Especiação e quimissorção de Pb(II) em rejeito de caulim Speciation and chemisorption of Pb(II) on kaolin waste

This study assesses the adsorption of Pb(II) on natural kaolin waste (KRnatural) and on that treated with 3 mol L-1 H2SO4 and HCl. Equilibrium and thermodynamic parameters were determined. The results indicate that the values of CEC, specific area and SiO2/Al2O3 ratio (4.6-6.0 cmol kg-1, 14.0-16.0 m² g-1 and 1.16-1.30, respectively) vary only slightly for the adsorbents; the concentration of Pb2+ is much higher than that of other species (PbOH+ and Pb(OH)2). The values of R L, ΔGº, ΔHº and ΔSº are typical of feasible, spontaneous, exothermic and ordered adsorption. The chemisorption on KRnatural is more feasible and ordered

Arthritic lesions and congenital fusion in foot bones of Panochthus sp. (Xenarthra, Cingulata)

ABSTRACT A set of lesions are re-described and new pathological findings in foot bones of Panochthus sp. (Xenarthra, Cingulata) are presented. The material reexamined in fact presents enthesiophytes instead of osteoartrithis, as previously interpreted. Furthermore, Calcium Pyrophosphate Deposition Disease (CPPD) was observed, a lesion absent in previous report. CPPD also was found in another set of foot bones and it was associated with a congenital fusion of two sesamoids. The material studied were collected in two natural tank deposits, one in Paraíba (material reexamined) and other in Rio Grande do Norte (new pathological findings) State