Breakthrough curves of synthetic and real acidic chrome-plating wastewater on a strongly basic Dowex 1X8 anion exchanger. Solution pH: 2.0; Cr(VI) concentration: 500 ppm; amount of resin: 5 g; throughput rate: 2.5 mL/min.

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Context 1

... the treatability of plating wastewater containing chromate, a 5,000 ppm Cr(VI) stock solution (containing 7.07 g K 2 Cr 2 O 7 per 500 mL) was pH adjusted and diluted tenfold to yield a 500-ppm Cr(VI) working solution at pH 2; 2,000 mL of this final solution was passed through a 5-g resin column at 2.5 mL/min to yield the breakthrough curves (see Fig. 3). Because an elution trial with 1 M NaOH was not efficient, complete elution was realized by using 125 mL of a mixture solution containing 15% NaCl and 1 M ...

Context 2

... of the strongly basic Dowex 1X8 resin for 500 ppm Cr(VI) synthetic solution at pH 2 was found as 2.78 mmol/g. The Cr(VI) uptake efficiency of the anionic resin at pH 2 was 98.0 ( 0.35)%, and the retained Cr could be quantitatively recovered (with an efficiency of 99.9 ( 0.27)%) by us- ing 125 ml of a 15% NaCl and 1 M NaOH mixture solution. (See Fig. 3 for break- through curves.) A lower concentration of NaCl in the eluting mixture solution (such as 10% NaCl in 1M NaOH) required a higher volume for quantitative Cr re- covery; for example, 220 mL of this mixture eluted Cr with 99.8 ( 0.39 )% effi- ciency. When NaNO 3 was replaced with NaCl, even better results were obtained; 150 mL of ...