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Topic Review
Potential Alternative Resources for Rare Earth Elements
Seventeen elements in the periodic table including fifteen lanthanides (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and Sc, as well as Y are often collectively referred to as rare earth elements (REE). The depleting REE ores and increasing mining costs are prompting us to consider alternative sources for these valuable metals, particularly from waste streams. Although REE concentrations in most of the alternative resources are lower than current REE ores, some sources including marine sediments, coal ash, and industrial wastes, such as red mud, are emerging as promising with significant concentrations of REE.
  • 453
  • 13 Apr 2023
Topic Review
Post-Occupancy Evaluation’s Applications for Improving Indoor Environment Quality
To improve buildings and their characteristics, the feedback provided directly by users is generally fundamental in order to be able to adapt the technical and structural functions to the well-being of users. The post-occupancy evaluation (POE) fits perfectly into this context. The POE, through qualitative and quantitative information on the interior environment, makes it possible to identify the differences between the performances modeled in the design phase and the real performances experienced by the occupants. 
  • 363
  • 02 Nov 2022
Topic Review
Possibilities for Blockchain-Enabled Guarantees of Origin
Guarantees of Origin (GOs) are widely used as insurances for the renewability of electricity supplies and proofs of compliance to renewable standards; however, they suffer from structural problems. Their transactional history cannot distinguish between those traded among market actors and the ones that come directly from power plants, giving rise to transparency issues. Certificate trading dissuades producers from investing in an increase in renewable capacity resulting in lack of additionality while complex frameworks and administrative structures emerge to keep track of the vast network of GOs. These issues can be resolved through the introduction of blockchain networks which can provide transparency and help incentivise renewable investment while increasing automation and process simplification.
  • 650
  • 17 Jan 2023
Topic Review
Portable X-ray Fluorescence Analysis of Organic Amendments
Portable XRF spectrometry (pXRF) has recently undergone significant technological improvements and is being applied in a wide range of studies. Despite pXRF advantages, this technique has rarely been used to characterize organic amendments and residues. pXRF correctly measures elements such as Fe, Pb, Zn, Mn, Ca, and K but gives conflicting results for elements such as Cr, Ni, and As. Among the reasons that may cause the low performance of the technique with certain elements or under certain measurement conditions would be the inadequacy of the analytical comparison procedures used (i.e., digestion with aqua regia), the lack of knowledge of the interfering effects of organic matter, and sample moisture on the XRF signals and the need for a standardized protocol for performing the measurements. However, the speed and low cost of the procedure forecast a greater future use of this technique, especially in cooperation with other fast spectroscopic techniques based on near-infrared (NIRS) or mid-infrared (MIR) spectroscopies. Chemometric procedures based on one or more of these techniques will allow the prediction of elements below the detection limit of pXRF instruments (Cd, Hg), or other properties of organic amendments (organic matter, N, electrical conductivity, cation exchange capacity).
  • 577
  • 05 Aug 2022
Topic Review
Portable Analytical Instruments in Mineral Exploration Studies
The classic approach to mineral exploration studies was to bring the field samples/drill cores collected during field studies to the laboratory, followed by laborious analysis procedures to generate the analytical data. This is very expensive, time-consuming, and difficult for exploring vast areas. However, rapid technological advances in field-portable analytical instruments, such as portable visible and near-infrared spectrophotometers, gamma-ray spectrometer, portable X-ray fluorescence spectrometers (pXRF), portable X-ray diffractometers (pXRD), portable laser-induced breakdown spectrometers (pLIBS), and µRaman spectrometer, have changed this scenario completely and increased their on-site applications in mineral exploration studies. LED fluorimeter is a potential portable tool in the hydrogeochemical prospecting studies of uranium. These instruments are currently providing direct, rapid, on-site, real-time, non-destructive, cost-effective identification, and determination of target elements, indicator minerals and pathfinder elements in rock, ore, soil, sediment, and water samples. These portable analytical instruments are currently helping to obtain accurate chemical and mineralogical information directly in the field with minimal or no sample preparation and providing decision-making support during fieldwork, as well as during drilling operations in several successful mineral exploration programs. 
  • 1.5K
  • 08 Apr 2022
Topic Review
Porphyry Mo Deposits
Porphyry Mo deposits are the most important type of Mo resource. They result from a high oxygen fugacity of the parent magma, which acts as an effective indicator for evaluating the mineralization. In the ore-forming system of porphyry Mo deposits, sulfur exists mainly as sulfate in highly oxidized magma but as sulfide in ores. What triggers the reduction in the mineralization system that leads to sulfide precipitation has not yet been determined. 
  • 548
  • 28 Jul 2023
Topic Review
Poor Air Quality in Urban Settings
Poor air quality (PAQ) is a global concern, especially in urban areas, and is often seen as an important element of social sustainability given its negative impact on health and quality of life. Smoke, odour and dust particles were perceived to be the most important indicators of PAQ, while the main sources of PAQ were waste and bush burning, vehicle use and power generators. The two most preferred control measures were proper waste management and the avoidance of bush burning. 
  • 455
  • 11 Feb 2022
Topic Review
Polyurethanes and Green Chemistry
Polyurethanes are most often called “green” when they contain natural, renewable additives in their network or chemical structure, such as mono- and polysaccharides, vegetable oils, polyphenols, or various compounds derived from agro-waste white biotechnology. The use of these natural substrates is in line with the principles of green chemistry. However, other principles among all 12 can also be used in the production of polyurethanes.
  • 757
  • 11 Nov 2021
Topic Review
Polymers in Wastewater Treatment
The utilization of various types of natural and modified polymers for removing toxicant dyes in wastewater generated by the dye industry is reviewed in this article. Dye wastewater contains large amounts of metals, surfactants, and organic matter, which have adverse effects on human health, potentially causing skin diseases and respiratory problems. The removal of dyes from wastewaters through chemical and physical processes has been addressed by many researchers. Currently, the use of natural and modified polymers for the removal of dyes from wastewater is becoming more common. Although modified polymers are preferred for the removal of dyes, due to their biodegradability and non-toxic nature, large amounts of polymers are required, resulting in higher costs. 
  • 4.3K
  • 20 Oct 2020
Topic Review
Polymeric Biodiesel
Biodiesel industry is expanding rapidly in accordance with the high energy demand and environmental deterioration related to the combustion of fossil fuel. However, poor physicochemical properties and the malperformance of biodiesel fuel still concern the researchers. In this flow, polymers were introduced in biodiesel industry to overcome such drawbacks. This article introduces polymeric biodiesel which is Hydroxyalkanoates methyl ester (HAME) and hydroxybutyrate methyl ester (HBME) that are sourced from carbon-enriched polymers with the help of microbial activity. Composition, production techniques, characteristics, and limitations of polymeric biodiese were explored. 
  • 807
  • 21 Oct 2022
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