Comparative evaluation of Cupressus sempervirens and Pinus pinaster-based natural adsorbents for arsenic (III) removal from contaminated water

This study evaluates the adsorption performance of natural biomaterials derived from Cupressus sempervirens (cypress) leaves, cones, and bark, and Pinus pinaster (pine) cone chips and bark for the removal of arsenic (III) from contaminated water. Batch experiments were conducted under environmentally relevant conditions (pH 6.8, room temperature, and tap water) to assess the effects of adsorbent dosage and initial arsenic concentration (0.1, 0.2, and 10 mg/L). Among all tested materials, cypress leaves exhibited the highest removal efficiency, reaching 49.8 % at 10 mg/L. The adsorption data fitted both Langmuir and Freundlich isotherms, with a maximum adsorption capacity ( Q max ) of 0.101 mg/g , and a better correlation with the Langmuir model ( R 2 = 0.997 ). Kinetic analysis indicated that the process follows a pseudo-second-order mechanism (R 2 = 0.999 ), with intra-particle diffusion as a secondary contributor. These results point out the advantages of low-cost, locally available plant-based adsorbents for arsenic remediation, particularly in low-resource or rural settings.