Phosphorus removal enhancement by porous adsorptive mortar using miscanthus and steel slag for highly adsorptive concrete

Abstract The low permeability and low adsorption capacity of conventional cement mortar are one of the decisive reasons for the poor adsorption performance of the adsorptive aggregates applied to adsorptive concrete. In this study, a porous adsorptive mortar is developed by combining chemical and physical methods to enhance the permeability and adsorption performance. Porous heat-treated miscanthus (HM) (0.5 wt% and 1.0 wt%) powder and steel slag (SS) (5.0 wt% and 10.0 wt%) powder with different dosages are investigated in this new adsorptive mortar. Results show that the excellent adsorption capacity of the adsorptive mortar of 30.4–74.2 mg/g, with a corresponding initial P-concentration of 1215.3–2967.5 mg/L. The leaching result, ICP-AES, XRD, FTIR, TG-DTG and SEM-EDS analyses confirm the Ca2+ leached from the adsorptive mortar and the SS, reacting with the PO43− to form Ca-P precipitates in solution. Moreover, the porous HM significantly improves the permeability of the developed mortar. It is can be concluded that the HM with a dosage of 0.5 wt% and the SS with a dosage of 10.0 wt% can be recommended for highly adsorptive mortar to improve phosphorus (P) removal capacity from stormwater, without obvious sacrifices on other properties.