Scientists from Saudi Arabia, Egypt, and the Sultanate of Oman have collaborated on a paper exploring the use of natural sorbents to tackle marine oil spills, a critical environmental issue. Their work has appeared in the journal Chemical Data Collections.
Study: Adsorption study of oil spill cleanup from sea water using natural sorbent. Image Credit: ImageBank4u/Shutterstock.com
Marine Oil Spills
Petrochemicals such as oil are used in a myriad of products such as energy, domestic fuel, and plastics. Modern industrial society has been built on fossil fuels, and their use has made possible the huge progress of the past few centuries.
Their use comes with serious drawbacks, however. Carbon emissions have been intrinsically linked with climate change, rising global temperatures, environmental disasters of increasing severity, and polar ice cap melting. Furthermore, petrochemicals and their products are one of the main causes of environmental pollution.
Marine oil spills in particular are incredibly damaging to the environment and coastal communities and are expensive to clean up, requiring massive operations to remediate. They can severely impact marine biodiversity, causing mass death of animals and plant life, and can have effects on the food chain. They can have an impact on the livelihoods of millions of people living along the coasts.
Cleaning Up Oil Spills
Due to the deleterious short and long-term effects of marine oil spills, strategies to clean them up have been an area of intense research focus over the past several decades. Numerous methods have been explored, such as mechanical skimming, microbial decomposition, and adsorption.
Several organic materials have been explored in studies for absorbing oil, such as wood chips, sugarcane bagasse, bark residues, and hemp fibers, which have demonstrated high capacities. Agricultural wastes have been extensively investigated due to benefits such as abundance, biodegradability, non-toxicity, low cost, and renewability.
There are drawbacks to using these waste materials for adsorption strategies, however. Their use can generate solid oil waste, which can be expensive to remove. This problem can be mitigated by using the resulting waste materials as biomass for power generation purposes.
The authors investigated the suitability of Lawsonia leaves, a natural sorbent, for oil spill cleanup. This plant is abundant in the Arab world, which has some of the most polluted seas in the world. These semi-closed seas are not regularly replenished, leading to the accumulation of harmful contaminants that affect the large coastal populations along them.
The leaves were washed in distilled water and dried for twenty-four hours at 80 oC to prepare them. A fine mesh was produced from the Lawsonia leaves after preparation. Waste motor oil and simulated seawater were used to evaluate the effectiveness of using Lawsonia leaves for oil adsorption purposes.
Lawsonia biomass was steeped in the oil/simulated seawater mixture until equilibrium. Once equilibrium was reached, the biomass was removed, drained for three minutes, and re-weighed. The biomass was then dried for twenty-four hours at 85 oC. Oil was desorbed with the use of a high-speed centrifuge.
Contact angle measurements and FT-IR analysis were used in the study to characterize the materials. Contact angle measurements revealed the hydrophobic nature of the biomass material and oil spread over the biomass’s surface, demonstrating hydrophilicity.
FT-IR analysis revealed that the sorption properties of the biomass is governed by its cellulose structure and hemicelluloses. The authors also conducted kinetic studies and sorption isotherm analysis. Thermodynamic studies confirmed that the method works best at low temperatures.
Evaluating the economic feasibility of reusing this abundant biomass was one of the main aims of the study. The economic feasibility of using Lawsonia sorbents was demonstrated adequately in the study. It was observed that removal efficiency was reduced over several absorption/desorption cycles. After four cycles, the removal efficiency was under 40%.
Sorption capabilities were compared to other agricultural wastes which have been studied for oil sorption. Results indicated that the adsorption efficiency of Lawsonia leaves is comparable to other agricultural biomass, demonstrating its suitability for oil cleanup purposes.
Due to the abundance and renewability of Lawsonia leaves, they can be considered a cost-effective sorption biomass for industrial-scale marine oil spill cleanup. This biomass is particularly beneficial for the Arab world due to the local availability.
The economic and commercial viability of spent biomass is further enhanced by using it as a value-added product (solid fuel) to meet the energy demands of multiple industries such as power generation and heavy manufacturing. This will also address environmental concerns due to oil-contaminated biomass and fits the aims of the circular economy.
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Mahmoud, M.A et al. (2022) Adsorption study of oil spill cleanup from sea water using natural sorbent Chemical Data Collections 100896 [online, pre-proof] sciencedirect.com. Available at: https://doi.org/10.1016/j.cdc.2022.100896
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