Zn-Fe Layered Double Hydroxides Synthesized by Three (03) Methods of Coprecipitation : Application to the Removal of Cochineal Red Dye from Aqueous Solution 


Vol. 22,  No. 12, pp. 3358-3367, Dec.  2021
10.1007/s12221-021-0988-8


  Abstract

Zn-Fe layered double hydroxides was prepared by three methods of coprecipitation : coprecipitation at constant pH (pH Cst), coprecipitation at variable pH (pH Var), and direct coprecipitation (DC). The Zn-Fe LDH was utilized as an effective adsorbent for removal of cochineal red dye (CR) from aqueous solutions. The structure of the prepared materials was characterized by XRD and FTIR. The effects of various experimental parameters such as initial pH, adsorbent dosage, initial dye concentration, contact time, and temperature have been investigated using a batch adsorption technique and their optimum conditions were ascertained to find the optimal conditions for a maximum adsorption. At 50 mg/l cochineal red dye concentration and 50 mg of adsorbent mass, Zn-Fe LDH prepared by coprecipitation at constant pH had 1.09 and 1.31 times more adsorption capacity than Zn-Fe LDH prepared by direct coprecipitation and coprecipitation at variable pH, respectively. The adsorption capacity of the studied adsorbents was in the order pH Cst > DC > pH Var. The removal of Cochineal Red dye reaches its maximum of 96.74 %, 95.70 %, and 92.48 % after 40 min, 50 min, and 80 min for Zn-Fe LDH prepared by coprecipitation at constant pH, direct coprecipitation, and coprecipitation at variable pH respectively with the use of the optimum masses of 50 mg, 80 mg, and 100 mg for these respective materials. Freundlich and Temkin isotherm models were applied to describe the equilibrium adsorption experimental data. The cochineal red dye adsorption follows the Temkin model for the materials synthesized by coprecipitation at variable pH and direct coprecipitation. This indicates that the adsorption is characterized by a uniform distribution of binding energies between the molecules adsorbed and adsorbents. The Zn-Fe LDH prepared by coprecipitation at constant pH follows the Freundlich model, indicating the heterogeneous nature of adsorption sites. The adsorption kinetics of the dye obeyed pseudo-second-order kinetic model. Thermodynamic study indicates that the adsorption process is spontaneous and endothermic in nature.

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  Cite this article

[IEEE Style]

R. M. a. N. Nasrallah, "Zn-Fe Layered Double Hydroxides Synthesized by Three (03) Methods of Coprecipitation : Application to the Removal of Cochineal Red Dye from Aqueous Solution," Fibers and Polymers, vol. 22, no. 12, pp. 3358-3367, 2021. DOI: 10.1007/s12221-021-0988-8.

[ACM Style]

Rachida Mendil and Noureddine Nasrallah. 2021. Zn-Fe Layered Double Hydroxides Synthesized by Three (03) Methods of Coprecipitation : Application to the Removal of Cochineal Red Dye from Aqueous Solution. Fibers and Polymers, 22, 12, (2021), 3358-3367. DOI: 10.1007/s12221-021-0988-8.

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