Leaf extracts as green substitute to toxic zinc chromate and zinc phosphate additives in Polyurethane primers for corrosion inhibition of steel

Corrosion inhibition of steel by Polyurethane Extract-primer (PEP) containing plant leaf extracts was compared with Polyurethane Conventional primer (PCP) containing zinc phosphate and zinc chromate as inhibitors. The primers were investigated using gasometric technique in 5 °C steps of temperature increase from 25 to 50 °C in 1.0 M HCl as corrodent. The PEP of 34.24 percent actives compared with PCP of 56.35 percent actives gave the same inhibition efficiencies of 82.4%. Extract primers of low percent active concentration were more effective and less expensive than that of conventional primers.

A Comparative Study on Conversion of Soluble Cr(VI) into Insoluble Cr(VI) and Reduction of Cr(VI) in Contaminated Groundwater at COPR Dump Site

The most common methodology for removal of Cr(VI) in literatures is the combination of reduction and precipitation process. The disadvantages of this method are presence of high total dissolved solids in the treated water and sludge generation. In order to find a new solution, efforts have been focussed to convert Cr(VI) present in the groundwater, into the useful products like zinc chromate and barium chromate under appropriate conditions. The efficiency of these conversions is compared with the efficiency of the reduction and precipitation process adopted in this study, using sodium metabisulphite. These experimental studies were carried out with stimulated water containing 2000 mg/L of Cr(VI) and then extended to Cr(VI) contaminated groundwater with same concentration. The results are compared and validated through batch experiments.