Efficient Adsorption of Chlortetracycline and Ibuprofen Onto Mg–Al Layered Double Hydroxide: Equilibrium, Kinetic, and Thermodynamic Studies

Abstract

Magnesium–aluminum layered double hydroxide (Mg─Al LDH) with a Mg/Al molar ratio of 2:1 was synthesized by a simple co-precipitation method and evaluated for the simultaneous removal of chlortetracycline (CTC) and ibuprofen (IBP) from aqueous solutions. SEM–EDX, FTIR, and XRD analyses confirmed the successful formation of a well-defined layered structure with a basal spacing of 7.65 Å and a pHpzc of 6.15. Batch adsorption experiments showed rapid equilibrium within 30 min for CTC and 60 min for IBP, with removal efficiencies reaching 99% under optimal conditions (293 K, adsorbent dosage 2 g L−1, initial concentration 50 mg L−1, pH 7). The adsorption kinetics followed the pseudo-second-order model for CTC and the pseudo-first-order model for IBP, while equilibrium data were best described by the Langmuir isotherm, yielding maximum adsorption capacities of 121.61 mg g−1 for CTC and 100.41 mg g−1 for IBP. Thermodynamic parameters indicated spontaneous and exothermic adsorption, with stronger interactions for CTC. The uncalcined Mg─Al LDH exhibited adsorption performance comparable to or exceeding that of many modified LDH-based materials, highlighting its potential as a simple, cost-effective, and sustainable adsorbent for pharmaceutical wastewater treatment.