WEEE: Booming for sustainable recycling

Microwave Encounters Ionic Liquid: Synergistic Mechanism, Synthesis and Emerging Applications

Progress in microwave (MW) energy application technology has stimulated remarkable advances in manufacturing and high-quality applications of ionic liquids (ILs) that are generally used as novel media in chemical engineering. This Review focuses on an emerging technology via the combination of MW energy and the usage of ILs, termed microwave-assisted ionic liquid (MAIL) technology. In comparison to conventional routes that rely on heat transfer through media, the contactless and unique MW heating exploits the electromagnetic wave-ions interactions to deliver energy to IL molecules, accelerating the process of material synthesis, catalytic reactions, and so on. In addition to the inherent advantages of ILs, including outstanding solubility, and well-tuned thermophysical properties, MAIL technology has exhibited great potential in process intensification to meet the requirement of efficient, economic chemical production. Here we start with an introduction to principles of MW heating, highlighting fundamental mechanisms of MW induced process intensification based on ILs. Next, the synergies of MW energy and ILs employed in materials synthesis, as well as their merits, are documented. The emerging applications of MAIL technologies are summarized in the next sections, involving tumor therapy, organic catalysis, separations, and bioconversions. Finally, the current challenges and future opportunities of this emerging technology are discussed.

A novel methodology for the estimation of failure behavior of "fair" smart meters and analysis of their circular economy chain

Electric power utilities are striving to address critical challenges such as energy consumption, material recovery, e-waste, procurement, and supplier working conditions. Currently, they are converting their old infrastructure into smart grids. The installation of smart meters is a key step in this process. Since a smart meter is an intelligent and modern measuring device that includes computer-aided measurements while also allowing intelligent management and determination of residential and industrial users' energy consumption and supply, their deployment in smart grids is of major importance. In this study, considering that the estimated number of smart meter units will be 188.12 million units by 2025, five different types of smart meters are used to estimate their failure behavior. We adopted the probability of smart meters' survival, considering the number of the components included in their PCBs, while the influence of their components follows an exponential distribution for a given lifetime. The meaning of the "fair" smart meter is introduced to solve critical concerns such as energy use, material consumption, e-waste, supplier sourcing, and labor conditions. To achieve the above targets, a circular economy chain analysis is implemented by dismantling the existing smart meters, classifying their materials into five primary groups and weighing them to obtain average values. Moreover, we calculate the average cost of the components using their equivalent market value as provided by stock markets to get the average weight of each component in terms of material cost. Finally, we introduce the "remanufacturing index" and the "reusing index" indices as procedure metrics to further quantify the circular economy chain results. The results show that the percentage of the reusing procedure in the "fair" smart meter circular economy chain is greater than the corresponding percentage of the remanufacturing procedure, while the percentage of the recycling procedure is increased as the recycling cost per unit, is also increased.

Lab scale optimization and two-step sequential bench scale reactor leaching tests for the chemical dissolution of Cu, Au & Ag from waste electrical and electronic equipment (WEEE)

Regulations force to Waste Electrical and Electronic Equipment (WEEE) management by recycling the materials by safe and suitable methods, due to generating massive amounts of WEEE. This research aims towards extract metals from waste random-access memory (RAM) devices in different solutions. In addition, the effect of different parameters such as reagent concentration, oxidant concentration and solid/liquid ratio were investigated with full factorial experimental design tests and analysis of variance (ANOVA). The results showed that the extraction of gold and silver was 96.81% and 99.02% respectively under the following conditions: concentration of 2% iodine and 3% hydrogen peroxide as oxidizing agent, 5% solid/liquid ratio and leaching period of 2 h. An increase of the hydrogen peroxide concentration increased gold and silver extraction. While about 79.30% silver was found to be extracted using 2 M sulfuric acid, 1.5 M ammonium persulfate, 5% solid/liquid ratio and leaching period of 5 h, 79.43% copper was extracted by using ammonia instead of sulfuric acid under the same conditions. Ammonium persulfate was found to be a good oxidizing agent for sulfuric acid and ammonia leaching, since it provided selective extraction of silver and copper respectively. Two-step sequential bench scale reactor leaching tests were conducted to extract copper (98.73%), gold (99.98%) and silver (96.90%) selectively with high extraction. Two-step leaching approach was concluded as the most appropriate method for selective extraction of targeted metals from waste RAM devices.

