Adsorption and kinetics of sodium lauryl sulfate from wastewater using activated carbon derived from sawdust biomass
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2026-08-21
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Okello Solomon
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Background and Problem Statement: Sodium Lauryl Sulfate (SLS) is an anionic surfactant widely used in domestic and industrial detergents. Its discharge into aquatic ecosystems poses significant environmental and toxicological risks, creating an urgent need for cheap and effective wastewater treatment methods.Objectives: This study aimed to synthesize activated carbon from locally sourced Tororo sawdust biomass and evaluate its performance in removing SLS from aqueous solutions.Methods: The adsorbent was synthesized via phosphoric acid activation at 800°C. Surface analysis was conducted using the standard iodine index and a JASCO FT/IR-6600 spectrometer. Batch adsorption experiments were performed to evaluate the effects of contact time (0–120 min), initial concentration (10–40 mg/L), solution pH (2.0–12.0), and adsorbent dosage (0.5–5.0 g/L). Surfactant tracking was managed via the Methylene Blue Active Substance (MBAS) method using a UV-Vis spectrophotometer at 652 nm.Key Findings: The synthesized carbon exhibited an excellent iodine number of approximately 940 mg/g. FTIR analysis confirmed a rich surface chemistry featuring hydroxyl (≈3280 cm⁻¹), aromatic (≈1600 cm⁻¹), and acid-phosphate (≈1060 cm⁻¹) groups. Adsorption kinetics fitted perfectly to the Pseudo-Second-Order model ( 0.9986), proving a chemisorption rate-limiting mechanism. Equilibrium studies strictly followed the Langmuir isotherm model (= 0.9932), showing a maximum monolayer capacity () of 8.26 mg/g. Peak removal (99.5%) occurred at pH 2.0 due to electrostatic attraction, while 2.0 g/L was identified as the practical optimum dosage, yielding 97.2% efficiency.Conclusion: The results demonstrate that sawdust-derived activated carbon is an elite, eco-friendly, and highly efficient bio-adsorbent for removing anionic surfactants from industrial wastewater streams
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