Oxygen-containing Functional Groups Research Articles

Molecular Dynamics Simulation of the Interaction within the Carboxymethyl Cellulose-Modified Montmorillonite Lamellae at Aggressive CuCl2 Concentrations.

To elucidate the degradation mechanism of the CMC-modified MMT composite at aggressive Cu2+ concentrations, large scale molecular dynamics simulation was conducted for CuCl2 concentrations ranging from 0 to 800 mM. Both CMC and MMT followed the Langmuir isotherm for Cu2+ adsorption, and the adsorption capacity of CMC (8.75 mmol/g) was much higher than that of MMT (0.83 mmol/g). Despite the CMC mass ratio being only 4.1%, it adsorbed up to 34.3% of the total adsorbed Cu2+. The Cu2+ attraction ability hierarchy of oxygen-containing functional groups in the CMC is as follows: carboxylic oxygens > alcoholic oxygens > carbinolic oxygens > bridging oxygens > glucose oxygens. Carboxyls were the most effective in chelating and complexing with Cu2+, and they could be intentionally added in artificially synthesized polymer-MMT composites for Cu2+ containment. Formation of the Cu2+ cation bridge between CMC and MMT at aggressive CuCl2 concentrations contributed to the transition of CMC density distribution from unimodality to bimodality and enhanced resistance of polymer elution. As the CuCl2 concentration increased, the stoichiometric ratio between the chelated Cu2+ and carboxylic oxygens increased from 1:2 to 1:1, suggesting the evolution of the Cu2+ chelation mechanism.

Improving strength and toughness of graphene film through metal ion bridging

The fangs, jaws, and mandibles of marine invertebrates such as Chiton and Glycera show excellent mechanical properties, which are mostly contributed to the interactions between metal (Fe, Cu, Zn, etc.) and oxygen-containing functional groups in proteins. Inspired by these load-bearing skeletal biomaterials, we improved tensile strength and toughness of graphene films through bridging graphene oxide (GO) nanosheets by metal ions. By optimizing the metal coordination form and density of cross-linking network. We revealed the relationship between mechanical properties and the unique spatial geometry of the GO nanosheets bridged by different valence metal ions. The results demonstrated that the divalent metal ions form tetrahedral geometry with carboxylate groups on the edges of the GO nanosheets, and the bond energy is relatively low, which is helpful for improving the toughness of resultant graphene films. While the trivalent metal ions are easily to form octahedral geometry with the GO nanosheets with higher bond energy, which is better for enhancing the tensile strength of graphene films. After reduction, the reduced GO (rGO) film bridged by divalent metal ions shows 43% improvement in toughness, while the rGO film bridged by trivalent metal ions shows 64% improvement in tensile strength. Our work reveals the mechanism of metal coordination bond energy and spatial geometry to improve the mechanical properties of graphene films, which lays a theoretical foundation for improving the tensile strength and toughness of resultant graphene films, and provides an avenue for fabricating high-performance graphene films and other two-dimensional nanocomposites.

Seeking the adsorption of tetracycline in water by Fe-modified sludge biochar at different pyrolysis temperatures.

The composite material SBC-Fe-x with sludge and Fe3+ was developed by different calcination temperatures (600, 700, and 800 °C) for the removal of tetracycline (TC). The adsorption rates of SBC-Fe-600, SBC-Fe-700, and SBC-Fe-800 were 77.5%, 89%, and 91%, respectively. Furthermore, the Langmuir model indicated that the maximum adsorption capacity of SBC-Fe-700 (157.93 mg/g) was three times greater than that of SBC-Fe-600. The conclusions were confirmed by a series of characterizations that SBC-Fe-700 showed a larger specific surface area, well-developed pore structure, rich oxygen-containing functional groups and a high degree of graphitization. The results of pH experiments indicated the broad applicability of SBC-Fe-700 for TC adsorption. In addition, SBC-Fe-700 suggested outstanding performance in different water environments. This work produced a feasible adsorbent for the removal of TC, and a new direction for sludge resource utilization was proposed.

