This study analyzes how solution pH and ionic strength influence the sorption of polycyclic aromatic hydrocarbons (PAHs) onto humic acids (HA) coated aluminum oxide. A series of batch experiments were performed to obtain the apparent sorption coefficient(Kp)for systems with different humic acid concentrations, pH values, ionic strengths, andKowvalues of the sorbate. According to those results, the value ofKpincreases as the ionic strength or hydrophobicity of the PAHs increases, or as the pH value decreases. In addition, the fluorescence quenching method was used to measure the HA‐PAHs binding constantKdom, allowing the estimation ofKpby an overall mechanistic sorption model (OMS model). In most cases, these two approaches display the same trends and have similar results, thereby confirming the feasibility of applying this model to the aqueous chemistry of the third‐phase effect and analyzing the environmental system.