Treatment of hydrochloric acid using Mg–Al layered double hydroxide intercalated with carbonate

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Abstract

Mg–Al layered double hydroxide intercalated with CO32− (CO3·Mg–Al LDH) was found to take up only low amounts of Cl during the treatment of hydrochloric acid. Low pH promotes the removal of Cl. HCl is considered to react with CO32− in the interlayers of Mg–Al LDH as a result of which Cl is probably intercalated in the interlayers. High pH of the Mg–Al LDH suspension leads to a lower extent of reaction between HCl and Mg–Al LDH, owing to the neutralization of the acid. We can state that the adsorption of Cl on Mg–Al LDH is best described by the Dubinin–Radushkevich adsorption isotherm. The maximum adsorption amounts were calculated to be 1.4 and 0.6 mmol/g for CO3·Mg–Al LDH with Mg/Al molar ratios of 2 and 4, respectively, whereas the adsorption energies were calculated to be 82 and 124 kJ/mol, respectively. In summary, the removal of Cl is caused by both the reaction between hydrochloric acid and CO32− in the interlayers of Mg–Al LDH as well as anion exchange between the HCO3 produced and a different Cl ion in hydrochloric acid. This explains why the adsorption is best expressed by the D–R adsorption isotherm, which assumes a heterogeneous surface and non-constant adsorption potential.

Original languageEnglish
Pages (from-to)21-26
Number of pages6
JournalJournal of Industrial and Engineering Chemistry
Volume39
DOIs
Publication statusPublished - 2016 Jul 25

Keywords

  • Adsorption isotherm
  • Hydrochloric acid
  • Layered double hydroxide
  • Treatment

ASJC Scopus subject areas

  • Chemical Engineering(all)

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