INTRODUCTION :
Common at industrial sites.
Found in the form of metal cyanide so difficult to recover.
Layered double hydroxide can be a good option for removal of cyanide complexes. INTRODUCTION
LAYERD DOUBLE HYDROXIDE :
M (II)1-x M(III)x (OH)2 [An-]x/n・yH2O M (II) = divalent cation
M (III) = trivalent cation
A = balancing anion
LDH also called as hydrotalcites.
Have positive charged brucite type structure with balancing anions such as Cl-, CO32-, SO42- etc.
Anionic layer can be replaced by other anions resulting in strong anion-exchange property. LAYERD DOUBLE HYDROXIDE
PREPARATION OF LDH :
PREPARATION OF LDH 0.25M [Fe3+] , 0.75M [Mg2+] and 0.2M [OH-] Mixture was aged at 750c for 18 hours under Nitrogen free atmosphere. Precipitate was filtered with decarbonated water and dried. Mixed with anionic SO4 solution
PROCESS OF TREATEMENT :
Entrapment of LDH on Nylon 66 PROCESS OF TREATEMENT LDH molecules Nylon membrane Water is passed through membrane SO4 ions CN ions
PERCENTAGE IMMOBILIZATION RATE :
PERCENTAGE IMMOBILIZATION RATE Type of LDHs % immobilization rate Cyanide (mg)/ LDH (g) Time (hr)