scholarly journals Role of Actinomycete sp. in Bio-extraction of Copper from Electronic Waste

2021 ◽  
Vol 12 (5) ◽  
pp. 6723-6740
Keyword(s):  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Nitrogen Sources ◽  
Dissolution Mechanism ◽  
Circuit Boards ◽  
Carbon And Nitrogen Sources ◽  
Nitrate Medium ◽  
Carbon And Nitrogen ◽  
Printed Circuit

Copper is bioleached from printed circuit boards (PCBs) using Actinomycete sp. It was identified by 16S rRNA, called Streptomyces graminofaciens. The tolerance of S. graminofaciens towards copper showed that it couldn’t live in the presence of copper sulfate. The process was carried out by culturing 3.09×103 CFU of S. graminofaciens in 50 ml of modified starch nitrate medium for three days at 200 rpm and 30C and then 0.5% e-waste was added for other 5 days. Glucose (0.01 g/ml) and ammonium sulfate (0.002g/ml) were the best carbon and nitrogen sources. At pH 5, the leached copper was 88.1%. The bio-dissolution mechanism was investigated via the production of enzymes of S. graminofaciens metabolites, which showed that the higher dissolution has occurred in an un-denatured sample (non-heating) than the denatured one (heating). FTIR spectra confirmed the action of S. graminofaciens through the disappearance and appearance of some peaks. SEM showed that the e-waste gained more pores as a result of bio-treatment, which refers to the liberation of metals in solution.

scholarly journals Bioleaching of Copper from Electronic Waste Using Aspergillus niger

2021 ◽  
Vol 12 (6) ◽  
pp. 8406-8425
Keyword(s):  
Aspergillus Niger ◽  
Hplc Analysis ◽  
Printed Circuit Boards ◽  
Color Change ◽  
Electronic Waste ◽  
Nitrogen Sources ◽  
Circuit Boards ◽  
Carbon And Nitrogen ◽  
Dioxins And Furans ◽  
Before And After

The recycling of printed circuit boards (PCBs) causes environmental problems by releasing dioxins and furans. The objective of this study is the recovery of copper from PCBs through the bioleaching process using Aspergillus niger which was isolated from the surface of Abu Tartur phosphate. In the bioleaching process, the optimum conditions were used to modify ammonium medium with inoculum spore size are 2Χ106 SFU/50 ml for 5 days at 30ͦ C in a pulp of 0.5% solid 150 mesh particle size and aeration at 200 rpm. Different carbon and nitrogen sources were used. Glucose (1.5%) and ammonium chloride (0.2%) were the best source of carbon and nitrogen, respectively. Also, the optimum initial medium’s pH was 7. At these conditions, about 100% of Cu was extracted. The mechanism of bioleaching was studied by detecting the production of organic acid through using brome cresol green as an indicator and HPLC analysis. The color change of agar medium of the incubated plate with A. niger from blue to yellow, and HPLC analysis showed detection malic and citric acids in the sample in presence e-waste higher than the sample without e-waste. E-waste before and after the bioleaching process was investigated using SEM. The surface of e-waste becomes more smooth and porous due to the bioleaching process.

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.

scholarly journals Analysis of the treatment of plastic from electrical and electronic waste in the Republic of Serbia and the testing of the recycling potential of non-metallic fractions of printed circuit boards

2017 ◽  
Vol 71 (3) ◽  
pp. 271-279
Author(s):  
Aleksandra Vucinic ◽  
Zeljko Kamberovic ◽  
Milisav Ranitovic ◽  
Tihomir Kovacevic ◽  
Irena Najcevic
Keyword(s):  
Chemical Composition ◽  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Mechanical Methods ◽  
The Republic ◽  
Electrical And Electronic Waste ◽  
Metallic Fractions

