Synthesis and characterization of PAMAM/SiO2 nanohybrid as a new promising adsorbent for pharmaceuticals

This research reports the synthesis of a dendritic adsorbent named polyamidoamine/silica (PAMAM/SiO2) nanohybrid and its application for adsorption of pharmaceutical pollutants from hospital wastewater. The characterization of the resulting nanohybrid was studied by the FTIR, XRD, TEM, SEM, BET, TGA and Zeta potential measurements. Then, a comparative evaluation was performed for four pharmaceuticals including clofibric acid, diclofenac, ibuprofen, and ketoprofen adsorption from aqueous solution by nanohybrid. Effects of various parameters such as nanohybrid dosage, drug concentration, pH of initial solution and contact time were investigated for a batch sorption system. The optimized operating conditions were 25 min, 298 K, pH = 9, 1 mg/L of adsorbent dose and 100 μg/L of adsorbate concentration. The maximum sorption capacity were 94, 134, 124 and 112 mg/g for clofibric acid, diclofenac, ibuprofen and ketoprofen, respectively. Various kinetic models have been studied to recognize the pharmaceuticals sorption mechanism onto nanohybrid. The results showed that the sorption process obeyed the pseudo-second order kinetic models. Analysis of the adsorption process proved that the Langmuir isotherm was the most adapted model. The thermodynamic parameters have been calculated and it demonstrated that adsorption of four pharmaceuticals using nanohybrid was endothermic and spontaneous. This study convinced that PAMAM/SiO2 nanohybrid could be an attractive, alternative, effective, economical, and environmentally friendly adsorbent for pharmaceutical pollutants from hospital wastewater.