Purification device comprising: - a hollow body which defines a duct suited to convey water, said duct being developed between a first mouth and a second mouth; - a purifying material placed in a first area of said duct between said first mouth and said second mouth, said purifying material being graphene, said graphene being held inside said first area by means of one or more holding elements; said hollow body comprising: - an inner tubular jacket; - an outer tubular jacket connected in a stable manner to said inner tubular jacket on the outside of the latter, in such a way that between said outer tubular jacket and said inner tubular jacket a first air space is defined which belongs to said duct, said first air space extending along a longitudinal direction between two opposite ends (9a, 9b) and comprising said first area; - one or more first holes suited to place said first air space in communication with the outside of said outer tubular jacket; - one or more second holes suited to place the inner volume of said inner tubular jacket in communication with said first air space, said purifying material being arranged in said first air space; said graphene taking on the shape of a plurality of independent plate-like elements, said holding elements being two water-permeable walls (21, 22) suited to prevent the passage of said plate-like elements and delimiting said first area on corresponding opposite sides respectively facing towards said first mouth and towards said second mouth, whereby: - the ratio between the mass of said plate-like elements and the volume of said first area is included between 15 and 50 mg/cm 3, and - a first one of said two water-permeable walls (21, 22) is arranged in said first air space and separates said first area from a second area of said first air space adjacent to said first holes in such a way as to maintain said second area free from said graphene. - a hollow body which defines a duct suited to convey water, said duct being developed between a first mouth and a second mouth; - a purifying material placed in a first area of said duct between said first mouth and said second mouth, said purifying material being graphene, said graphene being held inside said first area by means of one or more holding elements; said hollow body comprising: - an inner tubular jacket; - an outer tubular jacket connected in a stable manner to said inner tubular jacket on the outside of the latter, in such a way that between said outer tubular jacket and said inner tubular jacket a first air space is defined which belongs to said duct, said first air space extending along a longitudinal direction between two opposite ends (9a, 9b) and comprising said first area; - one or more first holes suited to place said first air space in communication with the outside of said outer tubular jacket; - one or more second holes suited to place the inner volume of said inner tubular jacket in communication with said first air space, said purifying material being arranged in said first air space; said graphene taking on the shape of a plurality of independent plate-like elements, said holding elements being two water-permeable walls (21, 22) suited to prevent the passage of said plate-like elements and delimiting said first area on corresponding opposite sides respectively facing towards said first mouth and towards said second mouth, whereby: - the ratio between the mass of said plate-like elements and the volume of said first area is included between 15 and 50 mg/cm 3, and - a first one of said two water-permeable walls (21, 22) is arranged in said first air space and separates said first area from a second area of said first air space adjacent to said first holes in such a way as to maintain said second area free from said graphene.