Recently, lignocellulose materials have shown potential for the removal of different pollutants from water. These materials have the potential to be used in wastewater treatment because they promote a circular economy, cleaner production, are inexpensive and readily available, and possess many functional groups that facilitate the removal of different pollutants in water. This study investigates the impact of acid-treatment on mahogany sawdust for the removal of the antibiotic rifampicin in water. Adsorption experiments were conducted with rifampicin dissolved in water at a concentration of 20 µg/mL. The concentration of rifampicin in aqueous solutions was measured using a UV-Vis spectrophotometer operating at a wavelength of 333 nm. Material properties were characterised using Fourier Transform Infrared Spectroscopy (FTIR), mastersizer, and Elemental Analyser. The particle size results show that there is a 34% decreased in mean particle size and a 50% increase in the specific surface area (SSA) of the treated sawdust. The adsorption experiments were conducted using a solution of rifampicin with 20 µg/mL concentration, in which untreated and treated mahogany sawdust had lowered the concentration of rifampicin by 20% and 48%, respectively, within 12 hours of its contact with the particles of the adsorbent. The results showed that the removal rate of rifampicin by treated sawdust was twice that of untreated, which can be attributed to an increase in the SSA of the treated sawdust.