Modification and characterization of hydrogel beads and its used as environmentally friendly adsorbent for the removal of reactive dyes

Abstract

An environmentally friendly hydrogel (R-L-Gel) beads adsorbent was prepared and modified from rabbit skin gelatin by sol-gel methods. It was characterized and applied for the adsorption of reactive brilliant orange X-GN (RO X-GN) and reactive brilliant blue KN-R (RB KN-R) dyes. The mean diameter of R-L-Gel beads synthesized by L-Arginine (L-Arg) were 4.78 mm, it has smaller surface pores (12.47 μm), larger surface area (2.681 m2/g), closer three-dimensional network structure, stronger intramolecular connection, improved thermal stability, strong structural stability, and higher isoelectric point (6.75). Batch adsorption experiments were performed to analyzed the effect of pH, adsorption kinetics and isotherm model. The maximum adsorption capacity of both dyes reached about 340.55 mg/g at pH 3, and adsorption behavior was more consistent with pseudo-second-order kinetics and Freundlich isotherm equation. R-L-Gel beads had high adsorption capacity, low swelling rate (SR = 872%) in the pH = 3, and moderate reusability. In addition, the beads loaded with reactive dyes (R-L-Gel-O/B) could adsorb again methylene blue (MB) and basic fuchsin (BF) dyes, and the adsorption capacity reached 185.55 mg/g and 271.01 mg/g, respectively. R-L-Gel beads had good application effect on mixed dyes wastewater, the decolorization rate (DR) reached 70%, After adsorption, the swelling rate of R-L-Gel and R-Gel beads were 2003%, 6060% and compressive strength was 0.395 and 0.058 MPa respectively. which was expected to become an excellent adsorbent in the water treatment industry.