Studies of Adsorption of Heavy Metals onto Spent Coffee Ground: Equilibrium, Regeneration, and Dynamic Performance in a Fixed-Bed Column

Figure 4

Adsorption-desorption cycles of Pb²⁺, Cu²⁺, and Cd²⁺ using nitric acid. Experimental conditions: 0.1 mM initial metal concentration, pH 4.5, and 25°C. Error bars represent standard deviation of triplicate measurements.