9 research outputs found
Oxidation of cyanide in aqueous solution by ozonisation in the presence of modified activated carbon
[EN] The aim of this study was to analyze the role of
activated carbon on cyanide ozonation in aqueous
phase. The results show that activated carbon
previously treated with ammonia had a marked effect
on the kinetics of cyanide removal. According to the
results obtained by FTIR and XPS techniques,
ammonia treatment increase the superficial
concentration of carbonyl groups, which in the
interaction with ozone could potentiate the generation
of highly oxidizing radicals on the medium, justifying
the results obtained.[ES] El objetivo de este trabajo fue analizar el papel que
desempeña el carbón activado en el proceso de
ozonización del anión cianuro. Los resultados
obtenidos muestran que el carbón activado
previamente tratado con amoniaco incrementó
considerablemente la velocidad de eliminación del
anión cianuro. Los resultados obtenidos mediante
FTIR y XPS muestran un incremento en la
concentración de grupos carbonilo, los cuales con
la interacción con el ozono podrían potenciar la
generación de radicales altamente oxidantes en el
medio justificándose así los resultados obtenidos.Agradezco el apoyo al Consejo Nacional de Ciencia
y Tecnología (CONACYT) por la beca otorgada
176351 para cursar el Doctorado en Ciencia y
Tecnología de los Materiales dentro del programa
de Doctorado de la Universidad Autónoma de
Coahuila en la Facultad de Ciencias Químicas de
Saltillo, Coahuila, MéxicoPeer reviewe
Use of Thermally Modified Jarosite for the Removal of Hexavalent Chromium by Adsorption
Jarosites are residues generated during the purification of zinc and are composed mainly of iron sulfates ((Na, K)Fe3(SO4)2(OH)6). Due to the large volume of jarosite generated during the process, these residues tend to be deposited in large land areas and are not used. In the present work, jarosite was used without heat treatment (JST) as an adsorbent of hexavalent chromium contained in a sample of wastewater from a chrome plating industry under the following conditions: C0 = 200 mg/L of Cr, T = 25 °C, and pH = 3. It was only possible to remove 34% of Cr (VI). Subsequently, a thermal treatment of a jarosite sample (JTT) was carried out at 600 °C. The heat-treated sample was later used as an adsorbent in the same conditions as those for JST. The maximum chromium removal was 53%, and the adsorption capacity was 10.99 mg/g. The experimental data were fitted to the Langmuir model and to the pseudo-second-order kinetic model. It was determined that the adsorption process involved electrostatic attractions between the surface of the positively charged adsorbent and the chromium anions contained in industrial wastewater