Abstract:
Iron nanoparticles are emerging as cost-effective and eco-friendly materials for
wastewater treatment. This study developed a sustainable method for synthesizing
iron-based nanoparticles using aqueous extracts of made tea and refused tea from
black and green tea varieties. Refused tea, which accounts for 4–6% of Sri Lanka’s total
tea production, is recognized as a waste material that can be used for environmental
remediation. This study allowed tea extracts (10% w/v, pH ~5.5) to react with 0.10 M
FeCl₃ under mechanical stirring at room temperature for 15 minutes, for the synthesis
of nanoparticles. FTIR, UV-Visible Spectroscopy, XRD, and SEM were employed for
characterization. FTIR confirmed involvement of polyphenolic functional groups in
iron reduction and stabilization, while Fe–O vibrations verified iron oxide formation.
Nanoparticle synthesis was confirmed by UV-Vis spectra, which showed strong
absorption around 390 nm. XRD indicated predominantly amorphous structures with
weak reflections corresponding to α-Fe. SEM analysis revealed irregular quasispherical
particles (30–80 nm) with agglomeration due to magnetic interactions.
Synthesis yield varied among tea types, with green tea samples showing higher yields
than black tea. The nanoparticles were evaluated for methyl orange dye removal under
optimized conditions (50 mg/L, pH 6.5, 120 min). Black made tea nanoparticles
achieved the highest removal efficiency (80.5%), followed by green made tea, green
refused tea, and black refused tea nanoparticles. Increased nanoparticle dosage further
improved removal efficiency. The findings demonstrate the potential of tea-derived
iron nanoparticles as sustainable and efficient adsorbents for dye-contaminated
wastewater treatment while promoting tea waste valorization.
