Switching Product Selectivity in CO2 Electroreduction via Cu-S Bond Length Variation.

Regulating competitive reaction pathways to direct the selectivity of electrochemical CO2 reduction reaction toward a desired product is crucial but remains challenging. Herein, switching product from HCOOH to CO is achieved by incorporating Sb element into the CuS, in which the Cu-S ionic bond is coupled with S-Sb covalent bond through bridging S atoms that elongates the Cu-S bond from 2.24 Å to 2.30 Å. Consequently, CuS with a shorter Cu-S bond exhibited a high selectivity for producing HCOOH, with a maximum Faradaic efficiency (FE) of 72%. Conversely, Cu3SbS4 characterized by an elongated Cu-S bond exhibited the most pronounced production of CO with a maximum FE of 60%. In situ spectroscopy combined with density functional theory calculations revealed that the altered Cu‒S bond length and local coordination environment make the *HCOO binding energy weaker on Cu3SbS4 compared to that on CuS. Notably, a volcano-shaped correlation between the Cu-S bond length and adsorption strength of *COOH indicates that Cu-S in Cu3SbS4 as double-active sites facilitates the adsorption of *COOH, and thus results in the high selectivity of Cu3SbS4 toward CO.

Rhizosphere environmental factors regulated the cadmium adsorption by vermicompost: Influence of pH and low-molecular-weight organic acids.

Vermicompost is a promising amendment for immobilization of cadmium (Cd) in soils; however, its effectiveness can be influenced by rhizosphere environment conditions, such as pH and the presence of low-molecular-weight organic acids (LMWOAs). In this study, a batch experiment was conducted to examine the characteristics of Cd adsorption by vermicompost at different pH (pH = 3, 5, and 7) and after the addition of different LMWOAs (oxalic acid; citric acid; malic acid). Furthermore, a series of morphology and structural analyses were conducted to elucidate the mechanisms of observed effects. The results showed that the adsorption capacity of vermicompost for Cd increased as pH increased, and chemisorption dominated the adsorption process. Changes in pH altered adsorption performance by affecting the -OH groups of alcohol/phenol and the -CH2 groups of aliphatics. Further, the addition of oxalic acid promoted Cd adsorption, and the effect was concentration dependent. Modifying the verimicompost surface with more adsorption sites might be the main reason. Conversely, citric acid and malic acid showed the ability to inhibit Cd adsorption by vermicompost. Citric acid caused a blocking effect by covering flocculent substances on the vermicompost surface while reducing surface adsorption sites by dissolving mineral components such as iron oxides. However, the action of malic acid did not appear to be related to changes in morphology or the structure of vermicompost. Overall, the results of this study partially explain the limited effectiveness of Cd immobilization within the rhizosphere by vermicompost, and provide theoretical support for regulating rhizosphere environments to improve the effectiveness of vermicompost immobilization of Cd.

Adsorption Characteristics of Ionic Surfactants on Anthracite Surface: A Combined Experimental and Modeling Study.

Ionic surfactants are widely used in coal dust control in mines, and their adsorption characteristics on the coal surface have a great influence on the coal dust control effect. In this investigation, anionic sodium dodecylbenzenesulfonate (SDBS) and cationic octadecyltrimethylammonium chloride (STAC) were selected to explore the adsorption characteristics of ionic surfactants on the surface of anthracite. The experimental results show that the adsorption rate and efficiency of STAC on the surface of anthracite are higher than that of SDBS; STAC can form a denser surfactant layer on the surface of anthracite, with a larger adsorption capacity and higher strength. Molecular dynamics simulations show that the adsorption between STAC and the surface of anthracite is tighter, and the distribution at the coal-water interface is more uniform; the surface of anthracite modified by STAC has a stronger binding ability to water molecules.

Adsorption-Desorption and Migration Behaviors of Oxaziclomefone in Different Agricultural Soils in China.

