New shape-selectivity discovered on graphene-based materials in catching tobacco specific nitrosamines

Effects of reduced graphene oxide nanomaterials on transformation of 14C-triclosan in soils

Increasing use and release of graphene nanomaterials and pharmaceutical and personal care products (PPCPs) in soil environment have polluted the environment and posed high ecological risks. However, little is understood about the interactive effects and mechanism of graphene on the behaviors of PPCPs in soil. In the present study, the effects of reduced graphene oxide nanomaterials (RGO) on the fate of triclosan in two typical soils (S1: silty loam; S2: silty clay loam) were investigated with 14C-triclosan, high-resolution mass spectrometry, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations, and microbial community structure analysis. The results showed that RGO prolonged the half-life of triclosan by 23.6-51.3 %, but delayed the formation of transformed products such as methyl triclosan and dechlorinated dimer of triclosan in the two typical soils. Mineralization of triclosan to 14CO2 was inhibited by 48.2-79.3 % in 500 mg kg-1 RGO in comparison with that in the control, whereas the bound residue was 54.2-56.4 % greater than the control. RGO also reduced the relative abundances of triclosan-degrading bacteria (Pseudomonas and Sphingomonas) in soils. Compared to silty loam, RGO more effectively inhibited triclosan degradation in silty clay loam. Furthermore, the DFT calculations suggested a strong association of the adsorption of triclosan on RGO with the van der Waals forces and π-π interactions. These results revealed that RGO inhibited the transformation of 14C-triclosan in soil through strong adsorption and triclosan-degrading bacteria inhibition in soils. Therefore, the presence of RGO may potentially enhance persistence of triclosan in soil. Overall, our study provides valuable insights into the risk assessment of triclosan in the presence of GNs in soil environment.

Advanced Materials Design for Adsorption of Toxic Substances in Cigarette Smoke

Cigarettes, despite being economically important legal consumer products, are highly addictive and harmful, particularly to the respiratory system. Tobacco smoke is a complex mixture containing over 7000 chemical compounds, 86 of which are identified to have "sufficient evidence of carcinogenicity" in either animal or human tests. Thus, tobacco smoke poses a significant health risk to humans. This article focuses on materials that help reduce the levels of major carcinogens in cigarette smoke; these include nicotine, polycyclic aromatic hydrocarbons, tobacco-specific nitrosamines, hydrogen cyanide, carbon monoxide, and formaldehyde. Specifically, the research progress on adsorption effects and mechanisms of advanced materials such as cellulose, zeolite, activated carbon, graphene, and molecularly imprinted polymers are highlighted. The future trends and prospects in this field are also discussed. Notably, with advancements in supramolecular chemistry and materials engineering, the design of functionally oriented materials has become increasingly multidisciplinary. Certainly, several advanced materials can play a critical role in reducing the harmful effects of cigarette smoke. This review aims to serve as an insightful reference for the design of hybrid and functionally oriented advanced materials.

Fabrication of Cellulose Filters Incorporating Metal-Organic Frameworks for Efficient Nicotine Adsorption from Cigarette Smoke

To prevent negative effects of smoking, there is constant research on the development of various types of sustainable filter materials, capable of removing toxic compounds present in cigarette smoke. Because of the extraordinary porosity and adsorption properties, metal-organic frameworks (MOFs) represent promising adsorbents for volatile toxic molecules such as nicotine. This study reports new hybrid materials wherein six types of common MOFs of different porosity and particle size are incorporated into sustainable cellulose fiber from bamboo pulp, resulting in a series of cellulose filter samples abbreviated as MOF@CF. The obtained hybrid cellulose filters were fully characterized and investigated in nicotine adsorption from cigarette smoke, using a specially designed experimental setup. The results revealed that the UiO-66@CF material features the best mechanical performance, facile recyclability, and excellent nicotine adsorption efficiency that attains 90% with relative standard deviations lower than 8.80%. This phenomenon may be caused by the large pore size, open metal sites, and high loading of UiO-66 in cellulose filters. Additionally, the high adsorption capacity showed almost 85% removal of nicotine after the third adsorption cycle. The DFT calculation methods allowed further investigation of the nicotine adsorption mechanism, showing that the energy difference between HOMO and LUMO for UiO-66 was the closest to that of nicotine, which further proves the adsorption ability of nicotine by this material. Owing to the flexibility, recyclability, and excellent adsorption performance, the prepared hybrid MOF@CF materials may find prospective applications in nicotine adsorption from cigarette smoke.

