Surface Oxygen-containing Functional Groups Research Articles

Efficient adsorption of antibiotics in aqueous solution through ZnCl2-activated biochar derived from Spartina alterniflora

In recent years, Spartina alterniflora as an invasive species has seriously threatened the native coastal ecosystem of China. There is a lack of effective management and utilization methods towards Spartina alterniflora at present. To realize the ecological remediation and resource utilization of Spartina alterniflora, the functional biochar (BC) materials were successfully prepared using Spartina alterniflora as the substrates via the high temperature calcination method, which were utilized for efficient removal of antibiotics. The biochar was further activated by ZnCl2 (ZnBC) and optimized under different calcination temperatures and ZnCl2 dosages to improve the adsorption ability. Among these biochar materials, the ZnCl2-activated biochar obtained under the mass ratio of Spartina alterniflora to ZnCl2 of 1:5 and calcination temperature of 600 °C (ZnBC-600) exhibited the strongest adsorption performance towards sulfadiazine (SDZ) and ciprofloxacin (CIP), which can be attributed to the larger specific surface area, richer pore structure and more abundant surface oxygen-containing functional groups. Additionally, the adsorption kinetics and isotherms demonstrated that the adsorption of both SDZ and CIP onto ZnBC-600 (1:5) followed the pseudo-second-order kinetic model and Freundlich model. At the same time, the performances of Spartina alterniflora biochar derived from different biomass were compared under the condition of activation with ZnCl2, presenting the superior performance of ZnCl2 activated Spartina alterniflora biochar. Moreover, the adsorption mechanism of ZnBC-600 (1:5) was proposed, illustrating the crucial roles of effects of electrostatic attraction, pore filling, oxygen-containing groups complexation, π-π stacking and hydrogen bonding in the adsorption of antibiotics. Above all, this study not only provides a feasible strategy for the preparation of functional biochar derived from Spartina alterniflora for removing organic pollutants, but also opens up a new pathway for resource utilization of Spartina alterniflora.

Effect on the adsorption performance and mechanism of antibiotics tetracyclines by the magnetic biochar used peanut shells as raw materials

Widespread environmental pollution caused by the misuse of tetracyclines (TCs) has become a global issue, necessitating the development of water treatment materials for antibiotic removal. Magnetic biochar (MBC) possesses several advantages, including a wide range of raw material sources and low cost, making it a potential adsorbent that overcomes the limitations of biochar (BC) regarding solid–liquid separation. In this study, peanut shell-derived magnetic biochar loaded with Fe3O4 (Fe3O4/BC) was prepared to study its adsorption performance and environmental factors for TCs. The adsorption mechanism was revealed using adsorption isotherms, adsorption kinetics and thermodynamics. The results showed that the total pore volume was increased, and surface oxygen-containing functional groups were formed of that before BC modification. In a wide pH range, Fe3O4/BC showed high adsorption performance for TCs, with an adsorption rate of over 85%. Chemical adsorption was the main adsorption mechanism, including hydrogen bonding, as well as π-π interactions, electrostatic interactions, intrapore diffusion and hydrophobic interactions. Moreover, reusability and obtaining cost of the material were analyzed, demonstrating its promising application prospects. This study will promote the application of Fe3O4/BC in the removal of antibiotics pollutants from water.

Interfacial carbon quantum dot thin film impacts on morphological and chemical structures of fluorine-doped tin oxide films

Morphology and chemical bonding states, including surface roughness, film density, F-doping, and oxygen vacancy (VO) concentration directly affect the electrical and optical properties of fluorine-doped tin oxide (FTO) films. In this study, morphology and chemical bonding states of FTO films are engineered simultaneously by introducing a carbon quantum dot (CQD) thin film as an interface layer during ultrasonic spray pyrolysis deposition. The abundant oxygen-containing surface functional groups and large surface free energy of the CQD thin film promoted (200) oriented crystal growth and accelerated nucleation of FTO, resulting in smooth and dense FTO film morphology. The abundant carboxyl surface functional groups on the CQDs generate active F− species that are effectively doped into SnO2. Formic acid, formed by dissociation of the carboxyl group, can serve as a strong reducing agent for extracting oxygen atoms from the SnO2 lattice, thereby increasing the VO concentration. The accelerated F-doping and VO concentration result in the generation of additional free electrons. The effects of the optimized CQD on the morphological and chemical structures of FTO films are demonstrated by their superior electrical (sheet resistance of ∼5.7 Ω/□) and optical properties (visible transmittance of ∼85.9 %) compared with bare FTO. Moreover, CQD/FTO used as transparent conducting electrodes in electrochromic (EC) application exhibited improved EC performances, including fast switching speeds (5.3 s and 2.3 s for bleaching and coloration, respectively) and high coloration efficiency (81.1 cm2/C) compared to that of bare FTO.

