Nanotechnology is increasingly recognized for its transformative potential across various industries, particularly in environmental applications. Addressing water contamination, specifically by persistent and toxic pollutants such as 4-Nitrophenol (4-NP), is critical for safeguarding human health. The challenge of removing 4-NP from industrial wastewater is significant due to its refractory nature.
This study explores a sustainable approach to mitigate this issue through the reduction of 4-NP to the less harmful 4-Aminophenol (4-AP), a vital precursor for paracetamol production. The research employs a green synthesis method for Cupric Oxide Nanoparticles (CuONPs) using leaf extracts from Tectona grandis (teak), rich in bioactive compounds, which facilitate the reduction of metallic ions to nanoparticles. CuONPs were synthesized in a 0.25L shake flask, utilizing the teak leaf extract (TLE) and Copper sulphate (CuSO4) precursor. X-ray diffraction analysis confirmed the crystalline size of the nanoparticles as 40 nm. These CuONPs effectively catalyzed the reduction of 4-NP to 4-AP.
To optimize the catalytic reduction process, the study systematically evaluated key parameters, including pH, synthesis time, and the volume ratio of extract to precursor. Optimal conditions were identified through screening studies, with the highest rate constant of 0.3337/min achieved at pH 7, a volume ratio of 4:1, and a synthesis time of 4 hours. Further optimization was conducted using Response Surface Methodology (RSM) with a Central Composite Design (CCD) approach, facilitated by Design-Expert 13 software. The statistical analysis of the model demonstrated high reliability, with a coefficient of correlation (R²) of 0.9814. The projected optimized rate constant was 0.44/min, which was experimentally validated as 0.434/min, yielding an R² value of 0.98.
These results validate the effectiveness of CuONPs in reducing 4-NP to 4-AP under the optimized conditions, showcasing the benefits of utilizing teak leaf extracts for nanoparticle synthesis. Future work will focus on scaling up the process and investigating the semiconducting properties of CuO nanoparticles to enhance their applicability in environmental remediation.
