Loofah plant—Derived biodegradable superhydrophobic sponge for effective removal of oil and microplastic from water

Recently, oil spills and microplastic have become vital worldwide environmental issues. In this study, inspired by the natural phenomenon, two types of biodegradable superhydrophobic sponges derived from the loofah plant were fabricated to deal with those contaminants. Loofah is a niche vegetable for food and eco-sponges and is very popular in Europe and Asia. A facile fabrication process is carried out with dip-coating techniques, which help to functionalize the surface of the natural loofah sponge with two types of natural wax (bee wax and palm wax). The fabricated materials named LS-B(2) and LS-P(2) showed excellent superhydrophobicity with a high water contact angle, which was fundamental for separating oil in the water mixture and capturing microplastics. The derived superhydrophobic sponges displayed a high oil absorption capacity in the range of 72 – 81 g.g-1 for LS-B(2) and LS-P(2). The separation efficiency reached over 99 % for the immiscible kerosene/water mixture and the fabricated material's excellent recyclability via simple squeezing. The sponges also can capture the microplastics at different concentrations with very high adsorption capacity (381–569 mg/g), reaching over 99% polystyrene microplastics from aqueous suspensions under continuous stirring conditions. With the natural abundance of the base material in nature and the ease of the fabrication process, this work could open the novel direction for a low-cost, high-performance, and large-scale application material in the future toward environmental sustainability.