Catalytic activation of peroxymonosulfate by intrinsic defects in amorphous carbon: Enhanced electronic transfer and oxygen-functional groups

Inherent defects in carbon material serve as an important way to enhance peroxymonosulfate (PMS) activity, however, the mechanism that activates PMS has always been ambiguous. Herein, the pyrolysis of straw with Prussian blue nanoparticles to prepare CoFe2O4/C (Carbon) was applied to analyze the mechanism of defective amorphous-C catalyzed activation of PMS. Amorphous-C structural defects increased the specific surface area of CoFe2O4/C (from 44.19 to 108.73 m2/g) with triggered electronic rearrangement, resulting in more PMS adsorption. CoFe2O4/C ensured the supply of low-valent metals (≡Co2+ and ≡Fe2+) simultaneously introduced a large number of surface oxygen-containing functional groups, which facilitated free radical generation. The structural defects enhanced electron transfer contributing to the direct oxidative degradation of BPA. Thus, 100 % removal of 450 µM BPA was achieved within 40 min attributed to the combined effect of catalyst-mediated ∙OH, 1O2, and electron transfer. Furthermore, the CoFe2O4/C/PMS system for BPA degradation exhibited universal pH suitability (4 ∼ 10) and low metal leaching (452.10 and 19.53 μg/L for Co and Fe, respectively). This study constructs systematic support for proposing the catalytic mechanism of carbon intrinsic defects activated PMS.

Tuning thermal and graphitization behaviors of lignin via complexation with transition metal ions for the synthesis of multilayer graphene-based materials.

Thermal conversion of kraft lignin, an abundant renewable aromatic substrate, into advanced carbon materials including graphitic carbon and multilayer/turbostratic graphene has recently attracted great interest. Our innovative catalytic upgrading approach integrated with molecular cracking and welding (MCW) enables mass production of lignin-derived multilayer graphene-based materials. To understand the critical role of metal catalysts in the synthesis of multilayer graphene, this study was focused on investigating the effects of transition metals (i.e., molybdenum (Mo), nickel (Ni), copper (Cu), and iron (Fe)) on thermal and graphitization behaviors of lignin. During the preparation of metal-lignin (M-lignin) complexes, Fenton-like reactions were observed with the formation of Fe- and Cu-lignin complexes, while Ni ions strongly interacted with oxygen-containing surface functional groups of lignin and Mo oxyanions weakly interacted with lignin through ionic bonding. Different chelation mechanisms of transition metal ions with lignin influenced the stabilization, graphitization, and MCW steps involved in thermal upgrading. The M-lignin complex behaviors in each of the three steps were characterized. It was found that multilayer graphene-based materials with nanoplatelets can be obtained from the Fe-lignin complex via MCW operation at 1000 °C under methane (CH4). Raman spectra indicated that Fe- and Ni-lignin complexes experienced a higher degree of graphitization than Cu- and Mo-lignin complexes during thermal treatment.

Inverse vulcanization induced oxygen modified porous polysulfides for efficient sorption of heavy metals.

The applications of polysulfides derived from natural plant oil and sulfur via the inverse vulcanization in the removal of heavy metals from aqueous solutions suffered from their low porosity and scarce surface functionality because of their hydrophobic surfaces and bulk characteristics. In this study, polysulfides from sulfur and palm oil (PSPs) with significantly enhanced porosity (13.7-24.1 m2/g) and surface oxygen-containing functional groups (6.9-8.6 wt.%) were synthesized with the optimization of process conditions including reaction time, temperature, and mass ratios of sulfur/palm oil/NaCl/sodium citrate. PSPs were applied as sorbents to remove heavy metals present in aqueous solutions. The integration of porosity and oxygen modification allowed a fast kinetic (4.0h) and enhanced maximum sorption capacities for Pb(II) (218.5mg/g), Cu(II) (74.8mg/g), and Cr(III) (68.4mg/g) at pH 5.0 and T 298K comparing with polysulfides made without NaCl/sodium citrate. The sorption behaviors of Pb(II), Cu(II), and Cr(III) on PSPs were highly dependent on the solution pH values and ionic strength. The sorption presented excellent anti-interference capability for the coexisting cations and anions. The sorption processes were endothermic and spontaneous. This work would guide the preparation of porous polysulfides with surface modification as efficient sorbents to remediate heavy metals from aqueous solutions.

