Limits...
Removal of Cr(VI) from aqueous environments using micelle-clay adsorption.

Qurie M, Khamis M, Manassra A, Ayyad I, Nir S, Scrano L, Bufo SA, Karaman R - ScientificWorldJournal (2013)

Bottom Line: Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions.Langmuir adsorption isotherm fitted the experimental data giving significant results.The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Chemical Technology, Faculty of Science and Technology, Al-Quds University, 20002 Jerusalem, Palestine ; Department of Science, University of Basilicata, Via dell'Ateneo Lucano 10, 85100 Potenza, Italy.

ABSTRACT
Removal of Cr(VI) from aqueous solutions under different conditions was investigated using either clay (montmorillonite) or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI) removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques.

Show MeSH

Related in: MedlinePlus

Removal of chromium by micelle-clay complex as total-Cr determined by AAS (■) and as Cr(VI) determined by UV-vis method (♦). Percent of Cr(VI) reduction to Cr(III) (●) is calculated as the difference between total-Cr and Cr(VI) percentages. pH = 2, contact time = 3 h, temperature = 25.0 ± 0.2°C, and adsorbent dosage = 5.0 g L−1. Data represent averages of triplicates ± SE.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3814082&req=5

fig2: Removal of chromium by micelle-clay complex as total-Cr determined by AAS (■) and as Cr(VI) determined by UV-vis method (♦). Percent of Cr(VI) reduction to Cr(III) (●) is calculated as the difference between total-Cr and Cr(VI) percentages. pH = 2, contact time = 3 h, temperature = 25.0 ± 0.2°C, and adsorbent dosage = 5.0 g L−1. Data represent averages of triplicates ± SE.

Mentions: In order to investigate the possibility of Cr(VI) reduction to Cr(III) upon adsorption onto the complex at different pH values, samples were collected at the end of adsorption trials (equilibrium already reached) performed on purpose at pH 2 and 6, using initial Cr(VI) concentrations 10–500 mg L−1, and were analyzed for selective determination of Cr(VI) by UV-vis method [17]. Solutions of Cr(VI) at the same concentrations and pH values used in the adsorption assays were kept in the same environmental conditions without adding the adsorbent and analyzed for Cr(VI) at the end of the time needed to complete the adsorption experiments. As shown in Figure 2, in the initial concentration range 50–200 mg L−1, the adsorbed percentages measured as total-Cr and Cr(VI) are very close at pH = 2. However, at initial concentration higher than 200 mg L−1, the retention curves of total-Cr and Cr(VI) start to advance farther, suggesting that another oxidation state of Cr can occur in these conditions. Presumably, reduction of Cr(VI) to Cr(III) takes place on the adsorbent followed by the release of Cr(III) into the solution leading to the observed deviation of retention curves. Similar results were also documented in the literature using other adsorbents [21, 22, 24–28].


Removal of Cr(VI) from aqueous environments using micelle-clay adsorption.

Qurie M, Khamis M, Manassra A, Ayyad I, Nir S, Scrano L, Bufo SA, Karaman R - ScientificWorldJournal (2013)

Removal of chromium by micelle-clay complex as total-Cr determined by AAS (■) and as Cr(VI) determined by UV-vis method (♦). Percent of Cr(VI) reduction to Cr(III) (●) is calculated as the difference between total-Cr and Cr(VI) percentages. pH = 2, contact time = 3 h, temperature = 25.0 ± 0.2°C, and adsorbent dosage = 5.0 g L−1. Data represent averages of triplicates ± SE.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814082&req=5

fig2: Removal of chromium by micelle-clay complex as total-Cr determined by AAS (■) and as Cr(VI) determined by UV-vis method (♦). Percent of Cr(VI) reduction to Cr(III) (●) is calculated as the difference between total-Cr and Cr(VI) percentages. pH = 2, contact time = 3 h, temperature = 25.0 ± 0.2°C, and adsorbent dosage = 5.0 g L−1. Data represent averages of triplicates ± SE.
Mentions: In order to investigate the possibility of Cr(VI) reduction to Cr(III) upon adsorption onto the complex at different pH values, samples were collected at the end of adsorption trials (equilibrium already reached) performed on purpose at pH 2 and 6, using initial Cr(VI) concentrations 10–500 mg L−1, and were analyzed for selective determination of Cr(VI) by UV-vis method [17]. Solutions of Cr(VI) at the same concentrations and pH values used in the adsorption assays were kept in the same environmental conditions without adding the adsorbent and analyzed for Cr(VI) at the end of the time needed to complete the adsorption experiments. As shown in Figure 2, in the initial concentration range 50–200 mg L−1, the adsorbed percentages measured as total-Cr and Cr(VI) are very close at pH = 2. However, at initial concentration higher than 200 mg L−1, the retention curves of total-Cr and Cr(VI) start to advance farther, suggesting that another oxidation state of Cr can occur in these conditions. Presumably, reduction of Cr(VI) to Cr(III) takes place on the adsorbent followed by the release of Cr(III) into the solution leading to the observed deviation of retention curves. Similar results were also documented in the literature using other adsorbents [21, 22, 24–28].

Bottom Line: Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions.Langmuir adsorption isotherm fitted the experimental data giving significant results.The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Chemical Technology, Faculty of Science and Technology, Al-Quds University, 20002 Jerusalem, Palestine ; Department of Science, University of Basilicata, Via dell'Ateneo Lucano 10, 85100 Potenza, Italy.

ABSTRACT
Removal of Cr(VI) from aqueous solutions under different conditions was investigated using either clay (montmorillonite) or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI) from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI) removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI) from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques.

Show MeSH
Related in: MedlinePlus