In present paper, the influence of the initial pH and concentration of Pb²⁺ on its adsorption by the natural (NZA) and Fe(III)-modified zeolite-alginate beads (FeA) was studied. Results showed that modification of the starting materials have a positive effect on their adsorption capacities (102 and 136 mg/g for the NZA and FeA, respectively). After encapsulation, the mechanism of lead adsorption by both adsorbents was changed and ion exchange dominates. The best adsorption was achieved for initial pH > 3.8. Cation exchange capacity, structural properties, and hydrophobicity of samples were also determined, and the presence of the alginate has no significant influence on investigated properties of samples. Experiments on wastewater from tailings of lead and zinc mine Grot, Serbia, showed that after treatment with both adsorbents, the content of the most abundant heavy metals (Pb, Zn, Hg, and Mn) significantly decreased.

Indigo carmine is a commonly used industrial blue dye. To determine its concentration in a commercially available food dye composed of a mixture of indigo carmine and D-glucose, this paper characterizes it through (ATR, KBr) FTIR micro-Raman as well as UV/Vis and clock: Briggs–Rauscher (BR) oscillatory reaction methods. The indigo carmine was detected in the bulk food dye only by applying micro-Raman spectroscopy, indicating a low percentage of the indigo carmine present. This research provides an improvement in the deviations from the experimental Raman spectrum as calculated by the B97D/cc-pVTZ level of theory one, resulting in a better geometrical optimization of the indigo carmine molecule compared to data within the literature. The analytical curves used to determine indigo carmine concentrations (and quantities) in an aqueous solution of food dye were applied by means of UV/Vis and BR methods. BR yielded significantly better analytical parameters: 100 times lower LOD and LOQ compared to commonly used UV/Vis. The remarkable sensitivity of the BR reaction towards indigo carmine suggests that not only does indigo carmine react in an oscillatory reaction but also its decomposition products, meaning that the multiple oxidation reactions have an important role in the BR’s indigo carmine mechanism. The novelty of this research is the investigation of indigo carmine using a clock BR reaction, opening new possibilities to determine indigo carmine in other complex samples (pharmaceutical, food, etc.).