Influence of the activation method of agro-industrial wastes in the removal of lead

Abstract

The adsorption on activated carbon has been shown to be very effective for the removal of heavy metals from water. This work details the removal of lead by adsorption onto activated carbon obtained from wastes of grape industrialization, in batch and column operation, under different conditions in order to correlate the adsorbents properties with their performance. Activated carbons, obtained from grape lex and grape stalk by physical and chemical activation, were characterized by Brunauer, Emmet and Teller (BET) surface area, pore volumes, point of zero charge pH and surface functional groups through Boehm method, Fourier transform infrared spectroscopy and temperature programmed decomposition. The results showed better textural properties for the adsorbents obtained by chemical activation, whose BET areas were 978 and 1,217 m2 g–1. Chemical characterization also showed a marked difference between both activation routes, yielding carbons with a marked basic character by physical activation and acid by the other way. Due to their dissimilar textural and chemical properties, all products exhibited different performance in batch and continuous assays. The maximum adsorption capacity was 49.95 mg g–1, achieved at a bed height of 15 cm and a feed concentration of 100 mg L–1 using steam activated grape lex briquettes as adsorbent.