Spectrophotometric Determination of Chromium(Ⅵ) in Environmental Water Samples after Separation and Enrichment by Adsorption on CeO2 Nanoparticles

Trace amounts of Cr(Ⅵ) was adsorbed and enriched on the surface of CeO2 nanoparticles, and desorbed by eluting with 2 mol·L-1 NaOH solution. The solution obtained was used for spectrophotometric determination of Cr(Ⅵ) with diphenylcarbazide as color reagent. In a medium of pH 4.0, with the adsorption time of 40 min and amount of adsorbent of 20 mg, the adsorption capacity of CeO2 nanoparticles toward Cr(Ⅵ) was found to be 696 μg·g-1. Measurement of absorbance was made at the absorption maximum of 540 nm. Linearity range of Cr(Ⅵ) was kept between 0.012 to 1.2 mg·L-1, with detection limit (3σ) of 0.01 mg·L-1. The proposed method was used in the determination of Cr(Ⅵ) in environmental water samples, and values of recovery found by standard addition method was 99.4%.