The effect of temperature on the co-combustion of hydrochar and NH3 using the ReaxFF method

The utilization of NH3, a carbon-free hydrogen carrier, can be optimized through its co-combustion with solids. However, prior studies have primarily focused on coal as the solid fuel, which entails its consumption. Considering that hydrochar possesses abundant oxygen-containing functional groups, as well as high mass and energy density, it presents itself as a promising alternative solid fuel to coal, thereby decreasing dependence on fossil fuels. Therefore, this study investigates the co-combustion of different proportions of hydrochar, NH3, and O2. Molecular dynamic simulations using the ReaxFF MD method were conducted to investigate the impact of temperature on combustion by analyzing product distribution, evolution of bonds, and gas characteristic curves. Additionally, N migration was examined to elucidate the processes leading to the generation of N2 and NOx from NH3. The results showed that temperature facilitated the progression of combustion as the total number of molecules increased (from 2614 at 2000 K to 3137 at 2500 K) and variety of products expanded (from 48 at 2000 K to 69 at 2500 K) with increasing temperature. With increasing temperature, the descent rate of NH3 and oxygen accelerated, whereas the quantities of H2 and H2O increased. Furthermore, during combustion, hydrochar underwent three stages: initial coke formation, subsequent tar generation, and organic gas production. Second, during N migration, hydrochar directly or indirectly participated in the formation of N2. In this process, hydrochar indirectly contributed to the formation of NH and NH2 intermediates, leading to the formation of N2. In contrast, the majority of NO was formed through the direct decomposition of hydrochar. Finally, because of the limited quantity of generated NO2, N existed primarily in the form of N2 and NO. These findings provide theoretical guidance for the combustion of NH3 using hydrochar.

Boosting acetaminophen degradation in water by peracetic acid activation: A novel approach using chestnut shell-derived biochar at varied pyrolysis temperatures

In this study, biochar derived from chestnut shells was synthesized through pyrolysis at varying temperatures from 300 °C to 900 °C. The study unveiled that the pyrolysis temperature is pivotal in defining the physical and chemical attributes of biochar, notably its adsorption capabilities and its role in activating peracetic acid (PAA) for the efficient removal of acetaminophen (APAP) from aquatic environments. Notably, the biochar processed at 900 °C, referred to as CN900, demonstrated an exceptional adsorption efficiency of 55.8 mg g−1, significantly outperforming its counterparts produced at lower temperatures (CN300, CN500, and CN700). This enhanced performance of CN900 is attributed to its increased surface area, improved micro-porosity, and a greater abundance of oxygen-containing functional groups, which are a consequence of the elevated pyrolysis temperature. These oxygen-rich functional groups, such as carbonyls, play a crucial role in facilitating the decomposition of the O–O bond in PAA, leading to the generation of reactive oxygen species (ROS) through electron transfer mechanisms. This investigation contributes to the development of sustainable and cost-effective materials for water purification, underscoring the potential of chestnut shell-derived biochar as an efficient adsorbent and catalyst for PAA activation, thereby offering a viable solution for environmental cleanup efforts.

Harnessing Green Electricity from Food: A Split Black Gram-Based Triboelectric Nanogenerator for a Self-Powered Autonomous Lighting System and Portable Electronics.

Triboelectric nanogenerators (TENGs) represent a promising solution to mounting environmental concerns associated with battery disposal amid the escalating demand for portable electronics. However, prevailing TENG fabrication predominantly relies on nonbiodegradable, nonbiocompatible, and synthetic materials, posing a grave ecological threat. To mitigate this, there is a pressing need to develop eco-friendly and green TENGs leveraging sustainable, naturally occurring materials. This study pioneers the use of split black gram (SBG) as a tribo-positive material for TENGs. SBG's effectiveness as a tribo-positive material stems from its abundance of oxygen-containing functional groups, as confirmed by FTIR analysis, facilitating electron donation during the triboelectric process. SBG offers compelling advantages, including widespread availability, cost-effectiveness, biodegradability, and hydrophobic and adhesive properties due to its richness in starch and protein, positioning it as an optimal choice for eco-conscious TENG manufacturing. The fabrication process of an SBG-TENG is not only economical and facile but also solvent-free, requiring no specialized tools. Demonstrating commendable performance, the SBG-TENG achieves a maximum power density of 15.36 μW/cm2 at 1 MΩ, with an open circuit voltage of 84 V and short circuit current of 28 μA, comparable to recent studies. In practical applications, the SBG-TENG seamlessly integrates with LEDs and portable electronic devices via a full bridge rectifier, successfully powering them postcapacitor charging. Moreover, an autonomous lighting system is developed by embedding the SBG-TENG in a foot mat, enabling wireless light control through human stepping on the mat, introducing power-saving functionality for residential and office environments. In essence, the introduction of the SBG-TENG not only delivers cost-effectiveness but also minimizes the environmental impact by harnessing sustainable energy from food sources.

