Synthesis of magnesium and calcium fluoroborate with fluoroboric acid and usability as flame retardant

Special boron products have common usage and they have become irreplaceable products in technology nowadays. Some of special boron products are boron hydrides, borates, borons, elemental boron and fluoroborates. Fluoroborates are used in textile industry as a flame retardant, catalyst in organic reactions, pesticides towards insects and fungis, in glasses to increase the optical properties and also many other fields. In this study, calcium fluoroborate and magnesium fluoroborate, which is one of metal fluoroborates, were syhnthesised by the wet method with the use of calcium oxide and fluoroboric acid and magnesium carbonate and fluoroboric acid as reactants respectively. Reactant mole ratio, temperature and reaction time were investigated as parameters and optimum synthesis conditions are determined. In characterization study, FTIR and BF4- ion selective electrode were used. Firstly, optimum mole ratio (nCaO/nHBF4) and (nMgCO3/nHBF4) was determined at constant temperature and found as 1:4 and 1:3. Then experiments were continued at constant mole ratio and different temperatures (30˚C, 50˚C, 70˚C, 90˚C, 100˚) for calcium fluoroborate and (30˚C, 40˚C, 50˚C, 60˚C, 70˚C) for magnesium fluoborate. Calcium fluoroborate was synthesized with 97% yield at 90°C and optimum period was determined as 100 minutes. Magnesium fluoroborate was synthesized with 98% yield at 50˚C and optimum period was determined as 90 minutes. Calcium fluoroborate and magnesium fluoroborate solutions were prepared at different concentrations. The solutions were impregnated to fabrics and then LOI test was performed to determine flame retardant characteristic of calcium fluoroborate and magnesium fluoroborate. It is observed that calcium fluoroborate and magnesium fluoroborate is very good flame retardant. Reaction rates were determined as first order equation for each product. Activation energy was determined and found as 19.14 kJ/mol.K for calcium fluoroborate and 6.75 kJ/mol.K for magnesium fluoroborate.