Degradation of Levofloxacin by a green zero-valent iron-loaded carbon composite activating peroxydisulfate system: Reactivity, products and mechanism

Effective removal of Cr(VI) from water by ball milling sulfur-modified micron zero-valent iron：Influencing factors and removal mechanism

To address the issues of ZVI's susceptibility to oxidation and aggregation, ball milling and Na2S·9H2O modification were employed on ZVI to enhance its efficiency in removing Cr(VI) from effluent. The characterization results expressed that S-mZVIbm had mesoporous and macroporous structures, enabling successful capture of Cr(VI). Moreover, S-mZVIbm had the highest adsorption capacity for Cr(VI) (350.04 mg/g) at pH = 2.00 and reached kinetic equilibrium within 420 min. Furthermore, the adsorption of Cr(VI) by S-mZVIbm conformed to the Avrami-fractional-order model, demonstrated that the adsorption process indicated a complex multi-adsorption process. Meanwhile, the adsorption also fit to Langmuir and Sips models, suggesting monolayer-level adsorption with heterogeneous sites located on S-mZVIbm. The S-mZVIbm could enhance Cr(VI) adsorption through various synergistic mechanisms, such as electrostatic interaction, chemical precipitation, surface complexation, and reduction. Overall, this research presented an innovative perspective for the modification of ZVI, and S-mZVIbm could be widely applied in the practical remediation of wastewater containing Cr(VI).

Synergic effect of Fe-Sn-Ag tri-metallic nanoparticles synthesized by a green chemistry method on their photocatalytic activity

This research work reports a novel co-precipitation methodology for the green synthesis of tri-metallic nanoparticles (TMNPs) of type: magnetite (Fe3O4NPs), tin (Sn), and silver (Ag), using an aqueous extract of Crocus sativus (ExCs) as a stabilizing agent (TMNPs Fe3O4NPs@Sn-Ag/ExCs), for the first time. The resulting TMNPs Fe3O4NPs@Sn-Ag/ExCs were characterized by Fourier-transform Infrared Spectroscopy (FT-IR), physical adsorption of nitrogen gas at low temperature by Brunauer-Emmett-Teller (BET) analysis, X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field-Emission Scanning Microscopy-Energy Dispersive Spectroscopy (FE-SEM-EDS) and Transmission Electron Microscopy-Energy Dispersive Spectroscopy (TEM-EDS). The TEM-EDS analysis presented TMNPs Fe3O4NPs@Sn-Ag/ExCs with a spherical morphology and a mode size of 13 nm. The crystallographic study of the TMNPs Fe3O4NPs@Sn-Ag/ExCs showed a proportionality between the full width at half maximum (FWHM) XRD peaks and the crystallite size, as well as the dhkl spacing (111) associated with the Ag in the TMNPs structure. The TMNPs Fe3O4NPs@Sn-Ag/ExCs were successfully used in the photodegradation of two over the counter commercial dyes, sky blue No. 39 and emerald green No. 27, resulting in a 100% efficiency for both dyes (90 min of reaction), using sunlight or LED radiation, and a high mineralization rate (>99% TOC removal).

Characterization of chitosan- and β-cyclodextrin-modified forms of magnesium-doped hydroxyapatites as enhanced carriers for levofloxacin: loading, release, and anti-inflammatory properties

An advanced form of magnesium-rich hydroxyapatite (Mg·HAP) was modified with two types of biopolymers, namely chitosan (CH/Mg·HAP) and β-cyclodextrin (CD/Mg·HAP), producing two types of bio-composites. The synthesized materials were developed as enhanced carriers for levofloxacin to control its loading, release, and anti-inflammatory properties. The polymeric modification significantly improved the loading efficiency to 281.4 mg g-1 for CH/Mg·HAP and 332.4 mg g-1 for CD/Mg·HAP compared with 218.3 mg g-1 for Mg·HAP. The loading behaviors were determined using conventional kinetic and isotherm models and mathematical parameters of new equilibrium models (the monolayer model of one energy). The estimated density of effective loading sites (Nm (LVX) = 88.03 mg g-1 (Mg·HAP), 115.8 mg g-1 (CH/Mg·HAP), and 138.5 mg g-1 (CD/Mg·HAP)) illustrates the markedly higher loading performance of the modified forms of Mg·HAP. Moreover, the loading energies (<40 kJ mol-1) in conjunction with the capacity of each loading site (n > 1) and Gaussian energies (<8 kJ mol-1) signify the physical trapping of LVX molecules in vertical orientation. The addressed materials validate prolonged and continuous release behaviors. These behaviors accelerated after the modification procedures, as the complete release was identified after 160 h (CH/Mg·HAP) and 200 h (CD/Mg·HAP). The releasing behaviors are regulated by both diffusion and erosion mechanisms, according to the kinetic investigations and diffusion exponent analysis (>0.45). The entrapping of LVX into Mg·HAP induces its anti-inflammatory properties against the generation of cytokines (IL-6 and IL-8) in human bronchial epithelia cells (NL20), and this effect displays further enhancement after the integration of chitosan and β-cyclodextrin.

Novel combination of iron-carbon composite and Fenton oxidation processes for high-concentration antibiotic wastewater treatment

The research presented herein explores the development of a novel iron-carbon composite, designed specifically for the improved treatment of high-concentration antibiotic wastewater. Employing a nitrogen-shielded thermal calcination approach, the investigation utilizes a blend of reductive iron powder, activated carbon, bentonite, copper powder, manganese dioxide, and ferric oxide to formulate an efficient iron-carbon composite. The oxygen exclusion process in iron-carbon particles results in distinctive electrochemical cells formation, markedly enhancing wastewater degradation efficiency. Iron-carbon micro-electrolysis not only boosts the biochemical degradability of concentrated antibiotic wastewater but also mitigates acute biological toxicity. In response to the increased Fe2+ levels found in micro-electrolysis wastewater, this research incorporates Fenton oxidation for advanced treatment of the micro-electrolysis byproducts. Through the synergistic application of iron-carbon micro-electrolysis and Fenton oxidation, this research accomplishes a significant decrease in the initial COD levels of high-concentration antibiotic wastewater, reducing them from 90,000 mg/L to about 30,000 mg/L, thus achieving an impressive removal efficiency of 66.9%. This integrated methodology effectively reduces the pollutant load, and the recycling of Fe2+ in the Fenton process additionally contributes to the reduction in both the volume and cost associated with solid waste treatment. This research underscores the considerable potential of the iron-carbon composite material in efficiently managing high-concentration antibiotic wastewater, thereby making a notable contribution to the field of environmental science.