Dear colleague,

Are you sure that iodine value is gonna increase after the oxidation of biodiesel fuel? It's gonna be lower surely. Have you obtained such a result of your study?

Dear Michael,

1. With many investigators have got decreasing trend  in iodine value . I am getting increase in iodine value for all samples. I repeated 3 times the iodine value procedure for all the samples. I could not understand what is going wrong. I will check the log book for sample identification. Hopefully could be a  blunder in sample identification.

2. The reason  for decrease in iodine value during oxidation was stated by  S Naz et al., "Reduction in iodine value was due to elimination of hydrogen adjacent to a double bond and the formation of free radicals". Is there any other reasons on why iodine value must decrease during oxidation. kindly simply the reason for decrease in iodine value.

paper reference Link : http://www.sciencedirect.com/ science/article/pii/ S0308814604001104.

Dear colleague,

Could you describe me the procedure of the experiment and info sources you've based the performance. The mechanisms of the reactions in the course of the iodine value estimation look as these:

R-HC=CH-R + 2IBr → R-BrC=CBr-R + 2HI

IBr + KI = KBr + I2

I2 + 2Na2S2O3 = Na2S4O6 + 2NaI

The link you provided is failed. An explanation showed in bold seems to be impossible. Please, try to download the article as an attachment.

Waiting for your reply.

MN

Upon oxidation, biodiesel properties like the acid value, peroxide value and viscosity increase, while the iodine value and the content of methyl esters decrease.

ABSTRACT

The purpose of this paper is to analyze the main issues concerned with the oxidative and storage stabilities of biodiesel and how they affect different metallic and polymeric materials present in automotive parts and in biodiesel storage structures. In addition, this work presents a review of the techniques used for measuring the oxidative stability and for evaluating the degradation of metallic and polymeric materials. When biodiesel is oxidized, a series of changes in its properties occurs. These changes not only affect biodiesel quality, but also the properties of the materials that are in contact with it. Upon oxidation, biodiesel properties like the acid value, peroxide value and viscosity increase, while the iodine value and the content of methyl esters decrease. The changes in the chemical and physical properties of biodiesel can affect the integrity and stability of the material. The situation reviewed in this paper, which talks about the stability of materials, could limit the extensive use of biodiesel. Such measures have been proposed in several countries, and it is a topic of great importance for biodiesel technology.

The oxidative stability of biodiesel and its impact on the deterioration of metallic and polymeric materials: a review

 Ernesto C. ZuletaI; Libia BaenaII; Luis A. RiosI; Jorge A. CalderónII,

J. Braz. Chem. Soc. vol.23 no.12 São Paulo Dec. 2012

www.scielo.br/scielo.php?script=sci_arttext&pid=S0103..

Dr. Krishna has just stated the same shown above. So you've gotta re-try the procedure

Iodine value decrease or increase during bio-diesel oxidation as during oxidation number of double  i.e. unsaturation is removed because of hydroxylation reaction. Hence Iodine value will decrease.?

The topicstarter's still keeping silence, although we posted interesting arguments, you see :)

Mr. Michael kindly apologize me. I had to relocate to  new place due to new job offer. Hence i could not interact.

Yes i agree  with Prof.Maddali  and  prof.Madhukar  on decrease in iodine value. Thanks to every one. I have sent the procedure and paper for your reference by mail as attachment.

Dear colleague, please, check your message box. Decrease of the IV after any oxidation process is thought to be well-known phenomenon, you know. There must be no doubts considering such a fact