N-containing Functional Groups Research Articles

Controlling the structure of nitrogen-doped zeolite-templated carbon for CO2 capture based on the synthesis conditions

The surface chemistry and the textural properties of nitrogen-doped zeolite-templated carbon materials (N-ZTC) are decisive for their functionality in CO2 capture. This study analyses how the synthesis conditions affect the structure, formation of N-containing functional groups, thermal stability and CO2 capture of N-ZTC in comparison with nitrogen-free ZTC. Faujasite as a hard template and chemical vapour depositions (CVD) with propene and acetonitrile were used for the synthesis of ZTC and N-ZTC, respectively. XRD, SEM, N2 and CO2 sorption, XPS and TG/DSC analyses showed that the structural ordering and microporous volume in N-ZTC increases with increasing synthesis temperature. Conversely, at higher temperatures, the content of basic pyridinic groups in N-ZTC decreases in favour of stable graphitic nitrogen. The Lewis acid−base interaction of CO2 with the pyridinic groups provides the highest adsorption heats, the highest affinity for CO2 compared to N2 and enhances CO2/N2 selectivity (CO2/N2 selectivities of 127, 95, 89, and 66 for N-ZTC750°C, N-ZTC800°C, N-ZTC850°C and ZTC, respectively). The maximum adsorption capacity was achieved for N-ZTC800°C still yielding a high content of basic groups and a larger micropore volume compared to N-ZTC750°C. The decisive factor for the selectivity is thus the presence of basic centres attainable in N-ZTC at a lower synthesis temperature. The maximum adsorption capacity is associated with a large microporous volume and basic centres in N-ZTC synthesised at medium temperatures. The energy of CO2 adsorption by Lewis acid−base interactions and well-developed micropores are decisive for high selectivity and large adsorption capacity for efficient CO2 capture using N-ZTC materials.

Preparation of porous lignocellulose biochar adsorbent by cold isostatic pressing pretreatment and study on Hg (II) adsorption properties of C and N dual activity sites

Utilizing corn straw (CS) mainly composed of lignocellulose to prepare physically modified biochar (PCSB) via cold isostatic pressing (CIP) in order to increase the biochar’ s Hg (II) adsorption capacity. The results of the characterization indicated that CIP pretreatment renders PCSB-400′ s structure more porous and higher N content of 16.65 %, leading to more N-containing functional groups partaking in the adsorption process. PCSB-400 adsorbed Hg (II) primarily via C/N synergistic complexation and electrostatic attraction between pores, in addition to the presence of redox reactions of surface functional groups on PCSB-400. The adsorption experiment reveals that PCSB-400 has a high selectivity for the adsorption of Hg (II). The adsorption process of Hg (II) by PCSB-400 more closely resembles the Langmuir model and pseudo-first-order adsorption kinetics equation. The adsorption quantity at saturation is 282.52 mg/g at 25 °C. This paper provided an effective idea to selectively remove Hg (II) in wastewater.

Synthesis of natural heteroatom co-doped porous carbon by co-pyrolysis of kapok tree and peanut bran coupled with microwave activation

The application of biomass-derived porous carbon in supercapacitors should focus on heteroatom doping and modulation of pore structure. This work presented a technique for synthesizing natural heteroatom co-doped porous carbon by co-pyrolysis coupled with microwave activation of the kapok tree (KT) and peanut bran (PB). PB is a natural heteroatom donor and a precursor of porous carbon. Some S-containing radicals and N-containing functional groups in PB are successfully retained in the biochar, facilitating heteroatom doping in NHDPC. When the mixing ratio of KT and PB is 1:1, the mesoporous volume of NHDPC-5PB can reach 1.81 cm3/g. Relative to the porous carbon NHDPC-0PB synthesized solely through KT pyrolysis, the mesoporous volume of NHDPC-5PB increases by 74.04 %. Moreover, the specific capacitance of NHDPC-5PB at 0.2 A/g attains 346.8 F/g, which is a 36.6 % increase compared to NHDPC-0PB. This study presents a new strategy to prepare natural heteroatom co-doped porous carbon by co-pyrolysis of heteroatom-rich biomass as a heteroatom donor with lignocellulosic biomass.

Facile hydrothermal assembly of three-dimensional GO-MTZE composite and its adsorption properties toward Cu2.

