WASTEWATER TREATMENT BY USING TAILORED-ACTIVATED CARBON CLOTHS

M. E. RAMOS; P. BONELLI; A. L. CUKIERMAN

Rosario, Santa Fe

Workshop; 1st Argentinian Workshop in Environmental Science / Taller Argentino en Ciencia Mediambiental; 2009

Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario

In recent years, interest in activated carbon cloths (ACC) has been significantly increased due to the growing number of applications for this novel form of activated carbon, which shows several technological advantages in comparison with traditional forms. Conventional activated carbons are widely used for the removal of pollutants from liquid and gaseous environments. However, most studies involving ACC in environmental applications are concerned with adsorption of gaseous pollutants. Quality and performance of ACC are determined by their textural characteristics and surface chemistry. As a consequence, ACC with particular features are required for their effective use in wastewater treatment. Pore size distribution and surface functional groups of activated carbons can often be tailored by a proper selection of the precursor and a careful control of the experimental conditions during their preparation. In particular, application of the chemical activation process enables to obtain adsorbents with a defined porous structure and to introduce different types of micro/mesoporosity by properly selecting the activating agent. Within this context, ACC are obtained from chemical activation of lyocell in the form of woven cloth by using different chemical reagents at otherwise pre-established experimental conditions. The feasibility of using the developed ACC in the uptake of pollutants from wastewater is evaluated from adsorption of methylene blue, a standard compound frequently employed as a primary indicator of the adsorption capacity of conventional activated carbons designed for removing organics from aqueous solutions. The influence of the chemical reagents used in the impregnation stage on porosity development, physico-chemical characteristics, and morphology of the ACC is investigated. Thermal treatment of the precursor impregnated with the different activating agents is carried out in an inert atmosphere at a final thermal treatment temperature of 864°C. In order to study porous structure of the adsorbents, nitrogen adsorption isotherms (77 K) are determined, and textural parameters are evaluated by means of Dubinin-Radushkevich equation. Characterization of ACC morphology is also carried out by scanning and transmission electron microscopy. The results obtained indicate that the activating agent markedly influences textural, physico-chemical and morphological features of the ACC. Moreover, although almost all ACC show good ability to decolorize the dilute solution of methylene blue used as a model of dye wastewater, differences in the compound uptake by the samples are found. They are dependent on the nature of the activating agent employed for ACC preparation. Hence, by a proper selection of the activating agent, the porosity of the ACC may be conveniently tailored for their potential use in tertiary wastewater treatment.