By Dr. Eyo Eyo, who runs the website https://eyowhite.com/
Wetlands are known to be one of the most valuable and yet vulnerable ecosystems on our planet. They help sustain the environment through critical services such as flood control, water purification, and carbon sequestration.
Unfortunately, many wetlands are under serious threat from various forms of contamination and pollution. This turn of events has no doubt disrupted and endangered the life of plants and animals that rely on wetlands. In the face of these challenges, research has in recent times discovered the potential for fruit peels to save the wet habitats.
What is a Wetland?
A wetland is an area of land that is either covered by water or saturated with water. Wetlands can be found in various climates, on every continent except Antarctica. They are known by different names such as swamps, peatlands, sloughs, marshes, muskegs, bogs, fens, potholes, and mires. In some wetlands that experience seasonal dryness or have slow-moving water, trees and other robust vegetation can thrive.
Threats to Wetlands
Wetlands are facing significant threats, making them one of the most endangered habitats on Earth. These dangers not only lead to a decrease in biodiversity but also put millions of lives at risk as wetlands serve as a vital source of drinking water. Global data suggests that approximately 83% of freshwater species are experiencing decline. Additionally, it is estimated that 40% of the world’s species depend on wetlands in some capacity, and the loss of these crucial areas is pushing many of these species towards extinction.
Pollution is a significant contributor to the destruction of wetlands. 80% of our worldwide wastewater is discharged into wetlands without any treatment. The pollution comes from various sources such as factories, fertilisers, pesticides, and large-scale spills, all of which pose grave dangers to wetland ecosystems.
Although it is fair to say that the natural courses of activities in the wetlands make them act as self-purifiers by helping to remove pollutants from the water. However, the current pace of developmental activities, industrialisation, urbanisation, etc have almost made it impossible for wetlands alone to play its role as natural purifiers.
Nevertheless, research has shown that natural compounds in fruit peels, such as pectin and cellulose, have the remarkable ability to adsorb pollutants from water thus restoring the health of these vital ecosystem. The use of fruit peels as absorbents for contaminants does certainly offer an environmentally friendly cost-effective, and sustainable solution to a growing problem.
The Adsorptive Power of Fruit Peels
Adsorption is a physical method of remediation that involves contaminants attaching to a solid surface. This technique is straightforward, affordable, and has minimal impact on the environment, making it an appealing choice for cleaning up polluted wetlands. Different types of adsorbents have been used for this purpose, such as synthetic materials, natural inorganic substances, and natural organic materials.
Synthetic adsorbents, although effective, are expensive and non-degradable, and this limits their sustainability potential. Natural inorganic adsorbents have limited buoyancy and lower sorption capacities, making them less suitable for environmental cleanup. However, natural organic adsorbents derived from renewable sources like agricultural waste and fruit peels are a great option for wetland remediation. They are cost-efficient, non-toxic, non-corrosive, fully active upon recycling, and contribute to a more sustainable approach to cleaning up wetlands.
Agricultural waste, such as fruit peels, has gained recognition for its potential as a material that can adsorb contaminants. With around 5 billion metric tons of agricultural waste generated globally each year, fruit peels are easily accessible and can be used to remove pollutants from the environment. For example, orange peels alone contribute approximately 32 million tons annually, making them a valuable resource in efforts to clean up our surroundings.
The porous structure and chemical composition of fruit peels enable them to effectively remove contaminants. These peels contain various functional groups, including carboxyl groups, which have the ability to bind with contaminants.
Orange Peels: A Promising Adsorption Material
Extensive research has been conducted on the ability of orange peels to adsorb contaminants, with a particular focus on heavy metals and dyes. However, their potential for oil adsorption has also been recognised.
While the adsorption capacity of orange peels may be lower compared to some other materials, it is still significant and offers advantages due to their low water uptake and abundance in nature. The structure of orange peels plays a crucial role in determining their adsorption capabilities.
Smooth surfaces generally have lower adsorption capacities compared to rough and porous structures, which provide more active sites for contaminant adsorption. Therefore, modifying the surface of orange peels through physical, chemical, and thermal processes can greatly enhance their ability to absorb contaminants.
Increasing the surface area of orange peels through physical methods can improve their rate of absorption. Finer particles result in larger surface areas and higher sorption capacities. In addition, heating orange peels at high temperatures increases porosity and surface area; however, extreme conditions can reduce their ability to absorb contaminants.
Chemical modification of orange peels involves treating them with bases like sodium hydroxide to convert methyl esters into carboxylates. This chemical transformation enhances structural properties such as porosity and roughness, leading to increased absorption capacities.
Carboxylic groups and pectin are identified as major functional groups responsible for absorbing contaminants in orange peels. Efficient absorption capacities can be achieved by combining chemical and thermal methods. This dual approach results in increased surface area, rough structures, and additional pore spaces within orange peels that enhance their ability to bind with contaminants.
Studies have demonstrated that modified fruit peels exhibit significantly higher absorption capacities than raw fruit peels. For instance, one study found that modified orange peel had an absorption capacity of 107.53 mg/g for lead—much higher than the absorption capacity of raw orange peel (3 mg/g).
Using fruit peels, especially orange peels, as natural adsorbents for wetland remediation provides a sustainable and affordable solution to the increasing issue of environmental contamination. The plentiful supply, low expense, and capacity to alter their surface characteristics make them highly promising options for eliminating different pollutants from polluted water sources.
Some factors to consider when using fruit peels for the cleanup of polluted wetlands:
- The effectiveness of fruit peels varies depending on the type used. For instance, orange peels are more efficient in removing heavy metals compared to banana peels.
- The method used to modify the fruit peels will also affect their effectiveness.
- The quantity of fruit peels required to remediate a polluted wetland will vary based on the extent of the contamination.
- Fruit peels should be used alongside other remediation techniques like dredging and bioremediation.
About the Author
Dr. Eyo Eyo is lecturer and researcher in sustainable science and engineering at the University of the West of England, United Kingdom. He is also a regular contributor to the Firoz Lalji Institute for Africa (FLIA) at the London School of Economics and Political Science (LSE) blog and the Elephant.info.
Learn more at his website: https://eyowhite.com/