Ciprofloxacin, ranitidine, and chlorphenamine removal from aqueous solution by adsorption. Mechanistic and regeneration analysis.

This work was supported by Consejo Nacional de Ciencia y Tecnología, for the schoolarship CVU49215Several studies have reported the presence of pharmaceuticals in freshwater bodies all around the world. For this investigation, the removal of the pharmaceuticals ciprofloxacin (CIP) ranitidine (RNT), and chlorphenamine (CPM) using lignocellulose-derived granular activated carbon (GAC) was analyzed, and the physicochemical mechanisms of removal were elucidated. Additionally, the textural and surface properties of the GAC were evaluated, the concentrations of the contaminants were monitored with UV–Vis Spectrophotometry. The results revealed that GAC is a mesoporous material with a surface area of 940 m2/g and an acidic character with a point of zero charge (pH PZC) around 2. The adsorption isotherms showed a consistent behavior with the Prausnitz–Radke model, reporting adsorption capacities of 668, 521, and 582μmol/g (221, 173 and 193 mg/g), at an equilibrium concentration of 50μmol/L, pH 7 and 25 °C for CIP, RNT and CPM, respectively. Moreover, studies at different pH levels, temperature, and reversibility suggested that adsorption obeys physical mechanisms, which led to the proposal of a chemical regeneration process with organic (ethanol and methanol) and inorganic (NaOH and HCl) diluents. Better results were obtained using the inorganic diluents, ranging between 44 and 73% thermodynamic desorption. Additionally, three reuse cycles were successfully performed at the best conditions, with a regeneration efficiency in the range of 68%–98% for each of the pharmaceuticals. The results demonstrate the viability of the use of GAC for the removal of drugs with different characteristics in scenarios that are very close to the real ones.Consejo Nacional de Ciencia y Tecnología CVU4921

Bioadsorción de plomo (II) presente en solución acuosa sobre residuos de fibras naturales procedentes de la industria ixtlera (Agave lechuguilla Torr. y Yucca carnerosana (TREL.) MCKELVEY)

"El plomo ha sido reconocido como uno de los metales más tóxicos por su efecto negativo sobre el ambiente. En el presente trabajo se evaluó el uso potencial de residuos de Agave lechuguilla Torr. (lechuguilla) y Yucca carnerosana (Trel.) McKelvey (yuca) procedentes de la industria ixtlera para remover iones Pb (II) presentes en solución acuosa. Los datos del equilibrio de bioadsorción mostraron que al aumentar el pH de la solución de 2.0 a 5.0, la capacidad de bioadsorción de ambos materiales se incrementa. Este efecto se explicó considerando que la carga superficial negativa de estos materiales es mayor al aumentar el pH y por ello se favorece la remoción de Pb (II). El efecto de la temperatura de la solución en las isotermas de bioadsorción, expuso la naturaleza endotérmica del proceso. La energía libre de Gibbs y la entropía calculada (ΔG° y ΔS°) indicaron la espontaneidad de la bioadsorción y la afinidad del Pb (II) en solución por los bioadsorbentes, respectivamente. La variación de las capacidades de bioadsorción de la lechuguilla y la yuca se atribuyó a la diferencia en el contenido de sitios ácidos y lignina, lo que condujo a la presencia de diversos mecanismos de bioadsorción. En ambos materiales, la bioadsorción de Pb (II) ocurre por los mecanismos de interacciones π-catión, atracciones electrostáticas e intercambio iónico; además en el caso de la lechuguilla se evidenció un proceso de microprecipitación.""Lead has been recognized as one of the most toxic metals due to its negative effect on the environment. In the present work, the potential use of Agave lechuguilla Torr. (lechuguilla) and Yucca carnerosana (Trel.) McKelvey (yucca) residues from the ixtle industry to remove Pb (II) ions in an aqueous solution was evaluated. The adsorption equilibrium data showed that when increasing the pH in the solution from 2.0 to 5.0, the biosorption capacity of both materials increases. This effect might be explained by the negative surface charge of these materials, which is greater at high pH, favoring the removal of Pb (II). The effect of the temperature of the solution on the biosorption isotherms revealed the endothermic nature of the biosorption process. The Gibbs free energy change and the calculated entropy (ΔG° and ΔS°) indicated the spontaneity of biosorption and the affinity of Pb (II) in the solution for biosorbents, respectively. The variation of the biosorption capacities of lechuguilla and yucca was attributed to the different content of acid sites and lignin, which resulted in the presence of different biosorption mechanisms. In both materials, the biosorption of Pb (II) occurs by π-cation interactions, electrostatic attractions and ion exchange; moreover, a microprecipitation process on lechuguilla was evinced.

ZIF-8 and Its Magnetic Functionalization as Vehicle for the Transport and Release of Ciprofloxacin

The use of nanomaterials for the controlled release of drugs aims to enhance their effectiveness, especially when poorly soluble in water, and achieve their rapid, localized, and effective administration. The present study focuses on the use of a Zeolitic Imidazolate Framework-8 (ZIF-8) as vehicle for the transport and controlled release of the antibiotic ciprofloxacin (CIP) as model due to its favorable physicochemical characteristics. The objective is to synthesize the ZIF-8 material loaded with CIP through encapsulation for subsequent release of the drug in neutral and acid physiological media. In addition, functionalization of the CIP/ZIF compound with magnetic nanoparticles (NP) was sought to increase its traceability through the possible use of magnetic fields. Characterizations by XRD, FT-IR, SEM-EDX, and TGA showed a satisfactory synthesis of both pure ZIF-8 and ciprofloxacin-loaded ZIF-8, with high crystallinity and thermal stability. The release profiles showed an abrupt initial release that stabilized over time. A much higher release (20–80% greater) was obtained in acid versus neutral pH in all cases, attributable to the collapse of the ZIF-8 structure in acid media. In addition, functionalization of the material with iron NPs did not affect the behavior of the system during drug release. Antimicrobial activity tests against E. coli and S. aureus showed that ZIF-8 per se exerts antimicrobial activity, while the compounds CIP/ZIF and magnetic CIP/ZIF increased the antimicrobial capacity of pure CIP by 10–20%. The ZIF-8 system has high potential as a drug carrier and release agent for the treatment of diseases, especially those that cause acidification of the cellular environment, achieving a rapid, localized, and targeted action with the possibility of achieving traceability of the system after its magnetic functionalization.P18-RT-419