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The need to develop advanced wastewater treatment techniques and their use has become a priority, the main goal being the efficient removal of pollutants, especially those of organic origin. This study presents the photo-degradation of a pharmaceutical wastewater containing Kabi cytarabine, using ultraviolet (UV) radiation, and a synthesized catalyst, a composite based on bismuth and iron oxides (BFO). The size of the bandgap was determined by UV spectroscopy, having a value of 2.27 eV. The specific surface was determined using the BET method, having a value of 0.7 m2 g−1. The material studied for the photo-degradation of cytarabine presents a remarkable photo-degradation efficiency of 97.9% for an initial concentration 0f 10 mg/L cytarabine Kabi when 0.15 g of material was used, during 120 min of interaction with UV radiation at 3 cm from the irradiation source. The material withstands five photo-degradation cycles with good results. At the same time, through this study, it was possible to establish that pyrimidine derivatives could be able to combat infections caused by Escherichia coli and Candida parapsilosis.

In an actual economic context, the demand for scandium has grown due to its applications in top technologies. However, further development of new technologies will lead to an increase in the market for Sc related to such technologies. The present study aims to improve and upgrade existing technology in terms of efficient scandium recovery, proposing a new material with selective adsorptive properties for scandium recovery. To highlight the impregnation of Amberlite XAD7HP resin with tri-n-octylphosphine oxide extractant by the solvent-impregnated resin method, the obtained adsorbent material was characterized by physico-chemical techniques. Further, the specific surface of the adsorbent and the zero-point charge of the adsorbent surface have been determined. Different parameters, such as initial concentration, adsorbent amount, contact time, or temperature, have been studied. The initial pH effect was investigated when a maximum adsorption capacity of 31.84 mg g−1 was obtained at pH > 3, using 0.1 g of adsorbent and a contact time of 90 min and 298 K. An attempt was made to discuss and provide a clear representation of the studied adsorption process, proposing a specific mechanism for Sc(III) recovery from aqueous solutions through kinetic, thermodynamic, and equilibrium studies. Adsorption/desorption studies reveal that the prepared adsorbent material can be reused five times.

In recent years, during industrial development, the expanding discharge of harmful metallic ions from different industrial wastes (such as arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, or zinc) into different water bodies has caused serious concern, with one of the problematic elements being represented by selenium (Se) ions. Selenium represents an essential microelement for human life and plays a vital role in human metabolism. In the human body, this element acts as a powerful antioxidant, being able to reduce the risk of the development of some cancers. Selenium is distributed in the environment in the form of selenate (SeO42–) and selenite (SeO32–), which are the result of natural/anthropogenic activities. Experimental data proved that both forms present some toxicity. In this context, in the last decade, only several studies regarding selenium’s removal from aqueous solutions have been conducted. Therefore, in the present study, we aim to use the sol–gel synthesis method to prepare a nanocomposite adsorbent material starting from sodium fluoride, silica, and iron oxide matrices (SiO2/Fe(acac)3/NaF), and to further test it for selenite adsorption. After preparation, the adsorbent material was characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The mechanism associated with the selenium adsorption process has been established based on kinetic, thermodynamic, and equilibrium studies. Pseudo second order is the kinetic model that best describes the obtained experimental data. Also, from the intraparticle diffusion study, it was observed that with increasing temperature the value of the diffusion constant, Kdiff, also increases. Sips isotherm was found to best describe the experimental data obtained, the maximum adsorption capacity being ~6.00 mg Se(IV) per g of adsorbent material. From a thermodynamic point of view, parameters such as ΔG0, ΔH0, and ΔS0 were evaluated, proving that the process studied is a physical one.