Oxaziclomefone is an organic heterocyclic herbicide which has been widely used in rice fields. The aim of this paper is to investigate the adsorption-desorption and migration of oxaziclomefone in four Chinese agricultural soils. All the four soils show high adsorption capacity for oxaziclomefone, with similar adsorption rates at 84.48%-96.70%. Four adsorption kinetic models were used to fit the adsorption kinetic characteristics and the elovich model was the best, indicating that chemical processes were involved in adsorption. For the isothermal adsorption behavior of oxaziclomefone, the Freundlich model shows the best, indicating that the adsorption sites for oxaziclomefone in soil were heterogeneous. The retention factor in the soil thin-layer plates ranges from 0.083 to 0.250 and the retention factor 0-10 cm layer of the soil column was > 50, indicating that the herbicide was not easily migration from all four soils. Because oxaziclomefone has low mobility in different soils and is not easily leached, it poses a low potential threat of contaminating surface water and groundwater.

Adsorption and Desorption Characteristics of Total Flavonoids from Acanthopanax senticosus on Macroporous Adsorption Resins.

We examined the application of six different resins with the aim of selecting a macroporous resin suitable for purifying Acanthopanax senticosus total flavonoids (ASTFs) from Acanthopanax senticosus crude extract (EAS) by comparing their adsorption/desorption capacities, which led to the selection of HPD-600. Research on the adsorption mechanism showed that the adsorption process had pseudo-second-order kinetics and fit the Freundlich adsorption model. Moreover, the analysis of thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. The optimal conditions for purification of ASTFs were determined as sample pH of 3, 60% ethanol concentration, and 3 BV·h-1 flow rate, for both adsorption and desorption, using volumes of 2.5 and 4 BV, respectively. The application of macroporous resin HPD-600 to enrich ASTFs resulted in an increase in the purity of total flavonoids, from 28.79% to 50.57%. Additionally, the antioxidant capacity of ASTFs was higher than that of EAS, but both were lower than that of L-ascorbic acid. The changes in ASTFs compositions were determined using ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), with the results illustrating that the levels of seven major flavonoids of ASTFs were increased compared to that in the crude extract.

Adsorption and desorption characteristics of ginsenosides from Panax ginseng C. A. Meyer on middle-pressure chromatogram isolated gels.

Four types of middle-pressure chromatogram isolated gels are evaluated for adsorption or desorption characteristics of ginsenosides from Panax ginseng. Among them, SP207SS and SP2MGS were selected for dynamic investigations based on their static adsorption or desorption capacity of total ginsenoside. Their adsorption kinetics was better explained by pseudosecond-order model and isotherms were preferably fitted to Langmuir model. Dynamic breakthrough experiments indicated an optimum sample loading speed of 4 bed volume/h for either SP207SS or SP2MGS. Desorption speed was determined to be 2 bed volume/h according to desorption amount of total ginsenoside in their effluents. Eight ginsenosides were identified and quantified by high performance liquid chromatography-triple quadropole-mass spectrometry in total ginsenoside extract and different fractions during stepwise dynamic elution. For SP207SS, 27.62% of loaded ginsenosides was detected in 40% ethanol fraction, while 59.12% of them were found in 60% ethanol fraction. As on SP2MGS, the number went to 53.71 and 44.43%, respectively. Recovery rate of ginsenosides were calculated to 78.65% for SP207SS and 89.53% for SP2MGS, respectively. Intriguingly, content of Rg1 and Re in 40% ethanol fraction from SP207SS became 20.1 and 18.6 times higher than that in total ginsenoside extract by one-step elution, which could be leveraged for the facile enrichment of these two ginsenosides from natural sources.

The Adsorption Behavior of Atrazine in Common Soils in Northeast China.

The objective of this study was to evaluate the adsorption capacity of atrazine and the effects of different environmental conditions such as temperature, pH, Ca2+ and biochar on the adsorption characteristics of atrazine in different types of soil using the intermittent adsorption method. The kinetic experiment showed that the adsorption of atrazine in albic, black and saline-alkaline soils reached equilibrium within 24 h. In the thermodynamics experiment, the Freundlich model effectively described the adsorption characteristics of atrazine in all three types of soil, indicating that the adsorption process forms multi-molecular layers. Lower soil pH conditions were more favorable for the absorption of atrazine. The addition of appropriate concentrations of Ca2+ or biochar could promote the adsorption of atrazine by the soil. Biochar could promote the fixation of atrazine in soils.

Adsorption property of Br-PADAP-impregnated multiwall carbon nanotubes towards uranium and its performance in the selective separation and determination of uranium in different environmental samples.

