A novel sustainable composite hydrogel containing nanocellulose to remove potentially toxic metals from contaminated water

Heavy metals deserve particular attention as they can cause serious health problems in living beings, such as genetic and physiologic diseases, even at low concentrations. Naturally, the need for techniques and processes to remove heavy metals from water emerges. Among those techniques, adsorption stands out because it is easy to implement, environmentally friendly, and inexpensive. This work developed a biodegradable composite corn starch-based hydrogels containing different contents of nanocellulose (CNS) (1, 3, and 5 wt%) as a reinforcement agent and chelating nanoparticles, with high adsorption capacity so that it can be used as an adsorbent in the removal of chromium and copper from contaminated waters. Starch-based hydrogel obtained crosslinked structure by modifying its spectra, crystallinity, and high thermal stability. Besides, a macroporous structure was observed, and the higher the CNS contents in the starch hydrogel matrix, the lower the specific surface area was verified, which can be listed with a greater crosslinking of the composite structure. For composite hydrogels containing different CNS contents, the hydrogel with 5 wt% nanocellulose showed adsorption capacities of 20.3 mg g-1 for copper and 3.5 mg g-1 for chromium. After the use, the hydrogels were biodegraded, showing a mass reduction of 79% (pure hydrogel) and 52% (hydrogel with 5 wt% nanocellulose) after 60 days buried in simulated soil. Thus, an environmentally friendly solution for minimizing wastewater contamination is proposed using a low-cost and eco-friendly green material.Graphical abstractGraphical representation of composite hydrogel containing nanocellulose to remove copper and chromium from contaminated water.