A general chemistry laboratory experiment using readily available chemicals is described to introduce college students to an exciting class of nanocomposite materials. In a one-step room temperature synthetic process, magnetite nanoparticles are embedded onto activated carbon matrix. The resultant nanocomposite has been shown to combine the adsorption ability of the activated carbon and the magnetic properties of the magnetite nanoparticles, enabling its application as a fast, effective, low-cost, and recyclable aromatic water pollutant adsorbent. This quality is illustrated by its rapid removal of the surrogate "pollutants", made of several dyes in the Fisher universal indicator, within 2-3 min. A successful "pollutant" removal is indicated by the absence of the rainbow colors because of the presence of the "pollutants" in the "polluted" water when different quantities of an acid or a base are added. The nanocomposite's reusability as the "pollutant" adsorbent is demonstrated after its used surface is regenerated using ethanol as the extracting solvent. The exercise allows students to (i) gain awareness of timely environmental issues; (ii) be exposed to the modern field of nanoscience; and (iii) appreciate the roles new and advanced materials play in keeping our water clean. Students have fun working in the lab and find the experience interesting and motivating. The experiment is also suitable for advanced high school students.