National Institute of Materials Physics (NIMP), Romania – Project Coordinator: Dr. Irina Zgura

Universitatea Bucuresti, Romania – Partner Leader: Conf. Univ. Dr. Marcela-Elisabeta Bărbînţă-Pătraşcu

MAGYAR AGRAR- ES ELETTUDOMANYI EGYETEM, Institute of Aquaculture and Environmental Safety, Hungary – Partner Leader: Dr. Judit Hahn

UNIVERSIDAD DE EXTREMADURA, Spain – Partner Leader: Dr. Antonia Pajares

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS, GEPEA UMR6144, France – Partner Leader: Dr. Pascale Gillon

NIMP’s team members:

Dr. Irina Zgura

Dr. Nicoleta Preda

Dr. Monica Enculescu

Dr. George Stan

Dr. Liviu Nedelcu

Dr. Oana Rasoga

Dr. Carmen Breazu

Dr. Paul Constantin Ganea

PostDoc Monica Dinescu

PhD student Madalina Chivu

Open-position

Open-position

Year 2024

During the implementation period (2024), activities were carried out regarding the preparation and characterization of the commercial metal oxide–based samples, evaluated in terms of morphological, structural and optical properties, both as monocomponent systems (ZnO, CuO) and as composites (ZnO–CuO). Structural characterization by X-ray diffraction (XRD) confirmed that the commercial powders exhibited diffraction peaks corresponding to hexagonal wurtzite ZnO and monoclinic CuO phases. The morphological properties were assessed through scanning electron microscopy (SEM), the images revealing particles with sizes below 100 nm, a result consistent with the partner’s DLS measurements.

Optical measurements (reflectance spectra and FTIR spectra) highlighted the optical signature of both ZnO and CuO components in the composite materials. Eco-impact (eco-toxicological) evaluation, including greenhouse/laboratory plant assays, urease activity testing, and photosynthesis/respiration measurements, indicated that:
i) the tested powder samples did not exhibit urease inhibition activity at 1 g/L concentration (due to the absence of bioactive surface compounds), and
ii) the samples did not present antioxidant properties (due to the lack of bioactive compounds capable of scavenging and neutralizing free radicals).
These results, together with the urease inhibition assays, demonstrate the necessity of using metal oxide nanoparticles obtained through ecological (plant-extract-based) synthesis, since phytoderived oxides possess surface phytomolecules that may induce relevant bioactivities.

Regarding the photocatalytic activity of commercial nanometric metal oxide powders, composite samples displayed better photocatalytic performance than monocomponent ZnO or CuO. The highest degradation efficiency was observed for the composite containing 3% CuO. At the optimum concentration, CuO acts as an electron trap, reducing electron–hole recombination and thus significantly enhancing photocatalytic performance.

Synthetic wastewater treated with commercial metal oxide powders prior to photocatalytic degradation (performed by the partner) caused deterioration of photosynthesis and respiration processes in plants, leading to premature plant death due to the presence of RhB in the water. After photocatalytic treatment using commercial metal oxide powders, the treated water showed a stimulatory effect on plant development, improving photosynthesis and respiration rates.

In the evaluation of RhB photodegradation using 3D-printed structures, longer irradiation times and significantly higher photocatalyst loadings (approximately 100-fold) were required. This is attributed to the substantially lower specific surface area of 3D-printed structures compared to commercial metal oxide powders. However, despite the increased irradiation time and catalyst quantity, the photocatalytic effect obtained with 3D structures was comparable to that of powdered catalysts, with several key advantages:
i) elimination of the filtration step, which is difficult to perform;
ii) easy separation and reuse of printed structures;
iii) production of treated water free of particulate impurities.
Composite-based 3D structures exhibited better photocatalytic behavior than monocomponent ZnO or CuO 3D samples, with improved degradation efficiency observed in structures containing 1% and 3% CuO.

Water treated with robocasted structures showed beneficial effects on plants, as confirmed by photosynthesis and respiration measurements, which were similar to the control samples. Among all robocast structures, the 3D ZnO97%–CuO3% composite displayed the highest RhB photodegradation efficiency. Based on these results, this composite was further selected for urease activity and ecotoxicity assessment. In treatments using water decontaminated with 3D_ZnO97%–CuO3%NPs, ecotoxicity studies indicated two essential aspects: lack of toxicity and potential applicability in agriculture.

