Synthesis of NiAl- layered double hydroxide with nitrate intercalation: Application in cyanide removal from steel industry effluent.

Cyanide contamination in steel plant wastewater is a challenge. Nitrate intercalated nickel aluminum layered double hydroxide (LDH) is specially designed and synthesized for adsorption of cyanide from wastewater. The LDH was characterized by Field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and BET surface analyzer. Formation of nanosized plate like LDH particles was confirmed by FESEM analysis. FTIR analysis confirmed the intercalation of nitrate ions in the interlayer space of nickel-aluminum layered double hydroxide. Adsorption of cyanide in the LDH matrix was identified by FTIR study. Ion exchange was the prevalent mechanism of cyanide adsorption. The specific surface area of LDH was 142 m/g with average pore size of 1.9 nm. The spent LDH could be regenerated using a chemical method and was reused up to five cycles. The efficiency of the LDH was evaluated using real life cyanide containing wastewater from steel plant.