Boron Removal Performance of a Solid Sorbent Derived from Waste Concrete

Abstract

Low-cost materials for boron removal need to be developed to reduce the overall cost of treatment of boron-containing wastewater. In this paper, the preparation of a boron removal material using waste concrete particles is described. With high initial boron concentrations (100 and 300 mg/L boron), the removal performance was insufficient and the dominant boron removal mechanism was estimated to be precipitation of calcium borate. With a low initial boron concentration (10 mg/L boron), more boron was removed by increasing the amount of the sorbent, and the boron removal can be attributed to ion exchange. After heat treatment of the material at 175 °C, an initial decrease in the boron removal rates was observed, but after 1440 min the residual boron concentrations for the heat-treated material were much lower than those for the untreated material. This improvement is thought to be due to the generation of metaettringite, the dehydration product of ettringite.