Commercial indium recovery processes development from various e-(industry) waste through the insightful integration of valorization processes: A perspective

Recycling of the waste LCD and recovery of indium which is an important classified critical raw material rarely have been industrially valorized for the circular economy due to lack of technology. Waste specific technology development is a cost-intensive and time-consuming process for the recycling industry. Hence, integrating existing technology for the purpose can address the e-waste issue in general and waste LCD in particular. Waste LCD and LCD industry itching wastewater are two important challenges can be addressed through an insightful combination of two. Hence, here possible integration of waste LCD leaching process with ITO wastewater treatment has been focused on indium recovery purpose. From our perspective process integration can be managed in two different ways, i.e., waste-to-waste mix stream process and integration of two different valorization processes for complete recovery of indium. With reference to indium recovery and context of e-waste recovery the process integration can be managed in two different ways, i.e., (i) waste LCD leaching with ITO etching industry wastewater then valorized (Waste-to-waste mix stream), (ii) Integration of waste LCD leaching process with ITO wastewater treatment process (integration of two valorization processes).Through proposed process semiconductor manufacturing industry and ITO recycling industry can address various issues like; (i) waste disposal, as well as indium recovery, (ii) brings back the material to production stream and address the circular economy, (ii) can be closed-loop process with industry and (iii) can be part of cradle-to-cradle technology management and lower the futuristic carbon economy, simultaneously.

Soldering mask laser removal from printed circuit boards aiming copper recycling

Management of waste of electric and electronic equipment (WEEE) is a key issue for modern societies; furthermore, it contains valuable materials that can be recycled, especially in printed circuit boards (PCB), which have approximately one-third of their weight in copper. In this study we demonstrated the use of laser to strip the covering soldering mask on PCB's, thus exposing the copper underneath so that extraction techniques may take place. Using a Q-Switched Nd:YAG laser operating at 1064nm and 532nm we tested the procedure under different energy conditions. The laser stripping of the soldering mask was achieved with satisfactory results by irradiation with 225mJ at 1064nm. However, when using similar parameters at 532nm the process of the coating ejection was not promoted properly, leading to a faulty detachment. Infrared laser PCB stripping presents itself to be technically viable and environmental friendly, since it uses no chemicals inputs, offering one more option to WEEE treatment and recycling.

Supply and demand of some critical metals and present status of their recycling in WEEE

New development and technological innovations make electrical and electronic equipment (EEE) more functional by using an increasing number of metals, particularly the critical metals (e.g. rare and precious metals) with specialized properties. As millions of people in emerging economies adopt a modern lifestyle, the demand for critical metals is soaring. However, the increasing demand causes the crisis of their supply because of their simple deficiency in the Earth's crust or geopolitical constraints which might create political issues for their supply. This paper focuses on the sustainable supply of typical critical metals (indium, rare earth elements (REEs), lithium, cobalt and precious metals) through recycling waste electrical and electronic equipment (WEEE). To illuminate this issue, the production, consumption, expected future demand, current recycling situation of critical metals, WEEE management and their recycling have been reviewed. We find that the demand of indium, REEs, lithium and cobalt in EEE will continuously increasing, while precious metals are decreasing because of new substitutions with less or even without precious metals. Although the generation of WEEE in 2014 was about 41.9 million tons (Mt), just about 15% (6.5 Mt) was treated environmentally. The inefficient collection of WEEE is the main obstacle to relieving the supply risk of critical metals. Furthermore, due to the widespread use in low concentrations, such as indium, their recycling is not just technological problem, but economic feasibility is. Finally, relevant recommendations are point out to address these issues.