The Systematic Adsorption of Diclofenac onto Waste Red Bricks Functionalized with Iron Oxides

In this study, waste red bricks were incorporated with iron oxides (goethite and hematite) and used for the removal of diclofenac (DCF) from aqueous solutions. The prepared waste red bricks were systematically characterized by XRF, XRD, BET, and SEM. The batch experiments were systematically conducted by investigating the adsorption kinetics, isotherms, thermodynamics, pH, and ionic strength effect. Results showed that the incorporation of iron oxides could enhance the adsorption capacity of DCF onto waste bricks, while the increased effect of hematite was better than goethite. DCF was adsorbed rapidly onto waste bricks, and the adsorption kinetic fitted the pseudo-second-order model perfectly, which could be attributed to the strong interaction between DCF and iron oxides. The increasing pH values decreased the adsorption capacity greatly, which may be due to the electrostatic repulsive interactions. The adsorption of DCF onto waste bricks was an exothermic reaction, and the adsorption isotherms fitted well with the Langmuir model. This study offers new guidelines for the utilization of construction waste, and shows useful methods for the elimination of micropollutants from aqueous solution.