Effective Remediation of an Antibacterial Drug from Aqua Matrix Using CaFe2O4/ZrO2 Nanocomposite Derived via Inorganic Chemical Pathway: Statistical Modelling by Response Surface Methodology

Acmella oleracea induced nanostructured Ca2Fe2O5 for evaluation of photo catalytic degradation of cardiovascular drugs and bio toxicity

Biosynthesis of nanoparticles is increasingly becoming popular due to the demand for sustainable technologies worldwide. In the present investigation, Acmella oleracea plant extract fuelled combustion technique followed by calcination at 600 °C was adopted to prepare nanocrystalline Ca₂Fe₂O₅. The prepared nano compound was characterised using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Ultra Violet (UV) spectroscopy, Infrared (IR) spectroscopy and its role was assessed for photocatalytic pollutant degradation along with bactericidal action in the concentration range of 1 μg/mL to 320 μg/mL. The photocatalytic degradation efficiency of pollutant drugs Clopidogrel Bisulphate and Asprin used for cardiovascular disorders is around 80% with 10 mg/L photocatalyst. The results showed that the photocatalytic activity increased with rising pH from 4, to 10, along with a significant antibacterial action against Enterococcus faecalis bacteria and a slight cytotoxic effect at high concentrations. The antibacterial property was reinforced by Minimum inhibitory concentrations (MIC) and Minimum bactericidal concentrations (MBC) studies with an average value of 0.103 at 600 nm which was further proved by significant anti-biofilm activeness. Adhesion tests in conjunction with cryogenic-scanning electron microscopy displayed a morphological change through agglomeration that caused an expansion in nano particles from 181 nm to 223.6 nm due to internalization followed by inactivation of bacteria. In addition, the non-toxicity of nano Ca₂Fe₂O₅ was confirmed by subtle cytological changes in microscopic images of Allium Cepa root cells in the concentration range 0.01-100 μg/mL and a slight inhibition in HeLa cell proliferation indicated by IC₅₀ value of 170.94 μg/mL. In total, the current investigation for the first time reveals the application of bio based synthesis of Nano Ca₂Fe₂O₅ to new possibilities in bioremediation namely degrading cardiovascular pharmaceutical pollutants, endodontic antibacterial action and cytological activity.

Mesoporous carbon structure impregnated with 2D engineered zirconium: A sustainable adsorbent for the removal of dyes from the aqueous solution

The key designing of new breeds of the adsorbents aimed to improve the physical, chemical and textural morphology along with surface functionalization, selectivity toward the contaminants, and regenerations efficiency. In this aspect, two adsorbents named wet oxidative and ultrasonicated zirconium impregnated composite, have been synthesized through two routes, i.e., wet oxidation and ultrasonication. In wet oxidation method, carbon-based materials are oxidized using an oxidant followed by impregnation, while in ultrasonication assisted route, the impregnation is carried out using acoustic phenomenon. The characterization study revealed that the wet oxidation process is more competent in impregnating zirconium and developing diverse porosity and functionalities. The maximum adsorption capacity of wet oxidative adsorbent was 812 mg/g for Reactive Blue 19 and 203.18 mg/g for Methylene Blue, that accentuated the efficiency of the adsorbent over raw activated carbon. The electrostatic interaction, hydrogen-bonding and ligand exchange phenomenon are the involved adsorption mechanism for dyes. The regeneration study finally asserts that the wet oxidative adsorbent shows an insignificant decrease in its capacity up to the 5^th-cycle (i.e., 87.67% removal at 5^th cycle) as compared to raw AC (46.71% removal at 5th cycle). Further, a continuous fixed-bed column study revealed a significant correlation between experimental breakthrough data and kinetic data. Thus, the developed adsorbent has a sedulous adsorption capacity to remove the most stubborn toxic dyes and can be used in industrial-scale applications.

