Purification of chromium(VI) finishing wastewaters using calcined and uncalcined Mg-Al-CO3-hydrotalcite.
The applicability of calcined and uncalcined hydrotalcite for the purification of industrial effluents has been studied using chromium finishing wastewaters. Using a batch method, the influence of the initial concentration of chromium (10-450mg/l), hydrotalcite (HT) dose (0.5-5g/l) and time (0.5-72h) has been evaluated. The process could be described by the Langmuir model and gave a maximum removal of chromium of 16.3mg Cr(VI)/g on uncalcined HT and 128mg Cr(VI)/g on calcined hydrotalcite (C-HT). Removal using the calcined product provided an effective system to treat chromium finishing wastewaters with the most stringent discharge limit for such industrial streams being achieved with between two and four consecutive removal cycles on C-HT at a dose of 2g/l.
Alvarez-Ayuso
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Department of Chemical Technology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2638 BL Delft, The Netherlands. e.alvarez@tnw.tudelft.nl
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D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D002857:Chromium / Q000737:chemistry*; D003247:Conservation of Natural Resources; D007220:Industrial Waste; D008276:Magnesium Hydroxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D002254:Carbonates; D007220:Industrial Waste; D014873:Water Pollutants; D002857:Chromium; C010467:hydrotalcite; C074702:chromium hexavalent ion; D000536:Aluminum Hydroxide; D008276:Magnesium Hydroxide