2.1. Materials and chemicals
Spent lead acid battery pastes were provided by Hubei Jinyang
Metallurgical Co., Ltd., China. The chemical compositions of the
spent lead acid battery pastes are shown in Table S3 in
Supplementary information.
Sodium citrate (Na3C6H5O7$2H2O, 99% purity), citric acid
(C6H8O7$H2O, 99.5% purity), hydrogen peroxide (H2O2, 30% purity),
stannous sulfate (SnSO4, 99% purity) and concentrated sulfuric acid
(98% purity) were obtained from Sino-pharmaceutical Company of
China.