Development of a new vacuum impregnation method at room atmosphere to produce silver-copper oxide nanoparticles on activated carbon for antibacterial applications.

A new impregnation method was tested in this study. Without a stabilizing agent, silver and copper metallic compounds were directly impregnated on activated carbon using vacuum impregnation followed by drying at 100°C and vacuum impregnation followed by thermal decomposition at 350°C in an ambient atmosphere. The effect of thermal decomposition on the structural, morphological, and textural characteristics of the modified nanomaterials was analysed by Brunauer-Emmett-Teller, X-ray diffraction, scanning electron microscopy, energy dispersive X-Ray, and transmission electron microscopy. The characteristics of the produced materials were not altered. Silver and CuO nanoparticles were identified in the samples with average diameters ranging from 33.3-36.8 nm and 29.0-33.3 nm, respectively. The materials were tested for their antibacterial capacity and for their potential to leach Ag and Cu into water, thus analysing the effect of the thermal decomposition process on the impregnation process. The vacuum impregnation process followed by thermal decomposition produced the best results, with the resultant material reducing bacterial abundance by 5.31-6.61 log and leaching only low concentrations of metals into the water (Ag - 0.010-0.025 mg L-1 and Cu - 0.270-0.361 mg L-1). Samples produced without the thermal decomposition step reached bacterial reductions of 1.86-1.97 log and yielded higher concentrations of metals in the water (Ag - 0.051-0.086 mg L-1 and Cu - 0.819-0.894 mg L-1).

Adsorption of cephalexin in aqueous media by graphene oxide: kinetics, isotherm, and thermodynamics.

The present study proposes the synthesis and characterization of graphene oxide (GO) and its application in the adsorption of the antibiotic cephalexin (CFX) in aqueous solution. The characterization of graphene oxide was obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential. The influence of pH on the batch adsorption process was investigated by analysing adsorption equilibrium isotherms and adsorption kinetics. The images obtained by SEM and TEM presented the typical morphology attributed to GO sheets. The kinetic adsorption tests showed that equilibrium was reached in 420 min, and an adsorption capacity of 164 mg g-1 was obtained. The models that best fit the experimental data were pseudo-second as well as the Langmuir isotherm. Therefore, GO was effective for removing the CFX antibiotic from aqueous solution by using a batch adsorption process.

Development of an activated carbon impregnation process with iron oxide nanoparticles by green synthesis for diclofenac adsorption.

The objective of this study was to impregnate the surface of palm coconut activated carbon with nanoparticles of iron compounds using Moringa oleifera leaf extracts and pomegranate leaf by a green synthesis method and to evaluate its adsorption capacity for sodium diclofenac. The adsorbent material was characterized by zeta potential, X-ray diffraction (XRD), N2 adsorption/desorption (BET method), transmission electronic microscopy (TEM), and scanning electronic microscopy (SEM) coupled to dispersive energy spectrometry X-ray (EDX) methods. To evaluate the adsorption capacity of sodium diclofenac, the influence of pH, kinetics, isotherms, and thermodynamic properties were analysed. The impregnated adsorbents showed efficiency in the adsorption of sodium diclofenac. The kinetic model that best fit the experimental data was the pseudo-second-order model, and the equilibrium model was the Langmuir model. As for the thermodynamic study, it was verified that the adsorption reaction for all adsorbents occurs in a spontaneous, favourable way, and it is endothermic by physisorption. Therefore, this process is promising because it is a clean and non-toxic method when compared with chemical methods for the synthesis of nanoparticles.