ICAPS 2024

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    Effective use of biochar from the fruit of Cerbera manghas (Wel Kaduru) in treatment of aquatic systems polluted by oil spills
    (Faculty of Science, University of Kelaniya Sri Lanka, 2024) Nishshanka, H. G. D. M.; De Silva, R. C. L
    Open oceans, other marine ecosystems, and inland surface waters are vital aquatic habitats that play a key role in maintaining the environmental balance. Pollution of these environments has become a serious concern in recent decades, with oil spills being a critical issue that needs effective remediation methods. Environmental impacts have been examined concerning the decline of mangroves, invertebrates, seabirds, marine mammals, and affects to the microbial communities. Oil spills can be cleaned up using physical, chemical, and biological methods. Skimmers, booms, and adsorbent materials are the main physical barriers and dispersants and solidifiers are the main chemicals used to treat oil spills. Biological treatments involve the use of microorganisms to degrade oil. Among these, the use of natural sorbents which is a physical method has emerged as a significant topic due to their low cost, high availability, biodegradability, ease of application, and buoyancy. Through this research, the potential use of the fruit of Cerbera manghas (Wel Kaduru), as a natural sorbent to cleanup of oil spills was studied. The fruit was selected by considering its availability mainly in the coastal as well as inland areas in Sri Lanka. Uniformly cut pieces of the dried fruit of Cerbera manghas were pyrolyzed (310–400 ℃, 20 min) in a household kiln under limited oxygen conditions to produce biochar. The efficiency of the produced biochar as a natural sorbent to remove oil was studied by varying several parameters: dosage, size, contact time, oil type, oil volume, salinity, and the effect of weathering. Variations were studied by changing a particular parameter at a time and measuring the adsorption capacities. The study examined different volumes of crude, engine, and motor oils, revealing that the maximum adsorption capacities for these oils ranged from 4.96 to 11.16 g oil/g biochar, depending on the oil type. Additionally, varying the dosage of biochar resulted in maximum adsorption capacities between 7.48 and 10.56 g oil/g biochar for each oil type, suggesting that higher biochar dosages lead to increased oil adsorption. Variation of the contact time of interaction of oil types with the biochar led to maximum adsorption capacities within 30‒45 min. Moreover, the amount of oil adsorbed on the sorbent decreased with time. Further, the extent of removal of oils was strongly affected by the size of the sorbent, as expected, suggesting that small sizes are more effective in the oil cleanup process. The oiladsorbed biochar can be subsequently used for energy production, and further, the ash remaining after burning of oil-adsorbed biochar could be used for dye removal. This adsorption process neither fits the Langmuir isotherm model nor the Freundlich model, indicating that the adsorption is a multilayer process and that the adsorbent is hydrophobic. The use of this natural sorbent would be a beneficial and an effective approach to cleanup oil spills in water sources in a practically applicable manner.