S9570-Fe(III), a modified chelating resin containing sulphonated monophosphonic acid bifunctional groups, was used for the fluoride removal from aqueous phase for the first time. The results specified that S9570-Fe(III) exhibited better adsorption towards the fluoride ions as compared to the other commonly used chelating resins having monofunctional group such as iminodiacetic acid, sulfonic acid or carboxylic acid. Adsorption thermodynamic and kinetic studies of S9570-Fe(III) chelating resin for the fluoride also have been carried out. The thermodynamic results demonstrated that the adsorption was a spontaneous process accompanied with a gradual decrease in entropy and the low temperature was favorable for the fluoride ion adsorption. The kinetic experiments showed that the resin exhibited a rapid initial adsorption behavior and the adsorption process more complied with the pseudo-second order reaction model which indicating that the whole adsorption process was controlled by a combined mechanism of intraparticle diffusion and chemical sorption. Adsorption mechanism of S9570-Fe(III) resin for fluoride ions was predicted. The study demonstrated the effectiveness of the phosphoric-sulfonic acid bifunctional group chelating resin to remove fluoride, and provided a novel type removal method for the fluoride.
Keywords: Chelating resin; Fluoride; Phosphoric-sulfonic acid bifunctional group; Sorption behavior.
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