SEM-EDX) respectively. The results thus indicate that bioleaching of Cu and Ni is bioleached by A. fumigatus A2DS.