Removal of Methylthioninium Chloride (MB) from Contaminated Water Media Using Activated Carbon Derived from Apricot Stones, a Low-cost Adsorbent

Abstract

The preparation of activated carbon from apricot stone (ASAC) with H3PO4 and its ability to remove the (MB) used in the textile industry from aqueous solutions are reported in this study. The FTIR spectroscopy is used to get information on interactions between the adsorbent and MB. A series of contact time experiments were undertaken in stirred batch adsorber to assess the effect of the system variables. The results were discussed and showed that ASAC can be successfully used in the wastewater treatment. A comparison of two models on the overall adsorption rate showed that the kinetic of adsorption was better described by the pseudo-second order model. The adsorption isotherms of MB onto ASAC are determined and correlated with common isotherms equations. The smaller RMSE values obtained for the Langmuir and Elovich models indicate the better curves fitting, the monolayer adsorption capacity of MB is found to be 46.03 mg/g at 25 oC and 142.42 mg/g at 70 oC and pH 10. The thermodynamic parameters indicate spontaneous and endothermic nature of the adsorption process. The positive entropy (ΔS°) shows that the randomness indecreases at the solid-solution interface during the MB adsorption onto ASAC, indicating that some structural exchange may occur among the active sites of the adsorbent and MB ions.

Keywords:

Apricot stone, Chlorure de méthylthioninium, Kinetic, Isotherm, Adsorption, Thermodynamic.