Iron (II) oxalate as precursor of magnetic composites for dye adsorption

One of the main problems of textile industry is related to the environmental impact caused by the disposal of waste containing residual synthetic dyes. Removal of dyes from waste water can be achieved by a number of methods. The adsorption method using materials with high rate and capacity is preferred compared to others in terms of high efficiency, easy handling and cost-effectiveness. However, easy separation of the adsorbed dyes from the environment is an important issue which requires a suitable adsorbent such as a magnetic composite. Therefore, magnetic gama-Fe2O3 a cost-effective, air-stable and non-toxic material is a good choice to prepare magnetic composites to permit easy separation. Thermal decomposition of oxalates is an interesting route to prepare these materials. When heated at 300ºC, iron (II) oxalate generates iron (III) oxide with gamma structure, which shows the desired magnetic property. This paper has as objective the preparation of iron (III) oxide magnetic composites with 'carbon black' (Vulcan-X) by heating iron (II) oxalate. The application of this composite in methylene blue (MB) adsorption in aqueous solution was also evaluated. Composites Vulcan-X/gamma-Fe2O3 with nominal ration (w:w) of (4:1), (3:1), (2:1), (1:1) and (1:2) were prepared. The formation of gamma-Fe2O3 was confirmed by XRD. The adsorption capacity of Vulcan-X to MB was determined as 275 mg/g, whereas, the (1:2) composite shows the adsorption capacity of 121 mg/g. Figure 1 shows the results of adsorption of MB (60 mgL-1) in (1:2) composite.