Performance of Zn-, Mg- and Ni-Al layered double hydroxides in treating an industrial textile wastewater

Fatima zahra Mahjoubi, Abderrahim Khalidi, Alaaeddine Elhalil, Rachid Elmoubarki, Omar Cherkaoui, Sadiq Mhamed, Noureddine BARKA

Abstract


In this study, Zn-Al, Mg-Al and Ni-Al layered double hydroxides were successfully synthesized via co-precipitation method. Samples were characterized by XRD, FTIR, TGA-DTA, TEM and pHPZC analysis. XRD patterns showed a basal spacing increase in the order of Zn-AlNO3 (8.85Å)> Mg-AlNO3 (7.95Å)> Ni-AlNO3 (7.82Å). TEM images indicated that the Zn-AlNO3 presents circular to shaped particles with an average particle size of approximately 30 to 40 nm. Small plates assigned to sheets with hexagonal form were observed in the case of Mg-AlNO3.Ni-AlNO3 display nanostructured sphere in diameter between 5 and 10 nm. The materials were used for the removal of methyl orange (MO), as a model dye and for the treatment of a real effluent generated by a textile factory. Maximum adsorption was occurred in acidic pH solution. Kinetic data were tested using pseudo-first-order, pseudo-second-order kinetic and intra-particle diffusion models. The best fit was obtained with the pseudo-second-order kinetic model. Equilibrium data were correlated to Langmuir, Freundlich, Sips and Redlich–Peterson isotherm models. The best conditions for color and COD removal from the textile effluent sample were obtained at lower values of pH. Reduction of COD to limits authorized by Moroccan standards was obtained with 0.5g/L of LDH dosage.


Keywords


Layered double hydroxide; Color removal; Chemical oxygen demand; Textile wastewater treatment

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