WO₃ nanoparticles were synthesized via a facile chemical precipitation method for the photocatalytic degradation of rhodamine B.

Heterogeneous photocatalysis using titanium dioxide (TiO₂) and zinc oxide (ZnO) has been widely studied in various applications, including organic pollutant remediation in aqueous systems. The popularity of these materials is based on their high photocatalytic activity, strong photosensitivity, and relatively low cost. However, their commercial application has been limited by their wide bandgaps, inability to absorb visible light, fast electron/hole recombination, and limited recyclability since the nanomaterial is difficult to recover. Researchers have developed several strategies to overcome these limitations. Chief amongst these is the coupling of different semi-conductor materials to produce heterojunction nanocomposite materials, which are both visible-light-active and easily recoverable. This review focuses on the advances made in the development of magnetic ferrite-based titanium oxide and zinc oxide nanocomposites. The physical and magnetic properties of the most widely used ferrite compounds are discussed. The spinel structured material had superior catalytic and magnetic performance when coupled to TiO₂ and ZnO. An assessment of the range of synthesis methods is also presented. A comprehensive review of the photocatalytic degradation of various priority organic pollutants using the ferrite-based nanocomposites revealed that degradation efficiency and magnetic recovery potential are dependent on factors such as the chemical composition of the heterojunction material, synthesis method, irradiation source, and structure of pollutant. It should be noted that very few studies have gone beyond the degradation efficiency studies. Very little information is available on the extent of mineralization and the subsequent formation of intermediate compounds when these composite catalysts are used. Additionally, potential degradation mechanisms have not been adequately reported.

Polymeric materials undergo degradation when exposed to outdoor conditions due to the synergistic effects of sunlight, air, heat, and moisture. The degradation can lead to a decline in mechanical properties, fading, surface cracking, and haziness, attributed to the cleavage of the polymer chains and oxidation reactions. Accelerated weathering testing is a useful technique to evaluate the comparative photodegradation of materials within a reasonable timeframe. This review gives an overview of the different degradation mechanisms occurring in conventional plastics and bio-based materials. Case studies on accelerated weathering and its effect on the mechanical properties of conventional plastics and biocomposites are discussed. Different techniques for analysing volatile organic emissions (VOCs) have been summarized and studies highlighting the characterization of VOCs from aged plastics and biocomposites after aging have been cited.

The aim of this work was to investigate a new, simple, one-pot combustion synthesis technique for creating sulphur-based CuS/ZnS p-n heterojunction nanocomposite photocatalysts. This study examined the photocatalytic activity and reusability of these nanocomposites in removing rhodamine B (RhB) dye under visible-light irradiation. Various methods of characterisation were employed to determine the properties of the materials, including particle morphology, crystalline phases, and bandgap energy. The intrinsic reaction parameters, such as catalyst loading, the pH level of the solution, and initial pollutant concentration, were varied to establish the optimal photodegradation conditions. The results showed that a binary CuS/ZnS catalyst with a 10 g L⁻¹ loading, at pH 5, degraded 97% of 5 ppm RhB dye after 270 min of visible light irradiation. Additionally, this composite catalyst exhibited excellent chemical stability and reusability, achieving 83% RhB dye removal after five recycling runs. Scavenger tests identified the photogenerated holes (h⁺) and superoxide free radicals (•O₂) as the primary reactive species responsible for degradation. This study provides valuable insight into the design of highly efficient nanomaterials for removing organic pollutants in wastewater, and a possible reaction mechanism is proposed.

The presence of priority and emerging aromatic-based pollutants in water sources is of growing concern as they are not bioavailable and are present in reuse plant feed streams. These pollutants have known mutagenic and carcinogenic effects and must therefore be removed. Adsorption has been widely accepted as a suitable remediation technology due to its simplicity. Clay-based adsorbents have attracted significant attention due to their low cost, environmentally benign properties and regeneration potential. The present work focused on the thermal modification of a commercial Layered Double Hydroxide (LDH) clay and its subsequent effectiveness as an adsorbent in the removal of phenol from wastewater. Calcination of the neat clay resulted in the formation of metal oxides with varying phases and crystallinity depending on the treatment temperature. The BET surface area increased by 233% upon calcination at 500 °C. The highest phenol removal (85%) was observed in the clay calcined at 500 °C compared to 10% for the neat clay. Optimization studies revealed a maximum adsorption capacity of 12 mg/g at an adsorbent loading of 10 g/L at pH 7. Phenol adsorption was postulated to occur via a two-stage intercalation and surface adsorption mechanism. The equilibrium data were best fitted on the Freundlich isotherm model which describes heterogeneous adsorption. The adsorption kinetics followed a pseudo-second-order kinetic model with rate constants of 4.4 x 10⁻³ g/mg.h for the first 12h and 6.1 x 10⁻³ g/mg.h thereafter.