This paper presents the analysis of the quantity of plastic and waste printed circuit boards obtained after the mechanical treatment of electrical and electronic waste (E-waste) in the Republic of Serbia, as well as the recycling of non-metallic fractions of waste printed circuit boards. The aim is to analyze the obtained recycled material and recommendation for possible application of recyclables. The data on the quantities and treatment of plastics and printed circuit boards obtained after the mechanical treatment of WEEE, were gained through questionnaires sent to the operators who treat this type of waste. The results of the questionnaire analysis showed that in 2014 the dismantling of E-waste isolated 1,870.95 t of plastic and 499.85 t of printed circuit boards. In the Republic of Serbia, E-waste recycling is performed exclusively by using mechanical methods. Mechanical methods consist of primary crushing and separation of the materials which have a utility value as secondary raw materials, from the components and materials that have hazardous properties. Respect to that, the recycling of printed circuit boards using some of the metallurgical processes with the aim of extracting copper, precious metals and non-metallic fraction is completely absent, and the circuit boards are exported as a whole. Given the number of printed circuit boards obtained by E-waste dismantling, and the fact that from an economic point of view, hydrometallurgical methods are very suitable technological solutions in the case of a smaller capacity, there is a possibility for establishing the facilities in the Republic of Serbia for the hydrometallurgical treatment that could be used for metals extraction, and non-metallic fractions, which also have their own value. Printed circuit boards granulate obtained after the mechanical pretreatment and the selective removal of metals by hydrometallurgical processes was used for the testing of the recycling potential. Granulometric analysis as well analysis of chemical composition of obtained fractions was performed. Subsequently, the manual classification of different types of polymeric material contained in the granulate was made, and both the apparent specific gravity and the chemical composition of the classified types of polymeric materials were determined. Chemical composition of granulate was determined by X-Ray Fluorescence (XRF) using Thermo Scientific Niton XL 3t, while the identification of residual polymers was determined by the FTIR (Fourier Transform Infrared Spectroscopy) method on the Bomen MB 100 device in range 4000 to 400 cm?1. Based on the results of this study, it can be concluded that after the hydrometallurgical treatment of printed circuit boards, and the separation of metals that have the highest value, the residual non-metallic fraction have the utility value and can be used for various purposes, such as developing new polymer materials for technical purposes that have been investigated by many researchers and mentioned in this article.

scholarly journals The Role of Focus Position in Single Pulse Laser Drilling of Highly Reflecting Materials

2019 ◽  
Vol 2 (1) ◽  
pp. 61-68
Author(s):  
György Meszlényi ◽  
Enikő Bitay
Keyword(s):  
Pulse Laser ◽  
Laser Processing ◽  
Printed Circuit Boards ◽  
Focal Spot ◽  
Single Pulse ◽  
Laser Drilling ◽  
Focus Position ◽  
Circuit Boards ◽  
Printed Circuit

Abstract The laser processing of materials which are highly reflective at laser wavelengths is problematic. We have to take into account that only a small part of the energy is absorbed, the main part being reflected. In this article we examine the laser processing of highly reflective copper and silver at 1070 nm wavelength. In laser drilling of printed circuit boards it is necessary to drill copper layer as well. In highly reflecting materials we can drill smaller holes because of the low energy efficiency. Naturally in single pulse laser drilling the focus position plays a key role: at the focal spot of the laser beam smaller diameter holes are produced, further from the focal spot, higher diameter holes are produced.

scholarly journals Regulation and Physiological Role of theDAS1 Gene, Encoding Dihydroxyacetone Synthase, in the Methylotrophic Yeast Candida boidinii

1998 ◽  
Vol 180 (22) ◽  
pp. 5885-5890 ◽  
Author(s):  
Yasuyoshi Sakai ◽  
Tomoyuki Nakagawa ◽  
Masayuki Shimase ◽  
Nobuo Kato
Keyword(s):  
Formate Dehydrogenase ◽  
Physiological Role ◽  
Nitrogen Sources ◽  
Host Genome ◽  
Candida Boidinii ◽  
Carbon And Nitrogen Sources ◽  
Gene Encoding ◽  
Carbon And Nitrogen ◽  
Dihydroxyacetone Synthase

ABSTRACT The physiological role of dihydroxyacetone synthase (DHAS) inCandida boidinii was evaluated at the molecular level. TheDAS1 gene, encoding DHAS, was cloned from the host genome, and regulation of its expression by various carbon and nitrogen sources was analyzed. Western and Northern analyses revealed thatDAS1 expression was regulated mainly at the mRNA level. The regulatory pattern of DHAS was similar to that of alcohol oxidase but distinct from that of two other enzymes in the formaldehyde dissimilation pathway, glutathione-dependent formaldehyde dehydrogenase and formate dehydrogenase. The DAS1 gene was disrupted in one step in the host genome (das1Δ strain), and the growth of the das1Δ strain in various carbon and nitrogen sources was compared with that of the wild-type strain. Thedas1Δ strain had completely lost the ability to grow on methanol, while the strain with a disruption of the formate dehydrogenase gene could survive (Y. Sakai et al., J. Bacteriol. 179:4480–4485, 1997). These and other experiments (e.g., those to determine the expression of the gene and the growth ability of thedas1Δ strain on media containing methylamine or choline as a nitrogen source) suggested that DAS1 is involved in assimilation rather than dissimilation or detoxification of formaldehyde in the cells.

