Camilo Freddy Mendoza Morejon

Photocatalytic degradation of H2S in the gas-phase using a continuous flow reactor coated with TiO2-based acrylic paint

ABSTRACT For the photocatalytic degradation of the hydrogen sulphide (H2S) in the gas-phase it was developed a rectangular reactor, coated with acrylic paint supported on fiber cement material. The surface formed by the paint coverage was characterized structural and morphologically by scanning electron microscopy with energy dispersive X-ray and X-ray diffraction analysis. The flow rate and the inlet concentration of H2S were evaluated as operational performance parameters of the reactor. Removal efficiencies of up to 94% were obtained at a flow rate of 2 L min−1 (residence time of 115 s) and inlet concentration of 31 ppm of H2S. In addition, the H2S degradation kinetics was modelled according to the Langmuir–Hinshelwood (L–H) model for the inlet concentrations of 8–23 ppm of H2S. The results suggest that flow rate has a more important influence on photocatalytic degradation than the inlet concentration. It is assumed that H2S has been oxidized to , a condition that led to a deactivation of the photocatalyst after 193 min of semi-continuous use.

ESTUDO DA EVAPORAÇÃO SOLAR DA SALMOURA NO PROCESSO DE CONCENTRAÇÃO DO LÍTIO DO SALAR DE UYUNI-BOLÍVIA

Na America do Sul se encontra o maior deserto de sal do mundo (salar de Uyuni-Bolivia com 10.000 km2 de superficie), metade da reserva mundial do litio esta disponivel para diversas aplicacoes. Na atualidade o Litio e obtido na forma de Carbonato, cuja etapa preliminar, visando o aumento da concentracao do litio na salmoura (Solucao composta de Li, K, Na, SO4, Cl, e Mg), utiliza processos de separacao por evaporacao solar a ceu aberto. No presente trabalho se apresenta resultados da influencia das variaveis operacionais no fluxo de evaporacao da salmoura do salar de Uyuni-Bolivia. A metodologia contemplou: a) o projeto/construcao do modulo experimental; b) o monitoramento transiente do fluxo de evaporacao, temperatura ambiente, umidade relativa e radiacao solar; e c) o estudo da composicao quimica dos elementos presentes na salmoura em funcao da porcentagem de evaporacao. Para as condicoes reais de operacao o fluxo de evaporacao da salmoura, numa superficie de contato de conveccao natural de 0,018m2, foi de 0,63 kgaguamh. A evaporacao global correspondeu a 51% da salmoura original, no qual a umidade relativa teve uma maior influencia quando comparado com a temperatura ambiente e a radiacao solar.