Three-dimensional (3D) graphene oxide (GO)-based aerogels, GO and 4-methyl-5-thiazoleethanol (MTZE) composites, were prepared by a facile hydrothermal method. Due to the hydrogen bonding and π-π stacking interactions, the produced 3D GO-MTZE composites possessed large cylindrical structures. The morphologies, composition, and chemical states of 3D GO-MTZE3:1 composite were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and N2 adsorption-desorption isotherms based on the Brunauer-Emmett-Teller (BET) method. The existence of nitrogen (N)-containing heterocyclic system and oxygen (O)-containing branched chain of MTZE contributed to the formation of 3D structures, while the complexation effect of heterocyclic sulfur (S)- and N-containing functional groups of MTZE for metal cations dominated the adsorption performance of 3D GO-MTZE3:1 composite, which could selectively adsorb copper ions (Cu2+). In addition, the better hydrophobic property of 3D GO-MTZE3:1 composite facilitates its facile recycling from aqueous solution after adsorption. The adsorption data of 3D GO-MTZE3:1 composite toward Cu2+ fitted well (R2 = 0.9996) with the linear pseudo-second-order kinetic model, giving an equilibrium rate constant (k2) of 0.0187gmg-1min-1. The linear Langmuir isothermal model could more accurately describe the experimental data, indicating the adsorption process is mainly dominated by the complexation interactions between MTZE and Cu2+. The thermodynamic parameters of ΔG° (< 0), ΔH° (> 0), and ΔS° (> 0) further indicate that the adsorption is a spontaneous and endothermic, confirming that the complexation between Cu2+ and 3D GO-MTZE3:1 composite occurs. Due to its high selectivity for Cu2+, good hydrophobicity, and excellent stability, the developed 3D GO-MTZE3:1 composite possesses might be promisingly used in the aqueous selective enrichment/removal of Cu2+.

O vacancy-rich doped WO3/GF as a novel electrode for an aqueous DHAQ/ K4Fe(CN)6 redox flow battery

In this study, a graphite felt (GF) electrode was modified with N and S heteroatoms before being loaded with Ti-doped or Nb-doped WO3 to produce Ti-WO3/GF-N-S and Nb-WO3/GF-N-S electrodes. X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy were used to analyze the crystal structure, morphology, and elemental state of the modified GF electrodes and investigate the impact of nonmetallic and metallic element doping. The influence of metal doping on the electronic distribution of the oxide was determined using first-principle calculations. The electrochemical properties of the modified GF were studied using cyclic voltammetry, electrochemical impedance spectroscopy, and single-cell tests. The results showed that Ti or Nb doping changed the energy band structure, bond length, and bond angle in the WO3 crystal and formed O vacancies. The chemical properties of Ti and Nb resulted in different numbers of O vacancies for the two doped-WO3.The doping of N and S heteroatoms on the carbon fibres altered the O vacancy concentration of WO3. The synergism between the two doping methods accelerated electron transfer in the anthraquinone redox reaction. In addition, the N-containing functional groups provide lone-pair electrons, which accelerate electron transfer and anthraquinone adsorption. Therefore, compared to the pristine GF, the discharge capacities of the Ti-WO3/GF-N-S and Nb-h-WO3/GF-N-S graphite GF electrodes increased by 58 % and 41 %, respectively, and the Nb-h-WO3/GF-N-S graphite GF electrodes exhibited a good capacity retention rate. This study broadens the practical applications of aqueous anthraquinone redox flow batteries.

Effects of cold plasma treatment on the biological performances of decellularized bovine pericardium extracellular matrix-based films for biomedical applications

