Green Synthesis of Iron Oxide Nanoparticles for Treating Coffee Cherry Pulping Wastewater: Environmental Implications

The disposal of coffee cherry pulping wastewater (CPWW) poses severe environmental risks, including water body eutrophication, soil acidification, and toxicity to aquatic life due to its high organic load (COD: 29,450 mg/L; BOD5: 16,500 mg/L), acidic pH (4.8), and elevated solids (TDS: 3240 mg/L; TSS: 4540 mg/L). To address this, we synthesized iron oxide nanoparticles from Ricinus communis L. seed extract via a green method and evaluated their efficacy in CPWW treatment. Characterization by XRD, SEM, and FTIR confirmed the formation of the nanoparticles stabilized by phytochemicals, with functional groups such as hydroxyl (OH) and amine (NH) critical for pollutant binding. At an optimal dosage of 0.08 g/100 mL, the nanoparticles achieved 74% COD removal, 69% TDS reduction, and 92% decolorization, significantly mitigating the pollutant load of the effluent, thereby minimizing risks to aquatic ecosystems and soil health. Furthermore, FTIR analysis of the treated sludge revealed the potential functional groups facilitating pollutant removal. This study highlights the dual environmental benefit of green-synthesized iron oxide nanoparticles: (1) a sustainable synthesis route avoiding toxic chemicals, and (2) high-efficiency pollutant removal, offering a scalable solution for coffee-processing industries to minimize their ecological footprint. By addressing the dual challenges of waste toxicity and treatment sustainability, this approach aligns with circular economy principles, promoting cleaner production in agro-industrial sectors.