Removal of Direct Red 81 from Aqueous Solution Using an Acidic Soil Containing Iron (Case Study of Lahijan Soil)

Direct Red 81, a dye widely used in textile industries, is frequently detected dye in water resources. High costs, the formation of hazardous byproducts, and high energy costs restrict the use of some removal methods. Therefore, the main objectives of this research are the feasibility of using soil containing iron as a low cost adsorbent to remove (Direct Red 81) from aqueous phase and determining the optimum conditions for maximum removal efficiency. The present study was conducted at a bench scale. The influence of different parameters including the number of adsorbents; initial concentration of dye solution and pH at different time intervals on dye removal efficiency were investigated.  The maximum removal rate of dye (84%) occurred in pH=7 in the presence of 1 g soil with the initial dye concentration of 50 mg/L at 30 min reaction time. Moreover, due to the effect of acidic pH and the iron content of used soil a significant increase was observed in the rate of Direct Red 81dye removal. In conclusion, using soil containing iron is an appropriate method for the removal of Direct Red 81 from aqueous solutions.