Recycling of exposed photographic X-ray films and recovery of silver using Bromelain

Abstract

In the present work an environmentally friendly recycling system to peel away the base coat from the X-ray film by using an enzyme was developed. Bromelain, a proteolytic enzyme extracted from the waste apex of pineapple was used for stripping the silver layer on the exposed film by hydrolysis of gelatin. The collected film can be reused for the manufacturing of X-ray film or other materials like fabrics, packaging films, recording tapes, and soft-drink bottles. The silver recovery conditions were optimized and the slurry obtained from the treatment of X-ray with Bromelain was analyzed using a scanning electron microscope. The slurry was smelted in the presence of flux (Na 2 CO 3) in a furnace to recover 99.9% pure silver. Thus it helps in the recycling of X-ray film and recovery of silver without any harm to the environment.

Purification, biochemical characterization and performance evaluation of an alkaline serine protease from Aspergillus flavus MTCC 9952 mutant

“…B21-2. Proteases from plant origins (Bromelain) have also been applied for this purpose as reported by Radha and Arun (2010).…”

“…Thus it is desirable to replace these methods by employing enzymes. Another advantage of enzymatic method is that the films after silver recovery can be reused for the manufacturing of X-ray film or other materials like fabrics, packaging films, recording tapes, and soft-drink bottles (Radha and Arun, 2010). Earlier, Nakiboglu et al (2001) recovered silver by using alkaline protease from Bacillus subtilis ATCC 6633 from waste photographic films.…”

Characterization and Potential Application of Bromelain from Pineapple (Ananas comosus) Waste (Peel) in Recovery of Silver from X-Ray Films

“…This includes bromelain enzymes extracted from pineapple cultivars found abroad in Ethiopia. A representative study conducted by Radha and Arun [ 2 ] indicates that crude bromelain extracted from the waste apex of pineapple needs 35 minutes to remove gelatin from X-ray films. This implies that crude bromelain extracted from pineapple fruit peel was significantly effective in gelatin hydrolysis.…”

“…It is used in large amounts for various purposes, especially in the photographic industry [ 1 ]. Photographic and X-ray films contain silver particles spread on the surface linked to the gelatin layer [ 2 ]. Due to this, photographic and mainly X-ray films have been taken as a good source of silver recovery.…”

“…The enzyme has been used widely in food [ 15 ], cosmetic [ 16 ], textile [ 17 ], leather [ 15 ], medical and pharmaceutical [ 18 ], and other industries. However, no one presents the importance of bromelain in the recovery of silver from waste X-rays and photographic films except Radha and Arun [ 2 ]. Their work has been also focused only on the extraction of bromelain from pineapple apex, but not from other parts of the plant.…”