A laboratory experiment has been developed to illustrate environmental and sustainability aspects, focusing on the wastewater treatment by means of superparamagnetic nanoparticles functionalized with humic acid. The experiment, conducted by a group of high school students, involves nanoparticle synthesis and minor characterization, followed by their interaction with typical metal ion contaminants in water. Coordination chemistry concepts were explored to help students understand the experiment, using competitive agents, such as ammonia, for recovering and recycling the nanoparticles, highlighting the great affinity of humic acid for the metal ions.