Investigation of the Adsorption Efficacy in Removal of Chloride Ions by Synthesized magnesium–aluminum hydroxide from Zanjan Lead &Zinc Industry wastewater

The presence of corrosive anions in industrial wastewater can have many environmental and economic problems.

In this study, layered magnesium–aluminum oxide was synthesized which has an extra positive charge and was used for adsorption of chloride ions from waste-water of lead and zinc industry.

 The synthesized crystalline material was investigated by X-ray diffraction spectroscopy, Scanning electron microscopy- energy dispersive spectroscopic analysis. X-ray diffraction spectroscopy results showed that there was no difference in the crystalline structure before and after chloride ion adsorption. Scanning electron microscopy- energy dispersive spectroscopic analysis showed the condensation of adsorbent after chloride ions adsorption and EDX analysis confirmed the presence of chloride and precipitation of Ca2+ ions after adsorption. Measurement of zeta-potential for synthesized layered magnesium–aluminum hydroxide confirmed the positive surface charge. Isotherm studies have shown the compatibility of experimental data with the Langmuir model, which indicates the interaction between adsorbent and chloride ions, the maximum adsorption capacity for the synthesized adsorbent with Mg / Al ratio of 4 was determined 153.8 mg/g at 60 ° C. The obtained values showed the intercalation rate follows pseudo-second-order. The experimental data confirmed adsorption capacity has been increased with increasing the adsorbent dosage from 1.5 to 4.5 gr and the equilibrium time increased from 90 min. to 4 h from 1.5 g adsorbent to 4.5 g. Thermodynamic studies revealed the adsorption occurs spontaneously and positive entropy changes indicated strengthening the interaction between adsorbent and chloride ions with increasing the temperature from 25 to 60°C.

Finally, it can be concluded synthesized double layered Al-Mg hydroxide can be a good candidate to reduce chlorine ions from lead and zinc Industry wastewaters.