The goal of this work is to investigate the effectiveness of amorphous SiO2−FexOy loaded by functionalization with Ce(SO4)2, Li2SO4, and 3-aminopropyltriethoxysilane (APTES) for CO2 adsorption. Silica and iron-based materials are gaining popularity due to their wide range of applications, such as catalysis, photocatalysis, imaging, etc.; however, there are very few studies regarding the adsorption of CO2 with the aforementioned materials. In our study, we proposed to test their ability in this direction by adding cerium sulfate and lithium sulfate. Three base materials were obtained and characterized using XRD, FTIR, RAMAN, TG, SEM, and BET followed by their functionalization with amino groups by using of the APTES precursor. The SEM images indicate an increase in size, forming clusters from 100 nm for base materials to 500 nm for functionalized materials. The results indicate a maximum CO2 adsorption of 1.58 mmol/g material for the SiO2−FexOy−Li−APTES sample.

In this work, the synthesis of ordered mesoporous silica of MCM-41 type was investigated aimed at improving its morphology by varying the synthesis conditions in a one-pot process, employing different temperatures and solvent conditions. 2-methoxyethanol was used as co-solvent to ethanol. The co-solvent ratio and the synthesis temperature were varied. The pore morphology of the materials was characterized by nitrogen porosimetry and small angle neutron scattering (SANS), and the particle morphology by transmission electron microscopy (TEM) and ultra-small angle neutron scattering (USANS). The thermal behavior was investigated by simultaneous thermogravimetry-differential scanning calorimetry (TG-DSC) measurements. The SANS and N2 sorption results demonstrated that a well-ordered mesoporous structure was obtained at all conditions in the synthesis at room temperature. Addition of methoxyethanol led to an increase of the pore wall thickness. Simultaneously, an increase of methoxyethanol content led to lowering of the mean particle size from 300 to 230 nm, according to the ultra-small angle scattering data. The ordered porosity and high specific surfaces make these materials suitable for applications such as adsorbents in environmental remediation. Batch adsorption measurements of metal ion removal from aqueous solutions of Cu(II) and Pb(II) showed that the materials exhibit dominantly monolayer surface adsorption characteristics. The adsorption capacities were 9.7 mg/g for Cu(II) and 18.8 mg/g for Pb(II) at pH 5, making these materials competitive in performance to various composite materials.

Magnetic iron oxide-silica shell nanocomposites with different iron oxide/silica ratio were synthesized and structurally characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), small-angle neutron scattering, magnetic and N2-sorption studies. The composite that resulted with the best properties in terms of contact surface area and saturation of magnetization was selected for Pb2+ adsorption studies from aqueous media. The material presented good absorption capacity (maximum adsorption capacity 14.9 mg·g−1) comparable with similar materials presented in literature. Its chemico-physical stability and adsorption capacity recommend the nanocomposite as a cheap adsorbent material for lead.

The remediation of arsenic contamination in potable water is an important and urgent concern, necessitating immediate attention. With this objective in mind, the present study investigated arsenic removal from water using batch adsorption and fixed-bed column techniques. The material employed in this study was a waste product derived from the treatment of groundwater water for potable purposes, having a substantial iron composition. The material’s properties were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FT-IR). The point of zero charge (pHPZC) was measured, and the pore size and specific surface area were determined using the BET method. Under static conditions, kinetic, thermodynamic, and equilibrium studies were carried out to explore the influencing factors on the adsorption process, namely the pH, contact time, temperature, and initial arsenic concentration in the solution. It was found that the adsorption process is spontaneous, endothermic, and of a physical nature. In the batch adsorption studies, the maximum removal percentage was 80.4% after 90 min, and in a dynamic regime in the fixed-bed column, the efficiency was 99.99% at a sludge:sand = 1:1 ratio for 380 min for a volume of water with arsenic of ~3000 mL. The kinetics of the adsorption process conformed to a pseudo-second-order model. In terms of the equilibrium studies, the Sips model yielded the most accurate representation of the data, revealing a maximum equilibrium capacity of 70.1 mg As(V)/g sludge. For the dynamic regime, the experimental data were fitted using the Bohart–Adams, Thomas, and Clark models, in order to establish the mechanism of the process. Additionally, desorption studies were conducted, serving as an essential step in validating the practical applicability of the adsorption process, specifically in relation to the reutilization of the adsorbent material.