Aqueous norfloxacin removal by novel biochar adsorbent prepared through ethanol-combined ball milling

ABSTRACT Ethanol combined-ball milling was used to modify corn-stover biochar. The adsorption performance and mechanisms of aqueous norfloxacin (NOR) onto the resulting biochar (C2H6O-BC) were evaluated. Ball-milling modulated its surface oxygen-containing functional groups and enhanced its specific surface area. The adsorption capacity of C2H6O-BC was 163 mg·g−1, and about 72% of the equilibrium adsorption capacity could be reached within 60 min. The electrostatic interaction was not the dominant mechanism when initial pH was lower than 8.00. The antagonistic effect of Cu(II) on NOR adsorption was observed. The fixed-bed column adsorption showed its potential to remove NOR and Cu(II) spontaneously. Sequential two-stage batch reaction experiment showed that it was a fast and efficient technology to remove NOR using C2H6O-BC. The adsorption mechanisms were suggested as π-π interactions, H-bonding and pore-filling. In summary, ethanol-combined ball milling in this study provided an efficient adsorbent for NOR.

Revealing the long-term impact of photodegradation and fragmentation on HDPE in the marine environment: Origins of microplastics and dissolved organics

The extensive usage of high-density polyethylene (HDPE) materials in marine environments raises concerns about their potential contribution to plastic pollution. Various factors contribute to the degradation of HDPE in marine environments, including UV radiation, seawater hydrolysis, biodegradation, and mechanical stress. Despite their supposed long lifespans, there is still a lack of understanding about the long-term degradation mechanisms that cause weathering of seawater-exposed HDPE products. In this research, the impact of UV radiation on the degradation of HDPE pile sleeves was studied in natural as well as laboratory settings to isolate the UV effect. After nine years of exposure to the marine environment in natural settings, the HDPE pile sleeves exhibited an increase in oxygen-containing surface functional groups and more morphological changes compared to accelerated UVB irradiation in the laboratory. This indicated that combined non-UV mechanisms may play a major role in HDPE degradation than UV irradiation alone. However, UVB irradiation was found to release dissolved organic carbon and total dissolved nitrogen from HDPE pile sleeves, reaching levels of up to 15 mg/L and 2 mg/L, respectively. Our findings underscore the significance of taking into account both UV and non-UV degradation mechanisms when evaluating the role of HDPE in contributing to marine plastic pollution.

Unlocking the full potential of citric acid-synthesized carbon dots as a supercapacitor electrode material via surface functionalization.

This research paper investigates the effect of functionalizing the surfaces of citric acid-synthesized carbon dots (CDs) with hyperbranched bis(methylol)propionic acid (bis-MPA) polyester hydroxyl polymers (HBPs) on their performance as electrode materials in a supercapacitor. Two types of HBPs with 16 and 64 peripheral hydroxyl groups were used to functionalize the CDs' oxygen-enriched surface. Here, CDs were used as electrode materials for the first time in symmetric supercapacitors without a composite material, and how surface modification affects the capacitance performance of CDs was investigated. Our results showed that the functionalization of green-emitting CDs with HBP resulted in the successful passivation of surface defects, which improved their stability and prevented further oxidation. The CDs with HBP passivation exhibited excellent electrochemical performance, with a high specific capacitance of 32.08 F g-1 at 0.1 A g-1 and good rate capability, indicating a faster ion transport rate at high current densities. Experimental EPR spectra of functionalized and non-functionalized CDs reveal distinct changes in g-factor values and line widths, confirming the impact of dangling bonds and spin-orbit interactions. The observed broader linewidth indicates a wider range of electron spin resonances due to energy-level splitting induced by spin-orbit coupling. The excellent electrochemical performance of CDs with HBP passivation can be attributed to the presence of oxygen-containing surface functional groups such as hydroxyl and carboxyl groups on their surfaces, which enhance the conductivity and charge transfer reactions. These results suggest that functionalization with polar HBPs is a promising strategy to enhance the electrochemical performance of CDs in supercapacitor applications.