Fabrication of nitrogen-doped graphene nanosheets anchored with carbon nanotubes for the degradation of tetracycline in saline water

The treatment of wastewater with high salinity is still a challenge because of the quenching effect of various anions on radical processes. The nonradical process may be a more promising pathway. Herein, a 3D structured nitrogen-doped graphene nanosheet anchored with carbon nanotubes (N-GS-CNTs) was prepared by direct pyrolysis of K₃Fe(CN)₆. The as-prepared catalyst can effectively activate peroxymonosulfate (PMS) for mineralization of tetracycline (TC) over a wide pH range (from 3 to 11) and even in high saline water (500 mM Cl^-, HCO₃^-, etc.). The degradation mechanism was elucidated by both experimental characterizations and DFT calculations. The high catalytic efficiency was attributed to accelerated electron transfer from donor (TC) to acceptor (PMS) in the presence of the catalyst, which acts as electron shuttle mediators to promote a nonradical process. At the same time, the catalyst also enhances the production of singlet oxygen (¹O₂), hence further increasing the degradation rate. This study not only provides a simple method for synthesizing N-GS-CNT catalysts but also provides new insights into the electron transfer pathway for the removal of organic pollutants under high salinity conditions.

Enhanced PAHs-contaminated site soils remediation by mixed persulfate and calcium peroxide

Polycyclic aromatic hydrocarbons (PAHs) remain in the site soils after relocated coking plants and oil refineries pose huge constraints to the subsequent land utilization. However, single persulfate (PS) or calcium peroxide (CP) remediation strategies can only inefficiently oxidize some PAHs in soil. This work sought to optimize PS/CP oxidation remediation strategy and verify its practical application effect in soil samples spiked with PAHs. The results showed that the mixed PS/CP oxidation remediation was better than the single oxidants strategies; it had high remediation performance in different particles and pollution loads of PAHs-contaminated soils. Simultaneously, reactive radicals (SO₄·^- and ·OH) were detected, and one side-product (CaSO₄) was characterized. This work optimized the mixed PS/CP system (0.3 mol/L PS, and 8 g/kg CP, together with 0.18 mol/L Fe²⁺ and 0.11 mol/L C₂O₄^2-), and the corresponding Total-PAHs removal rate was 85.41%. Compared to the cost based on benzopyrene (BaP) removal, the study provided a cost-effective mixed PS/CP oxidation remediation technique (1.22 $/ton), widely applicable in soils polluted with various organic contaminants represented such as PAHs.

Fate of sulfamethoxazole and potential formation of haloacetic acids during chlorine disinfection process in aquaculture water

There exist two common processes in fishery culture, i.e. antibiotic addition to reduce disease in fishery, and chlorination disinfection to inhibit infectious pathogenic microorganisms. However, antibiotic residues might play important reverse side roles for both aquaculture water pollution and potential formation of chlorination side products. Herein, the transformation behaviour, intermediates analyses and conversion pathway of antibiotic sulfamethoxazole (SMX), and potential generation of halogenated acetic acids (HAAs) in the process of chlorination in fishery water were examined, and the results revealed that the decomposing of SMX satisfied a pseudo first-order kinetic equation. Both the addition of available chlorine and high temperature had affirmative influences on the decontamination of SMX and production of HAAs, and the near-neutral pHs promoted the removal of SMX and generation of HAAs. Br^- was favorable for the removal of SMX and yields of brominated acetic acids (Br-AAs). Based on the identified intermediate products, the transformation path of SMX in chlorination process was propounded, to wit, the C-S and S-N bonds in the SMX molecules were firstly cracked, and the primeval intermediate groups are then transformed to form chloroanilines, chlorophenols, etc., and subsequently, chlorophenols were chlorinated and ring-opened to generate toxic HAAs. This study might be meaningful to evaluate the effective removal of sulfonamide antibiotic residues and the potential generation of halogenated DBPs (H-DBPs) when chlorinated in aquaculture water.