Comparative studies of ferric green rust and ferrihydrite coated sand: Role of synthesis routes

A comparative study of ferrihydrite and ferric green rust coated sand prepared by three synthesis routes has been outlined in the present contribution. The two minerals displayed inverse properties in terms of quantity of deposited iron for all three methods investigated. For ferric green rust coating, a newly proposed synthesis route named as dry contact method was efficient for the maximum quantity of iron with almost full coverage area. Considering the similar parameters, the modified wet synthesis method designated as reactive method provides the optimum results for ferrihydrite coated sand. These coatings have been characterised by different surface analysis techniques. In particular, due to the excellent sensitivity of miniaturised Mössbauer Spectrometer (MIMOS) it was possible to detect the lowest iron content (0.1 Fe w/w%). A distinct approach based on tribology between crystallised ferric green rust and sand has been proposed to explain the relatively high quality of coating using dry contact method.