RESUMEN

Microalgae are used as a lipid source for different applications, such as cosmetics and biofuel. The nonliving biomass and the byproduct from the lipid extraction procedure can efficiently remove antibiotics. This work has explored the potential use of Chlorella sp. biomasses for tetracycline (Tc) removal from highly concentrated aqueous media. Non-living biomass (NLB) is the biomass before the lipid extraction procedure, while lipid-extracted biomass (LEB) is the byproduct mentioned before. LEB removed 76.9% of Tc at 40 mg/L initial concentration and 40 mg of biomass, representing an adsorption capacity of 19.2 mg/g. Subsequently, NLB removed 68.0% of Tc at 50 mg/L and 60 mg of biomass, equivalent to 14.2 mg/g of adsorptive capacity. These results revealed an enhanced removal capacity by LEB compared with NLB and other microalgae-based materials. On the other hand, the adsorption kinetics followed the pseudo-second-order and Elovich models, suggesting chemisorption with interactions between adsorbates. The adsorption isotherms indicate a multilayer mechanism on a heterogeneous surface. Additionally, the interactions between the surface and the first layer of tetracycline are weak, and the formation of the subsequent layers is favored. The Chlorella sp. biomass after the lipid extraction process is a promising material for removing tetracycline; moreover, the use of this residue contributes to the zero-waste strategy.

RESUMEN

RESUMEN La contaminación del agua con colorantes sintéticos, resultado de las actividades industriales, es un problema latente en la sociedad. Su presencia, aun en concentraciones muy bajas, influye drásticamente en los procesos de fotosíntesis, porque impide la penetración de la luz, afectando la vida acuática e, incluso, la salud humana. La adsorción con carbón activado es una de las técnicas más empleadas para remover el color de los efluentes, pero sus altos costos han dirigido la atención de los investigadores hacia el estudio de materiales adsorbentes provenientes, principalmente, de la agroindustria. Este artículo presenta un estudio sobre la remoción del colorante azul directo 2 en disolución acuosa sobre borra de café sin tratar y modificada a 30±1°C, en una columna empacada. Se realizó la caracterización fisicoquímica de los adsorbentes, que incluye la evaluación de las propiedades de textura, mediante isotermas de adsorción, con N2 a 77K, la identificación y cuantificación de grupos funcionales orgánicos, con FTIR y el método de Boemh. El estudio en columna evaluó el efecto de la altura del lecho del adsorbente (Z = 3 y 6cm), el flujo volumétrico (Qv= 2 y 4cm3min-1) y la concentración inicial (Co = 8 y 14mgdm-3), sobre el tiempo de ruptura y la capacidad de adsorción. Los datos experimentales de las curvas de ruptura se ajustaron al modelo BDST (Bed Depth Service Time). Los resultados muestran que el rendimiento de la columna mejora con el incremento de Z y la disminución de Qv y Co, siendo la concentración inicial, el factor con mayor significancia.

ABSTRACT Water bodies contaminated with synthetic dyes from industrial activities is a latent problem in our society. Even in low concentration it influences drastically in photosynthesis process because it blocks sun rays affecting both life in water and human health as well. Adsorption with activated carbon is one of the most used techniques to remove dyes from effluents, but high costs have lead researchers to examine adsorbents materials coming from agroindustry. This article introduces a research about direct blue 2 removal in water solution over coffee grounds untreated and modified at 30±1°C in a packed column. A physicochemical characterization was carried out in adsorbents that involves the test of texture properties using isotherms of adsorption with N2 at 77K, the identification and quantification of organic functional groups with FTIR and the Boemh method. The study in column, tested the effect of the height of the bed of the adsorbent (Z = 3 y 6cm), the volumetric flow (Qv = 2 y 4cm3min-1) and the initial concentration (Co = 8 y 14mgdm-3) at the breakthrough time and the capacity of adsorption. The experimental data of breakthrough curves were fitted to BDST (Bed Depth Service Time) models. The results show that performance in the column improves as Z increases and Qv y Co decreases, being the initial concentration the factor with main significance.