Evaluation of desalination capacity based on activated carbon materials from agricultural by-products: Pomelo peel, jackfruit peel, and pineapple peel

Research on utilizing waste by-products such as coconut shell, pomelo peel, mango peel, pineapple peel, jackfruit peel, and mangosteen peel to produce activated carbon for desalination is a potential and sustainable direction. In the research, activated carbons from jackfruit peel, pomelo peel, and pineapple peel were activated with NaOH and heat-treated by the microwave method. The structure of activated carbon from agricultural by-products has some characteristics analyzed by scanning electron microscopy, Brunauer−Emmett−Teller analysis, and Fourier transform infrared spectroscopy. Remarkable results include a large surface area; porous structure with many capillaries; the surface of activated carbon having many functional groups such as −OH, −COOH, and −CO; and an amorphous structure. The best adsorption conditions were recorded with 2.794 and 2.588 mg g −1 at 5 g L −1 concentration, 0.4 g L −1 dose, 30 °C temperature, 4-h time for activated carbons from pomelo peel and jackfruit peel. Similarly, activated carbon from pineapple peel had an adsorption capacity of 2.823 mg g −1 at 5 g L −1 concentration, 30 °C temperature, 5-h time, and 0.4 g L −1 dose. The salt adsorption efficiency of activated carbon from waste sources follows the pseudo-first-order kinetic model (R 2 > 0.9). The desalination process using pomelo peel and pineapple peel activated carbon followed the Langmuir and Freundlich isotherm models (R 2 > 0.95), while jackfruit peel activated carbon followed the Dubinin−Radushkevich model (R 2 > 0.96), indicating their potential application in brine treatment. In addition, activated carbons from these waste sources can be regenerated and reused in the desalination cycle; however, their efficiency tends to decrease after the third regeneration when using regenerators such as sodium hydroxide, water, and acetic acid.