In this study, Ag-TiO2/rGO/halloysite nanotubes were synthesised from natural sources using a simple method. The material was characterised by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Raman spectroscopy, BET, scanning electron microscopy (SEM) and UV-vis DRS techniques. The as-synthesised material has a sandwich-like shape, with the active phase distributed evenly over the rGO/HNT support. Compared to pure TiO2, the material has a lower band gap energy (~2.7 eV) and a suitable specific surface area (~80 m2/g), making it able to participate effectively in the photochemical degradation of pollutants. The catalyst showed exceptional activity in the degradation of CIP antibiotics in water, achieving a conversion of about 90% after 5 h of irradiation at an initial CIP concentration of 20 ppm. This efficiency was significantly higher than that of pure TiO2 and Ag-TiO2, which could prove the important effect of the support and silver doping. The results of the experiments show that the process follows a pseudo-first-order kinetic model in the case of (1%)Ag wt. and pseudo-second-order in the case of (3%)Ag wt., which could be explained by the aggregation of silver and the increasing role of chemisorption. Tests with radical scavengers showed that the •OH radical had the greatest effect on CIP decomposition, while •O2− had the least. The neutral pH value and the high degree of mineralisation (approx. 80%) confirm the potential of the material for use in wastewater treatment.

The novel composite nanomaterials were synthesized via a simple method from two natural clay mineral sources, graphite and halloysite. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Brunauer-Emmet-Teller (BET) methods. The results showed that halloysite nanotubes are successfully intercalated between the graphene oxide layers. The adsorption capacity of the material with RY-145, a typical dye in textile wastewater, was evaluated. Also, the effects of adsorption time, initial concentration of pollutant, adsorbent dosage, speed of agitation and temperature were investigated. The adsorption efficiency of the material for RY-145 dye is about 99% after 4 hours with the high initial concentration of pollutant of 50ppm. Adsorption kinetics of the material for RY-145 match the pseudo-second order kinetic of Langmuir adsorption model. The outstanding performance of the nanocomposite as an adsorbent highlight the promising applications of the novel material in was water treatment processes.

A new generation photocatalyst CuFe2O4/rGO/halloysite nanotube (HNT) was manufactured using a simple procedure in this work. Material characterisation results reveal that the CuFe2O4 active phase with a size of around 30-40 nm is spread rather consistently across the sandwich-like structure of rGO/HNT. The material's bandgap energy is around 1.9 eV, which boosts the material's capacity to function even in the visible light area. The catalytic activity test showed that the catalyst, with an active phase composition of 70% by weight, was able to completely decomposing CIP after just 1 hour of light. The pHpzc value and pH impact were also investigated. The findings suggest that the material can completely handle CIP in a neutral environment (pH = 7). Scavenger tests also demonstrated the involvement of reactive radicals in CIP degradation, with holes (h+) and hydroxyl radicals (●OH) having the major effect. These important results constitute the basis for the in-depth investigations of the CIP degradation mechanism.

In this study, the CuFe2O4 on rGO/halloysite material was made in an uncomplicated manner. The catalyst has a sandwich-like shape with a uniform coating of the active phase on the rGO sheets and halloysite tubes. The catalyst’s large specific surface area (130 m2/g) and small band gap energy (1.9 eV) allow it to adsorb photons and photocatalyze organic contaminants effectively. In approximately 1 h of light, the catalyst showed high performance in achieving almost complete conversion in photodegrading CIP for an initial CIP concentration of 20 ppm. A pseudo-first-order rate law was followed by the process, as revealed by the experimental results. In addition, the pH effect and the contribution of intermediate reactive radicals that emerged during the photochemical process were explored. The results indicated that hydroxyl radicals and holes had a major impact on CIP decomposition, suggesting that the addition of these radicals could enhance CIP degradation efficiency at a larger scale. This study also confirmed the superiority of catalysis and photochemical processes in environmental treatments by the neutral pH values.