Dear Sir. Concerning your issue about the recovery soluble silica (around 200ppm) from alkaline solution (~11-12) using ion exchange resin. The determination of soluble silicates using the yellow silicomolybdate complex or by reduction of this complex to molybdenum blue is a method capable of wide application. The direct use of this method on complex organic mixtures is not, however, feasible and a method of separation of silica or removal of organic interference is necessary. During the course of an investigation requiring the determination of microgram quantities of silica in such circumstances, the authors have studied the separation and recovery of silica using an ion-exchange technique and shown it to be quantitative. The method has been successfully applied to the determination of silica in sodium alginate solutions but was unsuccessful in the separation of silica from sodium hydroxide solutions containing hemicellulose. I think the following below attached file may help you in your analysis.

Thanks

Thank you sir