# Performance of maize tassel activated carbon for COD removal from industrial wastewater under optimized conditions

## TL;DR

This paper explores using maize tassel-based activated carbon to efficiently and sustainably remove organic pollutants from industrial wastewater.

## Contribution

The study introduces maize tassel-derived activated carbon as a low-cost, high-performance alternative to commercial activated carbon for COD removal.

## Key findings

- MTAC achieved 92.8% COD removal at pH 6 and 30°C with an adsorption capacity of 464 mg/g.
- MTAC outperformed commercial activated carbon in adsorption capacity and cost-effectiveness.
- The material retained over 85% efficiency after five regeneration cycles, showing strong reusability.

## Abstract

Industrial wastewater, laden with hazardous organic and inorganic contaminants, poses critical environmental risks. Adsorption via activated carbon stands out as a scalable and efficient remediation strategy due to its simplicity and adaptability. This study evaluates maize tassel–derived activated carbon (MTAC), synthesized from agricultural waste, as a low-cost and sustainable solution to remove organic pollutants, with emphasis on reducing chemical oxygen demand (COD) in industrial effluents. A comprehensive assessment of critical parameters (pH, temperature, adsorbent dosage, contact time, and agitation speed) was performed to optimize the adsorption process. MTAC exhibited a high surface area of 510.4 m2/g, and characterization through FTIR, SEM, and XRD confirmed its porous structure and abundant surface functional groups. The adsorption performance was strongly influenced by pH, with the highest adsorption capacity (464 mg/g) and COD removal of 92.8% at pH 6 and 30 °C. Maximum efficiency (96.6%) was obtained at a dose of 3 g/L, with peak adsorption capacity (484 mg/g) achieved at 45 min and 200 rpm. Adsorption equilibrium data fitted well to the Langmuir model (R2 = 0.999), indicating monolayer adsorption with a maximum capacity of 484 mg/g, while Freundlich parameters confirmed favorable multilayer adsorption. Thermodynamic analysis revealed negative ΔG° values, confirming spontaneity, along with a negative ΔH° (− 0.523 kJ·mol⁻1), validating the exothermic nature of the process. Reusability tests demonstrated that MTAC retained more than 85% of its efficiency after five regeneration cycles, confirming its economic and practical viability. Comparative analysis further showed that MTAC outperformed commercial activated carbon (CAC) in adsorption capacity, COD removal, and cost-effectiveness. The utilization of maize tassel, an abundant agricultural byproduct, highlights its potential as a sustainable adsorbent that supports circular economy strategies and advances progress toward SDGs 6, 12, and 13.

The online version contains supplementary material available at 10.1038/s41598-025-24902-y.