scholarly journals Tuneable separation of gold by selective precipitation using a simple and recyclable diamide

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Luke M. M. Kinsman ◽  
Bryne T. Ngwenya ◽  
Carole A. Morrison ◽  
Jason B. Love
Keyword(s):  
Electronic Waste ◽  
Complete Collection ◽  
Selective Precipitation ◽  
Aqua Regia ◽  
X Ray ◽  
Acidic Solutions ◽  
Secondary Sources ◽  
Efficient Separation ◽  
Chemical Recognition ◽  
Metal Precipitation

AbstractThe efficient separation of metals from ores and secondary sources such as electronic waste is necessary to realising circularity in metal supply. Precipitation processes are increasingly popular and are reliant on designing and understanding chemical recognition to achieve selectivity. Here we show that a simple tertiary diamide precipitates gold selectively from aqueous acidic solutions, including from aqua regia solutions of electronic waste. The X-ray crystal structure of the precipitate displays an infinite chain of diamide cations interleaved with tetrachloridoaurate. Gold is released from the precipitate on contact with water, enabling ligand recycling. The diamide is highly selective, with its addition to 29 metals in 2 M HCl resulting in 70% gold uptake and minimal removal of other metals. At 6 M HCl, complete collection of gold, iron, tin, and platinum occurs, demonstrating that adaptable selective metal precipitation is controlled by just one variable. This discovery could be exploited in metal refining and recycling processes due to its tuneable selectivity under different leaching conditions, the avoidance of organic solvents inherent to biphasic extraction, and the straightforward recycling of the precipitant.

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 Development and Characterization of Biocompatible Membranes from Natural Chitosan and Gelatin for Pervaporative Separation of Water–Isopropanol Mixture

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2868
Author(s):  
Akshay S. Kulkarni ◽  
Ashok M. Sajjan ◽  
T. M. Yunus Khan ◽  
Irfan Anjum Badruddin ◽  
Sarfaraz Kamangar ◽  
...  
Keyword(s):  
Surface Characteristics ◽  
Permeation Flux ◽  
X Ray Diffraction ◽  
Natural Polymers ◽  
X Ray ◽  
Efficient Separation ◽  
Differential Scanning Colorimetry ◽  
Index Value ◽  
Pervaporation Separation

Natural polymers have attracted a lot of interest in researchers of late as they are environmentally friendly, biocompatible, and possess excellent characters. Membranes forming natural polymers have provided a whole new dimension to the separation technology. In this work, chitosan-gelatin blend membranes were fabricated using chitosan as the base and varying the amount of gelatin. Transport, mechanical, and surface characteristics of the fabricated membranes were examined in detail by means of the characterizing techniques such as Fourier transform infrared spectroscopy, differential scanning colorimetry, wide angle X-ray diffraction, scanning electron microscope, and thermogravimetric analysis. In order to analyze the water affinity of the developed blend chitosan-gelatin membranes, the percentage degree of swelling was examined. Out of the fabricated membranes, the membrane loaded with 15 mass% of gelatin exhibited the better pervaporation performance with a pervaporation separation index value of 266 at 30 °C for the solution containing 10% in terms of the mass of water, which is the highest among the contemporary membranes. All the fabricated membranes were stable during the pervaporation experiments, and permeation flux of water for the fabricated membranes was dominant in the overall total permeation flux, signifying that the developed membranes could be chosen for efficient separation of water–isopropanol mixture on a larger scale.

scholarly journals Selective chelating precipitation of palladium metal from electroplating wastewater using chitosan and its derivative

2020 ◽  
Vol 38 (3-4) ◽  
pp. 113-126
Author(s):  
Qiaoling Xie ◽  
Gaojie Liang ◽  
Tao Lin ◽  
Fuming Chen ◽  
Dandan Wang ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Photoelectron Spectroscopy ◽  
Water Soluble ◽  
Optimum Conditions ◽  
Chitosan Derivative ◽  
Aqua Regia ◽  
Electroplating Wastewater ◽  
X Ray ◽  
Approach Method ◽  
Palladium Metal