The Relevance of Carbon for Energy Transition: Ways to Assess Its Surface Properties and Standardize Their Characterization

Technical carbon blacks (CB) are well-established materials that gain increasing attraction in the context of electrification and transition towards renewable energy sources. Their availability, low price, and favorable properties (e.g., conductivity, specific surface area) make them ideal candidates as additives in batteries or as support material for electrocatalysts, e.g., in fuel cells [1]. However, due to the vast number of producers and manufacturing processes large variations in their properties can be observed making product quality control difficult.To this end, we report on ways and methods to standardize the characterization of CB materials that are specifically designed for fuel cell and battery applications. By applying analytical centrifugation (AC) and combining it with complementary methods (e.g., electrical conductivity measurements, Boehm titration), we identify parameters like particle size, morphology, and surface properties that are influential for the overall value chain in electrode manufacturing. This helps to minimize the effects of material inherent property fluctuations as well as process-related fluctuations on the final electrochemical performance.Four different CBs were investigated, and their various properties were assessed. Our results show that the degree of graphitization and hence the electrical conductivity in a CB can be correlated with the overall surface basicity. Moreover, these properties can be linked with their dispersibility features on the ink formulation level and studied via liquid phase characterization using Hansen Parameters (Fig. 1) [2]. In brief, the higher the basicity of a CB surface is, the better the interaction with non-polar/mildly polar aprotic solvents becomes. This is especially true when oxygen-containing surface functional groups that cause a higher overall polarity of the material are missing.Figure 1: Hansen interaction space (for polar, disperse and hydrogen bonding interactions) showing the location of various solvents that are used as probe liquids for determining the Hansen Similarity Parameters of the respective CBs in 3D space (a) and 2D representations (b-d).To conclude, we were able to identify differences in CB materials by applying AC-based characterization techniques. Those differences can have a huge impact on the overall process chain of electrode production as they are decisive not only in formulation considerations but also in the subsequent processing steps. In the future, we will focus on closing the process chain and try to apply our characterization routines for an efficient identification of decisive process parameters at every stage of production. Additionally, we want to transfer knowledge gained from lab-scale techniques (e.g., sonication methods) to industrially relevant mixing procedures. By this, we will give electrode manufacturers tools at hand for a fast characterization of feed materials to save costly and lengthy adjustments of processes due to quality fluctuations. An accelerated implementation of green energy solutions is sought by this approach.

Kaolinite-Composited Biochar and Hydrochar as Low-Cost Adsorbents for the Removal of Cadmium, Copper, Lead, and Zinc from Aqueous Solutions

During the last decade, due to an increase in anthropogenic activities, a higher environmental accumulation of heavy metals has been found, which has resulted in disturbed biogeochemical balance. Many kinds of remediation techniques have been practiced to mitigate heavy metal toxicity in the aqueous phase; however, adsorption is the most commonly accepted technique for efficient heavy metal removal. In this study, conocarpus waste was pretreated with 0%, 10%, and 20% kaolinite and pyrolyzed at 600 °C for 1 h to synthesize biochars (BC, BCK10, and BCK20, respectively), while hydrothermalized at 200 °C for 6 h to synthesize hydrochars (HC, HCK10, and HCK20, respectively). After characterization, synthesized materials were employed for the removal of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) from contaminated water. Experimental data was further subjected to isotherm and kinetic models to estimate the adsorption mechanism. Among all the tested adsorbents, kaolinite-synthesized materials revealed comparatively higher adsorption compared to pristine materials. It was found that pH 7 was optimum for the maximum removal of tested heavy metals. Adsorption of tested heavy metals was well explained by Langmuir and Freundlich isotherms, while pseudo-second order and Elovich kinetics models fitted well for adsorption kinetics. The maximum adsorption capacity, as predicted by the Langmuir isotherm, was the highest for BCK20 (63.19 mg g−1 for Cd, 228.05 mg g−1 for Cu, 248.33 mg g−1 for Pb, and 45.79 mg g−1 for Zn) compared to the other tested materials, and for HCK20 (31.93 mg g−1 for Cd, 181.78 mg g−1 for Cu, 231.85 mg g−1 for Pb, and 45.72 mg g−1), it was higher than pristine HC. Isotherm and kinetics modeling data indicated that multiple mechanisms were involved in Cd, Cu, Pb, and Zn removal, such as chemisorption and electrostatic interactions. The amount of oxygen-containing surface functional groups and SiO2 particles could be responsible for the maximum adsorption of heavy metals by BCK20 and HCK20. Our findings suggest that biochar, hydrochar, and their kaolinite-modified composites possess the excellent potential to remove heavy metals from contaminated aqueous media, and could be further applied to treat wastewater to mitigate heavy metal toxicity for a sustainable environment.

