Effect of Exchanged MgAl-Hydrotalcite with Carbonate on Increases of
Acid Neutralizing Capacity: A Good Candidate as an Antacid
Authors: Dib Mustapha , Bennani M. Naciri , Ouchetto Hajiba , Ouchetto Khadija , Hafid Abderrafia , Khouili Mostafa 
Published: May 2021

Background:
In this study, we determined the acid-neutralizing capacity (ANC) of
Mg/Al-Hydrotalcite-like compounds. The MgAl-hydrotalcites were synthesized by the co-precipitation
method at room temperature using Mg/Al molar ratios 2:3. The synthesized bioactive nanomaterials
were characterized by various physicochemical techniques such as TG/dTG, XRD, FT-IR
spectroscopy, BET/BHJ, and SEM/EDX. The antacid activity assay was done by converting both
synthesized samples into liquids, 1 g of which was added to 50 ml of deionized water at 37°C under
vigorous agitation. The acid-neutralizing capacity (ANC) was evaluated with 0.1N HCl. The
pH was constantly measured using a pH meter and values were recorded every minute up to 35
min. In order to improve the neutralizing power of the samples, we performed an exchange of chlorides
by carbonates on the MgAl-HT3 synthesized. The exchanged Mg/Al-Hydrotalcite (MgAl-
HTE) showed high acid neutralization capacity (up to 13.5 mEq/g).

Objective:
This study aimed to synthesize MgAl-hydrotalcite-like compounds and evaluate their
acid-neutralizing capacity. In order to can be good candidates for pharmaceutical applications as
antacid drugs.

Methods:
Following methods are used in this study:
- Preparation of MgAl-hydrotalcite-like compounds was done by coprecipitation methods.
- Characterization of samples was done by physico-chemical techniques such as TG/dTG, XRD,
FT-IR spectroscopy, BET/BHJ and SEM/EDX.
- Evaluation of acid-neutralizing capacity was done by titration procedure (Dose-titration).

Results:
This protocol describes the preparation of MgAl-hydrotalcite-like compounds using the
classical coprecipitation method. The synthesized samples were characterized by various physicochemical
techniques such as TG/dTG, XRD, FT-IR spectroscopy, BET/BHJ, and SEM/EDX. The
as-synthetized samples were used for the evaluation of their acid-neutralizing capacity (ANC). Further,
an exchanged of MgAl-Hydrotalcite with carbonate was done for the purpose to increase the
acid-neutralizing capacity.

Conclusion:
In summary, this study describes a simple synthesis of MgAl-Hydrotalcites compounds
by a co-precipitation method at constant pH around 10, with a ratio Mg/Al = 3:2 (referred
to as MgAl-HT3 and MgAl-HT2). An exchange of the chlorides (not eliminated by washing) by
the carbonates was carried out on hydrotalcite with a ratio Mg/Al = 3, and the solid obtained was
named MgAl-HT3E. The materials MgAl-HT2, MgAl-HT3, and MgAl-TH3E were used to evaluate
antacid activity. To this end, a study was conducted to determine the acid-neutralizing capacity
(ANC). As result, the MgAl-HT3E was able to increase acid-neutralizing capacity and maintain an
ideal pH. These results could be interesting to prepare novel antacid drugs (due to the low cost of
synthesized materials) essentially the hydrotalcite of mg/Al ratio equal to 3 because of its relatively
slow kinetics of releasing basic species and therefore of its beneficial action as an antacid.