Optimization of water removal from oil by eggplant stems using response surface methodology

Eggplant stems are among the most produced organic wastes. Unfortunately, the burning and irregular storage of eggplant stems outdoors causes both global air pollution and environmental pollution. Environmental impacts can be minimized by recycling eggplant stems, turning them into valuable products and using them as valuable additives. In this study, the water-binding capacity (WBC) and water-binding capacity in oil (WBCO) potential of eggplant stems was investigated. In the first step, optimization of the alkaline treatment of eggplant stems was carried out. Alkaline treatment optimization parameters such as sodium hydroxide (NaOH) concentration (0.050, 0.125 and 0.200 M), temperature (20, 40 and 60 degrees C) and reaction time (30, 90 and 150 min) were investigated using response surface methodology. In the second stage, WBC and WBCO tests of eggplant stems were carried out. According to the experimental results, capacity efficiencies of 30.64 and 98.20% were obtained for WBC and WBCO, respectively, at 0.125 M sodium hydroxide concentration, 60 degrees C temperature and 150 min reaction time. In addition, eggplant stems demonstrated the ability to retain water effectively for up to five cycles. The high WBC of eggplant stems in oil after alkali treatment showed that they could be a suitable and inexpensive candidate for use in biodiesel purification and methane production.