Adsorption of Pharmaceuticals and Personal Care Products on Granular Activated Carbon

Abstract

We investigated the adsorption to granular activated carbon of two pharmaceuticals (carbamazepine and sildenafil citrate) and a personal-care product (methylparaben) in aqueous solution, characterized the carbon, and evaluated its influence on the kinetics and adsorption equilibrium of the compounds under study. We adjusted data for the analysis of equilibrium to Langmuir and Freundlich models of adsorption isotherms and described adsorption rate using pseudo first-and second-order models; that same analysis was made on the basis of the behavior of the initial rate. In addition, we analyzed the potentiality of a nonlinear adjustment for studying kinetics and equilibrium of adsorption, an approach requiring neither knowledge of equilibrium conditions nor a-priori hypothetical suppositions regarding the order of reaction. The results indicated that the nonlinear model was capable of describing adsorption kinetic behavior, in order to determine concentrations adsorbed at equilibrium, adsorption rates of the system, maximum adsorption capacity, and global rate constant. Granular carbon exhibited an adsorption capacity for carbamazepine and methylparaben of ca. 323 mg/g and for sildenafil citrate of ca. 142 mg/g, though with slow adsorption kinetics characterized by average adsorption times of at least 168 h.

Removal of selected pharmaceuticals from aqueous matrices with activated carbon

“…Adsorption capacity for methyl paraben and CRB were 1.97, 1.27 mmol g -1 respectively, while this value was much lower, about 0.225 mmol g -1 for sildenafil citrate. The slow adsorption kinetics required at least 168 h average adsorption time [223]. Similar results were reported for adsorption of CRB with qm of 1.42 mmol g -1 onto GAC obtained from peach seeds [205].…”

“…In general, the major characteristics of AC used in water treatment are the following: pore diameter <1 nm, specific surface area up to 3000 m 2 g -1 and internal surface area in range of 800-1,000 m 2 g -1 [151,218]. Several studies investigated the removal efficiencies of the three target compounds, DCL, NPR and CRB onto activated carbon under batch conditions [188,194,211,217,[219][220][221][222][223][224][225].…”

Diagnóstico y remoción de contaminantes emergentes en aguas superficiales y cloacales

“…El volumen total de cada experimento fue de 50 mL. Con el fin de evitar el crecimiento bacteriano en las soluciones acuosas se adicionó azida sódica al 0,01% (Delgado et al, 2016).…”

“…La evolución temporal del compuesto adsorbido q t en diferentes concentraciones iniciales se analizó utilizando el modelo de seudo primer orden, el de seudo segundo orden y la ecuación de velocidad no lineal descrita anteriormente en la Ecuación 7.9, del Capítulo 7 (Delgado et al, 2016). También se aplicó el modelo de difusión intrapartícula para interpretar el posible mecanismo de adsorción.…”

“…Entre las ventajas del CAG se incluyen su aplicación simple y la posibilidad de su regeneración/reutilización. Debido a su tamaño de partícula más pequeño, el carbón activado en polvo (CAP) es más eficiente que el CAG (Delgado et al, 2016;Kim et al, 2010), convirtiéndose en una opción prometedora para reducir el vertimiento de contaminantes recalcitrantes sobre las aguas superficiales. Sin embargo, debido a que es un material difícil de manipular, no es muy utilizado en las PTAR a escala real, y la mayoría de los estudios reportados lo utilizan en sistemas en batch (Altmann et al, 2014).…”