Metal-Based Nanocomposite Materials for Efficient Photocatalytic Degradation of Phenanthrene from Aqueous Solutions

Remediation of phenanthrene by highly efficient CdS-SnS photocatalyst and its cytotoxic assessments

Cadmium sulfide-tin sulfide (CdS-SnS) nanoparticles are a novel kind of photocatalyst. These CdS-SnS nanoparticles are synthesized and characterized using UV-Vis, FT-IR, XRD, SEM-EDX, and DLS techniques, to understand their size distribution, crystalline nature, morphology, shape, optical properties, and elemental composition. This research offers insight into the efficient photocatalytic degradation of Phenanthrene (PHE) using CdS-SnS. The CdS-SnS NPs as photocatalyst can effectively photodegrade the polycyclic aromatic hydrocarbons (PAH) such as phenanthrene under simulated solar and UV light. UV-vis spectra of these nanoparticles exhibit peaks at 365 and 546 cm-1 respectively, the mean size of the CdS-SnS NPs in DLS is determined to be 78 nm. The CdS-SnS stretching frequency was observed at wave numbers below 700 cm-1, the absorption peak at 1123 cm-1 indicates the presence of C-N stretch or CS bond of thiourea, while the peak at 1350.38 cm-1 corresponds to the tris-amine C-N stretch in FT-IR. Additionally, the peaks observed at 2026 cm-1 indicate the presence of isothiocyanate (NCS). 1456.23 cm-1 represents the asymmetric scissor deformation vibration. EDAX revealed the presence of elemental Cd and Sn oxides. The antimicrobial studies showed that the CdS-SnS NPs at the concentration of 150 μg/mL, exhibit maximum inhibition (15 ± 1.25 mm) against the strains Proteus mirabilis followed by Staphylococcus epidermidis and Clostridium spp. Among fungal strains Colletotrichum spp. exhibits the maximum zone of inhibition (9 ± 0.25). This research also observed the cytotoxic effects of CdS-SnS NPs on HepG2 and ZF4 cells. HepG2 cells exhibited 50% inhibition at 50 μg/mL and 70% inhibition at 100 μg/mL concentrations, while ZF4 cells exhibited 50% inhibition at 50 μg/mL and 78% inhibition at 100 μg/mL concentrations, respectively. The parameters like concentration of PHE, concentration of CdS-SnS NPs, pH, and sources of irradiation on batch adsorption were examined to maximize the efficiency of the photodegradation process.

The implementation of ZnS-SnS BM NPs for phenanthrene degradation: An adsorptive photocatalyst approach and its toxicity studies in adult zebrafish

Phenanthrene is a persistent organic pollutant released by numerous industries. The purpose of the study is to construct a batch reactor for phenanthrene degradation using a bimetallic (BM) ZnS-SnS nanoparticle as a photocatalyst. ZnS-SnS BM NPs were used as a photocatalyst, employed from precursors Zinc acetate dihydrate and tin (II) chloride dihydrate, with crystalline cubic-shaped particle sizes. ZnS-SnS BM NPs were utilized in batch adsorption assays to assess the impact of phenanthrene degradation parameters on various PAHs (Polycyclic aromatic hydrocarbons) concentrations, pH levels, and irradiation sources. Adsorption kinetic and isotherm tests revealed that the pseudo-first order kinetic model, pseudo-second order kinetic model, and Langmuir isotherm model all fit effectively with the effective phenanthrene degradation using ZnS-SnS BM NPs. The degraded product were analyzed for GC-MS, revealing that organic pollutant phenanthrene was converted into harmless by-products like n-hexadecenoic acid, oleic acid, and octadecanoic acid. The toxicity of phenanthrene was observed to decrease with an increase in ZnS-SnS BM NPs concentration. ZnS-SnS BM NP concentration of 150 μg/mL, the zone of inhibition values was recorded highest zone of inhibition (19 ± 1.2 mm) against the strains S. epidermis followed by B. cereus and Clostridium spp. Further adult zebrafish were found to be less toxic to ZnS-SnS BM NPs after 96 h of exposure, with an LD50 of 100 μg/L. The toxicity escalated as concentrations increased. Behavior test showed normal swimming, learning, and memory in open tank and T-maze tests, while 100 μg/L showed pausing/frozen time in zebra fish therefore low doses are considered safe. Hence by employing ZnS-SnS BM NPs can be engaged in waste water treatment for PAH degradation.

G-C3N4-Ag composite mediated photocatalytic degradation of phenanthrene - A remedy for environmental pollution

In recent years, g-C3N4-Ag nanocomposite synthesis has gained considerable attention for its potential to treat polycyclic aromatic hydrocarbons (PAHs) and to act against bacteria and fungi. In this study, we present a novel approach to the synthesis of g-C3N4-Ag nanocomposite and evaluate its efficiency in both PAH removal and antimicrobial activity. The synthesis process involved the preparation of g-C3N4 by thermal polycondensation of melamine. The factors that affect the adsorption process of PAHs, like time, pH, irradiation type, and adsorbent dosage, were also evaluated. Isotherm models like Langmuir and Freundlich determined the adsorption capability of g-C3N4-Ag. In simulated models, phenanthrene was degraded to a maximum of 85% at lower concentrations of catalyst. The adsorption profile of phenanthrene obeys the pseudo-second-order and Freundlich isotherms pattern. The g-C3N4-Ag nanocomposite also exhibited antimicrobial activity against bacteria (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae) and fungi (Candida albicans). The present study is the first report stating the dual application of g-C3N4-Ag nanocomposite in reducing the concentration of PAH and killing bacterial and fungal pathogens. The higher adsorption capability proclaimed by g-C3N4-Ag nanocomposite shows the fabricated nanomaterial with great potential to remediate organic pollutants from the ecosystem.

