Zinc leaching potential of environmentally friendly zinc sources obtained from spent batteries

The use of highly effective sources of zinc in agriculture is necessary to achieve adequate crop quality and to avoid potential environmental hazards [1]. The use of synthetic chelating agents can lead to environmental risks such as contamination by leaching into aquifers [2]. There is currently a growing interest in the use of environmentally friendly zinc sources as an alternative to traditional ones [3]. This study focused on the evaluation of the leaching capacity of different Zn sources extracted from spent batteries with H2SO4 2M, H2SO4 0.25M or environmentally friendly complexes (glycine or citrate) in comparison with the traditional ZnSO4 source. Columns of 15 cm height and 1.5 cm diameter with 25 grams of washed sand were used for this. The treatment to carry 5 mg of Zn was added to each column and covered with another 5 g of sand. A flow of 10 ml/h of 0.01 M CaCl2 solution was added from the top of the columns. The leachates were collected in 20 ml portions until a total of 400 ml. The result showed distinct trends for the added treatments. The evolution of accumulated leached Zn for each of the treatments was fitted to the logistic model. The Zn-H2SO4 0.25M treatment achieved the highest percentages of total leached Zn at 400mL, accounting for more than 98% of the leached Zn with respect to the total Zn added to the columns. This percentage was statistically higher (P˂0.05) than the rest of the treatments, among which there were no significant differences in the total leached Zn, which reached percentages of between 72.68 and 77.12% (Zn-citrate and ZnSO4, respectively).

Acknowledgments: This research has been funded by the Ministerio de Ciencia e Innovación y Universidades (MCIU), Agencia  Estatal de Investigación (AEI), and European  Union  “NextGenerationEU”  with grant number  TED2021-131198B-I00 “GREEN-AGRO-REC”.

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