Removal of congo red dye from aqueous system using Phoenix dactylifera seeds

In this study, Phoenix dactylifera seeds (PDS) was used as a biosorbent for the removal of congo red (CR) dye from aqueous system. Biosorbent was characterized by some instrumental techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), transmission electron microscopy (TEM). The effect of various adsorption parameters such as initial dye concentration, sorbent dosage, contact time, pH, electrolyte, surfactants and temperature was optimized for maximum sorption of dye. Langmuir, Freundlich and Tempkin isotherms were applied for the interpretation of experimental data. Langmuir model was found to be best fitted with maximum adsorption capacity equal to 61.72 mg g(-1). The kinetic study showed that the adsorption process was described by pseudo-second order kinetics. The thermodynamic parameters such as energy change (Delta G degrees) enthalpy change (Delta H degrees) and entropy change (Delta S degrees) were found to be -3.51 kJ/mol, 22.89 kJ/mol and 87.130 J/mol/K, respectively. Recycling efficiency of PDS was investigated for the sorption of CR and after 5 cycles, the adsorption efficiency of PDS was reduced to 53.90% from 76.12%.The results indicated that Phoenix dactylifera seeds were used as a suitable sorbent for the adsorption of CR dye from aqueous solution in a feasible, spontaneous and endothermic way. (C) 2016 Elsevier B.V. All rights reserved.