Nano sized sulfide compounds of cerium and a process for the preparation thereof

A bioprocess for the preparation of a sulfide compound of cerium, which comprises the steps of:

• a) treating trivalent Cerium salt, optionally in combination with 0.005-0.1% w/v, of sodium sulfate, with a culture broth of sulfate-reducing bacteria (SRB), containing 0.05-1% v/v, of chloroform, under an inert atmosphere, at a temperature ranging between 25-40° C., at pH of 2 to 6 for a period in the range of 3 to 45 days in single or several installments such that a concentration of trivalent Cerium ions does not exceed 0.1% w/v at any point of time, to obtain a biomass,
• b) concentrating the biomass as obtained in step a) at a temperature ranging between 60 to 150° C. for a period in the range of 1 to 6 hours to obtain a concentrated biomass, and
• c) treating the concentrated biomass as obtained in step b) at a temperature between 600 to 1500° C. for a period in the range of 5 to 400 minutes followed by separation to obtain a sulfide of Cerium.