Recovery of silver from waste printed circuit boards (WPCBs) through hydrometallurgical route: A review

Mishra, Gyan Prakash; Jha, Rohit Kumar; Rao, Mudila Dhanunjaya; Meshram, Arunabh; Singh, K. K.

doi:10.1016/j.envc.2021.100073

Cited by 55 publications

(20 citation statements)

References 74 publications

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“…PCBs are integral components of most electronic waste. The silver content of PCBs is ∼0.12%, which is higher than that of natural argentiferous ore (∼0.08% silver) . E-waste is an urban mine and can be used as a raw material source to extract secondary silver.…”

Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Silver is widely used not only in jewelry, coins, and silverware but also in the electronics industry, which is the dominant consumer of silver because of its unique properties (e.g., electrical conductivity and corrosion resistance). 1 Silver is also incorporated into medical products, textiles, and cosmetics as an effective antibacterial agent. 2 Owing to its numerous applications, it is inevitable that silver will find its way into the aquatic system; the threat this poses to the environment and humans has attracted increasing attention.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption Studies on Ag(I) Using Poly(N-phenylglycine) Membrane and Application in Practical Silver Recycling

Lin

et al. 2022

ACS Appl. Polym. Mater.

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Adsorption methods offer advantages in the treatment of polluted water, particularly with the removal of heavy metal ions, because they are simple in process and no secondary pollutants are involved. Conductive polymers are good adsorbents because of their diverse functional groups and large, active surface areas. Poly(N-phenylglycine) (PNPG) is an emerging conductive polymer used in adsorption studies. In this study, a PNPG membrane was prepared by vacuum filtration, and characterization studies were performed to elucidate the reaction mechanism between the PNPG membrane and Ag(I). It was found that most benzenoid diamine structures undergo a redox reaction with Ag(I), while a minority undergo chelation. Through studies on the pH influence, adsorption kinetics, and adsorption isotherms, this adsorption process fits the pseudo-second-order and Langmuir models which indicate chemical adsorption and monolayer adsorption. The maximum Ag(I) adsorption capacity of the PNPG membrane, 366 mg g–1, was also close to the theoretically calculated value at pH 6. In addition, the PNPG membrane showed potential for the recovery of Ag from real solutions when leaching solutions of e-waste and municipal solid waste incineration fly ash were subjected to adsorption experiments.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adsorption Studies on Ag(I) Using Poly(N-phenylglycine) Membrane and Application in Practical Silver Recycling

Lin

et al. 2022

ACS Appl. Polym. Mater.

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“…Recovery of precious metal ions (such as silver, palladium, or gold) is desired because of their potential environmental risk when in water sources as well as their enormous commercial value. For example, silver content in waste of printed circuit boards (PCBs) can reach up to 0.2 wt %, 13 but its release should be limited to below its maximum allowable concentration in drinking water (0.1 mg L −1 ). 14 Through its recovery, silver can be reused in wide applications in home appliances, textiles, personal care products, electroplating, and the photography industry.…”

Section: ■ Introductionmentioning

confidence: 99%

Sustainable Design of Molybdenum Disulfide Nanocomposites for Silver Recovery

Livne

Yecheskel

Sarkar

et al. 2022

ACS Sustainable Chem. Eng.

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Recent increasing industrial demand for precious metals suggests recycling and regeneration as a means to decrease the energy consumption and cost associated with precious metal use. Molybdenum disulfide (MoS2) nanosheets have demonstrated selective and efficient adsorption potential toward heavy metals, but their application in recovering precious metals has not been reported. In this study, we affix MoS2 onto platforms to increase the sustainability and practicality of silver (used as a precious metal model) recovery from wastes, with the optimal design determined by effectiveness, sustainability, and scalability criteria. MoS2 was synthesized on three robust platformssand particles, alumina beads, and PTFE beadsusing bottom-up solvothermal methods. While a stable homogeneous molybdenum sulfides and oxides layer was formed over sand and alumina, PTFE beads were only partially coated. Silver was adsorbed onto MoS2@sand and MoS2@alumina at similar rates, but less was adsorbed on MoS2@PTFE. Recovery of silver from the nanocomposites was examined, and a thiourea and EDTA mixture was found to be the best desorbing solution, allowing over 80% silver recovery from MoS2@alumina. Our study indicates that among the platforms tested, alumina beads are the optimal MoS2 platform for precious metal recovery applications, allowing high adsorption and recovery rates with minimal Mo leaching. Overall, this study advances the utility and practical design of MoS2-based nanocomposites in water-treatment schemes, particularly for viable use in commercial aqueous metal recovery.

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“…At present, different studies have been carried out examining the extraction and separation of silver from secondary sources such as printed circuit, electronic, etc. This involves the use of hydrometallurgy routes [12,13] such as hydrochloric acid [14] and nitric acids [15] which are not economical due to high consumption of reagents and nitrogen toxicity to humans [16]. Different research work carried out to extract and separate different metals from lead-free solders has focused on major metals in alloys such as tin by using different methodologies such as the application of microwaves for recovering tin from tin silver copper alloy [17][18][19]; however, there is a previous study on separating silver by using a pyrometallurgical method [20], but the process has different drawbacks such as high costs due to the long cyclic process.…”

Section: Introductionmentioning

confidence: 99%

Separating Silver from Tin Silver Alloy Residue: Effect of Agitation Rate

Kabatesi

Wang

2022

Metals

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In this paper, research on the effects of agitation rate for desilvering tin silver alloy residue by using pyrometallurgy was carried out. SnAg alloy residue with 92 wt.% tin and 3.56 wt.% silver was used in this study, and 99.999 wt.% zinc was added as metal solvent. Residues were melted to a temperature of 400 °C for enriching tin silver alloy. The obtained tin silver alloy was melted in a temperature range of 450 °C to 500 °C by adding zinc to evaluate zinc dissolution. The obtained tin silver zinc was agitated at different agitation rates for 20 min at a temperature of 480 °C, then cooled down while stirring to an eutectic point of tin zinc alloy (198.9 °C) to remove silver zinc dross. X-ray Fluorescent-1800 (XRF-1800) and Field Emission Scanning Electron Microscopy Energy Dispersive Spectroscopy (FE-SEM-EDS) analyses were performed in this research. Different factors including holding time, zinc dissolution, agitation time and agitation rate were evaluated. The results revealed that an agitation rate of 600 RPM, 25% Zn and 60 min at a temperature of 198.9 °C were efficient. Zinc silver was removed as dross every 20 min to get 92% silver separation efficiency, and the use of supergravity centrifuge is highly recommended to get best separation efficiency.

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Recovery of silver from waste printed circuit boards (WPCBs) through hydrometallurgical route: A review

Cited by 55 publications

References 74 publications

Adsorption Studies on Ag(I) Using Poly(N-phenylglycine) Membrane and Application in Practical Silver Recycling

Adsorption Studies on Ag(I) Using Poly(N-phenylglycine) Membrane and Application in Practical Silver Recycling

Sustainable Design of Molybdenum Disulfide Nanocomposites for Silver Recovery

Separating Silver from Tin Silver Alloy Residue: Effect of Agitation Rate

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