This article reports on an investigation into the ability of modified lettuce leaves to extract chromium ions from aqueous solutions. These exciting new materials were prepared via rapid (5 h) environmentally friendly synthesis routes avoiding any secondary pollution. The influence of pH, metal concentration, the adsorption of the added amount, and water temperature on the selectivity and sensitivity of the removal process was investigated. The maximum theoretical adsorption rate of modified lettuce leaves, evaluated by the Langmuir adsorption model, was 99.98%. The proposed method was applied in the determination of Cr6+ in a sample of aqueous solution and was validated by comparison with activated carbon.