Active and stable materials that utilize solar radiation for promoting different reactions are critical for emerging technologies. Two of the most common polymeric carbon nitrides were prepared by the thermal polycondensation of melamine. The scope of this work is to investigate possible structural degradation before and after photoelectrochemical testing. The materials were characterized using synchrotron radiation and lab-based techniques, and subsequently degraded photoelectrochemically, followed by post-mortem analysis. Post-mortem investigations reveal: (1) carbon atoms bonded to three nitrogen atoms change into carbon atoms bonded to two nitrogen atoms and (2) the presence of methylene terminals in post-mortem materials. The study concludes that polymeric carbon nitrides are susceptible to photoelectrochemical degradation via ring opening.

Herein, we present the investigation of catalytical and fluorescence properties for Ni11(HPO3)8(OH)6 materials obtained through a hydrothermal approach. As part of the constant search for new materials that are both cost effective and electrocatalytically active for the oxygen evolution reaction (OER) in alkaline medium, the present study involves several graphite electrodes modified with Ni11(HPO3)8(OH)6 mixed with reduced graphene oxide (rGO) and carbon black. The experimental results obtained in 0.1 mol L–1 KOH electrolyte solution show the electrode modified with rGO, 5 mg carbon black and 1 mg nickel phosphite as displaying the highest current density. This performance can be attributed to the synergistic effect between nickel phosphite and the carbon materials. Investigation of the electrode’s OER performance in 0.1 mol L–1 KOH solution revealed a Tafel slope value of just 46 mV dec–1. By increasing the concentration to 0.5 and 1 mol L–1, this value increased as well, but there was a significant decrease in overpotential. Fluorescence properties were analyzed for the first time at the excitation length of 344 nm, and the observed strong and multiple emissions are described.

The antibacterial activity of zinc oxide particles has received significant interest worldwide, especially through the implementation of technology to synthesize particles in the nanometer range. This study aimed to determine the antimicrobial efficacy of silica-based iron oxide matrix (SiO2FexOy) synthesized with various amounts of ZnO (SiO2FexOyZnO) against various pathogens. It is observed that, with the addition of ZnO to the system, the average size of the porosity of the material increases, showing increasingly effective antibacterial properties. Zinc-iron-silica oxide matrix composites were synthesized using the sol–gel method. The synthesized materials were investigated physicochemically to highlight their structural properties, through scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Fourier-transform infrared spectroscopy (FT-IR). At the same time, surface area, pore size and total pore volume were determined for materials synthesized using the Brunauer–Emmett–Teller (BET) method. Although the material with 0.0001 g ZnO (600 m2/g) has the highest specific surface area, the best antimicrobial activity was obtained for the material with 1.0 g ZnO, when the average pore volume is the largest (~8 nm) for a specific surface of 306 m2/g. This indicates that the main role in the antibacterial effect has reactive oxygen species (ROS) generated by the ZnO that are located in the pores of the composite materials. The point of zero charge (pHpZc) is a very important parameter for the characterization of materials that indicate the acid-base behaviour. The pHpZc value varies between 4.9 and 6.3 and is influenced by the amount of ZnO with which the iron-silica oxide matrix is doped. From the antimicrobial studies carried out, it was found that for S. aureus the total antibacterial effect was obtained at the amount of 1.0 g ZnO. For Gram-negative bacteria, a total antibacterial effect was observed in S. flexneri (for the material with 0.1 g ZnO), followed by E. coli (for 1.0 g ZnO). For P. aeruginosa, the maximum inhibition rate obtained for the material with 1.0 g ZnO was approximately 49%.