Aim: Since decades, decellularized extracellular matrix (dECM)-derived materials have received worldwide attention as promising biomaterials for tissue engineering and biomedical applications. Soluble dECM is a versatile raw material that can be easily engineered into the desired shapes and structures. However, there are still some limitations restricting its use, including low hydrophilicity and smooth surfaces, which negatively influence cell adhesion/spreading. The objective of the present study was to investigate surface modification by nitrogen/hydrogen (N2/H2) low-pressure cold plasma treatment as a potential technique to improve the biological response of bovine pericardium dECM films. Methods: Bovine pericardium dECM was enzymatically digested and lyophilized prior to the preparation of thin films via solvent-casting method. Changes in surface properties after plasma treatment were investigated using water contact angle (WCA) and X-ray photoelectron spectroscopy (XPS) measurements. Immunofluorescence staining and resazurin assay for human dermal fibroblasts (HDFs) cultured on the dECM films were used to assess the bioactivity of dECM films. Finally, the hemocompatibility of the films was investigated via clotting time and hemolysis assay. Results: WCA and XPS results revealed that oxygen (O)- and N-containing functional groups were incorporated onto the film surface and an increase in hydrophilicity was observed after plasma treatment. In vitro experiments showed that cell adhesion in plasma-treated dECM films is much faster if compared to the untreated controls. Moreover, the fibroblast proliferation increased after plasma surface modifications. Finally, the hemocompatibility analysis results indicated a delayed blood clotting and no hemolytic effects for all the tested samples. Conclusions: These findings confirmed the potential of dECM as raw material for biocompatible thin films fabrication. Additionally, plasma surface treatment emerged as an eco-friendly and cost-effective strategy to enhance in vitro cell attachment and proliferation on dECM films, expanding their applications in biomedicine.

Mechanisms for NOx emission control and ash deposition mitigation in sludge-coal blend combustion

This paper introduces the coupled treatment of alkali and alkaline earth metals (AAEMs)-rich coal with ferric sludge as a method to efficiently and economically control sludge NOx emissions and mitigate coal ash deposition through fuel interactions. We utilized a pilot-scale drop tube furnace to quantify NOx emissions and ash deposition, supported by spectral and energy dispersive analyses. The results demonstrated co-combustion controls NOx emissions by catalyzing the reaction between char and NO and the transformation into more stable N-containing functional groups. It also facilitates the formation of harmless N2 instead of NOx by enabling Ca/Fe-based minerals to react with protein and pyrrolic nitrogen. At 950 °C, blending 10% ferric sludge mitigated ash deposition, thanks to the capture and dilution effect of Si/Al/Fe-based minerals in ferric sludge. However, blending ferric sludge aggravated ash deposition of AAEMs-rich coal at 1250 °C, due to the formation of eutectics by Fe-based minerals and Ca/Na-based feldspars. Besides, the control of NOx was reduced at 1250 °C. Therefore, the co-combustion of AAEMs-rich coal with 10% ferric sludge at 950 °C exhibited excellent performance in both emission control and ash deposition mitigation. This study, grounded in the characteristics of minerals, provides a theoretical foundation for the efficient and economical in-situ control of NOx emissions and ash deposition. It advances the development of low-carbon, environmentally friendly technologies for coupled sludge and coal combustion.

Enhancing Iodine Capture of Porous Organic Cages through N-Heteroatom Engineering.

Iodine radioisotopes, produced or released during nuclear-related activities, severely affect human health and the environment. The efficient removal of radioiodine from both aqueous and vapor phases is crucial for the sustainable development of nuclear energy. In this study, we propose an "N-heteroatom engineering" strategy to design three porous organic cages with N-containing functional groups for efficient iodine capture. Among the molecular cages investigated, FT-Cage incorporating tertiary amine groups and RT-Cage with secondary amine groups show higher adsorption capacity and much faster iodine release compared to IT-Cage with imine groups. Detailed investigations demonstrate the superiority of amine groups, along with the influence of crystal structures and porosity, for iodine capture. These findings provide valuable insights for the design of porous organic cages with enhanced capabilities for capturing iodine.

Machine-learning-aided prediction and engineering of nitrogen-containing functional groups of biochar derived from biomass pyrolysis

Biochar, derived through biomass pyrolysis, is an emerging carbonaceous material with significant potential in various applications. The performance of biochar in applications depends heavily on its surface characteristics, including its content of N-containing functional groups. In this study, machine learning (ML) was used for the prediction and engineering of biochar N-containing functional groups, specifically amine-N (N-A), pyrrolic-N (N-5), and pyridinic-N (N-6). The single-target random forest model accurately predicted N recovery in biochar (char-N yield) and N-A, N-5, and N-6 contents, achieving test R2 of 0.91–0.97. Model interpretations revealed that pyrolysis temperature was the most influential factor in predicting char-N yield, N-A, N-5, and N-6. The multi-target random forest model achieved an average test R2 of 0.93, and it was used to optimize pyrolysis parameters for designing biochar N-functional groups. This process was followed by experimental verification. Relative errors for the three N-containing functional groups were mostly within 15% (18.4% on average). The favorable results obtained from experimental verification demonstrate the significant potential of ML in biochar engineering.

