@article{10.11648/j.ajac.20221005.15,
  author = {Andry Tahina Rabeharitsara and Havosoa Andriamanantsoa and Nambinina Richard Randriana and Baholy Robijaona and Hanitra Marie Ratsimba},
  title = {Study of Esterification Between the Used Tire and Citric Acid Molecules},
  journal = {American Journal of Applied Chemistry},
  volume = {10},
  number = {5},
  pages = {148-155},
  doi = {10.11648/j.ajac.20221005.15},
  url = {https://doi.org/10.11648/j.ajac.20221005.15},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ajac.20221005.15},
  abstract = {The recovery and recycling of all used tires is a constant challenge in a century where respect for the environment is becoming increasingly important and a key success factor. The Environmental Protection Agency (EPA) has classified citric acid as “Generally Recognized as Safe – GRAS”, in consequence its use as raw material is beneficial for all and allowed to the study of its esterification with used tread tires. The tread tire samples utilized during all experimentations have 1.062wt.% of sulfur and they were characterized by titrations based on Boëhm titration such as its acid sites densities determined with NaOH-0.05N was 2.0421E-03 moles×g-1 and its basic sites densities determined by HCl-0.1N was 2.5984E-03 moles×g-1. Thus, the esterification with citric acid at 141°C under atmospheric pressure using a closed reflux assembly of the tire’s tread part was carried out such as the quantities of citric acid were in excess in comparison to the tire’s total sites quantities. A model molecule representative of the connections of the most important atoms in the tire was proposed and permitted to show the possible reactions-mechanisms occurring between the tire’s acid and basic sites and the citric acid molecules during their esterification together catalyzed by the protonic acid-H+ of the citric acid. It was demonstrated that the esterification between citric acid and tire’s acid/basic sites occurred efficiency whether on surface, whether in tire’s porous with a very important initial conversion of the sites until 90% only after 20mn. The calculated global observed speed constant of the esterification between citric acid and tire’s acid/basic sites is equal to 2.33L3×mol-3×h-1. It was noticed that during this esterification the citric acid esterified with the tire’s acid/basic sites was dehydrated and explained the formation of alkenes organic function which quantities increased even after 2 hours. Thereafter, these tire’s citric acid alkenes will form the first new sites and their addition reactions with citric acid molecules or dehydrated citric acid molecules gave citric acid polymers and/or poly-aromatics molecules which constituted the second new sites; their densities after 2 hours reactions were respectively 9.18E-04 moles×g-1 and 7.65E-04 moles×g-1. After 2 hours of reaction, a soft dark materials with precipitates dark grains were recovered.},
 year = {2022}
}

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TY  - JOUR
T1  - Study of Esterification Between the Used Tire and Citric Acid Molecules
AU  - Andry Tahina Rabeharitsara
AU  - Havosoa Andriamanantsoa
AU  - Nambinina Richard Randriana
AU  - Baholy Robijaona
AU  - Hanitra Marie Ratsimba
Y1  - 2022/10/11
PY  - 2022
N1  - https://doi.org/10.11648/j.ajac.20221005.15
DO  - 10.11648/j.ajac.20221005.15
T2  - American Journal of Applied Chemistry
JF  - American Journal of Applied Chemistry
JO  - American Journal of Applied Chemistry
SP  - 148
EP  - 155
PB  - Science Publishing Group
SN  - 2330-8745
UR  - https://doi.org/10.11648/j.ajac.20221005.15
AB  - The recovery and recycling of all used tires is a constant challenge in a century where respect for the environment is becoming increasingly important and a key success factor. The Environmental Protection Agency (EPA) has classified citric acid as “Generally Recognized as Safe – GRAS”, in consequence its use as raw material is beneficial for all and allowed to the study of its esterification with used tread tires. The tread tire samples utilized during all experimentations have 1.062wt.% of sulfur and they were characterized by titrations based on Boëhm titration such as its acid sites densities determined with NaOH-0.05N was 2.0421E-03 moles×g-1 and its basic sites densities determined by HCl-0.1N was 2.5984E-03 moles×g-1. Thus, the esterification with citric acid at 141°C under atmospheric pressure using a closed reflux assembly of the tire’s tread part was carried out such as the quantities of citric acid were in excess in comparison to the tire’s total sites quantities. A model molecule representative of the connections of the most important atoms in the tire was proposed and permitted to show the possible reactions-mechanisms occurring between the tire’s acid and basic sites and the citric acid molecules during their esterification together catalyzed by the protonic acid-H+ of the citric acid. It was demonstrated that the esterification between citric acid and tire’s acid/basic sites occurred efficiency whether on surface, whether in tire’s porous with a very important initial conversion of the sites until 90% only after 20mn. The calculated global observed speed constant of the esterification between citric acid and tire’s acid/basic sites is equal to 2.33L3×mol-3×h-1. It was noticed that during this esterification the citric acid esterified with the tire’s acid/basic sites was dehydrated and explained the formation of alkenes organic function which quantities increased even after 2 hours. Thereafter, these tire’s citric acid alkenes will form the first new sites and their addition reactions with citric acid molecules or dehydrated citric acid molecules gave citric acid polymers and/or poly-aromatics molecules which constituted the second new sites; their densities after 2 hours reactions were respectively 9.18E-04 moles×g-1 and 7.65E-04 moles×g-1. After 2 hours of reaction, a soft dark materials with precipitates dark grains were recovered.
VL  - 10
IS  - 5
ER  - 

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