Hydrothermal-enhanced pyrolysis for efficient NOX reduction and biochar valorization from food waste digestate

Pyrolysis has emerged as a promising technology for valorizing digestate resulting from the anaerobic digestion of food waste. However, the high NOX emissions during pyrolysis limit its application. This study proposed a hydrothermal coupled pyrolysis process to control the element transfer in digestate during biochar production. The efficient reduction of NOX emissions and the improvement of biochar adsorbability were realized. The hydrothermal process reduced the nitrogen content in solid digestate by 49.10 %–81.79 %, thus reducing the NOX precursors in syngas and the N-containing substances in bio-oil. Additionally, the specific surface area and the total pore volume of biochar were enhanced from 25 m2/g to 60–73 m2/g and 0.06 cm3/g to 0.12–0.14 cm3/g, respectively. More defects, oxygen-containing functional groups, and doped Ca on the biochar resulted in a high phosphate removal efficiency of 94 %. The proposed technology provides an efficient and environmentally friendly way to utilize the digestate.

Research on Microwave Pyrolysis Recovery and Reuse Performance of Carbon Fiber Composites

Carbon fiber-reinforced resin matrix composites find extensive applications across various industries. However, their widespread use also generates significant waste, leading to resource depletion and environmental concerns. Studying the production of composite materials using recovered carbon fiber is imperative to mitigate the environmental impact associated with waste from carbon fiber-reinforced resin matrix composites and optimize resource utilization. In this study, carbon fiber was reclaimed using the microwave pyrolysis–oxidation process. The reclaimed carbon fiber underwent a cutting process to produce shorter carbon fibers tailored to specific requirements, which were then used to fabricate composite plates reinforced with epoxy resin. The mechanical characteristics of the composite were analyzed, along with SEM, XPS, infrared, Raman, and contact angle analyses conducted on the recovered carbon fiber. The test findings suggested minimal variation in the surface morphology of the recovered carbon fiber materials. Post-recovery, an increase in the quantity of oxygen-containing functional groups was observed on the carbon fiber surface. Additionally, the contact angle between the carbon fiber surface and the epoxy adhesive decreased. The mechanical properties of the composite produced from the recovered carbon fiber decreased, including the impact strength, tensile strength, and bending strength, with the impact strength dropping by 24.14%, tensile strength by 15.94%, and bending strength by 8.24%, while maintaining overall reusability, thus paving the way for the comprehensive utilization of carbon fiber resources.

Study on the effects of inorganic salts and ionic surfactants on the wettability of coal based on the experimental and molecular dynamics investigations

Through the evaluation and preparation of a novel inorganic salt composite solution consisting of sodium dodecyl benzene sulfonate (SDBS), the nonionic surfactants polyethylene glycol pisooctyl phenyl ether (Triton X-100), and inorganic salt Na2SO4, based on surface tension, contact angle, settling time, wetting rate, and changes in the surface microstructure and functional groups of coal, this study analyzed the wetting behavior of the solution on coal dust and its adsorption capacity on the surface of coal particles. The results demonstrate that the composite solution of inorganic salts can significantly enhance the wettability of coal samples, reducing the contact angle to 21.54° and lowering the surface tension to 26.10 mN/m. After treatment with the solution, the relative content of oxygen-containing functional groups in the microscopic structure of the coal sample increased to 59.6 % and pores more prominent than 25 nm increased to 34.63 %. Molecular dynamics (MD) simulations of the water-inorganic salt composite solution-coal system are conducted using Materials Studio software, revealing that after the addition of the composite solution, the self-diffusion coefficient (D) of water molecules is 6.3 × 10-9 m2/s, the starting point of the composite solution is 15 Å, and the system's interaction energy increase to 14000 kcal/mol. It further elucidated the modification of the surface molecular structure of coal dust by the inorganic salt composite solution, increasing hydrogen bonds, enhancing wetting, and demonstrating a solid adsorption capability of the inorganic salt composite solution on the surface of coal dust.