Enhanced Peroxydisulfate (PDS) Activation for Sulfamethoxazole (SMX) Degradation by Modified Sludge Biochar: Focusing on the Role of Functional Groups

Modified sludge biochar, recognized for its notable economic and environmental benefits, demonstrates potential as an effective catalyst for peroxydisulfate (PDS) activation. Nevertheless, the specific mechanisms underlying its catalytic performance require more comprehensive investigation. In this study, a modified biochar (TSBC) doped with oxygen (O) and nitrogen (N) atoms was synthesized from sewage sludge and tannin extract, which significantly enhanced the activation of PDS for the degradation of sulfamethoxazole (SMX). The TSBC/PDS system demonstrated robust performance for SMX degradation, achieving over 90% efficiency over a wide pH range (3–10). Subsequent quenching experiments demonstrated that TSBC predominantly catalyzed PDS to generate O21, which effectively degraded SMX via a non-radical pathway. The O- and N-containing functional groups in TSBC were identified as the primary catalytic sites. Besides, density functional theory (DFT) calculations revealed that the incorporation of graphitic N significantly improved the adsorption capacity of PDS on the TSBC surface. Furthermore, based on the identification of intermediates and theoretical calculations, SMX was degraded mainly by two different pathways: S-N cleavage and O21 oxidation. This study offers a foundational framework for the targeted modification of sludge biochar, thereby expanding its applications.

Adsorption characteristics and mechanisms of water-soluble polymers (PVP and PEG) on kaolin and montmorillonite minerals

The excessive use and accumulation of water-soluble polymers (WSPs, known as “liquid plastics”) in the environment can pose potential risks to both ecosystems and human health, but the environmental fate of WSPs remains unclear. Here, the adsorption behavior of WSPs with different molecular weight on kaolinite (Kaol) and montmorillonite (Mt) were examined. The results showed that the adsorption of PEG and PVP on minerals were controlled by hydrogen bond and van der Waals force. The Fourier transform infrared (FTIR) spectra and two-dimensional correlation spectroscopy (2D-COS) analysis revealed that there were interactions between the Al-O and Si-O groups of the minerals and the polar O- or N-containing functional groups as well as the alkyl groups of PEG and PVP. The adsorption characteristics of WSPs were closely related to their molecular weight and the pore size of minerals. Due to the relatively large mesopore size of Kaol, both PEG and PVP were absorbed into inner spaces, for which the adsorption capacity increased with molecular weight of the polymers. For Mt, all types of PEG could enter its micropores, while PVP with larger molecular weights appeared to be confined externally, leading to a decrease in the adsorption capacity of PVP with increasing molecular weight. The findings of this study provide a theoretical basis for scientific evaluation of environmental processes of WSPs.

Hydrochars as slow-release phosphorus fertilizers for enhancing corn and soybean growth in an agricultural soil

Hydrochars as carbonaceous amendments rich in porous structures and nutrients can be used as promising slow-release fertilizers and soil health amendments. Yet, the performance of hydrochars derived from different feedstocks in improving crop plant growth and soil phosphorus (P) availability is not well understood. Here, a batch of sewage sludge (SS) and chicken manure (CM) derived hydrochars (SSCs and CMCs) were produced at 125 and 225 °C (SS125/225 and CM125/225) to investigate their characteristics and performances in improving the seedling growth of two representative crops, soybean (Glycine max) and corn (Zea mays), as well as the P availability in an acidic agricultural soil in comparison with triple super phosphate (TSP), a conventional P fertilizer. Compared with CMCs, SSCs with more porous and rougher surfaces contained relatively lower contents of carbon (C; 32.3–33.3%), hydrogen (H; 3.9–4.69%), and potassium (K; 29.2–51 mg g−1), but higher contents of P (37.4–85.4%) and nitrogen (N; 2.26–4.9%), as well as more O-containing and N-containing functional groups. The impacts of hydrochars on soybean and corn growth showed distinct variations. The application of SSCs showed little effect on soybean growth (i.e., biomass, chlorophyl contents, and number of leaves), while CMCs significantly increased its total dry biomass by 23.2–66.2%. For corn, both SSCs and CMCs increased the total dry biomass by 32.8–92.4% and 21.8–69.7%, respectively, compared to those in the un-amended soils. In addition, compared with the higher temperature hydrochars (SS225 and CM225), the lower temperature ones (SS125 and CM125) increased the total dry biomass by 24.6% and 34.9% for soybean and 44.8% and 39.3% for corn, respectively. The significant improvement in crop growth by hydrochars was mainly due to the direct nutrient supply (particularly P) by the hydrochars, which was supported by the increased soil and shoot P concentrations. Moreover, hydrochar application led to a rise in soil water soluble P (WSP) levels. However, as time progressed, these levels fell due to the fixation and adsorption of P via precipitation, electrostatic attraction, and ion exchange on the hydrochars. Contrarily, TSP maintained persistently high soil WSP levels, increasing the leaching risk of P through the soil profile. Our results provide direct evidence for hydrochars as slow-release P fertilizers to enhance crop growth and production and give better insights for producing functionalized P-rich chars as an alternative to chemical P fertilizers to maintain sustainable agricultural production.Graphical

