Abstract: The various embodiments herein provide a method of preparation of a nano-material for dechlorination of polychlorobiphenyls (PCB) from oil. The method involves preparing a modified bentonite prepared by treating with hexadecyl pyridinium bromide surfactant and dispersing the modified bentonite in cyclohexane. Aqueous solutions of metal ion such as Cadmium Nitrate or Zinc Nitrate and sulfide ions such as sodium sulfide are added alternately to obtain metal sulphide nano-particles. zinc nitrate is more preferable. The method of dechlorination of polychlorobiphenyls from oil involves irradiating a mixture of oil, nano-material and a solvent such as toluene under UV light for 2-6 h. A nano-material including a modified bentonite with a mono-layer of surfactant and metal sulphide nano-particles such as ZnS and CdS for remediation of oil containing PCB, is also provided.