In a recent issue of the journal RSC Advances, researchers Shreya Thakor, Gautam Priyadarshi, Bhakti Patel, Santosh Kumar Sahu, Sherzodbek Tashbaev, Gulomov Gafurjon Shavkatbek Ugli, Esha Rami, Dipak Kumar Sahoo, and Ashish Patel explore a sustainable solution to the growing problem of agricultural water pollution. As the global demand for food increases, the reliance on chemical herbicides like pendimethalin has led to significant contamination of water bodies through farm runoff. These chemicals are notoriously difficult to break down and pose serious risks to aquatic life and human health. The researchers addressed this challenge by developing a novel adsorbent made from the leaves of Bacopa monnieri, a common medicinal plant. By subjecting these leaves to high-heat treatment in a low-oxygen environment, they created biochar that acts like a scientific sponge for environmental toxins.

The results of the study are particularly impressive, showing that this plant-derived biochar can eliminate 97.56% of pendimethalin from contaminated water. This high level of efficiency was achieved under optimized conditions within 150 minutes of contact time. The material works through several natural forces, including physical trapping within its microscopic pores and chemical attractions that pull the herbicide molecules onto the biochar surface. Because the Brahmi plant is naturally rich in specific oxygenated groups and mineral traces like silicon and potassium, the resulting biochar provides an ideal surface for these complex interactions to occur. Even at low doses, the material showed a remarkable ability to capture the herbicide, making it an economically viable option for large-scale water treatment.

One of the most significant findings of this research is how well the biochar performs in realistic, messy environments. Most laboratory studies test one chemical at a time, but actual agricultural runoff contains a mixture of different pesticides and salts. When tested against combinations of three different pesticides, the biochar maintained a strong performance, removing approximately 73% of the target herbicide even when competing with other chemical compounds. Furthermore, the researchers discovered that the presence of common salts actually enhanced the cleaning process. In the presence of magnesium salts, the removal efficiency spiked to nearly 99%, suggesting that this material would be exceptionally effective in various types of natural water sources that contain dissolved minerals.

The study also delved into the specific mechanics of how the cleaning happens, revealing a sophisticated multi-step process. Initially, the herbicide molecules are drawn to the biochar through electrostatic forces and a process where the molecular rings of the chemical align with the carbon structures of the biochar. Following this rapid initial capture, hydrogen bonding further stabilizes the connection. Finally, the molecules settle deep into the internal structure of the biochar particles through a process called intraparticle diffusion. This multi-layered defense makes the biochar a robust tool for environmental remediation. Because the process is primarily driven by chemical interactions on the surface, the material is highly reliable across a range of water acidity levels, though it performs best in slightly alkaline conditions.

Ultimately, this research provides a clear pathway for turning agricultural waste into a high-value environmental tool. The use of Bacopa monnieri leaves is particularly advantageous because it is a renewable resource that can be processed relatively easily. The resulting biochar is not only low-cost but also eco-friendly, as it replaces the need for expensive synthetic chemicals or energy-intensive filtration systems. By successfully demonstrating that a simple plant-derived material can tackle complex herbicide mixtures and show enhanced results in the presence of natural salts, the authors have highlighted a practical and sustainable method for protecting global water resources from the unintended side effects of modern farming.

Source: Thakor, S., Priyadarshi, G., Patel, B., Sahu, S. K., Tashbaev, S., Ugli, G. G. S., Rami, E., Sahoo, D. K., & Patel, A. (2026). Development of novel biochar derived from Bacopa monnieri leaves for adsorptive removal of pendimethalin herbicide from binary and ternary pesticide mixture. RSC Advances, 16(1), 144-154.