Preparation of Crystallized Phosphorus Removal Material Using Gypsum Board and Evaluation of Phosphorus Removal Ability

Abstract

The authors have investigated the possibility of reusing gypsum board, a type of construction waste, as a phosphorus removal material by carbonating in an aqueous sodium carbonate solution to precipitate calcium carbonate on the surface after coating with a mixed solution of silica sol and binder. It became possible to prepare a phosphorus removal material with high phosphorus removal ability, but there were problems such as peeling of the calcium carbonate layer on the surface of the sample. In addition, the process of carbonation treatment after coating treatment was complicated and required a long time to prepare the sample. Therefore, in this study, by adding calcium carbonate powder to a mixed solution of silica sol and binder, calcium carbonate, which acts as a crystallization site for calcium phosphate, was supported on gypsum board without carbonation treatment using an aqueous sodium carbonate solution. The process used in this study significantly shortened sample preparation time. The phosphorus removal ratio increased with increasing the amount of calcium carbonate added to the coating solution, and by stirring during the coating process, the amount of calcium carbonate that could be supported on the gypsum board surface increased, further increasing the phosphorus removal ratio.