Accurate classification of the molecular characteristics of soluble portions from various lignites: Joint analysis of thermal dissolution experiments and data mining methods

Gas chromatography-mass spectrometry (GC-MS) was used to analyze the soluble portions (SPs) of eight lignites which were obtained by extracting using cyclohexane, methanol and ethanol, respectively, as the solvent. For thermal dissolution at 300 °C using cyclohexane, the intermolecular interactions between mobile phase and macromolecules in coal were weakened. Consequently, non- and low-polar compounds such as alkanes and aromatics were well dissolved. Methanol and ethanol were more likely to closely interact with oxygen-containing functional groups and promoted the breakage of hydrogen bonds and weak covalent bonds. Hierarchical cluster analysis classified all the 24 SPs, and the SPs from cyclohexane and ethanol solvents exhibited more similarity. Partial least squares discriminant analysis was established to reproduce the classification results of SPs entirely and accurately. The SPs were further classified by combining a small number of geochemical characteristic compounds rather than massive GC-MS data.

Enhanced adsorption capacity of antibiotics by calamus-biochar with phosphoric acid modification: Performance assessment and mechanism analysis

BackgroundAdsorption is one of the effective methods to remove antibiotics from water. Plant-based biochar can be effectively modified to enhance the adsorption capabilities of antibiotics. MethodsCalamus biochar (PBC) was modified by phosphoric acid to study its adsorption efficacy on erythromycin (ERY) and sulfamethoxazole (SMX). Significant FindingsPBC had a pore density of 0.771 m3·g−1, an average pore size of 5.14 nm, and an enormous surface area of 797 m2·g−1. PBC had been shown to incorporate a substantial quantity of functional groups containing oxygen by FTIR and XPS investigations. With these surface chemical and physical characteristics, PBC adsorbed 325 mg·g−1 of ERY and 216 mg·g−1 of SMX, which was tenfold higher compared to that of unmodified biochar and industrial-activated carbons. Quantitative analysis of adsorption mechanisms showed that the adsorption of ERY by PBC mainly included oxygen-containing functional group complexation and pore filling, whereas, the π-π interaction and pore filling were the leading mechanisms in the adsorption process of SMX. This research offers insights into the preparation of plant biochar with excellent antibiotic adsorption performance.

(Ca0.25La0.5Dy0.25)CrO3 Ceramic Fiber@Biomass-Derived Carbon Aerogel with Enhanced Solute Transport Channels for Highly Efficient Solar Interface Evaporation

The use of solar interface evaporation for seawater desalination or sewage treatment is an environmentally friendly and sustainable approach; however, achieving efficient solar energy utilization and ensuring the long-term stability of the evaporation devices are two major challenges for practical application. To address these issues, we developed a novel ceramic fiber@bioderived carbon composite aerogel with a continuous through-hole structure via electrospinning and freeze-casting methods. Specifically, an aerogel was prepared by incorporating perovskite oxide (Ca0.25La0.5Dy0.25)CrO3 ceramic fibers (CCFs) and amylopectin-derived carbon (ADC). The CCFs exhibited remarkable photothermal conversion efficiencies, and the ADC served as a connecting agent and imparted hydrophilicity to the aerogel due to its abundant oxygen-containing functional groups. After optimizing the composition and microstructure, the (Ca0.25La0.5Dy0.25)CrO3 ceramic fiber@biomass-derived carbon aerogel demonstrated remarkable properties, including efficient light absorption and rapid transport of water and solutes. Under 1 kW m−2 light intensity irradiation, this novel material exhibited a high temperature (48.3 °C), high evaporation rate (1.68 kg m−2 h−1), and impressive solar vapor conversion efficiency (91.6%). Moreover, it exhibited long-term stability in water evaporation even with highly concentrated salt solutions (25 wt%). Therefore, the (Ca0.25La0.5Dy0.25)CrO3 ceramic fiber@biomass-derived carbon aerogel holds great promise for various applications of solar interface evaporation.

