Corrosion Inhibition by an Aqueous Extract of Aloe Vera

Corrosion Inhibition by an Aqueous Extract of Aloe Vera (L.) Burm F. (Liliaceae)

V. Sribharathy[a]*, Susai Rajendran [a,b]*, P. Rengan[c], R. Nagalakshmi[d] 

Corresponding Authors
E-Mail: bharathy_chem@yahoo.co.in, srmjoany@sify.com

  1. [a]  PG and Research Department of GTN Arts College, Dindigul-624005, Tamilnadu, India. Email: srmjoany@sify.com

  2. [b]  RVS School of Engineering & Technology, GTN Arts College, Dindigul-624005, Tamil Nadu, India.

  3. [c]  Department of chemistry,Yadava college,Madurai, India, E.mail: akveni1972@gmail.com

  4. [d]  Department of chemistry, Aarupadai Veedu Institute of Technology, Chennai-603110, Tamilnadu, India. Email: nagalakshmirajan@gmail.com 

Introduction 

Plant extracts have become important as environmentally acceptable, readily available and renewable source for wide range of inhibitors.1 In general, the plant extracts are of inhibitors with high inhibition efficiency and of non toxicant. El-Etre et al. investigated Khillah extract 2 for the corrosion inhibition of SX 316 steel in acid media. Lawsonia extract 3 was studied for effect against acid induced corrosion of metals. Opuntia extract 4 was investigated for the 5 corrosion of Aluminium in acid medium and vanillin for the corrosion of mild steel in acid media. Yan Li et al Berberine isolated an alkaloid from Captis studied for its anticorrosion effect for mild steel corrosion in 7 H2SO4 medium 6 Fabrizio Zucchi and Ibrahim Hashi Omar have found that Papaia, Poinciana pulcherrima, Cassia occidentalis and Datura stramonmium seeds, Calotropis procera, Azydracta indica and Auforpio turkiale sap are useful as acid corrosion inhibitors. Sethuraman and Bothi raja8 have studied the acid extract of Datura metel as corrosion inhibitor for mild steel in acid medium. Quinine 9 has been studied for its anticorrosive effect of carbon steel in 1 M HCl by Mohamed Ismail Awad. Anthony et al. has studied the effect of caffeine against chloride corrosion of carbon steel.10 There are many methods by which corrosion can be controlled one such method is the use of inhibitors. These inhibitors when added is small quantity, decrease the rate of corrosion. Corrosion inhibitors usually contain polar groups with atoms such as nitrogen, sulphur and oxygen. Correspondingly inhibitors include a wide list of organic and inorganic compounds11 containing the functional groups such as aldehydes,12 amines,13,14 amino acids,15,16 nitro compounds,17,18 amides,19,20 ester,21,22 thio compounds,23,24 phosphates,25,26 phosphonates,27,28 ketones29,30 and carboxylic acids.31-33

The present work investigated the inhibition efficiency of an aqueous extract of plant material, Aloe vera (L) Burm f. (Liliaceae) extract, in controlling corrosion of carbon steel (CS) immersed in sea water in the absence and presence of inhibitor, using mass loss method ,analyzed the protective film by Fourier transform infrared (FTIR) spectroscopy and fluorescence spectroscopy, and proposed a suitable mechanism of corrosion inhibition, based on the results of the above studies and potentiodynamic polarization and the alternating current (AC) impedance spectra.

Experimental
Preparation of plant extract 

An aqueous extract was prepared by grinding 10 g of fresh extract of aloe vera (mannose-6-phosphate) gel, filtering and making up to 100 ml using double distilled water.

Preparation of specimens 

Carbon steel specimens (0.0267% S, 0.06% P, 0.4% Mn, 0.1% C and the rest iron) of dimensions 1.0 cm x 4.0 cm x 0.2 cm were polished to a mirror finish and degreased with trichloroethylene.

Weight loss method 

Relevant data of sea water used in the study, are given in Table 1. Three mild steel specimens were immersed in 100 ml of sea water containing various concentrations of the inhibitor for one day. The weight of the specimens before and after immersion were determined using Shimadzu balance, model AY 62. The corrosion products were cleansed with Clarke’s solution.34....

 

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