Effect of stainless-steel slag concentration in the fabrication of cost-effective ceramic membranes: Seawater pre-treatment application

Abstract

Steel slag is an industrial residue rich in metallic oxides (calcium, iron, silicon oxides and quartz). Due to the presence of calcium (CaO) and its reaction with metakaolinite, slag can be used to produce anorthite (CaAl2.Si2O8) in ceramic membranes that can be applied in the pre-treatment of seawater which are the aim of this work. The membranes were produced by uniaxial compression and sintered at 950, 1100 and 1150 °C. The effects of clay particle size, steel slag content (5%, 10% and 20%) and temperature on the apparent porosity, flexural strength, microstructure, hydraulic permeability, and permeate flux was investigated. Smaller clay particles sintered at 1150 °C significantly improved flexural strength. In addition, the hydraulic permeability of the ceramic membranes was improved with the increase of slag concentration, which can be explained by the reduction of the contact angle and membrane roughness. The results showed that the membrane with 20 wt% of slag has a hydraulic permeability of 5263.2 kg m−2 h−1. bar−1, which is considerably higher than the other membranes prepared in this work. The membrane with 20% of slag was subjected to the filtration of seawater and it showed a good performance as microfiltration membrane, it has removed 97.35% of turbidity. Use of stainless-steel slag for the fabrication of ceramic membrane is a promising option for the pretreatment of seawater for reverse osmosis desalination, and a good option to reduce the solid industrial residue which is discarded in the environment.