Treatment of water-based ink wastewater by a novel magnetic flocculant of boron-containing polysilicic acid ferric and zinc sulfate

Abstract Polysilicic acid ferric and zinc sulfate containing boron (PSBFZ) flocculants were prepared through reaction of sodium silicate, ferric trichloride, zinc sulfate and sodium tetraborate. A new type of magnetic flocculant PSBFZ-Fe3O4 was prepared through a simple method of solid state reaction at room temperature. The as-prepared PSBFZ and magnetic PSBFZ-Fe3O4 were used in treating water-based ink wastewater. The influence parameters (such as dosage, time, pH and temperature) on the removal rate of decolorization, turbidity and chemical oxygen demand (COD) were investigated. The results showed the products were suitable for neutral and basic water. When the dosage of PSBFZ-Fe3O4 was 0.3 g/L, the turbidity removal rate and the decolorization rate could reach 98.0 % and 98.5 % at room temperature, respectively. Through recycling by a magnet, the magnetic PSBFZ-Fe3O4 flocculants residues could be easily separated from the wastewater which makes the reusing of magnetic flocculants become possible.