Boron removal performance of a solid sorbent derived from waste concrete

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.