Year 2025

During the implementation period (2025), activities were carried out regarding the preparation and characterization of the phytosynthesized metal oxide–based samples, evaluated in terms of morphological, structural, and optical properties, both as monocomponent systems (ZnO, CuO) and as composites (ZnO–CuO). Structural characterization by X-ray diffraction (XRD) confirmed that the phytosynthesized powders exhibited diffraction peaks corresponding to hexagonal wurtzite ZnO and monoclinic CuO phases. The morphological properties were assessed through scanning electron microscopy (SEM), the images showing that the samples consist of particles with an average size of approximately 200 nm, a result consistent with the partner’s DLS measurements.

Optical measurements (reflectance spectra and FTIR spectra) highlighted the optical fingerprints of the two components, ZnO and CuO, in the composite materials. The eco-impact (eco-toxicological) evaluation, including testing on greenhouse/laboratory plants, urease activity assays, and assessment of photosynthesis and respiration, revealed that:
i) among the tested samples (ecoMO and their composites), only two samples (EcoZnO95%–CuO5%NPs and EcoZnO99%–CuO1%NPs) showed a more pronounced urease inhibition activity at a concentration of 1 g/L. The anti-ureolytic activity of EcoZnO95%–CuO5%NPs was 53.902%, while EcoZnO99%–CuO1%NPs was 43.33%. A slight inhibitory effect was also observed for EcoZnO100% and EcoCuO100%.
ii) the samples exhibit antioxidant properties, attributed to the presence of bioactive compounds capable of scavenging and eliminating free radicals from the environment. The highest AA% values were recorded for EcoCuO100%NPs and EcoZnO99%–CuO1%NPs.

Regarding the investigation of the photocatalytic activity of the phytosynthesized metal oxide powders, it was found that the composite samples exhibited superior photocatalytic performance compared to the monocomponent ZnO or CuO powders. The highest degradation efficiency was obtained for the composite containing 3% CuO. When comparing all results obtained on powdered eco-synthesized materials, EcoZnO97%–CuO3%NPs was identified as the most efficient in RhB and paracetamol photodegradation.

Analysis of synthetic wastewater treated with commercial metal oxide powders prior to photocatalytic degradation (performed by the partner) showed that the presence of RhB in the treated water accelerated senescence, ultimately causing premature plant death (similar to Stage I, 2024). Therefore, these plants could not be used for subsequent photosynthesis/respiration evaluation. The photosynthesis process of plants treated with water treated using eco-synthesized metal oxide powders (EcoZnO97%–CuO3%, 400°C, 2.5h) was not inhibited. Meanwhile, basil plants treated with RhB-containing water photocatalytically degraded in the presence of EcoMO powders and their composites exhibited a significant decrease in respiration, particularly for EcoZnO99–CuO1% and EcoZnO97–CuO3%.

For the evaluation of RhB photodegradation in the presence of 3D-printed structures, significantly larger quantities of photocatalyst were required (approximately 20-fold higher). This is attributed to the substantially lower specific surface area of the 3D-printed structures compared to powdered catalysts. Nevertheless, despite the higher catalyst loading, the use of 3D-printed structures in dye-containing wastewater treatment offers several important advantages:
i) elimination of the additional filtration step, which is laborious and challenging to implement;
ii) easy separation and reuse of the printed structures;
iii) obtaining treated water free from particulate impurities.

Composite-based 3D-printed samples exhibited better photocatalytic activity than monocomponent ZnO or CuO 3D samples. The effect of wastewater treated with robocast structures on plants was assessed through photosynthesis and respiration analysis. Results showed that:
i) photosynthesis was not affected by the treatments, and
ii) respiration remained unaffected in plants treated with water decontaminated using 3D EcoCuO100% and 3D EcoZnO99%–CuO1%. For other samples, a slowdown in respiration was observed.

When using water decontaminated with 3D EcoCuO100% and 3D EcoZnO99%–CuO1%, ecotoxicity studies highlighted important aspects, such as lack of toxicity and the potential applicability of these materials in agriculture.

Contact

Project Coordinator: Dr. Irina Zgura

Phone: +40-(0)21-3690185, +40-(0)21-2418100

Fax    : +40-21369 0177

e-mail: irina.zgura@infim.ro