Abstract
In order to improve copper leaching efficiency from the flexible printed circuit board (PCB) byAcidithiobacillus ferrooxidans, it is necessary to quantitatively measure the bacteria bioleaching copper under extreme acidic condition from flexible PCB. The inductively coupled plasma-atomic emission spectroscopy (ICP-AES) is a very accurate way to analyze metals in solution; this paper investigated the optimal conditions for copper bioleaching byAcidithiobacillus ferrooxidansfrom flexible PCB through ICP-AES. The conditions included particle size of flexible PCB powder, quantity of flexible PCB powder, initial pH of culture medium, bacteria inoculation, bacteria activation time, and quantity of FeSO4·7H2O. Prior to ICP-AES measurement, culture solution was digested by aqua regia. The experimental results demonstrated that flexible PCB contained one main metal (copper); this was associated with the structure of flexible PCB. The optimization conditions were in 50 mL medium, flexible PCB 10 g/L, particle size of flexible PCB 0.42~0.84 mm, culture medium initial pH 2.5, bacteria inoculation 5%, bacteria activation time 5 d, and quantity of FeSO4·7H2O 30 g/L. Under the optimization condition, the leaching rate of copper was 90.10%, which was 42.4% higher than the blank group. For the ICP-AES determination, it reached a conclusion that the best corresponding wavelength (nm) of copper will be 224.7 (nm).
Highlights
With the development of technology, printed circuit board (PCB) manufacturing technique has been widely improved
Traditional rigid PCB cannot be well applied in many areas because of its inflexibility, nonfolding, poor heat dissipation, and so forth
The aim of the present work was the characterization of using Acidithiobacillus ferrooxidans bioleaching copper from flexible PCB by inductively coupled plasma-atomic emission spectroscopy (ICP-AES)
Summary
With the development of technology, printed circuit board (PCB) manufacturing technique has been widely improved. Traditional rigid PCB cannot be well applied in many areas because of its inflexibility, nonfolding, poor heat dissipation, and so forth. If the flexible PCB were not recycled or treated appropriately, the heavy metals such as lead, copper, and nickel in flexible PCB would cause environmental pollution, which would be harmful to human [2,3,4]. According to its own characteristics, flexible PCB had a high metal content the three metals gold, copper, and nickel. As metals resources were increasingly scarce today, waste flexible PCB were of the same importance as waste rigid PCB, which both were good “secondary resources,” with high values, and recyclable
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