Photocatalytic degradation of polyethylene and polystyrene microplastics by α-Fe2O3/g-C3N4.

This study investigated the photodegradation of microplastics (MPs) by α-Fe2O3/g-C3N4. The effects of α-Fe2O3/g-C3N4 on MPs' surface were investigated through various techniques. With the addition of α-Fe2O3/g-C3N4 and under visible light irradiation, cracks and folds were observed on the MP films and particles. Compared to the treatment without photocatalyst addition, the mass loss of MPs increased with irradiation time when α-Fe2O3/g-C3N4 was added. Specifically, polystyrene films and particles in water showed 9.94% and 7.81% increased mass loss, respectively. The degradation of MPs using α-Fe2O3/g-C3N4 demonstrated the behavior consistent with the pseudo-first-order kinetic model. The presence of α-Fe2O3/g-C3N4 led to an increase in surface oxygen-containing functional groups and crystallinity while decreasing the average molecular weight of MPs. After 30days of irradiation, the characteristic tensile bands of MPs with α-Fe2O3/g-C3N4 significantly increased, and the detection of carboxyl bands indicated the formation of carboxylic acid, ketones, and lactones as degradation products.

Enhancement of alkali- and oxidation-modified biochars derived from water hyacinth for ammonium adsorption capacity

ABSTRACT Wastewater containing high concentrations of ammonium-nitrogen (NH4 +-N) is considered a major concern because its untreated discharge has a variety of adverse effects on the environment and human health. Adsorption using biochars is an easy and cost-effective wastewater treatment method. However, aquatic plants such as water hyacinth for biochar feedstock are considered unsuitable for adsorbent use due to limited NH4 +-N adsorption capacity. In this study, biochar made from water hyacinth was modified with potassium hydroxide (KOH) and hydrogen peroxide (H2O2) to obtain highly efficient adsorbent. This study aimed to enhance NH4 +-N adsorption capacity by KOH- and H2O2-treatments and identify NH4 +-N adsorption mechanism of the modified biochars derived from water hyacinth. The NH4 +-N adsorption of all biochars was dependent on the initial solution pH increasing from pH 2 to 4, then relatively constant from pH 4 to 8. Pseudo-second-order model and Langmuir model were found to be the best fit for NH4 +-N adsorption data. The maximum NH4 +-N adsorption capacity of biochars increased about 8 times (17.1 mg g−1) and 10 times (21.5 mg g−1) after KOH- and H2O2-modification, respectively, compared to pristine biochar (2.14 mg g−1). The main NH4 +-N adsorption mechanisms were suggested as cation exchange for both biochars particularly KOH-modified biochar, and hydrogen bonding by oxygen-containing surface functional groups for H2O2-modified biochar. This study suggested that aquatic plant-based biochar, which has been considered difficult to use, had potential as a promising alternative adsorbent for removing NH4 +-N from wastewater through modification.

Bamboo-based self-supporting electrodes via green activation for high-performance supercapacitors

As a potential high-efficiency energy storage device, supercapacitor electrode materials encounter persistent challenges, including limitations in energy density and stability, particularly at large loadings. In this work, a bamboo-based self-supporting thick electrode (∼30 mg cm−2) is prepared. The electrode takes full advantage of the vertical growth channels and surface oxygen-containing functional groups of bamboo, which improves the ion transport kinetics within its structure. Inspired by the fermentation process of bread with baking soda, the electrode material is prepared by KHCO3 activation at 1000 °C. The optimal sample exhibits a specific surface area of 903 m2 g−1 and an electrode specific capacitance of 142.7 F g−1 at current density of 1 A g−1. Furthermore, the assembled supercapacitor device exhibits excellent electrochemical performance even at high loadings. Specifically, the supercapacitor exhibits high energy density of 20.36 Wh kg−1 at 400 W kg−1. The device also has excellent cycling stability with a capacitance retention of 104.4 % after 10,000 cycles at a high current of 5 A g−1. Benefiting from the green preparation process, high energy density, and excellent cycling stability, the bamboo-based self-supporting thick electrode exhibits immense potential for further development and utilization.

