Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions

Rice husk modified with oxalic acid (MRH) was tested as a lowcost adsorbent for the removal of Neutral Red (NR) dye from aqueous solutions employing batch adsorption procedures. Such studies were conducted by varying various parameters such as the pH, the adsorbent dosage, the salt concentration, th...

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Main Authors: Weihua Zou, Hongjuan Bai, Ke Li, Xiaolan Shi, Runping Han
Format: Article
Language:English
Published: Hindawi - SAGE Publishing 2010-08-01
Series:Adsorption Science & Technology
Online Access:https://doi.org/10.1260/0263-6174.28.7.641
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spelling doaj-789a0e9a30354dbb8e288819487590a52021-04-02T09:20:00ZengHindawi - SAGE PublishingAdsorption Science & Technology0263-61742048-40382010-08-012810.1260/0263-6174.28.7.641Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous SolutionsWeihua Zou0Hongjuan Bai1Ke Li2Xiaolan Shi3Runping Han4 School of Chemical Engineering and Energy, Zhengzhou University, 100 Kexue Road, Zhengzhou, 450001, P. R. China School of Chemical Engineering and Energy, Zhengzhou University, 100 Kexue Road, Zhengzhou, 450001, P. R. China School of Chemical Engineering and Energy, Zhengzhou University, 100 Kexue Road, Zhengzhou, 450001, P. R. China School of Chemical Engineering and Energy, Zhengzhou University, 100 Kexue Road, Zhengzhou, 450001, P. R. China Department of Chemistry, Zhengzhou University, 100 Kexue Road, Zhengzhou 450001, P. R. ChinaRice husk modified with oxalic acid (MRH) was tested as a lowcost adsorbent for the removal of Neutral Red (NR) dye from aqueous solutions employing batch adsorption procedures. Such studies were conducted by varying various parameters such as the pH, the adsorbent dosage, the salt concentration, the contact time, the concentration of the adsorbate and the temperature. The kinetic experimental data were analyzed using three kinetic equations, viz. the pseudo-first-order equation, the pseudo-second-order equation and the intra-particle diffusion model equation, to examine the mechanism of adsorption and the potential rate-controlling step. The mechanism of the process was found to be complex, consisting of both surface adsorption and pore diffusion. The values of the effective diffusion parameter, D eff , were estimated to be of the order of 10 −8 cm 2 /s, indicated that intra-particle diffusion was not the rate-controlling step. The equilibrium adsorption data obtained at various temperatures were analyzed using the Langmuir, Freundlich and Redlich–Peterson isotherm models using non-linear regressive analysis. The equilibrium adsorption results were better fitted by the Langmuir and Redlich–Peterson isotherms relative to the Freundlich model. Calculated thermodynamic parameters showed that the adsorption of NR onto MRH was feasible, spontaneous and endothermic under the studied conditions. The carboxyl groups on the surface of the modified rice husk (MRH) were primarily responsible for the sorption of NR. It is suggested that MRH may be suitable as an adsorbent material for adsorbing NR from aqueous solutions.https://doi.org/10.1260/0263-6174.28.7.641
collection DOAJ
language English
format Article
sources DOAJ
author Weihua Zou
Hongjuan Bai
Ke Li
Xiaolan Shi
Runping Han
spellingShingle Weihua Zou
Hongjuan Bai
Ke Li
Xiaolan Shi
Runping Han
Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions
Adsorption Science & Technology
author_facet Weihua Zou
Hongjuan Bai
Ke Li
Xiaolan Shi
Runping Han
author_sort Weihua Zou
title Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions
title_short Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions
title_full Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions
title_fullStr Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions
title_full_unstemmed Use of Oxalic Acid-Modified Rice Husk for the Adsorption of Neutral Red from Aqueous Solutions
title_sort use of oxalic acid-modified rice husk for the adsorption of neutral red from aqueous solutions
publisher Hindawi - SAGE Publishing
series Adsorption Science & Technology
issn 0263-6174
2048-4038
publishDate 2010-08-01
description Rice husk modified with oxalic acid (MRH) was tested as a lowcost adsorbent for the removal of Neutral Red (NR) dye from aqueous solutions employing batch adsorption procedures. Such studies were conducted by varying various parameters such as the pH, the adsorbent dosage, the salt concentration, the contact time, the concentration of the adsorbate and the temperature. The kinetic experimental data were analyzed using three kinetic equations, viz. the pseudo-first-order equation, the pseudo-second-order equation and the intra-particle diffusion model equation, to examine the mechanism of adsorption and the potential rate-controlling step. The mechanism of the process was found to be complex, consisting of both surface adsorption and pore diffusion. The values of the effective diffusion parameter, D eff , were estimated to be of the order of 10 −8 cm 2 /s, indicated that intra-particle diffusion was not the rate-controlling step. The equilibrium adsorption data obtained at various temperatures were analyzed using the Langmuir, Freundlich and Redlich–Peterson isotherm models using non-linear regressive analysis. The equilibrium adsorption results were better fitted by the Langmuir and Redlich–Peterson isotherms relative to the Freundlich model. Calculated thermodynamic parameters showed that the adsorption of NR onto MRH was feasible, spontaneous and endothermic under the studied conditions. The carboxyl groups on the surface of the modified rice husk (MRH) were primarily responsible for the sorption of NR. It is suggested that MRH may be suitable as an adsorbent material for adsorbing NR from aqueous solutions.
url https://doi.org/10.1260/0263-6174.28.7.641
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