Publisher: Chemical Society of Nigeria

Synergistic Effect of Halide Ions On Corrosion Inhibition of Aluminium and Mild Steel In H2So4 Solutions Using Methyl Orange

A. I. Onen, B. T. Nwufo
KEYWORDS: Methyl orange, corrosion inhibitor, aluminium, mild steel, absorbance difference, physisorption

ABSTRACT:

The  corrosion  inhibition  of  aluminium  and  mild  steel  in  H2SO4  in  the  presence  of  Methyl  orange,  MO at  303-313K  was  studied  using  “Absorbance  difference”  technique.  The  results  showed  that  the inhibition  efficiency  (%IE)  increased  with  increase  in  inhibitor  concentration  and  decreased  with increase  in  temperature  within  the  range  303-313K  studied  in  the  absence  and  presence  of  the inhibitor  and  halides.  The  efficiencies  increased  in  the  order:  57.91%  MS  <  71.98%  Al.  The  effect  of halides,  namely  NaCl,  NaBr  and  NaI  is  also  reported. The  addition  of  halides  enhanced  the  inhibition efficiency  in  the  order:  Cl-  <  Br-  <  I-.  The  synergism  parameter  (SI)  evaluated  are  found  to  be  less  or equal  to  unity  for  aluminium  and  greater  or  equal  to  unity  for  mild  steel  corrosion.  Methyl  orange was  found  to  obey  Freundlich  and  Langmuir  adsorption  isotherms  at  all  concentrations  studied  for aluminium  and  mild  steel  corrosion.  Physical  adsorption  is  proposed  from  the  activation  energy values  (Ea  ≈  9.91kJmol-1  and  Ea  ≈  7.96kJmol-1)  obtained  for  aluminium  and  mild  steel  corrosion respectively.  The  results  obtained  from  this  study  were  treated  kinetically  and  values  of  Qads  (a thermodynamic parameter) evaluated and reported.     


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