Environmentally friendly starch/alginate aerogels for copper adsorption from aqueous media. A microstructural and kinetic study

LENCINA, MARÍA S.; PIQUERAS, CRISTIAN M.; VEGA, DANIEL A.; VILLAR, MARCELO A.; DEL BARRIO, MARÍA C.

JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART A-TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING

TAYLOR & FRANCIS INC

Año: 2023 p. 1 - 13

1093-4529

This work investigated the synthesis and characterization of alginate/starch porous materials and their application as copper ions adsorbents from aqueous media. Initially, pregel aqueous solutions with different biopolymer concentrations (1, 3, and 5% w/w) and alginate contents (25, 50, and 75% w/w) were prepared. Hydrogel formation was performed by internal and external gelation methods. Finally, the drying step was done via CO2scleading to aerogels and via freeze-drying leading to cryogels. Process parameter´s influence on the final properties of materials was evaluated by BET isotherms, SEM, EDS, and TGA. Regardless the gelation method applied, interesting materials with meso- and macro-pore structure were prepared from pregel mixtures with 3% w/w biopolymer concentration and an alginate content of only 25% w/w. Low alginate content reduces the final cost of the materials. Concerning copper removal, the adsorption data were well fitted to the pseudo-second order kinetic model for aerogels and cryogels, showing aerogels the highest adsorption capacity (40 mg/g) and removal efficiency (92%). Materials demonstrated excellent reusability throughout five consecutive adsorption/desorption cycles. Hence, environmentally friendly materials with a high practical value as low-cost bio adsorbents were synthesized, having great performance in the removal of copper ions from aqueous solution.