Highly efficient peanut shell activated carbon via hydrothermal carbonization and chemical activation for energy storage applications

In this study, the activated carbon samples from peanut shells (PS) are synthesized through hydrothermal carbonization (HTC) with and without activating agents, and their electrochemical properties are studied for supercapacitor applications. The raw precursor (PS) powder is loaded with an activating agent (ZnCl2 or H3PO4 or KOH) during the hydrothermal treatment at 200 °C for 7 h. The treatment with the activating agent facilitates the generation of oxygen-containing functional groups on the precursor surface, enhancing the porosity and electrochemical performance of the sample. Further, the samples are subjected to carbonization at 400 °C for 3 h. The powder XRD patterns show peaks at around 24–26° and 43°, corresponding to the amorphous and graphitic carbon, respectively. The morphological examination reveals more meso and macro pores when treated with the activating agent. Raman spectra manifest the amorphous carbon nature of the samples exhibiting ID and IG bands. The porous carbon treated with H3PO4 shows a specific surface area of 17.8 m2/g and a pore volume of 0.037 cm3g−1. The H3PO4 treated sample shows a high specific capacity (Cs) of 240 F/g at 1 A/g current density, an energy density (E) of 4.08 W h kg−1, and a power density (P) of 101.3 W kg−1. The Retention rate of the sample is approximately 90 % up to 1200 cycles. These types of hybrid supercapacitor materials are suitable for battery-type applications.

Exfoliation of Graphite into Graphene Oxide and Reduction by Plant Extract to Synthesize Graphene

Graphene oxide (GO) is a demand material in industrial field for many applications such as electronic devices, capacitor and sensor. This is due to its unique structures and excellent properties. The GO sheets were exfoliated from graphite rod in electrochemical exfoliation. To reduce GO, an electrochemical reduction of GO using green tea was carried out in this research. The conventional chemical reduction method consumed highly toxic and strongly hazardous chemicals such as hydrazine to reduce GO to reduced GO (RGO). Therefore, a green synthesis method was proposed by using green tea leaves extract as the reducing agent to synthesize RGO. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) results show that low amount of oxygen-containing functional groups was remained after green tea reduction due to weak reduction capability by green tea. In addition, EDX indicates that oxygen content of GO was decreased from 23.23 to 16.89 Mass% after green tea reduction.

Pyrite/biochar-activated peroxymonosulfate strengthens tetracycline degradation: Important roles of surface functional groups and Fe(Ⅱ)/Fe(Ⅲ) redox cycling

Nonradical species with high anti-interfering properties have shown significant advantages in complex wastewater treatment. Herein, a pyrite/biochar catalyst (FBC) was prepared using pine sawdust biochar (BC) as a support material loaded with pyrite (FeS2). It exhibited high activity and stability in the FBC/PMS system for effective activation of peroxymonosulfate (PMS) to degrade tetracycline (TC) over a wide pH range (3.0–9.0). According to the characterization and analysis data, a variety of oxygen-containing functional groups (CO, -OH) and Fe and S active sites on the FBC surface assisted in PMS decomposition to produce reactive oxygen species (ROS). The mechanism study showed that the redox cycling of Fe(Ⅱ)/Fe(Ⅲ) and the electron-transfer medium of the BC oxygen functional groups contributed to the formation of SO4•-, •OH, O2•-, 1O2 and FeⅣ=O, but 1O2 was the main active oxidant. The potential pathways for TC degradation were suggested, and the toxicity of by-products was predicted by toxicity evaluation. Furthermore, FBC/PMS system exhibited minimal sensitivity to interference of concomitant materials. Overall, this study provided a reference for the application of green advanced oxidation technology of iron-based mineral composites to treat pharmaceutical contaminants in real water.

Hemocompatibility and Preangiogenic Attributes of SiBxCyNzOm Coatings for Biomedical Applications.

