Spent alkaline and Zn-C batteries were placed in seawater, rainwater or landfill leachate at room temperature for up 30 days in order to simulate natural weathering. After the experiments pH and electrical conductivity of the liquid were measured. The precipitate formed and the filtrate were submitted to metal analysis by ICP-OES. Seawater is the most corrosive medium, followed by landfill leachate. Pb, Cd and Hg were mainly in the filtrate. Fe, Mn and Zn were generally dominant in the precipitate. Na and K account for the electrical conductivity and are good indicators of the corrosion stage of the batteries.

Mn, Zn, Fe, Cd, Pb and Hg were determined in Zn-C and alkaline batteries manufactured along almost 20 years. After samples disassembly the electroactive components were treated with aqua regia in bath ice for 24 h. Metals were analyzed by ICP-OES. Zn and Mn amounts did not vary significantly. Fe amount decreased, specially after 2000. Hg, Cd and Pb amounts dramatically decreased along time, being virtually absent in alkaline batteries manufactured after 2005. Pb still remains in Zn-C samples. Scanning electron microscopy of batteries manufactured in 1997 and 1998 showed the presence of Bi, In and Cr in the plastic/paper anode-cathode separator.

Recentemente apresentamos a produção de pós microporosos de sílica de alta pureza a partir de lixiviação ácida de vidros, com tamanho médio de poros próximo de 2,5 nm e 420 m2/g (BET) de área de superfície específica. Foram usados vidros a partir de fusão de dois tipos de resíduos de processamento industrial de xisto oleígeno brasileiro (xisto oleígeno retortado e fração superior da camada intermediária da formação de Irati). Dependendo da proporção dos dois resíduos empregados na formulação dos vidros, é obtida sílica na forma de gel ou de pó, após lixiviação. A lixiviação desses vidros com ácido clorídrico a 90 oC foi usada para produzir sílica microporosa em pó. Neste trabalho é estudado o efeito do tempo e da temperatura de envelhecimento na morfologia e na estrutura da sílica obtida na forma de pó. Estudos de envelhecimento foram efetuados em dois meios diferentes, um ácido (ácido clorídrico) e um básico (hidróxido de amônio) a diferentes tempos e temperaturas. DRX, MEV/EDX, MET, medidas de área de superfície específica e ATG/ATD foram usados para caracterizar esses materiais. Os resultados mostraram uma diminuição na área de superfície específica com aumento de tempo e de temperatura. Esse comportamento pode ser aparentemente associado a mecanismos de dissolução e re-precipitação.

Recently, we have reported the production of a microporous high purity silica powder from the acid leaching of glasses with average pore size around 2.5nm and specific surface area of 420m2/g (BET). The employed glasses derived from the melting of two types of waste from the industrial processing of Brazilian oil shale (retorted oil shale and the top fraction of the intermediate layer of Irati Formation). Depending on the proportion of the two wastes employed in the formulation of the glasses, either a silica gel or a powdered one is obtained, after leaching. The acid leaching of those glasses with hydrochloric acid, at 90 °C, was used to produce powdered microporous silica. In the present work it is studied the effect of aging time and temperature on the morphology and structure of the obtained powdered silica. Aging studies were performed in two different media, an acidic (hydrochloric acid) and a basic one (ammonium hydroxide) for different periods of time and temperatures. XRD, SEM/EDX, TEM, specific surface area measurements and DTA/TGA were used to characterize these materials. The results have shown a decrease of specific surface area with increasing time and temperature. Apparently, this behavior may be associated with dissolution and re-precipitation mechanisms.