Caustic Soda Solid

About This Product

Caustic soda solid is sodium hydroxide, NaOH, CAS number 1310-73-2, cast into blocks or rods rather than flaked or prilled. It is white, opaque and strongly alkaline, and dissolves in water with a large release of heat. The reason to buy caustic soda as solid blocks rather than flakes or pearls is surface area. All three are the same chemical, but sodium hydroxide is deliquescent and reacts with atmospheric carbon dioxide to form sodium carbonate, and both processes work on the exposed surface. A drum of blocks presents a small fraction of the surface that the same weight of flake does, so it holds its assay through long sea transport and through storage in humid climates where flake cakes into a solid mass and drifts out of specification. The trade-off comes at the point of use: blocks dissolve slowly and must be broken or charged whole into a dissolving tank, so the form suits a plant making up batch solutions rather than one metering a free-flowing solid into a continuous line. Three grades are offered, at 96, 98 and 99 percent, the 96 percent material being the usual choice where the caustic is consumed or neutralised rather than carried into the finished product. It is used for bauxite digestion in alumina refining, in metallurgical processing and pickling, as the alkali in chemical manufacture and neutralisation duties, and in water and effluent treatment where pH has to be raised. Bio Green Chem supplies caustic soda solid at 96, 98 and 99 percent minimum in 200 kg steel drums. It is UN 1823, Class 8, packing group II, corrosive to skin and eyes, and reacts violently with acids and with aluminium; handle to the safety data sheet.