Provided are graphene nanosheets having a polyaromatic hydrocarbon concentration of less than about 0.7% by weight and a tap density of less than about 0.08 g/cm3, as measured by ASTM B527-15 standard. The graphene nanosheets also have a specific surface area (B.E.T) greater than about 250 m2/g. Also provided are processes for producing graphene nanosheets as well as for removing polyaromatic hydrocarbons from graphene nanosheets, comprising heating said graphene nanosheets under oxidative atmosphere, at a temperature of at least about 200° C.