Eco-Friendly Lead Removal: Utilizing Modified and Unmodified Avocado Seed as a Low-Cost Biosorbent.
Keywords:
Adsorption, Heavy metals, Acid, Alkaline, IsothermAbstract
The removal of toxic heavy metals, particularly lead (Pb), from water is a major environmental and public health concern. Conventional remediation methods are often expensive and inaccessible, prompting the search for sustainable, low-cost alternatives. This study evaluated avocado seed (Persea americana), an agricultural waste, as a natural adsorbent for lead removal in three forms: unmodified, acid-modified, and alkaline-modified. Using a batch adsorption approach, key parameters including pH, contact time, temperature, adsorbent dosage, and initial lead concentration were systematically assessed. Optimal adsorption was achieved at pH 5, with 0.1 g of adsorbent, 60 °C, 90 minutes of contact time, and an initial lead concentration of 10 ppm, with both modified adsorbents outperforming the unmodified form. The acid-modified adsorbent followed the Langmuir isotherm and pseudo-second-order kinetics, indicating monolayer adsorption and chemisorption, while the alkaline-modified adsorbent conformed to the Freundlich model with pseudo-second-order kinetics, showing heterogeneous surface adsorption. Percentage removal of lead was highest for the acid-modified (99.96%), followed by alkaline-modified (99.05%) and unmodified (89.99%). These results demonstrate that surface modification significantly enhances adsorption efficiency and that lead removal is strongly pH-dependent.Downloads
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