Designing of biosafe, multifunctional alginate-nanoclay hydrogels for environmental applications: structure, swelling properties, and cadmium sorption
N.V. Guzenko, Olena Goncharuk, Yu. M. Samchenko, Konrad Terpiłowski, Katarzyna Grygorczuk-Płaneta, S. М. Dybkova, Bartosz Kondracki, Katarzyna Szewczuk‐Karpisz
Abstract
Composite hydrogels (HGs) based on sodium alginate (Alg), with nanoclay montmorillonite (MMT) and LaponiteRD (Lap) fillers, were synthesized using ionic cross-linking with calcium ions (Ca 2+ ). The HGs structure was investigated by SEM-EDX, XRD, and FTIR, whereas сation exchange capacity (CEC) and variable surface charge were determined using potentiometric titration. The influence of filler content, cross-linking agent concentration, and pH on the swelling and sorption capacity towards cadmium ions (Cd 2+ ) of HGs was analyzed in detail. The cross-linking agent concentration influenced the swelling mechanism of the alginate-based composites with clays as well as their specific type of water diffusion based on the Fick equation. The CaCl 2 concentration ( C CaCl2 ) of 0.3–0.5 wt% was found as optimal for synthesizing mechanically stable HGs with a large swelling degree and sorption ability for Cd 2+ ions. The sorption capacities calculated based on the Langmuir model were 1.36, 1.19, and 1.33 mmol/g for Alg, Alg/20%MMT, and Alg/20%Lap synthesized using 0.3 wt% CaCl 2 , respectively. The in vitro tests on genotoxicity and cytotoxicity of HGs, performed using the mouse fibroblast cell culture L-929, proved the biosafety of the developed composites for the environment. • Alginate-based hydrogels (HGs) were filled with two types of nanoclays. • Cross-linker concentration of 0.25 wt% provided maximum swelling for all systems. • HGs showed a great sorption activity and affinity for cadmium (Cd) ions. • The greatest efficiency of Cd removal was noted for HG with laponite (even 97.8 %). • All tested HGs were biosafe in terms of cytotoxicity and genotoxicity assays.