Abstract
The widespread use of jarosite-type compounds to eliminate impurities in the hydrometallurgical industry is due to their capability to incorporate several elements into their structures. Some of these elements are of environmental importance (Pb2+, Cr6+, As5+, Cd2+, Hg2+). For the present paper, AsO43- was incorporated into the lattice of synthetic jarosite in order to carry out a reactivity study. Alkaline decomposition is characterized by removal of sulfate and potassium ions from the lattice and formation of a gel consisting of iron hydroxides with absorbed arsenate. Decomposition curves show an induction period followed by a conversion period. The induction period is independent of particle size and exponentially decreases with temperature. The conversion period is characterized by formation of a hydroxide halo that surrounds an unreacted jarosite core. During the conversion period in NaOH media for [OH-] > 8 × 10-3 mol L-1, the process showed a reaction order of 1.86, and an apparent activation energy of 60.3 kJ mol-1 was obtained. On the other hand, during the conversion period in Ca(OH)2 media for [OH-] > 1.90 × 10-2 mol L-1, the reaction order was 1.15, and an apparent activation energy of 74.4 kJ mol-1 was obtained. The results are consistent with the spherical particle model with decreasing core and chemical control.
Highlights
Arsenic has been found in underground waters in several countries around the world at levels that surpass those established by the World Health Organization (10 μg L−1) [1]
It can be observed that alkaline decomposition starts with an induction period (θ), during which the external appearance of the synthetic jarosite with arsenic remains unaltered, and negligible traces of potassium ions were found in solution (Table 1)
The decomposition of the synthetic jarosite with arsenic in alkaline media presents an induction period, where there are no changes on the surface of the jarosite
Summary
Arsenic has been found in underground waters in several countries around the world at levels that surpass those established by the World Health Organization (10 μg L−1) [1]. This issue affects more than 70 countries, where the health of approximately 150 million people is at risk. 110 million people live in south and south east Asia [2], and the rest are found in countries such as Argentina, Mexico, Chile, Peru, United States, Brazil and Canada [3,4]. Arsenic cannot be eliminated, but it can be combined with other elements, such as iron, and turned
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