Influence of wettability alteration on water-blocking effect and gas desorption of coal

To resolve the water-blocking effect that reduces gas extraction after implementing hydraulic measures, alkyl polyglycoside (APG) and polyacrylamide (PAM) were used to treat coal samples to make wettability enhancement and medium wettability conversion, respectively. The contact angle, surface tension, solid surface energy, infrared spectroscopy, and high-pressure water injection desorption were performed to investigate the effects of reagents on the wettability alteration mechanism and desorption characteristics of coal. The results demonstrated that the surface energy, hydrogen bonds and oxygen-containing functional groups of coal alter wettability and gas desorption. The APG-treated coal samples exhibited increased surface energy, hydrogen bonds and oxygen-containing functional groups, whereas the PAM-treated coal samples demonstrated the opposite trend. The surface energy of coal reflects the state of APG and PAM molecules adsorbed on the coal surface, and the polar force of surface energy in coal follows a quadratic relationship with the volume of gas displacement desorption. Increasing the number of hydrogen bonds and oxygen-containing functional groups can improve wettability and decrease the interaction force between coal and methane molecules. This contributes to the lower atmospheric desorption of the APG-treated coal samples at high pressure. The total desorption volume of the APG-treated coal samples was 10–34% of that of the original coal at 0.737, 1.027, and 2.004 MPa gas pressures. The total desorption volume of PAM-treated samples at 2.004 MPa was 2.3474 cm3/g, which exceeded that of the original coal. Therefore, APG and PAM promoted gas desorption, and wettability enhancement yielded better results. This study provides an experimental approach for selecting the best reagent and excellent guidance for field applications.

A comprehensive review of graphene oxide-based membranes for efficient dye removal from water sources

In the realm of water treatment, the utilization of two-dimensional (2D) graphene and its derivative, graphene oxide (GO), has emerged as a pioneering avenue for the development of nanoporous membranes. These membranes hold immense promise due to the remarkable attributes inherent to GO, notably its expansive specific surface area and the profusion of oxygen-containing surface functional groups. This comprehensive review elucidates the recent advances in the fabrication and utilization of GO-based membranes, specifically tailored for the efficacious removal of dyes from aqueous environments. A detailed analysis of the key physicochemical characteristics, which distinctly influence the synthesis and performance of GO-based membranes, is performed. Furthermore, a profound explication of the intricate mechanisms underpinning the rejection of dyes by these membranes is presented, accompanied by a thorough investigation into the stability performance of the deployed GO-based membranes. A quick comparison of GO membranes with other 2D materials and the application potential of these membranes in treating real textile effluents is also provided. In the end, salient research gaps are pinpointed, leading to clear suggestions for overcoming the mentioned hurdles. This article aimed to help the research community understand GO-based membranes deeply, and also provide valuable ideas about their growing effectiveness in cleaning dyes from various wastewater sources.

Oxalic acid-modified activated carbons under hydrothermal condition for the adsorption of the 2-butanone.

Growing volatile organic compound (VOC) emission will cause air pollution and further threaten human health. Activated carbon is widely applied to treatment of VOCs in virtue of lower cost and excellent adsorption ability. In this work, the adsorption capacity of polarity VOCs on activated carbon is improved by oxalic acid (H2C2O4) hydrothermal modification. After 2M H2C2O4 modification, the adsorption capacity of 2-butanone rose from 312.60 to 345.98mg/g, and the time reaching saturation adsorption became shorter. BET results showed that both the specific surface area and total pore volume of 2M H2C2O4-modified activated carbon increased by 3.32% and 3.9%, respectively. Both FTIR and XPS characterization confirmed variation of the surface oxygen-containing functional groups (SOFGs), while quantitative analysis via Boehm titration showed the significant increase of total acidity (61.36%), particularly the carboxyl content increased by 96.28%. The results indicated modification process can not only change the pore structure but also the SOFGs of activated carbons. The dynamic adsorption curves conform to the Bangham kinetics model, indicating that the adsorption of 2-butanone on both activated carbon is controlled by the diffusion in the pore channel. The adsorption data was also modeled by the internal particle diffusion model, and the internal diffusion adsorption stage is the rate-controlling step. The stability before and after adsorption and the cycling performance were studied.

