Adsorption kinetic of arsenates as water pollutant on iron, manganese and iron-manganese-modified clinoptilolite-rich tuffs.

Arsenate adsorption from aqueous solutions onto clinoptilolite-heulandite rich tuffs modified with iron or manganese or a mixture of both iron and manganese in this work was investigated. A kinetic model was considered to describe the arsenates adsorption on each zeolitic material. The modified clinoptilolite-heulandite rich tuffs were characterized by scanning electron microscopy and X-ray diffraction analysis. The elemental composition and the specific surface area of the zeolitic material were also determined. The arsenate adsorption by the modified zeolites was carried on in a batch system considering a contact time from 5 min to 24h for the kinetic experimentation. The arsenic was detected by atomic absorption spectrometer using a hydride generator. The kinetics of the arsenate adsorption processes were described by the pseudo-second-order model and the obtained parameter k varies from 0.15 to 5.66 microg/gh. In general, the results suggested that the kinetic adsorption of arsenates on the modified clinoptilolite-rich tuffs depend of the metallic specie that modified the surface characteristics of the zeolitic material, the chemical nature of the metal as well as the association between different metallic chemical species in the zeolitic surface.

[Ethical problems faced by in managing HIV in workplace]. / Problèmes ethiques rencontrés par les médecins dans la gestion de l'infection VIH en milieu de travail.

This study which was conducted between September 1999 and June 2000 among occupational physicians aimed to appreciate ethical problems faced by physicians in managing HIV infection in workplace. A questionnaire was administrated by telephone to physicians included in the list of Occupational Physicians Association. Thirty eight physicians responded among the fourty four contacted. Thirty two ie 84.21% did face HIV infection in their workplace. The frequency of meeting cases was in between 1 to 5 for 68.75%. Thirty two did order the test either to depist or to conduct eatiologic diagnosis. Informed consent were asked by twenty one physicians. Six physicians ie 18.75% did inform the employer of serologic status, among them four said having obtain employee's consent to reveal status. For them, such revalation was the basis for financial involvment of employer in the treatment, and facilitates his tolerance of absenteeism. Four physicians signaled facing dilemma when a patient did not want to inform his or her partner of his (her) serologic status. They suggested a legal authorization to reveal patients status in such circumtances.