Chitosan and eggshells in water purification

Heavy Metal Detox: Can Chitosan and Eggshells Clean Our Water?

Lena Kashyap in Climate & Environment June 2025 • 4 min read.

"Exploring a Bio-Based Solution for Cadmium Contamination"

Water pollution from heavy metals is a serious environmental problem. Cadmium, in particular, poses a significant threat to both human health and the environment. Traditional methods for removing heavy metals can be costly and not always sustainable, highlighting the need for innovative, eco-friendly solutions.

Adsorption, a process where pollutants stick to a material, has emerged as a promising technique. Biopolymers, natural materials derived from living organisms, are gaining attention as effective and sustainable adsorbents. Chitosan, derived from chitin found in crustacean shells, stands out due to its ability to bind with heavy metals.

Researchers are exploring ways to boost chitosan's performance. A recent study investigated the effectiveness of chitosan composite, enhanced with epichlorohydrin crosslinking and eggshell particles, in removing cadmium from water. This approach aims to create a readily available, low-cost, and highly effective solution for water purification.

Chitosan and Eggshells: A Powerful Combination for Cadmium Removal

Chitosan and eggshells in water purification

The study focused on using chitosan and epichlorohydrin crosslinked with eggshell composite to remove cadmium from contaminated water. Cadmium adsorption is influenced by several factors, including the pH of the water and the amount of contact time between the chitosan composite and the contaminated water.

The study found that the optimal pH for cadmium adsorption was 6.0, and the equilibrium time was 40 minutes. The Langmuir equation was used to describe how cadmium ions attached to the chitosan and composite materials. Here’s a breakdown of the key components and findings:

Chitosan: A natural material derived from chitin, which is found in crustacean shells. It contains hydroxyl (-OH) and amine (-NH2) groups that can bind to heavy metals.
Epichlorohydrin: A crosslinking agent that improves the mechanical properties and stability of chitosan.
Eggshell Composite: Consists of eggshell particles, which are low-cost and readily available. These particles enhance the mechanical properties of the composite and provide additional surface area for cadmium adsorption.

The maximum adsorption capacity of chitosan was 1.008 mg/g, while the composite reached 11.7647 mg/g. The composite material outperformed chitosan alone, demonstrating the effectiveness of the modifications. Furthermore, the composite maintained better adsorption performance after regeneration compared to chitosan, indicating its potential for repeated use.

Turning Waste into a Resource: The Future of Water Purification

This research highlights the potential of using readily available and low-cost materials like chitosan and eggshells to tackle water contamination. By crosslinking chitosan with epichlorohydrin and reinforcing it with eggshell composite, the resulting material shows enhanced performance in removing cadmium ions from water. This approach offers a sustainable and environmentally friendly alternative to traditional methods, paving the way for cleaner and safer water resources.

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This article is based on research published under:

DOI-LINK: 10.1088/1757-899x/352/1/012047, Alternate LINK

Title: Comparison Of Cadmium Adsorption Onto Chitosan And Epichlorohydrin Crosslinked Chitosan/Eggshell Composite

Subject: General Medicine

Journal: IOP Conference Series: Materials Science and Engineering

Publisher: IOP Publishing

Authors: Rahmi, Marlina, Nisfayati

Published: 2018-05-01

Everything You Need To Know

What is Chitosan, and how does it work to remove cadmium?

Chitosan, derived from crustacean shells, is a biopolymer, making it a natural and sustainable adsorbent. It contains hydroxyl (-OH) and amine (-NH2) groups that effectively bind with heavy metals like cadmium. This characteristic makes Chitosan a key component in removing cadmium from contaminated water because it can physically capture and hold the metal ions. The effectiveness is amplified when combined with other materials to create a composite with enhanced properties.

Why is removing cadmium from water important?

Cadmium is a heavy metal that poses a significant threat to both human health and the environment when it contaminates water sources. Exposure to cadmium can lead to various health problems. The article explores the use of Chitosan and other materials to remove this harmful substance, demonstrating the importance of addressing water pollution and its consequences.

What were the key findings regarding the optimal conditions for cadmium removal?

The study found that the optimal pH for cadmium adsorption was 6.0, meaning the Chitosan composite works best at this acidity level. Also, the equilibrium time, the time needed for the adsorption process to reach completion, was 40 minutes. The Langmuir equation was used to model the adsorption process of the cadmium ions onto the Chitosan. These factors are crucial because they define the ideal conditions for the Chitosan composite to efficiently capture cadmium from water, ensuring effective water purification.

What is the role of Epichlorohydrin in this process?

Epichlorohydrin is used as a crosslinking agent in the composite material. It improves the mechanical strength and stability of Chitosan. By crosslinking with Epichlorohydrin, the Chitosan structure becomes more robust, allowing it to withstand the adsorption process and potentially be reused. It ensures the material maintains its integrity and effectiveness over time.

How do eggshells contribute to the effectiveness of cadmium removal?

The eggshell composite plays a crucial role in enhancing the performance of Chitosan. Eggshell particles are readily available and inexpensive. When combined with the chitosan and crosslinked with epichlorohydrin, it increases the overall surface area available for cadmium adsorption. This enhancement enables the composite material to adsorb significantly more cadmium compared to Chitosan alone, highlighting its potential in making water purification more efficient and sustainable.