scholarly journals Precious metal recovery from electronic waste by a porous porphyrin polymer

2020 ◽  
pp. 202000606 ◽  
Author(s):  
Yeongran Hong ◽  
Damien Thirion ◽  
Saravanan Subramanian ◽  
Mi Yoo ◽  
Hyuk Choi ◽  
...  
Keyword(s):  
Precious Metal ◽  
Density Functional ◽  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Precious Metals ◽  
Metal Recovery ◽  
Porous Polymer ◽  
Circuit Boards ◽  
Functional Theory ◽  
Printed Circuit

Urban mining of precious metals from electronic waste, such as printed circuit boards (PCB), is not yet feasible because of the lengthy isolation process, health risks, and environmental impact. Although porous polymers are particularly effective toward the capture of metal contaminants, those with porphyrin linkers have not yet been considered for precious metal recovery, despite their potential. Here, we report a porous porphyrin polymer that captures precious metals quantitatively from PCB leachate even in the presence of 63 elements from the Periodic Table. The nanoporous polymer is synthesized in two steps from widely available monomers without the need for costly catalysts and can be scaled up without loss of activity. Through a reductive capture mechanism, gold is recovered with 10 times the theoretical limit, reaching a record 1.62 g/g. With 99% uptake taking place in the first 30 min, the metal adsorbed to the porous polymer can be desorbed rapidly and reused for repetitive batches. Density functional theory (DFT) calculations indicate that energetically favorable multinuclear-Au binding enhances adsorption as clusters, leading to rapid capture, while Pt capture remains predominantly at single porphyrin sites.

scholarly journals Resources Recovery from Electronic Waste

2020 ◽  
Author(s):  
Mohit Arora
Keyword(s):  
Nitric Acid ◽  
Printed Circuit Boards ◽  
Extraction Efficiency ◽  
Electronic Waste ◽  
Mineral Processing ◽  
Metal Recovery ◽  
Circuit Boards ◽  
Gold Extraction ◽  
Printed Circuit ◽  
Thiosulfate Leaching

Printed Circuit Boards in electronic scrap are richest source of base and precious metals, promoting economic drive for metal recovery. Recovery of these metals is a difficult exercise due to complex nature of electronic waste. India is one of the leading electronic waste processing hubs where more than 95% recyclers are unorganised/non-formal, lacking such a recovery facility. An efficient metal recovery protocol with lesser environmental impact remains unavailable to unorganised recyclers. In current study, an attempt has been made to combine various hydrometallurgical methods to achieve efficient metal recovery from Printed Circuit Boards. Mimicking mineral processing protocols for metal recovery from electronic waste has been a key feature of presented research. Printed Circuit Boards of personal computers were reduced to a size ≤ 2.5 mm and were used as sample for metal recovery. Copper and silver were extracted by selective leaching using Nitric Acid. Maximum extraction efficiency of 96.8% and 99.9% were achieved for copper and silver respectively. Nitric Acid was extracted using solvent extraction method to minimize the environmental damage of remaining waste as well as for reuse in next leaching cycle. Electrodeposition of copper was done on copper cathode with stainless steel and lead anodes with a maximum recovery efficiency of 89.6%. For extraction and recovery of gold and silver, various techniques used in mineral processing were applied in this research. Thiosulfate leaching was chosen for gold extraction due to its proven environment friendly properties. Maximum gold extraction efficiency of 74.3% has been achieved in this work. To recover gold from pregnant solution, zinc cementation approach was used. Up to 85.9% gold was recovered with zinc cementation. Success of thiosulfate leaching and cementation confirms the validity of mineralprocessing techniques in metal recovery from electronic waste. Research in this study can serve as a backbone for potential environmentally sound technology towards efficient metal recovery from electronic waste for small and medium scale recyclers.

A Novel Flowsheet for the Recycling of Valuable Constituents from Waste Printed Circuit Boards

2011 ◽  
pp. 296-306
Author(s):  
Jingfeng He ◽  
Yaqun He ◽  
Nianxin Zhou ◽  
Chenlong Duan ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Separation Efficiency ◽  
Precious Metals ◽  
Metal Recovery ◽  
Recovery Ratio ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Waste Pcbs ◽  
Impact Crushing

