Toward to Obtaining Clean Water from Wastewater Using Friendly and Renewable Technology

This is a brief overwiew of work carried out by this group, in the hexavalent chromium removal and cyanide degradation in acuose solution by mean of photocatalysis, because this composed represent two of the most frequent and toxic in wastewaters, and the confinement of them is very costly for the industries and the governments

To reduce of hexavalent chromium: we used ZnO such as a catalist, (obtained by sol-gel at diferent conditins: pH of hidrolizis, anealing temperature, and ratio molar of precursor/solvent). We put in contact each obtained catalist with K2Cr4O7 in acuose solution 60 ppm, 250ml, in a bach type reactor, irradiated with a UV-Vis lamp (Spectroline XX-15N model) to a wavelength of 365 nm, agitation at room temperature during 6 hours, taking an initial sample without radiation to the 30 minutes and soon with radiation every 20 minutes.

For cyanide degrade: we realized the same procedimient but the solution in this case was KCN of the same molar concentration.

The residual hexavalente chromium concentration was measured by means of the spectroscopic technique with difenilcarbazide. And cyanide concentration in the samples was measured by mean potentiometry with cyanide ion selective electrode Orion model 720 A.

For this experiments we can say that general activity of ZnO employed is more eficient in the removal of hexavalent chromium that degradation of cyanide.