Ho, et al (2024) Arsenic adsorption by activated biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More derived from water hyacinth. Case Studies in Chemical and Environmental Engineering. https://doi.org/10.1016/j.cscee.2024.100907

Arsenic contamination in groundwater poses severe health risks across the globe. In response, a study explored the use of biochar derived from water hyacinth to adsorb arsenic from low-concentration water solutions. Water hyacinth, an invasive aquatic weed, was pyrolyzed at 550°C and then chemically treated with KOH and FeCl3 to enhance its arsenic adsorption properties.

The study demonstrated that the iron-modified biochar (Fe-WHB) had an excellent adsorption capacity across a wide pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More range (3–10), making it highly effective for arsenic removal. The adsorption process reached equilibrium within an hour and followed pseudo-first-order kinetics, indicating a fast and efficient process. The Freundlich isotherm model best described the adsorption, suggesting that it occurred on a heterogeneous surface, which allowed for multi-layer adsorption.

One key finding was that the presence of nitrate ions, which often coexist with arsenic in contaminated water, did not significantly affect the biochar’s arsenic adsorption capabilities. The biochar was also reusable, retaining its effectiveness across three cycles of use. The primary mechanisms involved in arsenic removal included physical adsorption, ion exchange, and some degree of chemical bonding due to the biochar’s iron content.

This study highlights the potential of water hyacinth-derived biochar as an eco-friendly, cost-effective solution for arsenic removal, especially in regions where both arsenic contamination and water hyacinth proliferation are prevalent.