Sorption experiments were conducted using glass bottles containing 0.1 g of the sorbents and 20 mL solution of metal ions or dyes, with an initial pH of about 6, initial concentration of metal ions of 300 mg/L and initial concentration of the dye solutions of 3 × 10−5 M. The glass bottles were placed on a slow-moving platform shaker (LCD Digital Linear Shaker, SK-L330-Pro, DLAB Scientific Inc., Los Angeles, CA, USA) for 5–6 h. The concentrations of metal ions in the solution, before and after sorption, were analyzed using an atomic adsorption spectrometer (AAS) (ContrAA 800 Spectrometer Analytik Jena, Jena, Germany). The concentration of dyes, before and after sorption, was determined using a UV–Vis spectrophotometer (UV–Vis SPEKOL 1300, Analytik Jena, Jena, Germany), based on the calibration curves determined at the specific wavelength of 497 nm for CR and 597 nm for DR15. The sorption capacity (SC) of the hydrogel beads was calculated with Equations (2) and (3).
where Cs = sorbed concentration of ions or dyes [g/L], V = volume of the sorption solution and m = weight of used sample [g].
where Cs = sorbed concentration of ions after 360 min (mol Me/g hydrogel beads), and M = active sites (AS) of hydrogel beads (mol AS/g hydrogel beads).
where Cs = sorbed concentration of ions or dyes [g/L], V = volume of the sorption solution and m = weight of used sample [g].
where Cs = sorbed concentration of ions after 360 min (mol Me/g hydrogel beads), and M = active sites (AS) of hydrogel beads (mol AS/g hydrogel beads).