A facile manufacture of highly adsorptive aggregates using steel slag and porous expanded silica for phosphorus removal

Abstract

Natural adsorptive materials are mainly based on physical adsorption and have limited adsorption capacity. Artificial adsorptive aggregates lead to great potential in improving water quality for water treatment. This study aims to develop a porous and sustainable adsorptive aggregate combining both chemical and physical adsorption capacities. Industrial by-product steel slag (SS) powder is used in conjunction with porous expanded silicate (ES) powder applying a non-sintered pelletizing method for producing sustainable high adsorptive aggregates, and bio-based miscanthus (M) is used to further increase its permeability and porosity. The results show that the bulk density of the resulting adsorptive aggregates varies from 570 kg/m3 to 882 kg/m3, with a bulk crushing strength of up to 5.1 MPa. Moreover, all adsorptive aggregates have outstanding resistance to salt and freeze-thaw cycles. Phosphorus (P) adsorption tests show that the adsorptive aggregates remove the P in aqueous solution (168 mg/L), with an adsorption capacity of 4.2 mg/g. The research demonstrates that sustainable high adsorptive aggregates with good mechanical properties can be produced applying the facile pelletizing method, suitable for the application in the field of water treatment such as adsorptive concrete, constructed wetlands and rainwater gardens.