Synthesis, Characterisation and Testing of Bismuth Vanadate-An Eco-friendly Yellow Pigment

摘要

Bismuth based pigments are environmentally friendly and can replace more hazardous yellow formulations containing lead, chromium or cadmium pigments. They offer brilliant greenish yellow and orange shades with high opacity and high colur strength. An improved method is developed for the preparation of bismuth vandate from an aqueous solution of sodium vanadate by adding a solution of bismuth nitrate in the presence of sodium acetate/acetic acid buffer. This avoids the polymerisation of vanadate ion in acidic solution as well as the formation of bismuthyl ion in alkaline solution. The pigment is characterised by measuring its bulk density, particle size, and oil absorption value. Its colour is matched with colours of standard yellow and orange pigments. An XRD study is also carried out which indicates the pigment to be of monoclinic form.