TY - JOUR
T1 - Experimental design and batch experiments for optimization of Cr(VI) removal from aqueous solutions by hydrous cerium oxide nanoparticles
AU - Albadarin, Ahmad B.
AU - Yang, Zheyu
AU - Mangwandi, Chirangano
AU - Glocheux, Yoann
AU - Walker, Gavin
AU - Ahmad, M. N.M.
PY - 2014/7
Y1 - 2014/7
N2 - Hydrous cerium oxide (HCO) was synthesized by intercalation of solutions of cerium(III) nitrate and sodium hydroxide and evaluated as an adsorbent for the removal of hexavalent chromium from aqueous solutions. Simple batch experiments and a 25 factorial experimental design were employed to screen the variables affecting Cr(VI) removal efficiency. The effects of the process variables; solution pH, initial Cr(VI) concentration, temperature, adsorbent dose and ionic strength were examined. Using the experimental results, a linear mathematical model representing the influence of the different variables and their interactions was obtained. Analysis of variance (ANOVA) demonstrated that Cr(VI) adsorption significantly increases with decreased solution pH, initial concentration and amount of adsorbent used (dose), but slightly decreased with an increase in temperature and ionic strength. The optimization study indicates 99% as the maximum removal at pH 2, 20°C, 1.923mM of metal concentration and a sorbent dose of 4g/dm3. At these optimal conditions, Langmuir, Freundlich and Redlich-Peterson isotherm models were obtained. The maximum adsorption capacity of Cr(VI) adsorbed by HCO was 0.828mmol/g, calculated by the Langmuir isotherm model. Desorption of chromium indicated that the HCO adsorbent can be regenerated using NaOH solution 0.1M (up to 85%). The adsorption interactions between the surface sites of HCO and the Cr(VI) ions were found to be a combined effect of both anion exchange and surface complexation with the formation of an inner-sphere complex.
AB - Hydrous cerium oxide (HCO) was synthesized by intercalation of solutions of cerium(III) nitrate and sodium hydroxide and evaluated as an adsorbent for the removal of hexavalent chromium from aqueous solutions. Simple batch experiments and a 25 factorial experimental design were employed to screen the variables affecting Cr(VI) removal efficiency. The effects of the process variables; solution pH, initial Cr(VI) concentration, temperature, adsorbent dose and ionic strength were examined. Using the experimental results, a linear mathematical model representing the influence of the different variables and their interactions was obtained. Analysis of variance (ANOVA) demonstrated that Cr(VI) adsorption significantly increases with decreased solution pH, initial concentration and amount of adsorbent used (dose), but slightly decreased with an increase in temperature and ionic strength. The optimization study indicates 99% as the maximum removal at pH 2, 20°C, 1.923mM of metal concentration and a sorbent dose of 4g/dm3. At these optimal conditions, Langmuir, Freundlich and Redlich-Peterson isotherm models were obtained. The maximum adsorption capacity of Cr(VI) adsorbed by HCO was 0.828mmol/g, calculated by the Langmuir isotherm model. Desorption of chromium indicated that the HCO adsorbent can be regenerated using NaOH solution 0.1M (up to 85%). The adsorption interactions between the surface sites of HCO and the Cr(VI) ions were found to be a combined effect of both anion exchange and surface complexation with the formation of an inner-sphere complex.
KW - Adsorption isotherm
KW - Chromium
KW - Desorption
KW - Hydrous cerium oxide
KW - Nanoparticles
KW - Optimization
UR - http://www.scopus.com/inward/record.url?scp=84903434006&partnerID=8YFLogxK
U2 - 10.1016/j.cherd.2013.10.015
DO - 10.1016/j.cherd.2013.10.015
M3 - Article
AN - SCOPUS:84903434006
SN - 0263-8762
VL - 92
SP - 1354
EP - 1362
JO - Chemical Engineering Research and Design
JF - Chemical Engineering Research and Design
IS - 7
ER -