Lignin-derived nitrogen doped hierarchical porous carbon spheres for highly efficient dichloromethane adsorption

Biomass-prepared porous carbon materials are promising solid adsorbents for the removal of volatile organic compounds (VOCs). However, their application is hindered due to the insufficient number of pores and poor surface activity. In this study, a lignin-derived nitrogen-doped hierarchical porous carbon sphere (NHPCS-0.5) with abundant surface active sites was synthesised through spray drying and carbonisation–activation methods. The optimised NHPCS-0.5 displayed a high BET specific surface area (2961 m2·g−1) and total pore volume (1.57 cm3·g−1), developed hierarchical porous distribution with micro-/meso-/macropores and satisfactory surface nitrogen content. Moreover, it exhibited an excellent dichloromethane adsorption capacity of 156 mg·g−1 and maintained 86% of initial capacity after five regeneration cycles, indicating an outstanding regenerative ability. The nitrogen introduction improved the micropore volume and adsorption capacity. Adsorption mechanism reveals that micropore filling and enhanced van der Waals interaction of carbon surface with dichloromethane molecule by N-containing functional groups played a vital role in adsorption, and mesopores contributed to the high adsorption rates. The above results indicate the potential of NHPCS-0.5 as an adsorbent for VOC removal and provide new ideas for the utilisation of lignin and design of carbon sphere materials.

Conversion of waste cork to N-doped porous carbons by urea-assisted hydrothermal method for enhanced VOC capture

Converting waste resources into porous carbon for pollutants capture is an effective strategy to achieve the environmental goal of “treating waste with waste”. Cork is an ideal precursor of porous carbons due to its ordered honeycomb-like cell structure and layered composition distribution. Herein, N-doped porous carbons (PCs) were prepared via two steps of urea-assisted hydrothermal carbonization and chemical activation to mitigate volatile organic compounds (VOCs) pollution. Results indicated that the obtained PC4-800 exhibited remarkable features for adsorption including high total pore volume (0.97 cm3/g) and specific surface area (1864.89 m2/g), as well as abundant N-containing functional groups. The excellent pore structure was primarily owing to the corrosion of the carbon matrix by the gas produced from the reaction of K2CO3 and N-containing functional groups. The adsorption results showed that the PC4-800 have an outstanding toluene adsorption capacity (867.03 mg/g) that outperforming majority of adsorbents previously reported. There are substantial pores in N-doped PCs with a pore width of 1.71–2.28 nm, which is 3 to 4 times the molecular dynamic diameter of toluene, and plays a crucial role in the absorption process. Moreover, the promotional influence of N-functional groups on the toluene adsorption process was verified through DFT calculation by Gaussian imitating, where N-6 generated π-electron enrichment sites on the surface of N-doped PCs, facilitating π-π dispersion with the benzene ring in toluene. This study provides a new strategy to convert waste cork into high-performance adsorbents for VOCs removal.

