Thermodynamic and kinetic study of the improvement of the adsorption efficiency of Hexavalent chromium (VI) ions by encapsulated modified prickly pear peel

Abstract

Selected biosorbents, Prickly Pear Peels (PPP) , that have been chemically activated by Zncl2 and encapsulated in calcium alginate beads , bear the hybrid biosorbent names CA-ZnPPP, and are used for the disposal of Cr (VI) with water-based solutions. CA-ZnPPP is characterized by FT-IR spectroscopy, and Scanning electron microscopy (SEM),subsequently Batch tests were undertaken to evaluate the impact of the variables, in particular the pH value in the first instance, the retention time, and the metal content in the course of adsorption . Langmuir’s isothermal model showed the greatest consistency with the test results and the biosorption rate of the single layer was 16.28 mg g -1 in less than 120 min working with 1.0 g L -1 of CA-ZnPPP , and apH of 2 . The pseudo-second order kinetic pattern correctly defined the results of the adsorption dynamics. Thermodynamic parameters (?G°, ?H°, and ?S°) in a temperature range of 298–328 K, have revealed that biosorption is exothermic and instantaneous. These values show that CA-ZnPPP is a favorable adsorption material for the removal of Cr (VI) in wastewater.