Biosynthetic amyloid fibril CsgA-Fe3O4 composites for sustainable removal of heavy metals from water

Removal of heavy metals from water has been a hot topic. However, few studies have been conducted for the tricky low concentration range. Experimental designs often have heavy metal concentrations much higher than the actual environmental loading, which leads to poor practical results of adsorbent materials. This study showed that amyloid fiber CsgA-Fe3O4 composites are ideal for the removal of heavy metals from water, especially at low concentrations. We constructed CsgA-Fe3O4 composites by fusing short functional peptides that specifically bind to Fe3O4 magnetic nanoparticles. The CsgA-Fe3O4 composites achieved 98.73 %, 98.43 %, and 93.00 % removal of 1 mg/L Cu2+, Cd2+, and Pb2+, respectively. Moreover, the adsorption rate remained above 80 % after six repeated adsorptions, indicating that CsgA-Fe3O4 was highly reusable. Meanwhile, the high removal rate (>90 %) of heavy metals in the simulated wastewater demonstrated the excellent environmental stability of CsgA-Fe3O4. Finally, by FT-IR and XPS characterization, we found that the adsorption mechanism of CsgA-Fe3O4 is mainly the complexation of surface oxygen-containing functional groups and heavy metal ions. In general, the CsgA-Fe3O4 composite is an efficient, inexpensive, and sustainable adsorption material for mitigating low concentrations of difficult-to-treat heavy metal pollution in water bodies.

Effects of ferrous sulfate modification on the fate of phosphorous in sewage sludge biochar and its releasing mechanisms in heavy metal contaminated soils.

Modifications of sludge biochar with metal-based materials can enhance its fertilizing efficiency and improve safety. To elucidate the effects of ferrous sulfate modification on the fate of phosphorus in sludge biochar and its effect on phosphorus fractionation in soil, we investigated the changes in fractionation and bioavailability of phosphorus in modified sludge biochar and studied the changes in soil characteristics, microbial diversity and response, bioavailability, plant uptake of phosphorus, and heavy metals in contaminated soils after treatment with ferrous sulfate modified sludge biochar. The results demonstrated that ferrous sulfate modifications were conducive to the formation of moderately labile phosphorus in sludge biochar, and the concentrations increased by a factor of 2.7 compared to control. The application of ferrous sulfate-modified sludge biochar to alkaline heavy metal-contaminated soils enhanced the bioavailable, labile, and moderately labile phosphorus contents by a factor of 2.9, 3.0, and 1.6, respectively, whereas it obviously reduced the leachability and bioavailability of heavy metals in soils, exhibited great potentials in the fertilization and remediation of actual heavy metal-contaminated soils in mining areas. The biochar-induced reduction in soil pH, enhancement of organic matter, surface oxygen-containing functional groups, the abundance of Gammaproteobacteria, and its phosphonate degradation activity were primarily responsible for the solubilization of phosphorus from modified biochar in heavy metal-contaminated soils.

Insight into the effects of different oxygen heteroatoms on nicotine adsorption from cigarette mainstream smoke

Cigarette smoke contains many chemicals, including nicotine, which is harmful and can cause health problems such as carcinogenesis disease, cardiovascular, respiratory, renal, and reproductive systems. Removal of nicotine from mainstream smoke can be done through adsorption with filters or solid adsorbents. In this study, we explored the use of activated carbons for the removal of nicotine from cigarette mainstream smoke. Activated carbons were prepared from dried hemp (Cannabis sativa) stem at an activation temperature of 350–550 °C using phosphoric acid as an activating agent. The results showed that the activated carbons with variable surface functional groups and porosity exhibited high efficiency for nicotine adsorption, removing 68–88% of nicotine from cigarette mainstream smoke. Through X-ray photoelectron spectroscopy and temperature-programmed desorption analyses, we identified that oxygen-containing functional groups, particularly carboxylic groups, exhibited a superior ability to adsorb nicotine. The computational analysis with DFT simulations further supported the importance of oxygen-containing surface functional groups in facilitating nicotine adsorption, with the carboxylic group providing the lowest adsorption energy among other functional groups.