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Identifying and quantifying accessible nutrients in the soil are critical in agriculture since plants require particular amounts of micro and macronutrients to grow successfully. However, there is no well-defined method for quantifying macronutrients in the field at present. In this work, chitosan and chitosan-molybdate membranes were deposited onto stainless steel (SS) and carbon (C) substrates and evaluated as promising candidates for the quantification of phosphorous species available in cultivated soil. The membranes were morphologically and structurally studied by atomic force microscopy and infrared spectroscopy to determine their appearance, roughness, and chemical conformation. Electrochemical impedance spectroscopy was the electrochemical tool used to evaluate the quantification capacity of phosphorus species of the membrane-based electrodes; it was found that the chitosan-molybdate membranes deposited onto the SS/C interface presented the best performance when the electrodes change in charge transfer resistance and chemical capacitance were measured as a function of the concentration of phosphorus species available in a synthetic sample. Thus, based on the presented results, chitosan biosensors have shown the capability of attracting ionic species, which contributes to the minimization of preference zones on the surface of a sensing electrode. [ABSTRACT FROM AUTHOR]

This work presents the construction of a reversible zinc ion battery using components recovered from exhausted Zn/C primary cells. The reduced cathode material from the primary battery served as raw material to synthesize birnessite-type manganese oxide, which, when working as a cathode in conjunction with an aqueous electrolyte and a recovered zinc anode, exhibits a reversible capacity of 289 mAh g−1 at 20 mA g−1. This performance is similar to that observed for manganese oxide synthesized from potassium permanganate reagent (270 mAh g−1 at 20 mA g−1). The structural characterization shows that the material obtained from recycling activities changes its morphology and surface area due to the presence of sodium ions during the synthesis process, and these remain in their structure. These changes promote a 60% capacity lost after being cycled at different charges, compared to 26% of δ-MnO2 synthesized from permanganate reagent. The long-term stability test shows that both batteries can retain their capacity after 1000 discharge/charge cycles at a load of 1000 mA g−1. The results support the sustainability of using a primary cell residue to get an electric energy storage device again. [ABSTRACT FROM AUTHOR]