Waste printed circuit boards (PCBs) contain a number of valuable constituents. It is of great significance to separate precious metals and non-metallic constituents from waste PCBs with appropriate methods for resource recycling and environment protection. A novel flowsheet for the recycling of waste PCBs using physical beneficiation methods was constructed. Waste PCBs were disassembled into substrates and slots firstly. The substrates were crushed to the size below 1mm through wet impact crushing and separated with a tapered column separation bed. The results indicated that products with integrated separation efficiency of 93.9% and metal recovery ratio of 93.7% were obtained by the primary separation with the water discharge of 5.5 m3/h, feed-rate of 250g/min and inclination angle of 35°. Waste PCBs slots components were crushed to the size of 0.5-5mm through impact crushing and separated with an active pulsing air classifier. The separation results showed that products with integration separation efficiency of 92.4% and metal recovery ratio of 96.2% were obtained with the airflow velocity of 2.90m/s and pulsing frequency of 2.33Hz. Precious metals could be obtained by further separation and purification of the metal components and the non-metal components could be used as refuse derived fuel. The flowsheet has great potential to be applied in the field of waste PCBs treatment and recycling.

scholarly journals Recovery of base and precious metals from PCBs (Printed Circuit Boards) in waste electrical and electronic equipment (WEEE)

2022 ◽  
Vol 13 (1) ◽  
pp. 001-011
Author(s):  
Yete Pélagie ◽  
Togbe FC Alexis ◽  
Yovo Franck ◽  
Suanon Fidèle ◽  
Sidohounde Assou ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Precious Metals ◽  
Developed Countries ◽  
Waste Recycling ◽  
Electronic Equipment ◽  
Circuit Boards ◽  
African Countries ◽  
Printed Circuit ◽  
Advantages And Disadvantages

Natural minerals are a powerful tool in politics when some have a major role in production. Its depletion is now a hot topic worldwide. Thus, the safety of the environment, natural surface water, groundwater and the protection of soils from chronic contamination by metallic and inorganic elements is a global concern. Indeed, industrialization and development have led to the generation of huge and varied amounts of waste, including electronic waste (e-waste), which is released into the environment. Although e-waste is classified as hazardous, most of it is not recycled and developed countries with strict environmental protection legislation send most of their e-waste to developing countries where regulations are lax. These electronic devices and components after being used are simply dumped into the environment due to lack of treatment and recycling strategy. As a result, they become a threat to the environment, ecosystems and humans. African countries are among the most vulnerable nations. But they are unfortunately ignored and underestimated. To date, there is no e-waste recycling unit (factory) in most African countries and mainly in the Republic of Benin. In response to this challenge, this study explored the different techniques used for the recycling of waste electrical/electronic equipment in order to develop a new environmentally friendly approach in future work, for the extraction and recycling of the usual and valuable metallic elements contained in electronic waste (printed circuit boards) released into the environment. For this purpose, a bibliographic research was carried out from 20 April to 16 October 2021. The results obtained allowed us to identify the advantages and disadvantages of existing recycling methods.

Precious metal recovery from waste printed circuit boards using cyanide and non-cyanide lixiviants – A review

2015 ◽  
Vol 45 ◽  
pp. 258-271 ◽  
Author(s):  
Ata Akcil ◽  
Ceren Erust ◽  
Chandra Sekhar Gahan ◽  
Mehmet Ozgun ◽  
Merve Sahin ◽  
...  
Keyword(s):  
Precious Metal ◽  
Printed Circuit Boards ◽  
Metal Recovery ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

scholarly journals Food Waste-Assisted Metal Extraction from Printed Circuit Boards: The Aspergillus niger Route

2021 ◽  
Vol 9 (5) ◽  
pp. 895
Author(s):  
Carlotta Alias ◽  
Daniela Bulgari ◽  
Fabjola Bilo ◽  
Laura Borgese ◽  
Alessandra Gianoncelli ◽  
...  
Keyword(s):  
Solid State ◽  
Aspergillus Niger ◽  
Food Waste ◽  
Solid State Fermentation ◽  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Metal Extraction ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards

A low-energy paradigm was adopted for sustainable, affordable, and effective urban waste valorization. Here a new, eco-designed, solid-state fermentation process is presented to obtain some useful bio-products by recycling of different wastes. Urban food waste and scraps from trimmings were used as a substrate for the production of citric acid (CA) by solid state fermentation of Aspergillus niger NRRL 334, with a yield of 20.50 mg of CA per gram of substrate. The acid solution was used to extract metals from waste printed circuit boards (WPCBs), one of the most common electronic waste. The leaching activity of the biological solution is comparable to a commercial CA one. Sn and Fe were the most leached metals (404.09 and 67.99 mg/L, respectively), followed by Ni and Zn (4.55 and 1.92 mg/L) without any pre-treatments as usually performed. Commercial CA extracted Fe more efficiently than the organic one (123.46 vs. 67.99 mg/L); vice versa, biological organic CA recovered Ni better than commercial CA (4.55 vs. 1.54 mg/L). This is the first approach that allows the extraction of metals from WPCBs through CA produced by A. niger directly grown on waste material without any sugar supplement. This “green” process could be an alternative for the recovery of valuable metals such as Fe, Pb, and Ni from electronic waste.

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