Layered double hydroxides (MgAl-LDHs) were synthesized from waste aluminum frames via co-precipitation and hydrothermal treatments and applied for salicylic acid (SA) removal from aqueous solutions. Characterization confirmed the hydrotalcite-like structure, with hydrothermal treatment yielding higher crystallinity. The materials exhibited specific surface areas ranging from 27.66 to 96.08 m2 g−1 and pore diameters between 36 and 39 Å. Thermogravimetric analysis revealed total mass losses between 31% and 37%, primarily attributed to interlayer water desorption and lamellae dehydroxylation. Batch adsorption studies indicated that the optimal conditions for SA removal were pH 5.0 and an adsorbent dosage of 7.5 g L−1. Equilibrium was reached within 90 min, and the kinetic data were best described by the pseudo-second-order model. The adsorption isotherms were favorable and best fitted by the Freundlich model (R2 > 0.99, ARE <0.10%), indicating multilayer adsorption on a heterogeneous surface, with a maximum experimental capacity of 16.29 mg g−1 at 30 °C. Thermodynamic analysis confirmed the process is spontaneous (ΔG° ranging from −11.47 to −11.79 kJ mol−1) and exothermic (ΔH° = −8.28 kJ mol−1), driven by physical interactions.