In vitro analysis of novel trimetallic (Ag-Cu-Ni TNC) to handle benzene and benzopyrene pollutants in an aqueous environment

In this study, a trimetallic nanocomposite comprising Silver Copper-Nickel (Ag-Cu-Ni TNC) was synthesized and analysed for its efficiency in degrading benzene and benzopyrene, which has five fused benzene rings. Fabrication of trimetallic nanocomposites were characterized using UV spectroscopy, FTIR studies, SEM EDAX, and DLS results. XRD confirmed the cubic crystalline Fcc structure of Ag-Cu-Ni TNC. Photocatalytic degradation analysis revealed that Ag-Cu-Ni TNC has the efficient photocatalytic ability, and the optimum condition required for efficient degradation of benzene and benzopyrene was identified as 2 μg/mL of PAH molecule, 10 μg/mL of Ag-Cu-Ni TNC at pH 5, stirring time of 2 h placed under UV light. Based on these optimum conditions, kinetic and isotherm studies were performed, revealing that the adsorption of benzene and benzopyrene by Ag-Cu-Ni TNC fits well with the Pseudo-second order kinetic model and Freundlich isotherm model. Thus, our study's adsorption of PAH molecule from aqueous solution takes place through chemisorption and involves heterogeneous adsorption phenomena.

In vitro analysis of iron oxide (Fe3O4) nanoparticle mediated degradation of polycyclic aromatic hydrocarbons (PAHs) and their antimicrobial activity

To degrade anthracene, magnetite nanoparticles were produced using a simple co-precipitation process. The fabricated nanoparticles have been analyzed for structural and optical properties. XRD examination revealed that the produced Fe3O4 nanoparticles were cubic phase, having a mean crystallite dimension of 18.84 nm. DLS determined the hydrodynamic diameter of Fe3O4 nanoparticles to be 182 nm. UV-Vis research revealed that Fe3O4 nanoparticles absorb at 390 nm. A peak at 895 cm-1 in the FT-IR study indicated the metal-oxygen connection. The synthesized Fe3O4 nanoparticles demonstrated an effective photocatalytic performance towards anthracene degradation and was found to be 86.55%. Furthermore, Fe3O4 nanoparticles showed the highest antimicrobial activity against Bacillus subtilis was 19.43 mm. The present study is the first and foremost study determining the dual role of Fe3O4 nanoparticles towards bioremediation and biomedical applications.

Adsorption characteristic analysis of PAHs on activated carbon with different functional groups by molecular simulation

As widespread organic pollutants in the environment, polycyclic aromatic hydrocarbons (PAHs) greatly threaten human health. The adsorption technology has become one of the main methods to deal with PAHs because of its low cost, simple design, and no secondary pollution. Among them, solid media have strong adsorption capacities for PAHs and are widely used. In this work, activated carbon was chosen as the solid adsorbent. The adsorption behavior of three PAHs (naphthalene, anthracene, and phenanthrene) on activated carbon was investigated at the molecular level by Grand Canonical Monte Carlo (GCMC) method. The effects of different functional groups (amino, carboxyl, hydroxyl, carbonyl, and hydrogen groups) and temperature effect on the adsorption isotherms and heat of adsorption of PAHs on activated carbon were calculated. The results showed that the carbonyl functional group increased the adsorption of PAH molecules by the most considerable amount among all the functional groups. Acid functional groups were more favorable to the adsorption of PAHs than alkali functional groups. The adsorption capacity and heat of adsorption of PAHs decreased when the temperature increased. The adsorption performance of bicyclic aromatic hydrocarbons was more influenced by temperature than that of tricyclic aromatic hydrocarbons.

Metagenomic Analysis of Microbial Alliances for Efficient Degradation of PHE: Microbial Community Structure and Reconstruction of Metabolic Network

Polycyclic aromatic hydrocarbons are a widespread organic pollutant worldwide. In this study, a highly efficient phenanthrene (PHE)-degrading microbial community was enriched from oil extraction soil, which could degrade 500 mg/L PHE within 4 days. Using 16S rRNA sequencing, the dominant bacteria in this community at the phylum level were found to be Proteobacteria, Actinobacteria, and Firmicutes. Metagenomic annotation of genes revealed the metabolic pathways and the contribution of different bacteria to the degradation process. Pseudomonadaceae contributed multiple functional genes in the degradation process. This study revealed the functional genes, metabolic pathways, and microbial interactions of the microbial community, which are expected to provide guidance for practical management.