In current clinical practices related to orthopedics, dental, and cardiovascular surgeries, a number of biomaterial coatings, such as hydroxyapatite (HAp), diamond-like carbon (DLC), have been used in combination with metallic substrates (stainless steel, Ti6Al4V alloy, etc.). Although SiBCN coatings are widely explored in material science for diverse applications, their potential remains largely unexplored for biomedical applications. With this motivation, the present work reports the development of SiBxCyNzOm coatings on a Ti6Al4V substrate, employing a reactive radiofrequency (RF) magnetron sputtering technique. Three different coating compositions (Si0.27B0.10C0.31N0.07O0.24, Si0.23B0.06C0.21N0.22O0.27, and Si0.20B0.05C0.19N0.20O0.35) were obtained using a Si2BC2N target and varying nitrogen flow rates. The hydrophilic properties of the as-synthesized coatings were rationalized in terms of an increase in the number of oxygen-containing functional groups (OH and NO) on the surface, as probed using XPS and FTIR analyses. Furthermore, the cellular monoculture of SVEC4-10 endothelial cells and L929 fibroblasts established good cytocompatibility. More importantly, the coculture system of SVEC4-10 and L929, in the absence of growth factors, demonstrated clear cellular phenotypical changes, with extensive sprouting leading to tube-like morphologies on the coating surfaces, when stimulated using a customized cell stimulator (StimuCell) with 1.15 V/cm direct current (DC) electric field strength for 1 h. In addition, the hemocompatibility assessment using human blood samples revealed clinically acceptable hemolysis, less erythrocyte adhesion, shorter plasma recalcification, and reduced risk for thrombosis on the SiBxCyNzOm coatings, when compared to uncoated Ti6Al4V. Taken together, the present study unambiguously establishes excellent cytocompatibility, hemocompatibility, and defines the preangiogenic properties of SiBxCyNzOm bioceramic coatings for potential biomedical applications.

Facile synthesis and optimization of graphene oxide reduction by annealing in hydrazine vapour in ambient air for potential application in perovskite solar cells

Graphene oxide (GO) was synthesized from graphite via a modified Hummer's method, followed by thermal and chemical reductions to produce reduced graphene oxide (RGO) samples at various temperatures. A suite of characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), UV-Visible Spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Hall effect measurements were employed to assess the structural, morphological, optical, and electrical properties of the samples. FTIR analysis confirmed the successful functionalization of graphite to GO and subsequent reduction to reduced graphene oxide, with peak intensities decreasing as the reduction temperature increased. UV-visible spectroscopy of GO showed a maximum absorption at 235 nm which confirmed the synthesis of GO while the reduction revealed a notable red shift in absorption peaks with increasing annealing temperature, and that signified a reduction in bandgap. XRD analyses demonstrated the removal of oxygen functional groups. The X-ray diffraction (XRD) analysis of GO showed diffraction at 2θ = 10.74° which revealed a fully oxidized graphene oxide with oxygen-containing functional groups, and hence an increase in interlayer spacing (d002) from 3.341 Å (graphite) to 8.228 Å (GO). Upon reduction, there is a gradual decrease in d002 from 8.228 Å (GO) to 3.387 Å (HRGO300), suggesting the gradual removal of intercalated oxygen molecules, and hence the gradual restoration of sp2 hybridisation in graphene. The EDS analysis revealed an increase in the carbon-to-oxygen (C/O) ratio from 1.78 in GO to 2.75 in HRGO300 as the annealing temperature for the reduction process increased which further confirmed the removal of oxygen functional groups. The Hall effect data showed hole mobility of 4.634 x101 (GO), 4.831 x101 (HRGO200), and 5.462 x100 (HRGO300) with conductivities of 8.985 x10-5 (GO), 1.087 x100 (HRGO200) and 1.791 x101 1/Ω cm, suggesting an increase in conductivity as the annealing temperature increased as revealed in the EDS. Out of the three samples identified as hole transport materials, the sample HRGO300 with the highest C/O ratio of 2.75 has the highest conductivity, and hence most suitable for application as hole transport material in perovskite solar cell.

Enhanced biotoxicity by co-exposure of aged polystyrene and ciprofloxacin: the adsorption and its influence factors.

