Banana Peel Fluoride Removal in Water Columns

ISEF Category: Environmental Engineering

Subcategory: Bioremediation  ·  Difficulty: Advanced  ·  Setup: School Lab  ·  Time: 1 to 2 Months

The Hook

A banana peel can become a tiny water filter. That sounds odd, but plant waste often has surface groups that bind dissolved chemicals. Your job is to see how well it can trap fluoride as water moves through a column. The real test is not just whether it works, but how long it works before clean water starts slipping through.

What Is It?

This project studies a biosorbent, which is a natural material that grabs pollutants from water. In this case, the material comes from banana peels. You turn the peel into a packed column, then send fluoride-containing water through it and track when fluoride begins to appear in the outflow. That first sign of fluoride in the output is called breakthrough.

Think of the column like a sponge in a pipe. At first, the sponge has lots of open spots, so it catches the pollutant well. Over time, those spots fill up, and more fluoride passes through. By changing flow rate, you can test how fast water can move before the column stops doing a good job. The Thomas and Yoon-Nelson models are math tools that help describe that behavior and compare conditions.

Why This Is a Good Topic

This is a strong science fair topic because you can test one clear variable, flow rate, and measure a real treatment outcome. It connects to drinking water quality, low-cost filtration, and waste reuse. You can collect data with common lab tools, then use models to turn your results into something more than a simple before-and-after test. That gives you room to show planning, measurement, and analysis skills.

Research Questions

• How does flow rate change the breakthrough time of a banana-peel biosorbent column for fluoride removal?
• What is the effect of bed height on the fluoride adsorption capacity of the column?
• Does pre-treatment of the banana peel change the column's removal efficiency?
• To what extent does initial fluoride concentration affect the shape of the breakthrough curve?
• Which flow rate gives the best balance between removal efficiency and treatment speed?
• How does the fitted Thomas model compare with the Yoon-Nelson model for your column data?

Basic Materials

• Dried banana peels.
• Column tube or clear plastic tubing for a packed bed.
• Filter paper or mesh to hold the biosorbent in place.
• Fluoride test kit or fluoride ion-selective electrode.
• Digital scale with 0.1 g accuracy.
• Graduated cylinder.
• Beakers or collection cups.
• Funnel.
• Stirring rod.
• Distilled water.
• Sodium fluoride standard solution or fluoride test standards.
• Timer or stopwatch.
• Notebook or spreadsheet for data logging.

Advanced Materials

• Fluoride ion-selective electrode with meter.
• Peristaltic pump or syringe pump.
• Glass chromatography column or jacketed column tube.
• Vacuum oven or drying oven.
• Muffle furnace, if you plan to study ash-based treatment variants.
• Analytical balance.
• Shaker table for sorbent preparation tests.
• pH meter and conductivity meter.
• UV-Vis spectrophotometer, if using a colorimetric fluoride assay.
• Laboratory glassware for flow and sample collection.
• Software for nonlinear model fitting and regression analysis.
• Personal protective equipment and waste collection containers.

Software & Tools

• Google Sheets: Organizes breakthrough data, makes plots, and helps you compare runs.
• Python: Fits Thomas and Yoon-Nelson models and checks which model matches your data best.
• ImageJ: Measures color intensity if you use a color-based fluoride assay.
• JASP: Runs basic statistics and compares treatment groups without paid software.
• NIH PubChem: Helps you look up fluoride chemistry and related compound information.

Experiment Steps

1. Define the one column variable you will change first, such as flow rate, while keeping the rest of the setup fixed.
2. Choose a way to measure fluoride in each collected fraction and confirm that it can detect the concentration range you expect.
3. Build a plan for the packed column so the bed geometry, particle size, and support layers stay consistent across trials.
4. Design controls that separate real fluoride removal from simple dilution, leakage, or poor packing.
5. Decide how you will turn collected samples into breakthrough curves and fit those curves to the Thomas and Yoon-Nelson models.
6. Set up a comparison plan for interpreting which condition gives the best balance of capacity, speed, and model fit.

Common Pitfalls

• Packing the banana peel too tightly, which blocks flow and makes the column look better or worse than it really is.
• Using peels with uneven drying or grinding, which changes surface area from run to run.
• Measuring fluoride with a method that does not match your expected concentration range, which flattens the breakthrough curve.
• Letting the column channel water along one side, which lowers contact between the water and the biosorbent.
• Changing pH or ionic strength without tracking it, which can shift fluoride binding and confuse the flow-rate results.

What Makes This Competitive

A class-level project shows that banana peels can remove fluoride. A stronger project shows how and why the removal changes under different flow conditions. You can stand out by collecting careful breakthrough data, testing more than one model, and comparing fit quality with real statistics. You get even stronger if you compare untreated peels with one simple pre-treatment or structure change and explain the mechanism behind the difference.

Project Variations

• Test orange peel, coconut husk, or rice husk as a comparison biosorbent for fluoride breakthrough.
• Change the column design by comparing different bed heights or particle sizes instead of only changing flow rate.
• Use a colorimetric fluoride assay and smartphone analysis instead of an electrode to measure the breakthrough curve.

Learn More

• PubMed: Search review articles on fluoride adsorption, biosorbents, and fixed-bed column modeling.
• NOAA Drinking Water resources: Find background on water quality, contaminants, and treatment concepts on the NOAA website.
• USGS Water Science School: Read plain-language pages on groundwater chemistry and drinking water contaminants.
• NIH PubChem: Look up fluoride properties and related chemical information for background research.
• MIT OpenCourseWare: Search for chemical engineering or environmental engineering lectures on adsorption and mass transfer.