User:Hxu459/sandbox

“Article evaluation” 1. Phosphorus cycle Evaluating content: •	The points covered in the content are related to this topic but more relevance is expected, for example, in the part of phosphorus cycling, the phosphatr cycling in the soil environment is ignored. •	The article link to other Wikipedia articles as well. Evaluating tone: •	The article is neutral and I think there is no heavily biased. Evaluating sources: •	The sources are a little bit out-of-date and more recent papers are satisfied. •	More main stream sources are expected.

2. Nitrogen cycle Evaluating content: •	The points covered in the content are related to this topic and very comprehensive. It covers all nitrogen cycling processes in details. •	Some relevant contents are needed to provide, especially nitrogen cycling in different environmental media like soil, waste water treatment plants. •	The information is new and updated. Evaluating tone: •	The article is neutral and the viewpoints are in the medium. Evaluating sources: •	The sources are a little bit out-of-date but the papers chosen are from main-stream and great journals.

3. Hydrogen cycle Evaluating content: •	The contents need to be update because many aspects of hydrogen cycling haven’t been provided. •	In the biotic cycles part, it doesn’t provide the name of microorganism driving hydrogen cycling and lacking details of cycling processes. Evaluating tone: •	The article is neutral and no personal preference is in the article. Evaluating sources: •	The sources covers main-stream papers and comes from reliable references.

Rare Earth Elements_Recycling and reusing REEs

Literature published in 2004 suggests that, along with previously established pollution mitigation, a more circular supply chain would help mitigate some of the pollution at the extraction point. This means recycling and reusing REEs that are already in use or reaching the end of their life cycle. A study published in 2014 suggests a method to recycle REEs from waste nickel-metal hydride batteries, demonstrating a recovery rate of 95.16%. Rare-earth elements could also be recovered from industrial wastes with practical potential to reduce environmental and health impacts from mining, waste-generation and imports if known and experimental processes are scaled up. A study suggests that "fulfillment of the circular economy approach could reduce up to 200 times the impact in the climate change category and up to 70 times the cost due to the REE mining." In most of the reported studies reviewed by a scientific review, "secondary waste is subjected to chemical and or bioleaching followed by solvent extraction processes for clean separation of REEs." Another study focuses on concentrate REEs via concomitant leaching and electrochemical extraction from monazite, investigated a two-stage recovery strategy focused on the recovery of Nd and La from monazite ore that combines microbially based leaching with electrochemical extraction.This new sustainable and promising technology is suitable for primary ores and can further be optimized for secondary resources. Recently, a method developed recovers REEs from NdFeB by one-step selective precipitation in phosphoric acid, meanwhile, the dissolved iron was recovered by oxalic acid. The purity of recycling REEs through this method attains 97.17%.

Potential methods
The rare earth elements (REEs) are vital to modern technologies and society and are amongst the most critical elements. Despite this, typically only around 1% of REEs are recycled from end-products, with the rest deporting to waste and being removed from the materials cycle. Recycling and reusing REEs play an important role in high technology fields and manufacturing environmental friendly products all around the world.

REEs recycling and reuse have been increasingly focused on in recent years. The main concerns include environmental pollution during REE recycling and increasing recycling efficiency. Literature published in 2004 suggests that, along with previously established pollution mitigation, a more circular supply chain would help mitigate some of the pollution at the extraction point. This means recycling and reusing REEs that are already in use or reaching the end of their life cycle. A study published in 2014 suggests a method to recycle REEs from waste nickel-metal hydride batteries, demonstrating a recovery rate of 95.16%. Rare-earth elements could also be recovered from industrial wastes with practical potential to reduce environmental and health impacts from mining, waste-generation and imports if known and experimental processes are scaled up. A study suggests that "fulfillment of the circular economy approach could reduce up to 200 times the impact in the climate change category and up to 70 times the cost due to the REE mining." In most of the reported studies reviewed by a scientific review, "secondary waste is subjected to chemical and or bioleaching followed by solvent extraction processes for clean separation of REEs."

Currently, people take two essential resources into consideration for the secure supple of REEs: one is to extract REEs from primary resources like mines harboring REE-bearing ores, regolith-hosted clay deposits, ocean bed sediments, coal fly ash , etc. A work developed a green system for recovery of REEs from coal fly ash by using citrate and oxalate who are strong organic ligand and capable of complexing or precipItating with REE. The other one is from secondary resources such as electronic, industrial waste and municipal waste. E-waste contains a significant concentration of REEs, and thus is primary option for REE recycling now. According to a study, approximately 50 million metric tons of electronic waste are dumped in landfills worldwide each year. Despite the fact that e-waste contains a significant amount of rare earth elements (REE), only 12.5% of e-waste is currently being recycled for all metals.

Challenges
For now, there are some obstacles during REE recycling and reuse. One big challenge is REE separation chemistry. Specifically, the process of isolating and refining individual rare earth elements (REE) presents a difficulty due to their similar chemical properties. In order to reduce the environmental pollution released during REE isolation and also diversify their sources, there is a clear necessity for the development of novel separation technologies that can lower the cost of large-scale REE separation and recycling. In this condition, the Critical Materials Institute (CMI) under the Department of Energy has devised a technique that involves utilizing Gluconobacter bacteria to metabolize sugars, producing acids that can dissolve and separate rare earth elements (REE) from shredded electronic waste.