Thermally treated watermelon peels (TWMP) have been utilized for the removal of methyl parathion (MP) pesticide from water by Memon et al. [173]. Maximum adsorption (99 ± 1%) was achieved for (0.38–3.80) × 10−4 mol/dm3 of MP solution, using 0.1 g of adsorbent in 20 mL of solution for 60 min agitation time at pH 6. Activated carbons prepared from waste cassava peel (an agricultural waste from the food processing industry) employing physical and chemical methods have been investigated for their efficiency in the removal of dyes and metal ions from aqueous solutions [174]. The adsorbent was found to be effective for model pollutants removal from water. The ability of pomelo peel to remove Cd(II) from aqueous solution by Saikaew et al. was investigated [175]. Cadmium removal was found to increase significantly by increasing the pH of the solution from 1 to 5. At pH 5, the cadmium removal reached a maximum value. The equilibrium process was described well by the Langmuir isotherm model, with a maximum sorption capacity of 21.83 mg/g. The sorption was relatively quick (approximately 20 min) and adsorption kinetics followed pseudo-second-order model.