Wastewater treatment and concrete construction chemical produced using a new process

Sodium aluminate is commonly used in waste water treatment plants to remove suspended solids, some metals and dissolved silica. In construction, sodium aluminate is used during cold weather to accelerate the solidification of concrete. Other areas where sodium aluminate is used include paper production, refractory bricks and alumina production.

The most common methods used to prepare solid sodium aluminate utilise an initial step to give an aqueous sodium aluminate solution. Solid sodium aluminate is yielded by drying.

In this work by César A. Contreras, Satoshi Sugita and Esthela Ramos, researchers from Universidad de Guanajuato in Mexico, the preparation of sodium aluminate was investigated using basic aluminium sulphate (BAS) as a precursor. This latter compound was obtained by homogeneous precipitation of aluminium sulphate aqueous solution using ammonium bisulfite as a precipitant. In the next step of the process, the preparation of sodium dawsonite was investigated by treating BAS with a sodium carbonate aqueous solution. Finally, this latter compound was heated at different temperatures to determine the formation temperature of sodium aluminate.

The researchers found that this method could be used to obtain crystalline sodium aluminate by heating sodium dawsonite at 900°C for 30 minutes.