In response to the novel coronavirus referred to as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – a virus that causes COVID-19 disease has led to wide use of sanitizers and disinfectants. This, in turn, triggered concerns on their potential deleterious effects to human health and the environment due to numerous chemicals incorporated in both product categories. Here, the current state of science regarding the occurrence and ecological effects of different classes of chemicals in these products (e.g., ultraviolent filters, fragrances, etc.) are summarized in different natural (e.g., rivers) and engineered (e.g., wastewater treatment plants) systems. Data collected in the literature suggests chemicals incorporated in sanitizers and disinfectants are present in the environment, and a large portion are toxic to fish, algae, and daphnia. Using the risk quotient approach based on occurrence data, we found eight chemicals that posed the highest risk to aquatic organisms in freshwater systems were benzalkonium chloride, 4-chloro-m-cresol, sodium ortho phenyl phenate, hydrogen peroxide, 1, 2-propanediol, 4-Methyl-benzilidine-camphor, ethylhexyl methoxy cinnamate, and octocrylene. Considering limited occurrence and effects information for most chemicals, further studies on environmental monitoring and potential consequences of long-term exposure in aquatic ecosystems are recommended.

The increasing presence of pharmaceuticals, particularly antiretroviral drugs (ARVs), in wastewater has raised concerns regarding their environmental and health impacts. Photocatalysis, driven by advanced photocatalysts, such as coloured TiO₂, ZnO, and composites with carbon-based materials, has shown promise as an effective method for degrading these pollutants. Despite significant laboratory-scale success, challenges remain in scaling this technology for real-world applications, particularly in terms of photocatalyst stability, the formation of toxic degradation by-products, and economic feasibility. This paper explores the current state of photocatalytic degradation for ARVDs, emphasizing the need for further research into degradation pathways, the development of more efficient and cost-effective photocatalysts, and the integration of photocatalysis into hybrid treatment systems. The future of photocatalysis in wastewater treatment hinges on improving scalability, reactor design, and hybrid systems that combine photocatalysis with traditional treatment methods to ensure comprehensive pollutant removal. Innovations in catalyst design and reactor optimization are essential for advancing photocatalysis as a viable solution for large-scale wastewater treatment.

The escalating discharge of synthetic dyes, such as brilliant green (BG), into aquatic ecosystems poses severe environmental and health risks because of their toxicity, carcinogenicity, and bioaccumulation potential. This study reports the synthesis of black titanium dioxide (B-TiO ₂ ) via the chemical reduction of commercial Degussa P25 TiO ₂ using NaBH ₄ at 300 °C under a N ₂ atmosphere, aiming to enhance the visible-light photocatalytic activity for BG removal. Comprehensive characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer-Emmett-Teller (BET) analysis, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) confirmed the introduction of Ti ³ ⁺ defects and oxygen vacancies, resulting in a reduced bandgap (≈2.3 eV), extended visible-light absorption, increased surface area, and improved charge separation. Photocatalytic evaluations under visible-light irradiation ( λ > 420 nm) exhibited optimal BG removal (10 mg/L) at a catalyst load of 1 g/L and pH 11, achieving optimal removal in 30 min, adhering to pseudo-first-order kinetics ( k = 0.062 min ⁻¹ ). Radical-scavenging experiments identified superoxide radicals (O ₂ ^•⁻ ) as the primary reactive species, with minor contributions from hydroxyl radicals (•OH) and holes (h⁺). The catalyst demonstrated good reusability, maintaining > 95% efficiency over four cycles. These findings underscore B-TiO ₂ as a robust solar-driven photocatalyst for sustainable wastewater remediation, in alignment with the UN’s Sustainable Development Goals for clean water and health.

The extensive use of antiretroviral drugs (ARVs) for HIV/AIDS treatment in South Africa has generated a new class of persistent contaminants within the aquatic environment. This review consolidates current evidence on the occurrence, transformation products, ecotoxicological effects, and removal efficiencies of ARVs in South Africa’s water resources. Measured concentrations of compounds such as efavirenz, nevirapine, and lamivudine frequently exceed international ecotoxicological thresholds, reflecting the limitations of conventional wastewater treatment systems designed primarily for nutrient and organic load removal. Because ARVs are only partially metabolized in humans and exhibit high polarity and chemical stability, they persist in effluents, surface waters, and occasionally in drinking water. Chronic exposure studies indicate potential adverse effects on aquatic organisms across trophic levels, including oxidative stress, endocrine disruption, developmental abnormalities, and altered enzymatic activity. The review critically evaluates advanced treatment approaches such as photocatalytic advanced oxidation processes (AOPs), highlighting their efficiencies, scalability, and cost implications for South African contexts. Major research and policy gaps include limited long-term ecotoxicological data, inadequate nationwide monitoring, and the absence of ARV-specific water quality thresholds. The study proposes the integration of ARV monitoring into South Africa’s Green Drop framework, the adoption of visible-light-driven photocatalysis for energy-efficient remediation, and alignment of national water policies with the UN Sustainable Development Goals. By explicitly linking environmental contamination with public health resilience and equity, this review underscores the urgent need for coordinated interventions to ensure that the life-saving benefits of antiretroviral therapy do not compromise aquatic ecosystem integrity.

The escalating discharge of synthetic dyes, such as brilliant green (BG), into aquatic ecosystems poses severe environmental and health risks due to their toxicity, carcinogenicity, and bioaccumulation potential. This study reports on the synthesis of black titanium dioxide (B-TiO2) via chemical reduction of commercial Degussa using NaBH4 at 300 °C under N2 atmosphere, aiming to enhance visible-light photocatalytic activity for BG degradation. Comprehensive characterization via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), Brunauer-Emmett-Teller (BET) analysis, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS) confirmed the introduction of Ti³⁺ defects and oxygen vacancies, resulting in a reduced bandgap (~1.5 eV), extended visible-light absorption, increased surface area, and improved charge separation. Photocatalytic evaluations under visible-light irradiation (λ > 240 nm) exhibited optimal degradation of BG (10 mg/L) at a catalyst load of 1 g/L and pH 11, achieving complete mineralization in 30 min adhering to pseudo-first-order kinetics (k = 0.062 min⁻¹). Radical scavenging experiments identified superoxide radicals (O2⁻•) as the primary reactive species, with minor contributions from hydroxyl radicals (•OH) and holes (h⁺). The catalyst demonstrated remarkable reusability, maintaining 100% efficiency over four cycles. These findings underscore B-TiO2 as a robust, solar-driven photocatalyst for sustainable wastewater remediation, in alignment with UN’s Sustainable Development Goals for clean water and health.