Transformation simulation of N-containing functional groups in coal pyrolysis and combustion processes by using ReaxFF

In order to explore the formation mechanism of NOx precursors and NOx during coal pyrolysis and combustion, four typical N-containing functional groups in coal, including pyridine-N (N-6), pyrrole-N (N-5), protonation-N (N-Q) and oxidized pyridine-N (N-X), were taken for study. Firstly, the thermal reaction processes of N-containing functional groups under different conditions were simulated via ReaxFF, then the transformation processes of N-containing functional groups to NOx precursors were obtained via Ovito, finally the reaction networks of NOx precursors and NOx were built via ReacNetGenerator. According to the study results, we speculated that the transformation process of N-containing functional groups to NOx precursors involved 4 steps, including the ring opening of N-6 and N-5, the shift of N atom to the edge, the shortening of carbon chain and the formation of NOx precursors. Besides, we found that the increasing of temperature greatly promoted the transformation processes of NO to HNO and HO2N.

Electrospun microcrystalline cellulose/chitosan porous composite nanofibrous membranes modified by non-thermal plasma for gaseous formaldehyde adsorption

To develop a green and facile adsorbent for removing indoor polluted formaldehyde (HCHO) gas, the biomass porous nanofibrous membranes (BPNMs) derived from microcrystalline cellulose/chitosan were fabricated by electrospinning. The enhanced chemical adsorption sites with diverse oxygen (O) and nitrogen (N)-containing functional groups were introduced on the surface of BPNMs by non-thermal plasma modification under carbon dioxide (CO2) and nitrogen (N2) atmospheres. The average nanofiber diameters of nanofibrous membranes and their nanomechanical elastic modulus and hardness values decreased from 341 nm to 175–317 nm and from 2.00 GPa and 0.25 GPa to 1.70 GPa and 0.21 GPa, respectively, after plasma activation. The plasma-activated nanofibers showed superior hydrophilicity (WCA = 0°) and higher crystallinity than that of the control. The optimal HCHO adsorption capacity (134.16 mg g−1) of BPNMs was achieved under a N2 atmosphere at a plasma power of 30 W and for 3 min, which was 62.42 % higher compared with the control. Pyrrolic N, pyridinic N, CO and O–C=O were the most significant O and N-containing functional groups for the improved chemical adsorption of the BPNMs. The adsorption mechanism involved a synergistic combination of physical and chemical adsorption. This study provides a novel strategy that combines clean plasma activation with electrospinning to efficiently remove gaseous HCHO.

High-Efficiency Corrosion Inhibitor of Biomass-Derived High-Yield Carbon Quantum Dots for Q235 Carbon Steel in 1 M HCl Solution.

Eco-friendly self-doped carbon quantum dots (ZCQDs) with excellent corrosion inhibition ability were prepared via solid-phase pyrolysis only using Zanthoxylum bungeanum leaves as the raw material. Compared with the relevant research, a simpler and higher yield (25%) preparation process for carbon quantum dots was proposed. ZCQDs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy, and the average size of ZCQDs with multitudes of O- and N-containing functional groups was about 2.53 nm. The prepared ZCQDs were used to inhibit the corrosion of Q235 steel in HCl solution, and the inhibition behavior was investigated through weight loss, electrochemical test, surface analysis, and adsorption thermodynamic analyses. The results showed that the ZCQDs, acted as a mixed corrosion inhibitor, have an effective corrosion inhibition for Q235, the corrosion inhibition efficiency reached 95.98% at 200 mg/L, and at this concentration, effective protection of at least 132h (IE > 90%) is provided. Moreover, the adsorption mechanism of ZCQDs was consistent with that of Redlich-Peterson adsorption, including chemisorption and physisorption. A new corrosion inhibition mechanism of ZCQDs has been thoroughly studied and proposed; ZCQDs have functional groups containing O and N, which can form a protective barrier through physical adsorption and chemisorption, but the coverage of the protective film is low at low concentrations. With the increase of concentration, the protective film formed by ZCQDs on the metal surface will first increase the coverage and then adsorb more ZCQDs on the protective film to form a thicker and denser protective film to protect the metal. The carbon quantum dots prepared in this paper have advantages including a green, renewable precursor, a fast method, high yield, and excellent corrosion inhibition. Therefore, this work can inspire and facilitate, to a certain extent, the future application of doped carbon quantum dots as efficient corrosion inhibitors in HCl solutions.

