Aplicação de escolecita na retenção de metais pesados em solução aquosa

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

Scolecite is a type of zeolite which can found associated to the basalts of the Paraná Continental lgneous Province (PCIP). In this work, the potentiality of scolecite as a new material for heavy metals removaI (Pb2+, CU2+, Zn2+, Ni2+, Co2+ and Cd2+) from aqueous solutions is evaluated. The samples used in the experiments were collected in Morro Reuter - RS and characterized by X-ray diffraction and X-ray fluorescence. The experiments of were carried out by immersion of 0.5 g of pulverized sample in aqueous solutions of the metallic ions (prepared from their nitrates) and kept under constant agitation for 24 h, at ambient temperature. The initial and final concentrations of the metals in the solutions were determined by atomic absorption spectrometry. The initial concentration (5 to 60 mg L-1), pH (4 - 6) and the liquid/solid ratio (200, 1000 and 2000) and scolecite granulometry were altered in the experiments to evaluate their influence in of ion exchange processo Scolecite showed great affinity for Pb2+ , with retention values of about 11 mg g-1 (pH 5.5 and Ci = 60 mg L-1) of zeolite. In same experimental conditions, the other ions presented decreasing retention values, Le., Cu2+ (8.2 mg g-1), Zn2+ (6.2 mg g-1), Ni2+ (2.6 mg g-1), Co2+ (2.4 mg g-1) and Cd2+ (0.06 mg g-1), resulting in the following sequence of selectivity: Pb2+ >CU2+ >Zn2+ » Ni2+ >Co2+» Cd2+. The relative removal efficiency was higher in more diluted solutions (5 - 15 mg L-1). The ions affinity for scolecite was interpreted with help of hydrolysis constants, and it was concluded that internal and external sphere complexes are formed (Pb2+ e CU2+) at the solid-water interface and external sphere complexes for the other cations. Results indicate that scolecite could useful in secondary treatment of waste water, especially for Pb2+ e Cu2+ removal

ASSUNTO(S)

metais pesados troca ionica

ACESSO AO ARTIGO

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