Inhibition of mild steel corrosion in acidic medium using coconut coir dust extracted from water and methanol as solvents

Published Date
25 September 2014, Vol.20(5):3612–3622, doi:10.1016/j.jiec.2013.12.056

Author 

S.A. Umoren ^,,

I.B. Obot

A.U. Israel

P.O. Asuquo

M.M. Solomon

U.M. Eduok

A.P. Udoh

• Materials and Corrosion Protection Research Laboratory, Department of Chemistry, Faculty of Science, University of Uyo, Uyo, Nigeria

Received 17 October 2013. Accepted 18 December 2013. Available online 25 December 2013.

Highlights

• •
  Methanol and water extracts of coconut coir dust inhibited mild steel corrosion in H₂SO₄.
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  The adsorption of ME and WE follow Temkin and Freundlich isotherm models, respectively.
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  The extracts behave as a mixed-type inhibitor but under cathodic control.
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  Results from all the methods are in reasonable agreement.
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  ME is a better inhibitor than WE of coconut coir dust.

Abstract

Corrosion inhibition of mild steel in H₂SO₄ by water and methanol extracts of coconut coir dust was studied using chemical and electrochemical techniques. It was found that the extracts inhibited the acid induced corrosion of mild steel. The inhibition efficiency increased with increase in extracts concentration but decreased with increase in temperature. Methanol extract was found to be a better inhibitor. The adsorption of the extracts’ components onto the mild steel surface follow Temkin and Freundlich adsorption isotherms for methanol and water extracts respectively. Polarization studies show that the extracts act as mixed typed inhibitor but under cathodic control.

Keywords

• Acid corrosion
• Mild steel
• Corrosion inhibition
• Coconut coir dust

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• DOC (1.5M)

• ⁎ 
  Corresponding author. Tel.: +234 8094208559.

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Coconut coir as biosorbent for Cr(VI) removal from laboratory wastewater

Published Date
30 November 2008, Vol.159(2):252–256, doi:10.1016/j.jhazmat.2008.02.014

Author 

Mário H. Gonzalez ^a,c

Geórgia C.L. Araújo ^b

Claudia B. Pelizaro ^a,c

Eveline A. Menezes ^a,c

Sherlan G. Lemos ^c

Gilberto Batista de Sousa ^a

Ana Rita A. Nogueira ^a,,,

• aGrupo de Análise Instrumental Aplicada, Embrapa Pecuária Sudeste, P.O. Box 339, 13560-970 São Carlos, SP, Brazil
• bEscola de Artes, Ciências e Humanidades da Universidade de São Paulo, Av. Arlindo Bettio, 1000, Ermelino Matarazzo, 03828-000 São Paulo, SP, Brazil
• cDepartamento de Química, Universidade Federal de São Carlos, Rodovia Washington Luis, P.O. Box 245, 13565-905 São Carlos, SP, Brazil

Received 21 December 2006. Revised 8 February 2008. Accepted 11 February 2008. Available online 15 February 2008.

Abstract

A high cost-effective treatment of sulphochromic waste is proposed employing a raw coconut coir as biosorbent for Cr(VI) removal. The ideal pH and sorption kinetic, sorption capacities, and sorption sites were the studied biosorbent parameters. After testing five different isotherm models with standard solutions, Redlich–Peterson and Toth best fitted the experimental data, obtaining a theoretical Cr(VI) sorption capacity (SC) of 6.3 mg g⁻¹. Acid–base potentiometric titration indicated around of 73% of sorption sites were from phenolic compounds, probably lignin. Differences between sorption sites in the coconut coir before and after Cr adsorption identified from Fourier transform infrared spectra suggested a modification of sorption sites after sulphochromic waste treatment, indicating that the sorption mechanism involves organic matter oxidation and chromium uptake. For sulphocromic waste treatment, the SC was improved to 26.8 ± 0.2 mg g⁻¹, and no adsorbed Cr(VI) was reduced, remaining only Cr(III) in the final solution. The adsorbed material was calcinated to obtain Cr₂O_3, with a reduction of more than 60% of the original mass.

Keywords

Cr(VI)

Biosorption

Coconut coir

Sulphochromic wastewater treatment

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• ⁎ 
  Corresponding author. Tel.: +55 1633615611; fax: +55 1633615754.
  
  

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Equilibrium modeling and kinetic studies on the adsorption of basic dye by a low-cost adsorbent: Coconut (Cocos nucifera) bunch waste

Published Date
1 October 2008, Vol.158(1):65–72, doi:10.1016/j.jhazmat.2008.01.034

Author 

B.H. Hameed ^,

D.K. Mahmoud

A.L. Ahmad

• School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia

Received 10 November 2007. Revised 12 January 2008. Accepted 14 January 2008. Available online 19 January 2008.

Abstract

In this paper, the ability of coconut bunch waste (CBW), an agricultural waste available in large quantity in Malaysia, to remove basic dye (methylene blue) from aqueous solution by adsorption was studied. Batch mode experiments were conducted at 30 °C to study the effects of pH and initial concentration of methylene blue (MB). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 70.92 mg/g at 30 °C. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model.

Keywords

Coconut bunch waste

Methylene blue

Adsorption isotherm

Equilibrium

Kinetics

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• ⁎ 
  Corresponding author. Tel.: +60 4 599 6422; fax: +604 594 1013.
  
  

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