Purpose <p>This study investigates the practical implications of total petroleum hydrocarbons (TPHs) desorption modelling during phyto- and myco-remediation of petroleum-contaminated soils and sediments optimised with Tween 80.</p> Materials and methods <p>Data from a 90-day phyto- and myco-remediation experiment involving sunflowers, ferns, palm wine, and Pleurotus ostreatus, with or without Tween 80, were used for TPHs desorption modelling using both the Langmuir and Freundlich models. The data used for the desorption modelling in this report were obtained from phyto- and myco-remediation experiments conducted by Dickson et al. (2025a, b), and Dickson (2025).</p> Results and discussion <p>There was a corresponding increase in desorption parameters with increasing remediation efficiency. For instance, increased remediation efficiency on the addition of Tween 80 to each treatment resulted in the following increase in values for both the Csm and b-constants of the Langmuir isotherms. Sunflower (from Csm = 100 and b = 0.07 in T3, to Csm = 20,000, b = 99,721 in T4), Ferns (from Csm = 333 and b = 8 in T5, to Csm = 25,000 and b = 5,271 in T6), Palm wine (from Csm = 50,000 and b = 8,929 in T7, to Csm = 200,000 and b = 86,768 in T8), and P. ostreatus (from Csm = 250,000 and b = 82,847 in T9, to Csm = 500,000 and b = 170,028 in T10).</p> Conclusions <p>TPHs desorption in the highly contaminated soils was largely a combination of physical and chemical desorption mechanisms enhanced by the presence of the phyto- and myco-remediation agents, and the Tween 80. This signifies that processes which enhance both the physical and chemical desorption of TPHs in soils and sediments, will promote the phyto- and myco-remediation of TPHs in such matrices. This study also demonstrates that Tween 80 enhances soil remediation by increasing the desorption of pollutants.</p>