📄 chemistry

Organochlorine Pesticides Sorption onto Agro-waste Biochar: Optimization of Independent Adsorption Parameters using a Full Factorial Design

This study demonstrates that unripe plantain peel-derived activated carbon, optimized via a full 2³ factorial design, achieves 98.23% removal of cyclodiene pesticides from wastewater under specific conditions of pH 3.0, 5 g/100mL dosage, and 30°C temperature.

Original authors: Temitope. O Fakoya, John. A.O Oyekunle, Abolanle. S Adekunle, Cornelius. A Aboderin, Kolade. O Faloye, Ikechukwu. P Ejidike, Emmanuel. G Fakola

Published 2026-08-12

📖 3 min read☕ Coffee break read

CC BY 4.0

Original authors: Temitope. O Fakoya, John. A.O Oyekunle, Abolanle. S Adekunle, Cornelius. A Aboderin, Kolade. O Faloye, Ikechukwu. P Ejidike, Emmanuel. G Fakola

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

Imagine the world's water as a giant, invisible soup. Sometimes, this soup gets contaminated with "ghosts"—chemicals that are hard to see but stick around for a long time. One group of these ghosts is called organochlorine pesticides, specifically a type known as "cyclodienes." These are like stubborn stains that don't wash away easily; they love to hide in fat, travel up the food chain, and can make people and animals very sick if they stay in the water too long. To clean this soup, scientists usually use a special sponge called activated carbon to soak up the bad chemicals. But buying these sponges is expensive, like trying to buy a new car every time you want to clean a spill. So, scientists started looking for cheaper, eco-friendly sponges made from things we throw away, like fruit peels. The big question is: can a simple, discarded banana-like peel actually work as well as the fancy, expensive sponges to catch these chemical ghosts?

This study dives into that exact question using a clever trick called "full factorial design," which is like a scientific recipe book that helps you figure out the perfect mix of ingredients without having to cook every single possible meal. The researchers took unripe plantain peels (the green, starchy kind you find in Nigeria) and turned them into a super-sponge called "biochar" by heating them up and treating them with acid. They then tested this new sponge in a lab to see how well it could grab cyclodiene pesticides out of water. But they didn't just guess the best conditions; they used a statistical map to find the perfect combination of three things: how acidic the water was (pH), how much sponge they used, and how hot the water was.

The team discovered that their plantain peel sponge was a superstar, but only if you treated it just right. They found that the sponge worked best when the water was quite sour (a pH of 3.0), when the water was cool (30°C), and when they used a generous amount of the sponge (5 grams for every 100 milliliters of water). When they got these conditions perfect, the sponge managed to catch 98.23% of the pesticide ghosts, leaving the water almost completely clean.

The study also revealed some interesting rules about how the sponge behaves. It turns out that heat is the enemy here; as the water got hotter (up to 50°C), the sponge got less effective, suggesting that the process of catching the chemicals releases heat, much like how a warm hug feels different than a cold one. The acidity of the water was also crucial because it changed the electrical charge on the sponge's surface, making it more attractive to the pesticide molecules. By using their statistical map, the researchers proved that temperature and pH were the most important factors, and that they worked together in a dance where changing one changed the effect of the other.

In the end, the paper shows that we don't need to spend a fortune to clean our water. By turning a common farm waste product into a high-tech sponge and using a smart mathematical approach to find the perfect settings, we can remove nearly all of these dangerous pesticides. The study confirms that this method is not just a lucky guess but a statistically solid way to clean water, offering a hopeful, low-cost solution for a global problem.

Technical Summary: Organochlorine Pesticides Sorption onto Agro-waste Biochar

Problem Statement
Cyclodiene organochlorine pesticides (OCPs) pose a significant environmental and health risk due to their persistence, lipophilic nature, and tendency to bioaccumulate in the food chain, leading to severe health effects such as cancer and endocrine disruption. While various water treatment technologies exist, many are expensive or generate secondary wastes. Commercial activated carbon is effective but costly, necessitating the development of affordable, eco-friendly alternatives derived from agro-waste. Furthermore, while operational factors like pH, temperature, and dosage are known to influence adsorption, the specific interactions between these variables for cyclodiene removal have not been thoroughly documented using statistical optimization techniques.

Methodology
This study utilized unripe plantain peel (UPP), an abundant agro-waste in tropical Africa, as a precursor for producing acid-activated carbon (AMPP). The preparation involved cleaning, drying, carbonization at 300°C, and chemical activation using 2M sulfuric acid. The resulting adsorbent was characterized using Scanning Electron Microscopy (SEM) for surface morphology and Fourier Transform Infrared (FTIR) spectroscopy for functional groups.

The removal of cyclodienes from synthetic wastewater was investigated in batch mode. To optimize the process and minimize the number of experiments, a $2^3$ full factorial experimental design was employed. This design evaluated three independent variables at two levels each:

Temperature: 30°C (low) to 50°C (high)
Solution pH: 3.0 (low) to 9.0 (high)
Adsorbent Dosage: 2.0 g/100mL (low) to 10.0 g/100mL (high)

The synthetic wastewater contained a mixture of pesticides including heptachlor, aldrin, dieldrin, endrin, and others. Residual concentrations were measured using Gas Chromatography-Electron Capture Detector (GC-ECD). Statistical analysis, including Analysis of Variance (ANOVA), Pareto charts, and regression modeling, was conducted using Minitab software to determine significant factors and interactions.

Key Results

Adsorbent Characterization: Acid activation significantly altered the surface properties of the biochar. The AMPP exhibited a rough, cloud-like, and highly porous structure compared to the untreated UPP. FTIR analysis confirmed the presence of functional groups such as hydroxyl (O-H), carbonyl (C=O), and amine groups, with acid activation leading to the oxidation of certain groups, thereby enhancing surface reactivity.
Preliminary Experiments: Equilibrium was reached at 90 minutes. Removal efficiency was highest at acidic pH (3.0) and decreased as pH increased, suggesting electrostatic attraction between protonated surface sites and pesticide molecules. Adsorption was found to be an exothermic process, with maximum removal at 30°C.
Statistical Optimization: The $2^3$ $2^{3}$ factorial design yielded a regression model with a high coefficient of determination ( $R^2 = 98.24\%$ $R^{2} = 98.24%$ ; Adjusted $R^2 = 96.69\%$ $R^{2} = 96.69%$ ).
- Significant Factors: Process temperature and solution pH were the most significant factors, both showing negative effects (i.e., lower levels improved removal). Adsorbent dosage showed a positive effect in the regression model, though preliminary experiments indicated that removal efficiency peaked at a medium dosage (5 g/100mL) and declined at higher doses (10 g/100mL).
- Interactions: Significant two-way interactions were observed, particularly between temperature and pH.
- Optimal Conditions: The model identified the optimal conditions for maximum cyclodiene removal as pH 3.0, an adsorbent dosage of 5 g/100mL, and a temperature of 30°C.
Performance: Under these optimized conditions, the system achieved a cyclodiene uptake efficiency of 98.23%.

Significance and Claims
The paper claims that the developed acid-activated plantain peel biochar is a highly effective, low-cost adsorbent for removing cyclodiene pesticides from wastewater. The primary contribution of this work is the application of a full factorial design to systematically optimize the adsorption process, successfully identifying that temperature and pH are the dominant factors influencing removal efficiency. The study demonstrates that statistical tools can effectively reduce experimental workload while accurately predicting optimal operating conditions, achieving near-complete removal of target pollutants without the high costs associated with commercial activated carbon. The authors conclude that the agro-waste derived adsorbent offers a viable, sustainable solution for the remediation of organochlorine pesticides.

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