Recycling of Printed Circuit Boards by Direct Molding Technology

2019 ◽  
Author(s):  
F. Quadrini ◽  
D. Bellisario ◽  
G. M. Tedde ◽  
L. Santo
Keyword(s):  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Flexural Modulus ◽  
Circuit Boards ◽  
Low Friction ◽  
Environmentally Conscious ◽  
Printed Circuit ◽  
Waste Pcbs ◽  
Pure Compression ◽  
Organic Fractions

Abstract The recovery and reuse of printed circuit boards (PCBs) is becoming crucial in the management of electronic waste that is undergoing an exponential increase. In this study, a simple and eco-friendly process for recycling waste PCBs is discussed. In particular, composite panels were produced by reusing 100% of waste PCBs without the addition of any additive or virgin material. After a two-step grinding process, ground PCB was used to mold panels by direct molding which is pure compression molding without material sorting. Results were very promising in terms of process feasibility and part performances. Molded samples had density about 1.45 g/cm3, flexural modulus and flexural about 3 GPa and 16 MPa, respectively. A smooth surface with low friction coefficient was obtained for the recycled panels. The study shows that despite the presence of metal and other non-metal non-organic fractions, waste PCBs can be re-processed in profitable and environmentally conscious way without the addition of any bonding agent or additive. The recycling technology can be extended to the reuse of the non-metallic fraction only, after separation and recovery of metals.

Isolation and characterization of copper leaching microbes from sanitary landfills for copper bioleaching of waste printed circuit boards

2021 ◽  
Author(s):  
Muhammad Syafiq Razali ◽  
Fatimah Azizah Riyadi ◽  
Fazrena Nadia Md Ak ◽  
Muhamad Ali Muhammad Yuzir ◽  
Nor’azizi Othman ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Acid Leaching ◽  
Metal Extraction ◽  
Soluble Form ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Isolation And Characterization

Abstract Electronic waste has been the fastest increasing waste generated globally and predicted to surpass 111 million tons per year by the end of 2050. The amount of e-waste is a concern not just due to its volume, but also due to its high composition of heavy metal elements, which has leads to increased development of urban mining in terms of heavy metal extraction. One common method of extraction, i.e., acid leaching, is known for its harmful residual leachate, in which can have a high impact on the environment. This focuses on the alternative leaching techniques known as bioleaching, which take advantages of microbial activity in mobilization of metal into a more soluble form. Strains from sanitary landfill soil were isolated in acidic media and identified as Bacillus sp. strain SE, Lysinibacillus sp. strain SE2, Bacillus sp. strain S1A, and Oryzobacter sp. strain SC. Among the isolated stains, the identified strain Oryzobacter sp. strain SC was able to extract up to 23.36 ppm copper from waste printed circuit boards using a two-step bioleaching process, confirming the ability of the strain to perform bioleaching of copper from e-waste.

Studies on leaching characteristics of electronic waste for metal recovery using inorganic and organic acids and base

2020 ◽  
pp. 0734242X2093192
Author(s):  
Debarati Das ◽  
Siddhartha Mukherjee ◽  
Mahua Ghosh Chaudhuri
Keyword(s):  
Printed Circuit Boards ◽  
Electronic Waste ◽  
Circuit Boards ◽  
X Ray Diffraction ◽  
Aqua Regia ◽  
X Ray ◽  
Printed Circuit ◽  
Inorganic Acids ◽  
Acid And Base ◽  
Before And After

In this paper, we report leaching of precious and scattered metals such as gold (Au), copper (Cu), nickel (Ni), zinc (Zn), iron (Fe), and lead (Pb) from printed circuit boards of scrap mobile phones by hydrometallurgical process using inorganic acid, organic acid and base. The amount of metals leached by different leachants are quantified using atomic absorption spectroscopy. Among various inorganic acids, aqua regia (mixture of nitric acid (HNO3) and hydrochloric acid) is found to be the strongest leachant for most of the metals such as Zn (2.04 wt %), Fe (17.90 wt %), Ni (0.66 wt %), Pb (5.86 wt %) and Au (0.04 wt %). The basic leachant, ammonium thiosulphate is found to be very effective in leaching of Au (0.03125 wt %). The dissolution of Cu in HNO3 gives the highest amount of Cu in the solvent, that is, ∼ 7.52 wt %. The metallic phases present in the electronic waste before and after leaching are identified by X-ray diffraction analysis. The microscopic structure has been studied using a scanning electron microscope which depicts erosion of the structure after leaching.

scholarly journals Decomposition of LCD screen inverter by pyrolysis

2019 ◽  
Vol 116 ◽  
pp. 00024
Author(s):  
Agnieszka Gurgul ◽  
Włodzimierz Szczepaniak ◽  
Monika Zabłocka-Malicka
Keyword(s):  
Printed Circuit Boards ◽  
Pyrolysis Temperature ◽  
Technology Development ◽  
Electronic Waste ◽  
Complex Structure ◽  
Circuit Boards ◽  
Gas Emission ◽  
Waste Sample ◽  
Printed Circuit ◽  
Waste Pcbs

PCBs (Printed Circuit Boards) are important parts of electronic equipment and their use increases with technology development. Recycling of waste PCBs is challenging due to their complex structure and receives wide concerns as the amount of this type of waste is growing rapidly. In the article, the experiment of pyrolysis carried out with electronic waste sample was presented. The material employed in the present work was inverter of the LCD screen that it the example of the multilayer PCB. The correlation between pyrolysis temperature and gas emission from the system, which is associated with epoxy resin decomposition, is presented in the article.

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