Zorflex® activated carbon fibers (ACF), reference FM100 198B, are used before and after an oxidizing procedure with H3PO4 to study the adsorption of Pb2+. The point of zero charge was determined for the modified and unmodified fiber giving values of 2.3 and 4.3, respectively. After oxidizing the ACF, the fiber showed to have a greater Pb2+ adsorption capacity in comparison with the unmodified fiber, which is related with the acid sites increase, where lead was mainly adsorbed. Determination of the BET area was carried out by nitrogen physisorption at 77K. ACFs presented superficial areas between 1000 and 1500 m²/g showing mostly, a microporous structure. The preliminary design of an adsorbent using the modified fiber is presented where the fiber superior physicochemical properties over the unmodified one are observed.

The present work shows a simple way to design a process scale-up, for an adsorber, from laboratory to industrial level using breakthrough curves in fixed beds developed through the continuous detection of the Pb(II) ion concentration in the effluent of the bed. This procedure was developed in order to examine its efficiency and to be compared with an experimental method developed in the laboratory, which produced similar results. The feasibility of this design lies on the fact that neither tedious calculations nor mass transfer coefficients are required in order to plot the mentioned curves. The procedure was developed by applying concepts such as mass transfer zone (MTZ) and length of unused bed (LUB), which are the dynamic basis of the adsorption process in fixed beds. As a complement to the experimentation, within a pilot plan scale, a filter was developed to handle the most important adsorption parameters and to control the variables that change the operating conditions during the process.

Este trabajo describe una manera simple de diseñar un proceso de escalado, para un adsorbedor, desde nivel de laboratorio a escala industrial usando curvas de paso en lechos fijos, desarrollado a través de la detección continua de la concentración de Pb(II) en el efluente del lecho. El procedimiento fue medido con el objeto de examinar su eficiencia y para ser comparado con un método experimental desarrollado en el laboratorio que dio lugar a resultados similares. La factibilidad del diseño se basa en la ausencia de cálculos tediosos y coeficientes de transferencia en el graficado de las curvas mencionadas. El procedimiento fue desarrollado aplicando conceptos tales como los de zona de transferencia de masa (MTZ) y longitud del lecho no usado (LUB), que constituyen la base dinámica del proceso de adsorción en lechos fijos. Como complemento a la parte experimental en el proceso de escalado, se desarrolló un filtro para controlar los parámetros de adsorción más importantes y para observar las variables que modifican las condiciones de operación durante el proceso.

An activated carbon was obtained by chemical activation with phosphoric acid, CM, from a mineral carbon. Afterwards, the carbon was modified with 2 and 5 molL-1, CMox2 and CMox5 nitric acid solutions to increase the surface acid group contents. Immersion enthalpy at pH 4 values and Pb2+ adsorption isotherms were determined by immersing activated carbons in aqueous solution. The surface area values of the adsorbents and total pore volume were approximately 560 m².g-1 and 0.36 cm³g-1, respectively. As regards chemical characteristics, activated carbons had higher acid sites content, 0.92-2.42 meq g-1, than basic sites, 0.63-0.12 meq g-1. pH values were between 7.4 and 4.5 at the point of zero charge, pH PZC. The adsorbed quantity of Pb2+ and the immersion enthalpy in solution of different pH values for CM activated carbon showed that the values are the highest for pH 4, 15.7 mgg-1 and 27.6 Jg-1 respectively. Pb2+ adsorption isotherms and immersion enthalpy were determined for modified activated carbons and the highest values were obtained for the activated carbon that showed the highest content of total acid sites on the surface.