Cobalt-nickel mixed oxide surface: A promising adsorbent for the removal of PR dye from water

A mixed oxide of cobalt (Co) and nickel (Ni) with an approximate composition of Co(0.4)Ni(0.4)O(0.2) was prepared chemically by precipitating from the corresponding metal carbonates and heating the mixture of carbonates at 650 degrees C under ambient atmosphere. The mixed (Co-Ni) oxide thus prepared was characterized by IR, SEM and XRD methods. The composition of the mixed metal oxide was obtained by EDX analysis. The surface behavior of the Co-Ni mixed oxidematrix was tested by adsorption studies and pH(pzc) measurement. The Co-Ni mixed oxide matrix behaves as a charged adsorbent at the pH media higher and lower than its pH(pzc) value (9.50) and thus found to be capable of anchoring the oppositely charged species onto its surface. Removal of cationic and anionic dyestuffs, viz., methylene blue (MB) and procion red (PR), respectively, was attempted using themixed oxide surface as adsorbent. Although both the dyes can be removed by the mixed oxide, the extent of PR removal (similar to 70%) seems to be much higher than that of MB (similar to 20%) demonstrating the superior performance of the Co-Ni mixed oxide for its use as adsorbent in removing the anionic PR dyestuff from water. (C) 2010 Elsevier B.V. All rights reserved.