From banana peel to diesel sponge: A new, eco-friendly method for cleaning oil spills

Engineers from Adamson University, the University of the Philippines Diliman, and the University of Santo Tomas have successfully converted a common kitchen scrap into a powerful tool for environmental cleanup. By transforming discarded saba banana peels into a specialized biochar, the team has created a low-cost, sustainable adsorbent capable of efficiently removing diesel oil from water. This approach not only addresses the significant challenge of hydrocarbon pollution from industrial activities and accidental spills but also provides a valuable new use for agricultural waste, aligning with the principles of a circular economy.

Crafting a Superior Sorbent

The researchers produced the banana peel biochar (BPBC) using a process called slow pyrolysis, which involves heating the dried and powdered banana peels to 585.9°C in an oxygen-free environment. A suite of characterization techniques was then employed to analyze the material's properties. The analysis confirmed that the resulting BPBC possessed a highly porous structure, excellent thermal stability, and a notably hydrophobic character, meaning it repels water while attracting oil. These intrinsic properties make it an ideal candidate for selectively capturing oil-based contaminants from aqueous environments.

Putting the Biochar to the Test

To evaluate the BPBC's effectiveness, the team conducted a series of batch adsorption experiments. They systematically tested how different environmental conditions—including the amount of adsorbent, pH level, water salinity, and contact time—affected the biochar's ability to soak up diesel oil. The results were clear: increasing the biochar dosage, contact duration, and salinity level significantly enhanced the diesel oil removal. Interestingly, variations in pH between 5 and 9 had no meaningful impact on the adsorbent's performance, suggesting its utility across a range of water conditions.

Achieving Peak Adsorption Capacity

Through statistical modeling and optimization, the researchers identified the ideal conditions for maximizing diesel oil removal: an adsorbent dose of 2.5 grams per liter, a pH of 7.0, a salinity of 44,999.95 mg/L, and a contact time of 240 minutes. Under these optimal parameters, the biochar demonstrated a remarkable sorption capacity of 5.3352 grams of diesel oil per gram of adsorbent. This performance is superior to many other biochar-based adsorbents reported in scientific literature, positioning banana peel biochar as a highly competitive material for oil spill remediation.

Corresponding author Edgar Clyde R. Lopez stated, "Our work demonstrates a practical and effective way to upcycle agricultural waste into a high-value product for environmental protection. By taking something as common as a banana peel and turning it into an efficient oil adsorbent, we offer a tangible solution that is both sustainable and accessible. This research contributes a significant step toward developing greener technologies for tackling pollution and managing our natural resources more responsibly."

Understanding the Cleanup Mechanism

The investigation into the adsorption process showed that it follows a first-order kinetic model and fits the BET isotherm model. This indicates a complex mechanism where diesel oil molecules are not only physically trapped within the biochar's porous network but also form multiple layers on its surface through a combination of chemical and physical interactions. Post-adsorption analysis confirmed the presence of adsorbed diesel oil on the biochar's surface, validating its efficacy. While the study provides a strong proof-of-concept, the experiments were performed in a controlled laboratory setting with synthetic contaminated water.

The promising outcomes of this research pave the way for further development. Future work will focus on testing the banana peel biochar in real-world contaminated water sources, evaluating its potential for regeneration and reuse, and exploring methods to scale up its production. Advanced computational modeling could also provide deeper insights into the specific interactions between the biochar and oil molecules, helping to refine and enhance the adsorbent for even greater efficiency in tackling environmental pollution.

Corresponding Author: Edgar Clyde R. Lopez

Original Source: https://doi.org/10.1007/s44246-024-00100-9

Contributions: All authors contributed to the study’s conception and design. Material preparation, data collection, and analysis were performed by Jefrick Jun Daniel T. Urgel, Justin Marwin A. Briones, Emmanuel Jr. B. Diaz, Kirstin Margaux N. Dimaculangan, Kayla L. Rangel, and Edgar Clyde R. Lopez. The first draft of the manuscript was written by Edgar Clyde R. Lopez and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.