The Effect of Synthetic Polycation Poly-2-Dimethylaminoethylmethacrylate on Biological Activity of Mammalian Resident and Nonresident Cells

Cationic polymers are the positively charged macromolecules that have in their structure N-containing functional groups such as primary, secondary and tertiary amine groups; quaternary ammonium groups and others. The effect of synthetic polycation poly-2-dimethylaminoethylmethacrylate (PDMAEM) on biological activity of animal fibroblasts (CHL V-79 RJK) and human red blood cells (RBCs) was studied. The influence of PDMAEM on cell adhesion using fibroblast culture was analyzed. Cultural plastic treated or untreated by polycation was used as substrate. The polycation adsorption on polystyrene surface did not change the adhesive capacity of fibroblasts. Pretreatment of fibroblasts with PDMAEM did not influence at low concentrations (0.1 and 1 μg/mL) the adhesive properties of cells plated on the untreated plastic surface. At high concentrations (10 and 100 μg/mL) PDMAEM inhibited the attachment of fibroblasts to this substrate. Relationship between the inhibition of cell adhesion under PDMAEM action and the toxic effect on fibroblast viability has been found. The PDMAEM treatment of human RBCs at high doses led to the damage of cells and release of hemoglobin to incubation medium. At low doses PDMAEM practically did not influence the hemolysis of RBCs. It was shown that PDMAEM induced the change of the shape and aggregation of RBCs. The toxic effect of PDMAEM on human RBCs coincided as a whole with such effect for animal fibroblasts. Possible cell targets upon the PDMAEM effect are discussed.

High nitrogen content bimolecular co-functionalized graphene nanoflakes for hypertoxic Cr(VI) removal: Insights into adsorption behavior and mechanisms

The proven high carcinogenicity to humans and high destructive force to the environment determine the extreme urgency of eliminating hypertoxic Cr(VI) in water bodies. Herein, a route of room temperature synthesis and secondary grafting was proposed to fabricate graphene oxide-based nanoadsorbent co-functionalized with polydopamine and branched polyethyleneimine (GOPP) to remove Cr(VI). The flexible decoration of polydopamine and polyethyleneimine on GO flakes could gradually enhance the amount of N-containing functional groups and realize selective removal of Cr(VI) with the maximum experimental adsorption capacity of 564.7 mg/g, displaying a significantly high separation factor against alkali metal, alkaline earth metal, and other transition metal ions. Various combination mechanisms, such as electrostatic attraction, reduction, complexation, and hydrogen bonding, were demonstrated to be involved in the adsorption process of Cr(VI) by XPS, ESP, and DFT calculations. And the interaction energies of the five protonated configurations of primary amine, tertiary amine, secondary amine, imine, and secondary amine on the ring with HCrO4− were: −22.66, −12.08, −24.92, −24.26, −27.64 kcal/mol. In the actual industrial wastewater study, a Cr(VI) removal rate of 85.8% was realized. This work provided a viable idea for the elimination of Cr(VI) and was expected to be applied in the field of wastewater treatment.

Fabrication of Nitrogen-Doped Carbon@Magnesium Silicate Composite by One-Step Hydrothermal Method and Its High-Efficiency Adsorption of As(V) and Tetracycline.

Tetracycline (TC) and arsenic contaminants are two main pollutants in aquaculture and livestock husbandry, and they have drawn worldwide attention. To address this issue, a novel N-doped carbon@magnesium silicate (CMS) was fabricated via a facile and low-cost hydrothermal route, adopting glucose and ammonia as C and N sources, respectively. The synergetic combination of carbon and magnesium silicate makes CMS possess a high surface area of 201 m2/g and abundant functional groups. Due to the abundant C- and N-containing functional groups and Mg-containing adsorptive sites, the maximum adsorption capacity values of CMS towards As(V) and TC are 498.75 mg/g and 1228.5 mg/g, respectively. The type of adsorption of As(V) and TC onto CMS is monolayer adsorption. An adsorption kinetic study revealed that the mass transfer and intraparticle process dominates the sorption rate of As(V) and TC adsorption onto CMS, respectively. Various functional groups synthetically participate in the adsorption process through complexion, π-π EDA interactions, and hydrogen bonds. This work provides a one-step, low-cost route to fabricate a N-doped carbonaceous adsorbent with a high surface area and abundant functional groups, which has great potential in the application of practical sewage treatment.