Specific features of mass transfer of silicon compounds through reverse osmosis membranes

Summary

In the process of siliferous natural water treatment with different mineralization levels in two-stage reverse osmosis units the transfer of colloid (polymer) silica forms through permselective membranes at the second stage of water desiliconization takes place. Based on the results of the studies carried out in industrial-scale two-stage reverse osmosis units an attempt to analyze the results obtained in the model that took into account the efficiency of sediment formation on the active surface of a reverse osmosis membrane was made. The summary of the experimental results on siliferous natural water treatment with reverse osmosis is presented. A physico-chemical model of colloid silicon transfer through membranes is suggested that provides for precoat filtration effects and silicon depolymerization and polymerization processes during the solution passing through the corresponding filtering layers. In case of dynamic phase equilibrium availability precoat filtration results in the increase of dissolved silicon concentration fed on the effective membrane surface and subsequent (backward) recovery of the equilibrium composition in permeate. A proximate mathematical model for stable conditions of mass transfer is suggested.

Key words

sorption , reverse osmosis , natural water , colloid silicon , precoat filtration , membrane transfer