Optimization of water-binding capacity and water removal from oil by eggplant stems using response surfaces methodology

Eggplant stems are among the most produced organic wastes. Unfortunately, the burning and irregular storage of these eggplant stems outdoors causes serious damage to 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, water-binding capacity (WBC) and water-binding capacity in oil (WBCO) potential of eggplant stems were investigated. At the first step, optimization alkaline-treated of eggplant stems carried out. Alkaline-treated optimization parameters such as NaOH concentration (0.05, 0.125, and 0.2 M), temperature (20, 40, and 60 °C), and reaction time (30, 90, and 150 minutes) was investigated using response surface methodology (RSM). In the second step, both water holding capacity and water holding capacity in oil tests were performed for each experimental set. As a result of the experiments, 30.64 %, and 98.20% capacity efficiency respectively WBC, and WBOC were obtained for 0.125 M NaOH concentration, 60 °C temperature, and 150 minutes reaction time. In addition, eggplant stems have demonstrated the ability to effectively retain water for up to 5 cycles. The high water-binding capacity of eggplant stems in oil after alkali treatment shows that it can be a suitable and inexpensive candidate, especially for biodiesel purification and methane production.