Extraction of Silver by Glucose

Abstract

Unprecedented silver ion leaching, in the range of 0.7 ppm was seen when metallic silver was heated in water at 70 8 8Ci np resence of simple carbohydrates,s uch as glucose, making it ag reen method of silver extraction. Extraction was facilitated by the presence of anions,s uch as carbonate and phosphate.S tudies confirm at wo-step mechanism of silver release,f irst forming silver ions at the metal surface and later complexation of ionic silver with glucose;such complexes have been detected by mass spectrometry.E xtraction leads to microscopic roughening of the surface making it Raman active with an enhancement factor of 510 8 .Noble metals are resistant to chemical corrosion. Extraction of noble metals from minerals and subsequent processing requires highly reactive conditions and toxic chemicals. [1] Silver, one of the important and precious coinage metals is sourced from the ores,and mostly extracted by chemical and electrolytic methods. [2] Major use of silver lies in photography and 60 %o ft he total silver produced every year is recycled from photographic plates. [3] This situation demands extraction and recycling of silver via green methods at mild conditions. Silver ions react strongly with biomolecules including carbohydrates,p eptides and DNA. [4] Similar interactions with biomolecules are observed in biomineralization pathways in microorganisms. [5] Silver nanoparticles are made using glucose and starch as reducing as well as capping agents. [4][5][6] Herein, we show the extreme chemical affinity of silver to carbohydrates leading to their extraction in solution, directly from the metallic state,w hich is enhanced in presence of common ions suggesting an ew method of extractive metallurgy.T he process is thermodynamically favorable as seen from ac alorimetric study.C ontinuous extraction of silver leads to corrosion of the surface and subsequent microscopic roughness was observed. This roughened surface acts as an effective substrate for surface enhanced Raman spectroscopy (SERS).In at ypical experiment, as ilver foil of 6cm6cma rea and 3gin mass leaches out 656 ppb silver in 27.8 mm glucose (G) solution in 7days,when the extraction was performed at 70 8 8Ci naT eflon beaker. Surface area and mass of the silver foil were kept constant for all the experiments.T his foil decreases its mass by 0.5 %inthis time.Exposure for 90 days can lead to 10 %m ass loss of the silver foil, in the above condition. Time dependent variation of the mass during an experiment is shown in Figure 1. Silver mirrors coated on glass slides also show similar leaching.H owever,a sw ek eep our reaction in stirring conditions,t he silver mirror gets damaged and therefore we continued our experiments with silver foils.Theweight loss is due to the leaching of Ag as Ag + and the existence of glucose-Ag + (G-Ag + )complexes in the solution was studied. G-Ag + and 2G-Ag + complexes were detected by electrospray ionization mass spectrometry (ESI MS) ( Figure 2). In tandem mass spectrometry (ESI MS/MS), the G-Ag + complex ions (m/z 28...

Tribochemical Degradation of Polytetrafluoroethylene in Water and Generation of Nanoplastics

“…Baksi et al have shown the mechanism of the extraction of silver by glucose. 7 A similar type of degradation was observed when metal ions (Cu 2+ ) were added to the water in the absence of glucose (Figure S11). No considerable degradation was found in the absence of glucose.…”

“…Peaks from the material obtained from copper and stainless steel vessels and pure PTFE are shown in Figure 2Aa,b,c, respectively. Peaks labeled as 1, 2, 3, 4, 5, 6, and 7 represent CF 2 wagging (1), CF 2 twisting (2), CF 3 symmetric deformation (3), CF 2 symmetric stretching (4), CF 2 asymmetric stretching (5), C−C stretching (6), and C−F stretching (7), respectively. 5 A new peak was seen at 472 and 473 cm −1 for copper and iron-containing samples, respectively which is absent in pure PTFE.…”

Multifunctional Inosine Monophosphate Coordinated Metal–Organic Hydrogel: Multistimuli Responsiveness, Self-Healing Properties, and Separation of Water from Organic Solvents

“…This result could be attributed to a 1:1 stoichiometry saturation of Ag + ions coordination to IMP, and the excess Ag + ions can interact with the sugar moiety of IMP. 55 Additionally, the influence of IMP concentration on the rheological property of the hydrogels was investigated. For this, hydrogels were obtained by complexation of a fixed concentration of Ag + ions with varying amounts of IMP (50− 100 mM).…”

Increased Antibacterial and Antibiofilm Properties of Silver Nanoparticles Using Silver Fluoride as Precursor

“…The effect of treatments with nanoparticles is always lower with respect to what found with silver salts and as a consequence lower MIC values are found than in the case of ionic silver, see Figure 3 A,C. It has been hypothesized that this is due the easier cellular uptake of silver ions in such conditions, thanks to the formation of Ag + -glucose complexes [ 28 , 29 ] Moreover, also a decreased mobility of nanoparticles in biofilms with respect to ions has to be taken into account [ 30 ]. This is due to their different dimensions and to the trapping effect exerted by EPS (Extracellular Polymeric Substance) on nanoparticles.…”