A study on selective chelating precipitation of palladium metal from real electroplating wastewater using chitosan and its water-soluble derivative was conducted. The pH parameter, the concentrations of chitosan and its water-soluble derivative and the chelating precipitation time were experimentally investigated, and the optimum conditions were determined. The results revealed that both chitosan and its water-soluble derivative acted as chelating precipitation agents. Rapid chelating precipitation occurred when chitosan was added to real electroplating wastewater containing the chitosan derivative, thereby improving removal efficiency of palladium in different forms up to 95% under the optimum condition of 0.2 g/L chitosan and 0.16 mg/L derivative at pH 2.5. Then, dissolution experiments showed that chelating precipitation products could be dissolved in aqua regia. Additionally, selective chelating precipitation of palladium by chitosan and its derivative was characterized using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Thus, it can be concluded that the combined utilization of chitosan and its water-soluble derivative is a promising approach method for the removal of different forms of palladium from real electroplating wastewater.

scholarly journals Facile method for the selective recovery of Gd and Pr from LCD screen wastes using ultrasound-assisted leaching

2020 ◽  
Vol 30 (1) ◽  
Author(s):  
Astrid D. Toache-Pérez ◽  
Ana M. Bolarín-Miró ◽  
Félix Sánchez-De Jesús ◽  
Gretchen T. Lapidus
Keyword(s):  
Inductively Coupled Plasma ◽  
Liquid Crystal Display ◽  
Electronic Waste ◽  
Milled Powder ◽  
Iron Alloy ◽  
Magnetic Behavior ◽  
Extraction Process ◽  
Original Material ◽  
X Ray ◽  
Ultrasound Assisted

AbstractRare earth elements (REE) are essential for the production of technological devices. However, their high demand and low availability, together with an increase in electronic waste generation, compel the development of efficient, economic and green methods for recovering these elements from electronic waste. In this work, a facile method for selective recovering of REE from Liquid Crystal Display (LCD) screen wastes, employing ultrasound assisted leaching is presented. The screen wastes were milled and sieved to pass through a − 325 mesh sieve (44 μm). The milled powder was subjected to ultrasound-assisted leaching in an aqueous medium, at room temperature (25 °C) and pH 6 for 60 min. Subsequently, a magnetic separation was applied to the leach residue. Inductively coupled plasma was employed to quantitatively analyze the composition of the LCD powders and determine the effectiveness of the extraction process. Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy allowed qualitative chemical analysis of the solid materials. The results show that the LCD screen wastes are formed, mainly, by amorphous oxides of Si, Fe, In, Sn and REE. The amount of Gadolinium (Gd) and Praseodymium (Pr) in the wastes were 93 and 24 mg kg− 1, respectively, which justifies their recovery. X-ray diffraction analysis of the magnetic portion of the leached residue, confirmed the presence of an amorphous phase together with crystalline metallic iron alloy. The magnetic behavior, obtained by Vibration Sample Magnetometry, helped to understand the nature of the residues. The formation of this metallic alloy is attributed to the effect of high power ultrasonic during the leach. It was confirmed that the magnetic residue concentrates and recovers 87 wt% of Gd and 85 wt% of Pr contained in the original material. Therefore, ultrasound-assisted leaching is a selective and facile method for recovering Gd and Pr from waste LCD.

Rare earth recovery from end-of-life motors employing green chemistry design principles

2016 ◽  
Vol 18 (3) ◽  
pp. 753-759 ◽  
Author(s):  
H. M. Dhammika Bandara ◽  
Kathleen D. Field ◽  
Marion H. Emmert
Keyword(s):  
Rare Earth ◽  
Green Chemistry ◽  
Rare Earth Elements ◽  
End Of Life ◽  
Recovery Rate ◽  
Design Principles ◽  
Selective Dissolution ◽  
Selective Precipitation ◽  
Efficient Process ◽  
Efficient Separation

This manuscript describes the development of an efficient process for the recovery of rare earth elements from materials mixtures such as in motors with a recovery rate of >80%. Selective dissolution enables efficient separation of steel and copper and selective precipitation of RE salts is the key for obtaining pure RE products.

