Green and simple approach for flotation, preconcentration and enhanced spectrophotometric assessment of Ni(II) in aqueous solution by complexation with 1-(3,5-dihydroxybenzylidene)thiosemicarbazone

Abstract

In the current work, 1-(3,5-dihydroxybenzylidene)thiosemicarbazone (H3L) was produced under mechanochemical ball milling conditions using para-toluenesulfonic acid (p-TSA) as a catalyst in a solvent-free reaction. The generated material was characterized using a number of physical and spectroscopic methods. The synthetic material was also tested as an effective organic chelating agent in the flotation, preconcentration, and spectrophotometric measurement of Ni(II) in aqueous solutions, where H3L reacted with Ni(II) to produce a coffee colored complex. Oleic acid (HOL) was used as a foaming agent to help the complex that was generated float to the scum layer. The concentration of Ni(II) was assessed using a spectrophotometer at 370 nm. The several factors that impact the flotation-separation process were evaluated and adjusted, including pH, the concentration of (Ni(II), H3L, and HOL), surfactant type, sample volume, temperature, shaking duration, and ionic strength. Nearly 100% of Ni(II)-H3L were successfully separated at 25 °C and pH 5 after 5 min of shaking. Utilizing the molar ratio approach, the stoichiometric ratio of the produced complex was determined to be (1:2) of M:L. The formation constant (Kf) was determined as 2.25 × 104. The analytical characteristics of the procedure (limit of detection, limit of quantification, and range of linearity) were evaluated and found to be (0.22 ng/mL, 0.74 ng/mL, and 5–400 ng/mL), respectively. The suggested method was employed to separate Ni(II) that had been spiked into some real water samples. Ni(II) was successfully preconcentrated from different aqueous volumes with a preconcentration factor of 200. Finally, the mechanism for the flotation-separation process was suggested.