In a study of the phenomenon of catalyst deactivation during storage, Au/TiO₂ catalyst was stored under various conditions, viz. vacuum, nitrogen, air, refrigeration, dark, and light, and tested for CO oxidation activity at regular intervals. The data shows that the catalyst deactivates under all the storage conditions over 12 months and that storage in vacuum significantly enhances the rate and extent of deactivation. Storage in light accelerates the deactivation. The catalyst appears to deactivate through a combination of Au(III) reduction, Au nanoparticle agglomeration, loss of surface hydroxyl groups, loss of surface moisture, and accumulation of surface carbonates and formates. The rate and extent of catalyst deactivation can be limited by storing the catalyst in the dark at sub ambient temperature (refrigerator) and under inert atmosphere.

Tin oxide (SnO) materials have gained significant attention in recent years for their potential application in industrial wastewater treatment. This abstract provides an overview of the use of SnO materials in various treatment processes and their effectiveness in removing pollutants from wastewater. SnO materials exhibit excellent adsorption and catalytic properties, making them suitable for the removal of various contaminants, including heavy metals, organic compounds, and dyes. The unique surface chemistry and high surface area of SnO nanoparticles enable efficient adsorption and reaction with pollutants, leading to their successful removal from wastewater. Additionally, SnO-based photocatalysts have shown promising results in the degradation of organic pollutants under ultraviolet (UV) light irradiation. Moreover, SnO materials can be easily synthesized, and their surface properties can be tailored by controlling the synthesis parameters, such as particle size, morphology, and doping. However, challenges still exist in terms of cost-effectiveness, long-term stability, and large-scale implementation of SnO materials in wastewater treatment processes. Further research and development efforts are necessary to optimize the performance of SnO materials, enhance their stability, and address their limitations for practical application in industrial wastewater treatment systems. Overall, SnO materials hold great potential as effective adsorbents and catalysts for pollutant removal, contributing to the advancement of sustainable wastewater treatment technologies.

Although mining plays a vital role in the economic development of many countries, devastating environmental repercussions are associated with it. The extraction of mineral resources inevitably results in the generation of acid mine drainage (AMD), which entails intricate oxidation interactions that occur under ambient conditions in abandoned and active mines. The arbitrary release of AMD can lead to a series of long-term environmental problems, degradation of aquatic habitats and health complications. Over the years, extensive progress has been made in the prevention and treatment of AMD, with some processes even progressing as far as the commercialisation level. This chapter therefore discusses the process of AMD formation, preventative and control measures and AMD treatment options applicable to both operating and developed mines, as well as to researchers interested in environmental remediation and rehabilitation. Advances in mineral beneficiation and water reclamation strategies employed in the AMD treatment processes are highlighted to shed light on strides being made towards promoting a circular economy in mining industries. The featured work therefore demonstrates the global progress towards environmental protection and water resource management. The challenges and loopholes associated with the current AMD treatment methods are deliberated and possible future prospects in the field are proposed.

Chromite is considered a strategic mineral in the global economy. It is mainly used as an essential raw material in the production of stainless steel and other metal alloys due to its corrosion and heat resistance properties. High-grade chromite resources are gradually depleting; with the increasing chromite demand in metallurgical applications, studies have focused on exploring low-grade and alternative chromite sources. This study proposes a cost-effective processing flowsheet for the low-grade middle group 2 (MG2) chromite layer, a poorly explored chromatite seam within the South African bushveld igneous complex (BIC). The study involved mineralogical characterization followed by gravity and magnetic separation of the low-grade MG2 ore at 18.18% Cr₂O₃. Characterization by XRD and Auto-SEM revealed that the ore mainly consists of pyroxene, chromite, and feldspar, with other minerals in trace quantities. The gravity separation test by shaking table upgraded the chromite (Cr₂O₃) to 42.0% at high chromite recoveries, whereas the laboratory Slon wet high-intensity magnetic separation method (SLon WHIMS) upgraded the chromite in the feed to 42.95% grade at lower chromite recoveries. Desliming the sample before the gravity and magnetic separation tests significantly improved the separation. The magnetic separation tests further demonstrated that chromite within the MG2 layer is sensitive to magnetic separation due to its high iron content. The adapted flowsheet is proposed as a cost-effective flowsheet for processing the low-grade MG2 layer. The flow sheet can be optimized by conducting the SLon WHIMS tests at high intensities followed by fine gravity tests by spiral circuits to maximize the chromite recovery while achieving commercial chromite grades and a Cr:Fe ratio greater than 1.5.

The transformation of titania to its nanomaterial form has gained significant interest due to its superior properties that are viable for many applications. Herein, Titanium dioxide nanotubes (TNT) were synthesized using a hydrothermal method from Degussa P25 precursor. Sodium hydroxide base concentration was varied from 5.00 M to 12.50 M at 1.25 M increments to study its effect on titanium dioxide nanotubes properties. The morphology, crystalline phase and surface area was analyzed using TEM, SEM, XRD, Raman spectroscopy and BET. TNTs electrocatalytic activity was tested using a potentiostat. The 5.00 M base concentration results showed particle growth with insufficient transition to nanotubes morphology. TEM images show P25 transformation to well-defined nanotubes from 6.25 M to 10.00 M base concentrations. The BET results indicate that as the base concentration increased, the surface area of the TNT improved from 56.10 m ² g ⁻¹ to an optimum 317.57 m ² g ⁻¹ for 8.75 M TNT material. XRD and Raman results indicate that lower base concentrations (5.00 M to 7.50 M) do not affect the crystallinity of a nanomaterial. However, high base concentrations from 8.75 M show a gradual disappearance of catalytically active anatase phase at 2Ɵ degrees above 63.0°. TNT’s test as an anode material for potassium-ion battery application shows an irreversible reaction. That could be due to sluggish kinetics, poor conductivity, and passivation layer development. This study shows that TNTs with enhanced properties and well-defined nanotubes are attainable at lower base concentrations (6.25, 7.50 & 8.75 M) than the conventional 10.00 M using the one-step dynamic hydrothermal method.