Industrial dyes, such as the widely used methyl orange (MO), represent a significant and stubborn environmental pollutant. These compounds are designed to be stable, so they don’t break down easily in conventional wastewater treatment plants. Their presence in water blocks sunlight, harms aquatic life, and can lead to the formation of carcinogenic compounds. To fight this, scientists use a powerful method called photocatalytic oxidation, which uses light to activate a catalyst that destroys these pollutants. The problem is that the best catalysts are often expensive. A new study by Galih Dwiki Ramanda and colleagues, published in EKSAKTA: Journal of Sciences and Data Analysis, demonstrates a promising, low-cost alternative made from one of the world’s most abundant agricultural wastes: palm leaves.

The research team set out to “valorize” this waste—turning a low-value (or negative-value) product into something useful. They collected palm leaves, washed and dried them, and then soaked them in a nickel chloride solution. Two different concentrations were used to create two batches: one with 10% nickel (Ni10-BC) and one with 30% nickel (Ni30-BC). These soaked leaves were then placed in a furnace and pyrolyzed—heated to 600 C in the absence of oxygen—to convert the plant matter into a porous, black, carbon-rich material known as 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, which was now decorated with tiny nickel nanoparticles. X-ray diffraction analysis confirmed that this one-step process successfully formed and dispersed single nickel nanoparticles across the biochar’s structure.

This new material works by harnessing the power of UV light. When the light strikes the Ni-BC catalyst, it excites electrons, creating highly reactive molecules called reactive oxygen species (ROS)—primarily hydroxyl and superoxide radicals. These ROS are extremely powerful oxidizers that physically attack the complex azo bonds and aromatic rings of the methyl orange dye, breaking them down into simpler, less harmful compounds. The nickel nanoparticles play a crucial role by acting as active sites that improve charge separation, which essentially “supercharges” the catalyst and prevents it from short-circuiting, allowing it to generate more ROS to destroy the pollutant.

To test its effectiveness, the team dispersed 0.2 grams of their new catalyst into 100 mL of a 50 ppm methyl orange solution and placed it under a UV lamp for 120 minutes. The results clearly showed that more nickel led to better performance. The Ni30-BC catalyst (30% nickel) successfully degraded 74.73% of the dye. The Ni10-BC catalyst (10% nickel) was far less effective, removing only 50.01%. Both were a major improvement over the control tests: pristine biochar (with no nickel) only removed 31.94% of the dye, and using UV light alone (photolysis) barely made a dent, degrading only 8.67%. The degradation followed pseudo-first-order kinetics, meaning the reaction rate was dependent on the dye concentration. The rate constant (k) for the 30% catalyst was nearly double that of the 10% version, confirming its superior activity.

One of the most practical features of this new catalyst is its magnetism. This allows for simple and efficient recovery from the water after treatment. A large magnet can be used to pull the catalyst powder out of the solution, allowing it to be cleaned and potentially reused. Interestingly, the team found a trade-off: the 10% nickel sample was more magnetic than the 30% sample, which they attribute to particle clumping at higher nickel concentrations. While the authors note that their catalyst’s 74.73% efficiency is not yet as high as expensive oxide-based catalysts (which can top 95%), this work proves that abundant agricultural waste can be transformed into a low-cost, effective, and easily recoverable platform for tackling water pollution, paving the way for a more sustainable and circular economy.

Source: Ramanda, G. D., Fatimah, I., Sagadevan, S., & Bin Johan, M. R. (2025). Ni-decorated biochar from palm leaves waste as low-cost photocatalyst for dye degradation of methyl orange. EKSAKTA: Journal of Sciences and Data Analysis, 6(2), 53-61.