Adsorption removal of Brilliant green and Safranin‐O contaminants from water using a hydrogel based on carboxymethyl cellulose and sodium alginate crosslinked by epichlorohydrin

Abstract The current study investigates the adsorption properties of a chemically crosslinked hydrogel based on sodium alginate (NaALG) and carboxymethyl cellulose (CMC). The structural characteristics of the investigated hydrogel are described using information from Fourier Transform–infrared spectra, X‐ray diffraction patterns and field emission scanning electron microscopy pictures. The NaALG/epichlorohydrin (ECH)/CMC hydrogel was synthesised under optimised conditions with respect to the swelling percentage. Various reaction parameters were varied to obtain the maximum swelling percentage. The synthesised hydrogel was taken as an adsorbent in the decolorisation of Brilliant green (BG) and Safranin‐O (SO) dyes from water. According to the kinetic investigations, the decolorisation equilibrium of SO by NaALG/ECH/CMC was discovered in 4 hours (98.98%), while the removal of BG by NaALG/ECH/CMC took 6 hours (97.7%). Chemical processes were used to describe the decolorisation mechanisms, which significantly supported the pseudo‐first‐order model. NaALG/ECH/CMC hydrogel absorption was indicated to take place in monolayer adsorption form (Langmuir isotherm). The highest adsorption capacity for BG was discovered to be 864.8 mg g⁻¹ and for SO it was 193.1 mg g⁻¹, by synthesised hydrogel, where “mg” refers to the commercial colourant and not to the pure dye. Therefore, the synthesised hydrogel can be considered as a smart device for the adsorption of dye in water purification tasks.