Abstract
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.
Highlights
The electrolytic process to obtain zinc is one of the most widely used hydrometallurgical processes
The study of the adsorption mechanisms of hexavalent chromium contained in a sample of industrial wastewater from a chrome plating process was carried out, using jarosites thermally treated at 600 ◦C (JTT) as a low-cost adsorbent material
The adsorption tests were carried out using a specific amount of jarosites without heat treatment (JST) and subsequently repeated with jarosite treated at 600 ◦C (JTT)
Summary
The electrolytic process to obtain zinc is one of the most widely used hydrometallurgical processes. The tolerable levels of hexavalent chromium in surface water and drinking water are 0.1 mg/L and 0.05 mg/L, respectively [15] Various techniques such as precipitation, adsorption, ion exchange, and electrocoagulation have been used for the treatment of wastewater containing Cr (VI); the adsorption process is flexible in design and operation and, in most cases, offers high removal efficiency [15,16,17,18,19]. The study of the adsorption mechanisms of hexavalent chromium contained in a sample of industrial wastewater from a chrome plating process was carried out, using jarosites thermally treated at 600 ◦C (JTT) as a low-cost adsorbent material
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