Determination of minerals in platinum concentrates from the Transvaal by X-ray methods

1932 ◽  
Vol 23 (138) ◽  
pp. 188-206 ◽  
Author(s):  
F. A. Bannister
Keyword(s):  
Solid Solution ◽  
New Mineral ◽  
Early Analysis ◽  
Aqua Regia ◽  
X Ray ◽  
Ray Methods ◽  
Platinum Mineral ◽  
Insoluble Portion

Concentrates from the platiniferous norites of the Bushveld, Transvaal, are not completely soluble in aqua regia. The insoluble portion consists of steel-grey fragments first analysed chemically by R. A. Cooper and considered by him to be a new platinum mineral represented by the formula Pt(As,S)2. The name cooperite was proposed for the new mineral by F. Wartenweiller, and after further work Cooper decided that the arsenic found in the early analysis was due to the presence of sperrylite, and he changed the formula to PtS2. H. Schneiderhöhn observed simple twinning and, less frequently, polysynthetie lamellae on polished sections of mineral grains from the same deposits, and he suggested that cooperite is probably orthorhombic and isomorphous with marcasite. The latest account of the new mineral has been published by H. R. Adam who gave several analyses of cooperite from the Rustenburg and Potgietersrust districts and concluded that the ‘mineral is PtS2 with a small amount of excess metal (platinum, palladium, and nickel) present in solid solution’.

scholarly journals Prediction of As, Cd, Cr, Hg, Ni, and Se Concentrations in Organic Amendments Using Portable X-ray Fluorescence and Multivariate Modeling

2020 ◽  
Vol 10 (17) ◽  
pp. 5726
Author(s):  
Rafael López-Núñez ◽  
Fátima Ajmal-Poley ◽  
Pilar Burgos-Doménech
Keyword(s):  
Organic Amendments ◽  
Linear Functions ◽  
Organic Fertilizers ◽  
Regression Equations ◽  
Sewage Sludges ◽  
Aqua Regia ◽  
X Ray ◽  
Exchange Programme ◽  
Analytical Laboratories

Portable X-ray fluorescence (pXRF) has been a widely used technique in various applications. However, its use for the analysis of organic amendments (composts, sewage sludges, organic fertilizers) is scarce. In these matrices, concentrations of some elements are below their detection limit. The objective of this work was to find multiple linear regression equations that were able to predict the aqua-regia-soluble concentrations of the elements As, Cd, Cr, Hg, Ni, and Se using the pXRF readings of other measurable elements as predictor variables. For this, a set of 30 samples of organic amendments (composts, sewage sludges, and organic fertilizers) from the Manure and Refuse Sample Exchange Programme of the Wageningen Evaluating Programs for Analytical Laboratories (MARSEP-WEPAL) was used. Several amendment type-dependent single or multiple linear functions were found based on 1, 2, or 3 predictors. The predictor readings corresponded to the concentration of elements of geogenic (Fe, Si, Ti, Cl, Zr Al, Ca, S, Mn, and Ba), anthropogenic (Zn and Pb), and agricultural (P and K) origin. The regression coefficients of these functions were r = 0.90–0.99; therefore, they allowed for the quantitative determination of the target elements. These results will allow for fast and reliable analysis of organic amendments using pXRF that is valid for quality control in treatment plants.

Synthesis and degradable properties of cycloaliphatic epoxy resin from renewable biomass-based furfural

RSC Advances ◽  
2015 ◽  
Vol 5 (115) ◽  
pp. 95126-95132 ◽  
Author(s):  
Linni Zhao ◽  
Lin Zhang ◽  
Zhonggang Wang
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Precious Metal ◽  
Electronic Waste ◽  
Acidic Solutions ◽  
Renewable Biomass ◽  
Cycloaliphatic Epoxy ◽  
Cycloaliphatic Epoxy Resin

Furfural-based diepoxide with acetal linkages is synthesized. The cured product can degrade in acidic solutions, showing applications in recovery of precious metal and carbon fiber from electronic waste and composite materials fabricated with it.

Recovery of Gold and Silver from Secondary Sources of Electronic Waste Processing by Thiourea Leaching

JOM ◽  
2018 ◽  
Vol 70 (8) ◽  
pp. 1616-1621 ◽  
Author(s):  
Hyunju Lee ◽  
Emily Molstad ◽  
Brajendra Mishra
Keyword(s):  
Electronic Waste ◽  
Waste Processing ◽  
Secondary Sources
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