Gamma radiolysis of ceftriaxone sodium for water treatment: assessments of the activity

Waste Valorization of a Recycled ZnCoFe Mixed Metal Oxide/Ceftriaxone Waste Layered Nanoadsorbent for Further Dye Removal

Waste valorization of spent wastewater nanoadsorbents is a promising technique to support the circular economy strategies. The terrible rise of heavy metal pollution in the environment is considered a serious threat to the terrestrial and aquatic environment. This led to the necessity of developing cost-effective, operation-convenient, and recyclable adsorbents. ZnCoFe mixed metal oxide (MMO) was synthesized using co-precipitation. The sample was characterized using X-ray powder diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Factors affecting the adsorption process such as pH, the dose of adsorbent, and time were investigated. ZnCoFe MMO showed the maximum adsorption capacity of 118.45 mg/g for ceftriaxone sodium. The spent MMO was recycled as an adsorbent for malachite green (MG) removal. Interestingly, the spent adsorbent showed 94% removal percent for MG as compared to the fresh MMO (90%). The kinetic investigation of the adsorption process was performed and discussed. In addition, ZnCoFe MMO was tested as an antimicrobial agent. The proposed approach opens up a new avenue for recycling wastes after adsorption into value-added materials for utilization in adsorbent production with excellent performance as antimicrobial agents.

Experimental and computational study of hydrolysis and photolysis of antibiotic ceftriaxone: Degradation kinetics, pathways, and toxicity

In this work, we have experimentally and computationally investigated the process of hydrolysis and photolysis of cephalosporin antibiotics with ceftriaxone (CEF) as a model compound. The CEF hydrolysis was investigated in ultrapure and natural water, at 25 ± 1 °C and 4 ± 1 °C in the dark. It was found that CEF after 100 and 900 days at 25 ± 1°C and 4 ± 1 °C, respectively practically completely removed from ultrapure water. The CEF hydrolysis in natural water was five and three times slower at 25 ± 1 °C and 4 ± 1 °C, respectively than in ultrapure water. Further, the efficiency of direct photolysis (solar/UVA-B) and solar/H₂O₂ treatment of CEF was investigated. Under UVA-B radiation 95.6% of CEF was removed after 60 min, while for the same time of solar radiation degradation was practically not observed (only 3.2%). Also, the effects of different concentrations of H₂O₂ (0-150 mM) in the presence/absence of solar radiation were studied. The most efficient solar/H₂O₂ treatment was in the presence of 90 mM H₂O₂, whereby 66.8% of CEF was removed after 60 min (41.8% by indirect photolysis, 21.8% by H₂O₂-oxidation, and 3.2% by direct photolysis). Radial distribution functions (RDF) provided information about the distribution of water around the CEF molecule. Aside from the RDF, investigation of intramolecular noncovalent interactions and calculations of bond dissociation energies for hydrogen abstraction enabled understanding of degradation mechanism of CEF. In order to investigate sensitivity of CEF towards the radical attacks, the concept of Fukui functions was used. The structures of intermediates and degradation pathways were suggested by UHPLC-LTQ OrbiTrap MS and density functional theory calculations. Toxicity assessments showed that intermediates formed during hydrolysis exerted only mild cell growth effects in selected cell lines.

The Green Method in Water Management: Electron Beam Treatment

During the prebiotic era, radiolytic transformations in the oceans played a key role in purifying water from toxic impurities and, thus, played a role in the formation of the aquatic environment of our planet, making it suitable for the emergence of life. Today, the planet again faces the challenge of how to provide people with clean water. Therefore, it is reasonable to look back at past historical stages and again consider the possibility of neutralizing pollutants in water by means of radiolysis, which has already been tested by time. Modern radiolytic treatments can be much faster and safer thanks to the advent of powerful electron accelerators and high-rate electron beam treatment (ELT) of water and wastewater. Radiolytic treatment of water using accelerated electrons corresponds to the essence of advanced oxidative technologies and green chemistry. The ELT of water instantly generates a high concentration of short-lived radicals that can quickly neutralize and decompose chemical and bacterial pollutants. Due to the ability of accelerated electrons to penetrate into a substance, ELT provides the decomposition of both dissolved and suspended pollutants. The cleaning effect of ELT is due to the ability to inactivate toxic and chromophore functional groups, transform impurities into an easily removable form, damage the DNA of microorganisms and their spore forms, and increase the biodegradability of organic impurities. The use of ELT in water treatment provides significant savings in chemical reagents, thereby improving quality and reducing the number of cleaning steps. The compactness, high degree of automation of the equipment used, energy efficiency, high productivity, and excellent compatibility with traditional water treatment methods are important advantages of ELT. Unlike conventional chemicals, the excess radicals generated in the ELT process are converted back to water and hydrogen; thus, the chemical and corrosive activity of water does not increase. Equipping research institutes with electron accelerators, developing cheaper accelerators, and granting government support for pilot projects are key conditions for introducing ELT into water treatment practice.

Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium

Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO₂-TiO₂/Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO₂-TiO₂/Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N₂ adsorption-desorption. Results showed that RuO₂, TiO₂ and Nano-G were composited successfully, and RuO₂ and TiO₂ nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO₂-TiO₂/Nano-G composite was higher than that of TiO₂/Nano-G composite and Nano-G. Electrochemical performances of RuO₂-TiO₂/Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO₂-TiO₂/Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO₂-TiO₂/Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO₂, TiO₂ and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO₂-TiO₂/Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater.