Recovery of silver from radiographic fixer

Phycoremediation of X-ray developer solution towards silver removal with concomitant lipid production

The present research is mainly focusing on the characterization of X-ray developer solution and its toxic tolerance studies with Desmodesmus armatus towards the phycoremediation studies for removal of pollutants, silver, and concomitant lipid production. The characterization results suggested the presence of 1.229 ± 0.004 g/l BOD, 27.29 ± 0.230 g/l COD with a silver content of 0.01791 ± 0.000 g/l. The tolerance and toxicity limits of with X-ray developer solution reveals the remarkable growth of microalgae in 3:1.dilution ratio of BBM in the X-ray developer solutions. The phycoremediation with 19 days period shown the noticeable results with a relative BOD (20.86%), COD (13.88%), with 57.10% corresponding total phosphorous removal. The phycoremediation also has proven better relative silver removal potential of 44.06% on the 19th day with concomitant 1.392% lipid production. Overall, the present study shows the potential phycoremediation strategy of hazardous X-ray developer solutions with possible concurrent lipid production through a sustainable approach.

Sonochemically recovered silver oxide nanoparticles from the wastewater of photo film processing units as an electrode material for supercapacitor and sensing of 2, 4, 6-trichlorophenol in agricultural soil samples

The present work describes the sensing application and supercapacitive behavior of silver oxide nanoparticles recovered from wastewater of photo film processing units via one-pot green sonochemical recovery process. The recovered silver oxide nanoparticles (Ag₂O NPs) were characterized by spectral techniques such as FT-IR, Raman, UV-Vis and analytical tools such as XRD, FE-SEM, TEM, EDX, XPS and BET. In view of Ag₂O NPs as electrode material with wide technological applications, the recovered Ag₂O NPs were examined for their sensing and supercapacitive behavior. The developed sensor was explored to detect 2, 4, 6-trichlorophenol, and as expected it shows moral parameters which are required of an effective sensor. Therefore, it was exploited for the quantification of 2, 4, 6-trichlorophenol in soil samples from the agricultural area. Cyclic voltammetric (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopic (EIS) studies on the recovered Ag₂O NPs coated Ni foam electrode depicted the pronounced capacitive behavior. The GCD studies revealed an enhanced electrochemical performance, particularly with the large specific capacitance of 530 F/g at a current density of 1 A/g. The cyclic stability of the electrode material was identified with 88% retention in specific capacitance even after 5000 GCD cycles. These results strongly proved that the recovered Ag₂O NPs are potential candidates for sensing and supercapacitor applications.

Removal of silver from photographic wastewater effluent using Acinetobacter baumannii BL54

Acinetobacter baumannii BL54, a silver (Ag) resistant micro-organism was isolated from clinical samples collected at the Armed Forces Medical College hospital in Pune, India. The strain BL54 removed a high quantity of silver (2.85 mg/g biomass) from photographic wastewater effluent. Treatment of the cells with 10 mM EDTA or agitating the culture did not affect the removal process, while altering pH of the wastewater or pre-treating the cells with 0.5 mM 2,4-dinitrophenol (DNP), 20 μM N,N'-dicyclohexylcarbodiimide (DCC), 25 μg/mL cefotaxime, and polymyxin-B resulted in considerable decrease in removal of silver by the organism. Dead cells, or a Ags plasmid-cured derivative (BL54.1) removed little silver, which was mainly surface bound. The results, compared with accumulation of Ag by a sensitive culture of Escherichia coli K12 J53.2, suggest that A. baumannii BL54 has good potential for bioremediation of silver from photographic wastewater effluents. Key words: Acinetobacter, silver resistance, silver removal.