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 (X) between two opposite ends 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 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 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 (X) between two opposite ends 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 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 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. <EOS>