A new environmentally friendly and economical recycling process for extracting metals from spent lithium-ion batteries (LIBs) using sulfuric acid and malonic acid as leaching agents is proposed. By applying Box−Behnken design (BBD) and response surface methodology (RSM) optimization techniques, the global optimal solution of the maximum leaching rate of metals in spent LIBs is realized. The results show that under the optimal conditions of 0.93 M H 2 SO 4 , 0.85 M malonic acid, and a liquid/ solid ratio of 61 g•L −1 , a temperature of 70 °C and 5 vol % of 30% H 2 O 2 , 99.79% Li, 99.46% Ni, 97.24% Co, and 96.88% Mn are recovered within 81 min. The error between the theoretical value and the actual value of the metal leaching rate predicted by the regression model is less than 1.0%. Additionally, the study of leaching kinetics reveals that the leaching process of Li, Ni, Co, and Mn in spent cathode materials was affected by the synergistic effect of interfacial mass transfer and solid product layer diffusion. Economic analysis reveals that evaluation index should be fully considered when formulating recovery processes for different metals. This process can reduce the environmental risks of heavy metal disposal and allow the reuse of metals recovered from spent LIBs.

Sodium hydrogen sulfate (NaHSO3) in aqueous solution was sprayed on bell pepper (Capsicum annuum) plants beginning at first anthesis to test its effects as a photorespiration represser and resulting effects on yield. NaHSO3 sprays promoted plant height, stem diameter, fruit number and plant weight and increased the net assimilation rate, thus increasing yield. Concentrations of 60, 100, 120, 130, 200, 240 and 300 ppm were all effective, with 200 ppm optimum. Sprays repeated for three times at 7 day intervals were more effective in increasing growth and yield of bell pepper than spraying once or twice. This technique has gained acceptance as a practical method for improving production of bell pepper in Northeast China. Additional research is underway to further refine this practice.