Abstract
This study investigates the potential for using XShP-02 chromium spinel sludge (rich fraction) from the Aktobe Ferroalloy Plant as a sorbent for the removal of phenol from the effluent of oil refineries. The sludge was subjected to alkaline modification with 1 M NaOH at 70°C, followed by calcination at 450 °C. The physicochemical properties were characterised using XRF, SEM, IR spectroscopy and TGA/DSC. The Langmuir and Redlich–Peterson models provide the best description of the adsorption equilibrium (R² = 1.000). The maximum adsorption capacity is 36.00 mg/g; an optimal dose of 0.30 g/100 ml ensures the removal of 96 % of phenol. ΔG° = - 5.97 kJ/mol confirms the spontaneous physical nature of the adsorption and the possibility of sorbent regeneration.