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Nanoparticle Based Inorganic Coagulants For Cyanide Removal From Industrial Wastewaters

Kuppusamy Kuppusamy*, a, Roberto Brionesa, and Ranjani Krishnanb

aEnvironmental Bioprocesses Unit, Institute of Engineering, National Autonomous University of Mexico,
Mexico City, 04510 MEXICO


This is an abstract for a presentation given at the
10th Foresight Conference on Molecular Nanotechnology



Cyanide(CN) as sodium cyanide (NaCN) or HydroCyanide (HCN) is widely used in industrial processes. CN always associated with other heavy metals as metal cyanate complexes and conventional technologies are inefficient in removing CN and metals from the Industrial waste stream. By using Minox technology cyanide along with residual metals from the industrial waste water can be removed either as cyanate (CNO-) and it will be much less toxic than CN or completely oxidised in to CO2 and N2.

Destruction of CN by alkaline chlorination accomplished by adding MINOX MP (nAl2(OH)x.nSiO2. nNa2O) and Califloc (nAl2(OH) x. Clx) at optimum dosage adjusting pH 10-10.5. At this level CN will be transformed into CNO- Additional chlorination is necessary if the concentration of CN exceeds more than 1000 ppm.

						          Minox MP		
 CN + nAl2 (OH)x.nSiO2. nNa2O + nAl2(OH) x. Clx ----------------- CNO{ + NaOH + NaOCl + 
						     Califloc/ pH 10

Optimum conditions for this reaction:
pH 10-10.5
HRT (Hydraulic Retention Time): 20-40 Min.
As an advantage of the first reaction most of the residual heavy metals will be precipitated along with aluminohydroxy silicate as insoluble one.

Additional oxidation of Cyanide can be further oxidised by adding extra Califloc and/or Sodium Hypochlorite (NaOCl) through acid hydrolysis. At pH range 2-3. Incase if necessary it is advisable to use sulphuric acid (H2SO4) after addiiton of Califloc and NaOCl to achieve complete hydrolysis of CNO- in to CO2 and N2.

CNO{ + NaOCl    CALIFLOC CO2 ^+ N2^KKKKK...+ɥGKKK.(2)
	pH 2.0

Optimum conditions for this reaction:
pH: 2-3
HRT (Hydraulic Retention Time): 10-15 Min.
At this second step of acid hydrolysis most of the cyanate will be transformed into CO2 and N2. After this step the waste water can be adjusted to pH 5-6 for disposal and residual aluminium will be precipitaed at this step.

*Corresponding Address:
Kuppusamy Kuppusamy
Environmental Bioprocesses Unit, Institute of Engineering, National Autonomous University of Mexico
Coyoacan, Mexico City, 04510 MEXICO
Phone: 00 52 55 5622 3325 Fax: 00 5255 5280 2098


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