Microplastics (MPs), as emerging contaminants, usually experience aging processes in natural environments and further affect their interactions with coexisted contaminants, resulting in unpredictable ecological risks. Herein, the effect of MPs aging on their adsorption for coexisting antibiotics and their joint biotoxicity have been investigated. Results showed that the adsorption capacity of aged polystyrene (PS, 100 d and 50 d) for ciprofloxacin (CIP) was 1.10-4.09 times higher than virgin PS due to the larger BET surface area and increased oxygen-containing functional groups of aged PS. Following the increased adsorption capacity of aged PS, the joint toxicity of aged PS and CIP to Shewanella Oneidensis MR-1 (MR-1) was 1.03-1.34 times higher than virgin PS and CIP. Combined with the adsorption process, CIP posed higher toxicity to MR-1 compared to aged PS due to the rapid adsorption of aged PS for CIP in the first 12h. After that, the adsorption process tended to be gentle and hence the joint toxicity to MR-1 was gradually dominated by aged PS. A similar transformation between the adsorption rate and the joint toxicity of PS and CIP was observed under different conditions. This study supplied a novel perception of the synergistic effects of PS aging and CIP on ecological health.

Unraveling the Role of Humic Acid in the Oxidation of Phenolic Contaminants by Soluble Manganese Oxo-Anions.

Humic acid (HA) is ubiquitous in natural aquatic environments and effectively accelerates decontamination by permanganate (Mn(VII)). However, the detailed mechanism remains uncertain. Herein, the intrinsic mechanisms of HA's impact on phenolics oxidation by Mn(VII) and its intermediate manganese oxo-anions were systematically studied. Results suggested that HA facilitated the transfer of a single electron from Mn(VII), resulting in the sequential formation of Mn(VI) and Mn(V). The formed Mn(V) was further reduced to Mn(III) through a double electron transfer process by HA. Mn(III) was responsible for the HA-boosted oxidation as the active species attacking pollutants, while Mn(VI) and Mn(V) tended to act as intermediate species due to their own instability. In addition, HA could serve as a stabilizer to form a complex with produced Mn(III) and retard the disproportionation of Mn(III). Notably, manganese oxo-anions did not mineralize HA but essentially changed its composition. According to the results of Fourier-transform ion cyclotron resonance mass spectrometry and the second derivative analysis of Fourier-transform infrared spectroscopy, we found that manganese oxo-anions triggered the decomposition of C-H bonds on HA and subsequently produced oxygen-containing functional groups (i.e., C-O). This study might shed new light on the HA/manganese oxo-anion process.

Synergistic enhancement of N, S co-modified biochar for removal of tetracycline hydrochloride from aqueous solution: Tunable micro-mesoporosity and chemisorption sites

The misuse of tetracycline hydrochloride (TCH) antibiotics has caused irreversible hazards to ecosystem. In this study, a series of porous biochar with tunable micro-mesoporosity and chemisorption sites are designed by cleverly exploiting the pyrolysis properties of active agents in various temperature regions. Benefiting from the existence of more pore structures matching the adsorbate while exposing more chemisorption sites, the maximum adsorption capacity (Qm) of NSC-1.0 for TCH is up to 1480.1 mg g−1 at 303 K. A combination of model fitting, post characterization and density functional theory (DFT) calculations confirms that the adsorption process involves the pore filling, the formation of non-covalent bonds (weak hydrogen bond, π-π stacking, electrostatic interaction) and ligand covalent bonding (Lewis acid-base interaction). The Qm is positively correlated with the volume of pore size greater than 1 nm (R2 = 0.9879), indicating that the pore filling effect is a decisive factor for adsorption performance. Post-characterization directly demonstrates that weak hydrogen bonding and π-π stacking are pivotal physical interactions for adsorption. DFT calculations show that partial N, S species and oxygen-containing functional groups can significantly reduce the adsorption energy of intrinsic graphene, especially the chemisorption sites of pyrrolic N (N5) and thiophene S (S5) containing lone-pair electrons. Furthermore, the competitiveness of NSC-1.0 is revealed in practical evaluation, including cation strength, regenerability, actual water source and fixed-bed column. This study not only contributes new insights to synergistically enhance the removal of macromolecular antibiotics by coupling matchable pore sizes and chemisorption sites, but also develops theoretical support for the fabrication of such efficient adsorbents.