Synthesis of Silica-Potassium-Nitrogen from Carbamide and Potassium Silicate by CO₂ Precipitator

Abstract

Potassium silicate is well known as a fertilizer and source of silica for plants growth. This study aims to infiltrate nitrogen from carbamide (urea) into potassium silicate solution to produced silica potassium nitrogen (Si-K-N) matrix by precipitation method using CO2 as precipitator. Potassium silicate in the range of 3-8% SiO2 was obtained by extracting silica from geothermal sludge using potassium hydroxide solution. Carbamide is added to the potassium silicate solution allowed by mixing and flowing of CO2 gas in reactor glass. The result of IR spectra indicated the presence of N-H groups, potassium and silica in the gel matrix produced from precipitation process while no N-H group appears in the gel matrix produced from precipitation in the absence of carbamide. X-ray fluorescence showed the composition of the product Si-K-N in the range of 40 to 50 %SiO2 and in the range of 50 to 60 %K2O.

Structure and Properties of the Xerogels Based on Potassium Silicate Liquid Glass and Urea

“…This process favors gelation of the system. At the same time, the additional treatment with CO 2 allows completing the gel formation due to increased pH values [ 12 , 13 ].…”

“…However, an acceptable water resistance of the dried gels based on this system occurred at relatively low contents of urea (less of 5 wt.%). It was also recognized [ 12 ] that CO 2 bubbling could reduce the pH of such solutions and support gelation in the potassium–silicate colloidal solutions. The precipitates obtained by CO 2 bubbling through the urea–alkali silicate colloidal solution (24 h) were separated from the residual aqueous solutions and dried to produce the xerogels.…”