Two-Dimensional Infrared Correlation Spectroscopy, Conductor-like Screening Model for Real Solvents, and Density Functional Theory Study on the Adsorption Mechanism of Polyvinylpolypyrrolidone for Effective Phenol Removal in an Aqueous Medium

The discharge of industrial effluents, such as phenol, into aquatic and soil environments is a global problem due to its serious negative impacts on human health and aquatic ecosystems. In this study, the ability of polyvinylpolypyrrolidone (PVPP) to remove phenol from an aqueous medium was investigated. The results showed that a significant proportion of phenol (up to 74.91%) was removed using PVPP at pH 6.5. Isotherm adsorption experiments of phenol on PVPP indicated that the best-fit adsorption was obtained using Langmuir models. The response peaks of the hydroxyl groups of phenol (OH) and the carboxyl groups (i.e., C=O) of PVPP were altered, indicating the formation of a hydrogen bond between the PVPP and phenol during phenol removal, as characterized using 1D and 2D IR spectroscopy. The resulting complexes were successfully characterized based on their thermodynamic properties, Mulliken charge, and electronic transition using the DFT approach. To clarify the types of interactions taking place in the complex systems, quantum theory of atoms in molecules (QTAIM) analysis, reduced density gradient noncovalent interaction (RDG-NCI) approach, and conductor-like screening model for real solvents (COSMO-RS) approach were also successfully calculated. The results showed that the interactions that occurred in the process of removing phenol by PVPP were through hydrogen bonding (based on RDG-NCI and COSMO-RS), which was identified as an intermediate type (∇2ρ(r) > 0 and H < 0, QTAIM). To gain a deeper understanding of how these interactions occurred, further characterization was performed based on adsorption mechanisms using molecular electrostatic potential, global reactivity, and local reactivity descriptors. The results showed that during hydrogen bond formation, PVPP acts as a nucleophile, whereas phenol acts as an electrophile and the O9 atom (i.e., donor electron) reacts with the H22 atom (i.e., acceptor electron).

Non-covalent and covalent immobilization of papain onto Ti3C2 MXene nanosheets

Papain was immobilized onto Ti₃C₂ MXene nanosheets by physical adsorption and physical adsorption combined with covalent crosslinking with glutaraldehyde. Ti₃C₂ MXene nanosheets were prepared by hydrofluoric acid etching method. The resulting products were well characterized by SEM, BET, XRD, FTIR, XPS. The optimized immobilization conditions are pH 6.5, immobilization time of 20 h, immobilization temperature of 10℃, and 10 mL 2 mg mL^-1 papain, the amount of papain immobilized was 156 mg g^-1, the activity of the immobilized papain determined was 1701 U∙g^-1. The immobilized papain exhibited enhanced pH and temperature endurances, immobilized papain also showed improved storage stability (39.25 % and 65.57 % after 20 days of storage at 4 °C). papain reusability was significantly improved after immobilization and it retained more than 50 % of its initial activity after 5 repeated cycles. Interestingly, the results of immobilized enzymes demonstrated that the immobilization of enzymes on Ti₃C₂ MXene is feasible. Such approach could be transferred to other support systems for anchoring enzyme.

Magnetic solid-phase extraction of tobacco-specific N-nitrosamines using magnetic graphene composite as sorbent

Tobacco-specific N-nitrosamines are carcinogenic components in mainstream cigarette smoke. To explore tobacco-specific N-nitrosamine release levels in cigarettes, a magnetic solid-phase extraction procedure using magnetic graphene composite as sorbent for fast enrichment of tobacco-specific N-nitrosamine was developed. Under optimal conditions, a tobacco-specific N-nitrosamine determination method was successfully proposed by combining magnetic solid-phase extraction procedure and high-performance liquid chromatography coupled with tandem mass spectrometry. The method's limit of detection for tobacco-specific N-nitrosamines in mainstream cigarette smoke ranged from 0.018 to 0.057 ng/cigarette. Good linearities were obtained with correlation coefficients above 0.9992. The accuracies of tobacco-specific N-nitrosamines in a spiked mainstream cigarette smoke sample were from 89.3 to 109.4%, with a relative standard deviation of less than 11.2%. The proposed method has the merits of rapidity and high sensitivity. Finally, the method was successfully applied to tobacco-specific N-nitrosamine analysis in real samples.

Efficiently capturing tobacco specific nitrosamines with Hβ zeolite in solution

The high-efficiency capture of Tobacco Specific Nitrosamines by Hβ zeolite in solution is reported for the first time, along with the adsorption of 4-methylnitrosamino-1-3-pyridyl-1-butanone in aqueous solution. Different from other zeolites such as NaZSM-5, the specific pore size of Hβ exerted a crucial function endowing the zeolite a higher removal of TSNA and selectivity of NNK. The adsorption thermodynamics of NNK by Hβ in aqueous adsorption was fitted to Temkin adsorption model with a linearly decreasing isosteric heat of adsorption. In addition, the adsorptive capacity of Hβ zeolite for NNK reached over 70 mg g-1, offering a powerful sorbent of TSNA to protect environment.