Significant tasks of the presented research are the development of multifunctional materials capable both to detect/capture carbon dioxide and to monitor toxic metal ions from waters, thus contributing to maintaining a sustainable and clean environment. The purpose of this work was to synthesize, characterize (NMR, FT-IR, UV-Vis, Fluorescence, AFM) and exploit the optical and emission properties of a carboxyl-substituted A3B porphyrin, 5-(4-carboxy-phenyl)-10,15,20-tris-(4-methyl-phenyl)–porphyrin, and based on it, to develop novel composite material able to adsorb carbon dioxide. This porphyrin-k-carrageenan composite material can capture CO2 in ambient conditions with a performance of 6.97 mmol/1 g adsorbent. Another aim of our research was to extend this porphyrin- k-carrageenan material’s functionality toward Mn2+ detection from polluted waters and from medical samples, relying on its synergistic partnership with gold nanoparticles (AuNPs). The plasmonic porphyrin-k-carrageenan-AuNPs material detected Mn2+ in the range of concentration of 4.56 × 10−5 M to 9.39 × 10−5 M (5–11 mg/L), which can be useful for monitoring health of humans exposed to polluted water sources or those who ingested high dietary manganese.

Aggressive industrial development over the last century involved different heavy metals being used, including high quantities of molybdenum, which need to be treated before discharge in industrial waters. Molybdenum’s market price and industrial applicability make its recovery a big challenge. In the present study the possibility to recover molybdenum ions from aqueous solutions by adsorption on a composite material based on silica matrix and iron oxides—SiO2FexOy—was evaluated. Tests were performed in order to determine the influence of adsorbent material dose, initial solution pH, contact time and temperature over adsorption capacity of synthesized adsorbent material. For better understanding of the adsorption process, the obtained experimental data were modelled using Langmuir, Freundlich and Sips adsorption isotherms. Based on the obtained data, it can proved that the Sips isotherm was describing with better orderliness the studied process, obtaining a maximum adsorption capacity of 10.95 mg MoO42− for each gram of material. By modelling the studied adsorption process, it was proven that the pseudo-second order model is accurately describing the adsorption process. By fitting experimental data with Weber-Morris model, it was proven that MoO42− adsorption is a complex process, occurring in two different steps, one controlled by diffusion and the second one controlled by mass transfer. Further, studies were performed in order to determine the optimum pH value needed to obtain maximum adsorption capacity, but also to determine which are the adsorbed species. From pH and desorption studies, it was proven that molybdate adsorption is a physical process. In order to establish the adsorption mechanism, the thermodynamic parameters (ΔG0, ΔH0 and ΔS0) were determined.

In the present study, new magnetic nanocomposites were successfully prepared by combustion method, characterized by X-ray diffraction, Fourier transform infrared spectroscopy, magnetic measurements, N2 adsorption–desorption thermal analysis, and scanning electron microscopy, and tested as adsorbents for the removal of anionic dyes (Acid Yellow 42 and Acid Red 213) from aqueous solutions. The influence of process variables solution pH, adsorbent dose, initial dye concentration and temperature on the adsorption was evaluated. The best kinetic model that fitted with experimental data was a pseudo-second order model, and the equilibrium data were correlated by Langmuir isotherm model for the investigated dyes. Maximum removal efficiencies of 98.54% and 97.58% was obtained for Acid Yellow 42 and Acid Red 213, respectively, indicating the superior adsorption capacity of the new synthesized magnetic nanocomposites. The thermodynamic parameters indicated the spontaneous and endothermic nature of the adsorption process.

Polymer electrolyte membrane fuel cells require cheap and active electrocatalysts to drive the oxygen reduction reaction. Nitrogen-doped carbons have been extensively studied regarding their oxygen reduction reaction. The work at hand looks beyond the nitrogen chemistry and brings to light the role of oxygen. Nitrogen-doped nanocarbons were obtained by a radio-frequency plasma route at 0, 100, 250, and 350 W. The lateral size of the graphitic domain, determined from Raman spectroscopy, showed that the nitrogen plasma treatment decreased the crystallite size. Synchrotron radiation photoelectron spectroscopy showed a similar nitrogen chemistry, albeit the nitrogen concentration increased with the plasma power. Lateral crystallite size and several nitrogen moieties were plotted against the onset potential determined from oxygen reduction reaction curves. There was no correlation between the electrochemical activity and the sample structure, as determine from Raman and synchrotron radiation photoelectron spectroscopy. Near-edge X-ray absorption fine structure (NEXAFS) was performed to unravel the carbon and nitrogen local structure. A difference analysis of the NEXAFS spectra showed that the oxygen surrounding the pyridinic nitrogen was critical in achieving high onset potentials. The work shows that there were more factors at play, other than carbon organization and nitrogen chemistry.

