This study presents responses to questionnaires submitted to 30 experts from diverse professional backgrounds about one of the oldest settlements in India, i.e., Varanasi. Expert interviews provided diverse perspectives on the challenges of urban settings and their transformation. To decipher the subjective responses, this data was analysed using MAXQDA24, a data analysis tool that facilitates quick analysis, coding, and presentation of large qualitative datasets. The expert highlights that the visual representation of the city, including its religious, educational, and historical significance, is highly prominent. Additionally, the study suggests the establishment of a city-level heritage body to a) maintain heritage properties, b) plan different neighborhoods for different perceptual experiences to segregate the footfall, and c) involve the local community. Overall, this study offers a unique expert-driven perspective on the current conditions and the transforming fabric of Varanasi.
This review article presents a comprehensive evaluation of rare earth element (REE) recovery from primary, secondary, and tertiary sources, emphasizing extraction technologies, resource distribution, and sustainability. Primary sources, including bastnäsite, monazite, and xenotime, are assessed in terms of their global geological distribution, mineral characteristics, and beneficiation processes such as hydrometallurgy and flotation. The review critically evaluates global production patterns and challenges, including environmental burdens and China’s dominance in both mining and refining. For secondary sources, the study highlights the REE potential in coal fly ash, red mud, mine tailings, and phosphogypsum. Detailed analysis of extraction methods—ranging from acid leaching and bioleaching to advanced techniques like flash Joule heating and supercritical fluid extraction—highlights their viability for sustainable recovery. Tertiary sources, mainly end-of-life products such as e-waste, magnets, batteries, and fluorescent lamps, are explored with a focus on recycling technologies. Techniques such as hydrometallurgy, bioleaching, and ionic liquid extraction are examined for their effectiveness in selective REE recovery. The review addresses critical bottlenecks in industrial-scale implementation, such as low recycling rates and the need for improved policy frameworks. By integrating insights from each source type, this work proposes a roadmap for diversified, sustainable, and resilient REE supply chains.
The urea oxidation reaction (UOR) has been proposed as an alternative to anodic oxygen evolution for an improved cell voltage and cost-effective H2 production by water electrolysis. However, the progress in this field is limited by the lack of efficient UOR electrocatalysts. Herein, we report two different active catalysts, [CoNi(O)OHs], formed by the in situ anodic activation of the cyanide-bridged polymer [CoNi(O)OH-1] and CoNi-layered double hydroxide [CoNi(O)OH-2] for the electrochemical UOR. In CoNi(O)OH-1, the Co-leaching during the anodic activation produced a Ni-rich CoNi(O)OH phase, forming a crystalline-amorphous heterojunction with a highly disordered structure. The defect-rich structure of CoNi(O)OH-1 facilitates the oxidation of Ni2+ to Ni3+, stabilizes the Ni3+ valence state, and thereby provides dynamically accessible active sites for the UOR. As a result, CoNi(O)OH-1 achieved a current density of 400 mA cm-2 at a potential of 1.34 V vs. RHE, far better than that of CoNi(O)OH-2 (1.45 V vs. RHE) and Ni(O)OH (1.57 V vs. RHE). Furthermore, operando Raman spectroscopy reveals the adsorption of urea molecules on the catalyst surface, followed by dehydrogenation, and C-N bond cleavage during the UOR.
Para-benzoquinone (PBQ) is a harmful pollutant that can negatively affect both water life and human health. It is known to be cytotoxic and mutagenic. PBQ often enters water bodies through industrial waste and from the breakdown of other toxic pollutants. Accordingly, there is a strong need for fast, accurate, and reliable methods to detect PBQ in water. In this study, a highly stable and electrocatalytically active electrochemical sensor is developed by modifying a glassy carbon electrode with copper(II) benzene-1,3-dicarboxylate and graphitic carbon nitride (CuBDC.gCN) nanocomposite via a controlled electrodeposition technique. The structural and morphological features of CuBDC.gCN composite and its electrodeposited interface are elucidated through extensive characterizations, including X-ray diffraction, infrared spectroscopy, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. Square wave voltammetry and cyclic voltammetry are employed to evaluate the sensor's electrochemical response. CuBDC.gCN|GCE displayed exceptional electrocatalytic performance toward PBQ, evidenced by a 31.7-fold enhancement in peak current and a notable negative shift of 0.13 V, compared to bare GCE. The sensor exhibited high sensitivity, with a wide linear detection range of 2.5-100.0 mu M and a low detection limit of 38.2 nM. The sensor exhibited excellent selectivity, repeatability, and reproducibility, affirming its practical applicability for the interference-free, electrochemical monitoring of PBQ in environmental samples.
