Removal of Ponceau S by adsorption onto aluminophosphate: efficiency and modeling

Ponceau S (PS) is an azo dye widely used for versatile applications in foods and biochemistry; nevertheless, it is suspected to be toxic and carcinogenic. In this research article, the removal of PS from aqueous solution was investigated by adsorption onto alumino-phosphate (AlPO4). This adsorbent has been synthesized by precipitation from solution of aluminum salt. It was an amorphous solid with a specific area and pHzpc of 100 m2/g and 4.6, respectively. The efficiency of PS sorption as a function of pH, initial PS concentration, AlPO4 dose and temperature was studied. The present PS sorption dynamics followed the pseudo-first-order model and the calculated sorption capacity was in good agreement with the experimental values. The compliance of isotherm models such as Langmuir, Freundlich and Sips was also verified. Among the isotherm models, Sips was deemed to be the better fit than others. PS sorption as a function of temperature explicates an exothermic nature of sorption which decreased from 9.12 mg g-1 (300 K) to 6.08 mg g-1 (315 K). The adsorbed PS on AlPO4 was easily desorbed by washing at pH 7 and the adsorption equilibrium was established in the first 8 min. The PS laden adsorbent was also regenerated by heating at 600°C for 30 min and the regenerated AlPO4 was attempted for its continual utilization for the adsorption of PS successfully. © 2017 Desalination Publications. All rights reserved.