The emerging field of using titanium dioxide (TiO₂)-based photosensitizers for enhancing photocatalytic removal of thiazine dyes such as methylene blue (MB) from water has long been recognized for its exceptional photocatalytic properties, making it an attractive material for environmental remediation and energy conversion. However, its wide bandgap limits its responsiveness to visible light. As such, the utilization of TiO₂-based photosensitizers for the removal of thiazine dyes, presents a promising avenue for diverse applications. In addressing the dual challenges of environmental pollution and harnessing sustainable energy sources, this review focuses on the removal of thiazine dyes from water and their subsequent application as photosensitizers for TiO₂ materials. Thiazine dyes, ubiquitous in industrial effluents, pose environmental concerns due to their persistence and potential toxicity. Conversely, this innovative approach involves employing TiO₂ materials as photocatalysts, utilizing the unique properties of thiazine dyes to enhance light absorption. Studies have shown that beyond the conventional role of thiazine dyes as colorants, they can serve as effective photosensitizers when coupled with TiO₂. This tandem not only facilitates the elimination of thiazine dyes, such as MB, from water but also augments the improvement of the photocatalytic performance of TiO₂ materials. The synergy between dye sensitizers and TiO₂ enhances the overall efficiency of processes like dye degradation and water splitting. Dye sensitizers, acting as light energy absorbers, can efficiently transfer this energy to TiO₂, thereby promoting electron transfer and generating reactive oxygen species (ROS). These ROS, in turn, initiate chemical reactions, rendering dye sensitizers valuable in applications such as wastewater treatment, solar energy conversion, and environmental remediation. As such, it is crucial to acknowledge the potential drawbacks associated with thiazine dyes, including toxicity and non-biodegradability. Consequently, careful consideration must be given to thiazine dye application and disposal. Therefore, this review manuscript delves into the comprehensive exploration of TiO₂-based photosensitizers, shedding light on their efficacy in various photocatalytic processes for thiazine dye removal.

Water contamination is a pervasive global issue that endangers both human health and aquatic ecosystems, highlighting the critical need for sustainable and effective pollutant removal methods. This review examines the advancements in heterogeneous photocatalysis, with a particular focus on titanium dioxide (TiO₂) as a promising material for wastewater treatment. Emphasizing visible light-driven TiO₂ photocatalysis, the discussion explores its potential to overcome the limitations of conventional UV-driven systems, providing a more sustainable approach to water remediation. The key attributes of TiO₂, including its high oxidizing power, photochemical stability, non-toxicity, and cost-effectiveness, are detailed alongside recent innovations aimed at enhancing its performance under visible light. The review critically analyzes synthesis techniques, photocatalytic mechanisms, and factors influencing efficiency, offering a comprehensive understanding of the state-of-the-art in this field. Challenges and future directions for optimizing TiO₂-based systems, particularly their integration into real-world applications, are also explored, emphasizing environmental sustainability and scalability. This synthesis of current knowledge seeks to inspire innovative strategies for addressing the pressing global challenge of water pollution through advanced TiO₂ photocatalytic technologies. Graphical abstract

ZSM-22/polyethersulfone membranes were prepared for salt rejection using modelled brackish water. The membranes were fabricated via direct ZSM-22 incorporation into a polymer matrix, thereby inducing the water permeability, hydrophilicity and fouling resistance of the pristine polyethersulfone (PES) membrane. A ZSM-22 zeolite material with a 60 Si/Al ratio, high crystallinity and needle-like morphologies was produced and effectively used as a nanoadditive in the development of ZSM-22/PES membranes with nominal loadings of 0–0.75 wt.%. The characterisation and membrane performance evaluation of the resulting materials with XRD, BET, FTIR, TEM, SEM and contact angle as well as dead-end cell, respectively, showed improved water permeability in comparison with the pristine PES membrane. These ZSM-22/PES membranes were found to be more effective and superior in the processing of modelled brackish water. The salt rejection of the prepared membranes for NaCl and MgCl₂ was effective, while they exhibited quite improved water flux and flux recovery ratios in the membrane permeability and anti-fouling test. This indicates that different amounts of ZSM-22 nanoadditives produce widely divergent influences on the performance of the pristine PES membrane. As such, over 55% of salt rejection is observed, which means that the obtained membranes are effective in salt removal from water.

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.

Fabrication of the ZSM-22/Polyethersulfone (ZSM-22/PES) membranes as selective salt filters represent a growing membrane technological area in separation with the potential of high economic reward based on its low energy requirements. The incorporation of ZSM-22 zeolite material as additives into the PES polymer matrix has the prospective advantage of combining both the zeolite and polymer features while overcoming the limitations associated with both materials. This work investigated the influence of the nature of the silica precursor on ZSM-22 zeolite hydrothermally synthesised using colloidal (C60) and fumed (C60) silica to Si/Al of 60. The successful synthesis of the highly crystalline zeolitic materials was confirmed through XRD, FTIR, and SEM with EDX. The ZSM-22 additives were directly dispersed into a PES polymeric matrix to form a casting solution for the preparation of the ZSM-22/PES selective substrate layers via a phase inversion method for salts rejection. The polymeric PES was selected as an organic network in which the content of the ZSM-22 zeolite (ranging between 0 and 1.0 wt.%), was obtained and characterised by XRD, FTIR, and SEM analysis, as well as water contact angle (WCA) measurement and dead-end filtration cell. The phase inversion preparation method has induced the resulting ZSM-22/PES NF substrates anisotropy, as attributed to a high water flux to the above 700 L·m⁻²·h⁻¹; high selectivity and rejection of salts to above 80% is revealed by the obtained results. The materials also exhibited improved antifouling behavior to above 70% flux recovery ratios. As such, the nature of the silica precursor influences ZSM-22 zeolite synthesis as a potential additive in the PES polymer matrix and led to the enhanced performance of the pure PES ultrafiltration membrane.