International Journal of Environment and Climate Change

Heavy-metal contamination of wastewater has increased interest in using agricultural waste as potential low-cost bioadsorbents. This study compared rice husk (RH), sugarcane bagasse (SB), and pinecone (PC) for the removal of Pb(II) and Cu(II) from wastewater and characterised the materials using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The untreated residues were washed, ground, and sieved to 200–250 µm, then investigated in triplicate batch experiments at an adsorbent dose of 10 g/L, an agitation speed of 150 rpm, a contact time of 120 min, and a temperature of 27 ± 2 °C. SEM revealed porous, layered, and fibrous structures in RH; granular and fibrous structures in SB; and rough, flaky surfaces with microcracks and pores in PC. EDX showed that SB had the highest carbon content (68.4 ± 3.4 wt.%), followed by PC (67.6 ± 3.3 wt.%) and RH (48.0 ± 2.4 wt.%). RH had the highest silicon content (19.8 ± 0.9 wt.%). PC recorded the highest Pb(II) removal efficiency (72.94 ± 2.60%), followed by RH (51.20 ± 2.20%) and SB (27.91 ± 1.40%). Cu(II) removal was also highest for PC (98.11 ± 3.20%), followed by SB (94.36 ± 2.70%) and RH (88.40 ± 2.40%). Under the studied conditions, PC performed best for both metals and merits further assessment for wastewater treatment. Further studies under a wider range of operating conditions are needed to establish the suitability of pinecone as a practical bioadsorbent for wastewater treatment.