Removal of Oil Spills on Water Using Biochar of the Fruit of Cerbera manghas (Wel Kaduru)

Abstract

Marine ecosystems and inland surface water are important in maintaining the natural environmental balance, yet pollution, especially oil spills, has become a serious concern recently. Natural sorbents have emerged as a sustainable solution for oil spill removal, mainly due to their low-cost, availability, biodegradation, and buoyancy. Through this research, the capability of Cerbera manghas (Wel Kaduru in Sinhala) fruit, a natural sorbent and waste material, was investigated for oil spill removal. The efficiency of biochar produced by this natural sorbent was optimized for dosage, size, pore morphology, contact time, oil type, oil volume and salinity. Maximum adsorption capacities for crude, engine and motor oils are in the range of 4.90 +/- 0.00 and 11.10 +/- 0.03 g oil/g biochar, highlighting the fact that the maximum capacity strongly depends on the oil type. Moreover, with the variation of the biochar dosage, the maximum adsorption capacity ranges from 7.40 +/- 0.01 to 10.50 +/- 0.02 g oil/g biochar, indicating that the extent of oil adsorption increases with the biochar dosage. Variation of the contact time leads to maximum adsorption capacities within 30 ‒ 45 min. Oil removal is affected by the sorbent size, suggesting that smaller sizes are more effective. Another important aspect is that oil-adsorbed biochar can be used for energy production, as determined through temperature measurements, and residual ash could be used for dye removal. This highlights that oil-adsorbed biochar can also be utilized effectively without direct disposal. This adsorption process neither fits the Langmuir nor the Freundlich isotherm model, indicating multilayer adsorption and hydrophobic behavior. Functional groups determined by FTIR, surface images observed through SEM and metallic constituents detected by XRF aid mechanistic interpretation of oil removal. Overall, this biochar offers an effective approach to cleanup oil spills in water sources in a practical and sustainable manner.