Pharmaceuticals and pesticides are emerging contaminants problematic in the aquatic environment because of their adverse effects on aquatic life and humans. In order to remove them from water, photocatalysis is one of the most modern technologies to be used. First, newly synthesized photocatalysts were successfully prepared using a sol–gel method and characterized by different techniques (XRD, FTIR, UV/Vis, BET and SEM/EDX). The photocatalytic properties of TiO2, ZnO and MgO nanoparticles were examined according to their removal from water for two antibiotics (ciprofloxacin and ceftriaxone) and two herbicides (tembotrione and fluroxypyr) exposed to UV/simulated sunlight (SS). TiO2 proved to be the most efficient nanopowder under UV and SS. Addition of (NH4)2S2O8 led to the faster removal of both antibiotics and herbicide fluroxypyr. The main intermediates were separated and identified for the herbicides and antibiotic ciprofloxacin. Finally, the toxicity of each emerging pollutant mixture and formed intermediates was assessed on wheat germination and biomass production.

Metalloporphyrins are highly recognized for their capacity to act as sensitive substances used in formulation of optical, fluorescent, and electrochemical sensors. A novel compound, namely Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl) porphyrin, was synthesized by metalation with PtCl2(PhCN)2 of the corresponding porphyrin base and was fully characterized by UV-vis, fluorimetry, FT-IR, 1H-NMR, and 13C-NMR methods. The fluorescence response of this Pt-porphyrin in the presence of different concentrations of hydrogen peroxide was investigated. Besides, modified glassy carbon electrodes with this Pt-porphyrin (Pt-Porf-GCE) were realized and several electrochemical characterizations were comparatively performed with bare glassy carbon electrodes (GCE), in the absence or presence of hydrogen peroxide. The Pt-porphyrin demonstrated to be a successful sensitive material for the detection of hydrogen peroxide both by fluorimetric method in a concentration range relevant for biological samples (1.05–3.9 × 10−7 M) and by electrochemical method, in a larger concentration range from 1 × 10−6 M to 5 × 10−5 M. Based on different methods, this Pt-porphyrin can cover detection in diverse fields, from medical tests to food and agricultural monitoring, proving high accuracy (correlation coefficients over 99%) in both fluorimetric and electrochemical measurements.

A facile sol-gel route has been applied to synthesize hybrid silica-PVA-iron oxide nanocomposite materials. A step-by-step calcination (processing temperatures up to 400 °C) was applied in order to oxidize the organics together with the iron precursor. Transmission electron microscopy, X-ray diffraction, small angle neutron scattering, and nitrogen porosimetry were used to determine the temperature-induced morpho-textural modifications. In vitro cytotoxicity assay was conducted by monitoring the cell viability by the means of MTT assay to qualify the materials as MRI contrast agents or as drug carriers. Two cell lines were considered: the HaCaT (human keratinocyte cell line) and the A375 tumour cell line of human melanoma. Five concentrations of 10 µg/mL, 30 µg/mL, 50 µg/mL, 100 µg/mL, and 200 µg/mL were tested, while using DMSO (dimethylsulfoxid) and PBS (phosphate saline buffer) as solvents. The HaCaT and A375 cell lines were exposed to the prepared agent suspensions for 24 h. In the case of DMSO (dimethyl sulfoxide) suspensions, the effect on human keratinocytes migration and proliferation were also evaluated. The results indicate that only the concentrations of 100 μg/mL and 200 μg/mL of the nanocomposite in DMSO induced a slight decrease in the HaCaT cell viability. The PBS based in vitro assay showed that the nanocomposite did not present toxicity on the HaCaT cells, even at high doses (200 μg/mL agent).