A newer efficient U(VI) ion adsorbent was synthesized by impregnating Br-PADAP [2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol] onto multiwall carbon nanotubes (MWCNTs). The effects of various operation conditions on uranium adsorption (i.e., pH contact time, temperature, and initial uranium concentration) were systematically evaluated using batch experiments. The results indicated that the uranium adsorption on modified MWNCTs (5.571 × 10-3g/mg × min) reached faster equilibrium than that on pristine MWNCTs (4.832 × 10-3g/mg × min), reflecting the involvement of appropriate functional groups of Br-PADAP on the chelating ion-exchange mechanism of U(VI) adsorption. Modified MWNCTs (83.4mg/g) exhibited significantly higher maximum Langmuir adsorption capacity than pristine MWNCTs (15.1mg/g). Approximately 99% of uranium adsorbed onto modified MWNCTs can be desorbed by 2.5mL of 1M HNO3 solution. Therefore, Br-PADAP-modified MWNCTs can server as a promising adsorbent for efficient uranium adsorption applications in water treatment. Subsequently, the proposed solid-phase extraction (using a mini-column packed with Br-PADAP/MWCNT) was successfully utilized for analysing trace uranium levels by the ICP-AES method in different environmental samples with a pre-concentration factor of 300-fold. The coexistence of other ions demonstrated an insignificant interference on the separative pre-concentration of uranium. the detection limit was recognized as 0.14µg/L, and the relative standard deviation was approximately 3.3% (n = 7).

[Adsorption characteristics of proteins on membrane surface and effect of protein solution environment on permeation behavior of berberine].

In order to explore the adsorption characteristics of proteins on the membrane surface and the effect of protein solution environment on the permeation behavior of berberine, berberine and proteins were used as the research object to prepare simulated solution. Low field NMR, static adsorption experiment and membrane separation experiment were used to study the interaction between the proteins and ceramic membrane or between the proteins and berberine. The static adsorption capacity of proteins, membrane relative flux, rejection rate of proteins, transmittance rate of berberine and the adsorption rate of proteins and berberine were used as the evaluation index. Meanwhile, the membrane resistance distribution, the particle size distribution and the scanning electron microscope (SEM) were determined to investigate the adsorption characteristics of proteins on ceramic membrane and the effect on membrane separation process of berberine. The results showed that the ceramic membrane could adsorb the proteins and the adsorption model was consistent with Langmuir adsorption model. In simulating the membrane separation process, proteins were the main factor to cause membrane fouling. However, when the concentration of proteins was 1 g•L⁻¹, the proteins had no significant effect on membrane separation process of berberine.

Simulation study of the effect of OGs on the adsorption of formaldehyde on modified activated carbon.

CONTEXT: To explore the impact of OGs (OGs) on formaldehyde (HCHO) adsorption by modified activated carbon, this paper studied the influence of OGs on HCHO adsorption characteristics, varying the groups including ester, carboxyl, and hydroxyl. Employing density functional theory (DFT), the effects of various OGs on the structure of N-doped activated carbon through GGA-PBE exchange-correlation functionals by Materials Studio combined with Gaussian software. The types of weak interactions during the adsorption process were calculated by RDG, elucidating the mechanism through which the three OGs affect HCHO adsorption on N-doped activated carbon. The dynamic adsorption process of HCHO was simulated by molecular dynamics (MD). The influence and proportion of OGs on HCHO adsorption were subsequently analyzed using van der Waals and electrostatic interactions, determining differences in formaldehyde adsorption effects across OG types. The carboxyl group exhibits the most robust synergistic adsorption effect on the modified activated carbon. There is a notable alteration in the position and distribution of electrostatic potential extremes observed following carboxyl modification. The calculation results show that the adsorption energy of hydroxyl groups on modified activated carbon is the highest, at -5.07 kcal/mol, with a transfer charge of 0.014 e. Following the introduction of carboxyl groups, the proportion of electrostatic interactions escalated from the initial 24% to 38%. This study will provide new ideas for guiding the design of activated carbon for efficient adsorption of formaldehyde. METHODS: The modified activated carbon fragments of three OGs were constructed by Materials Studio and Gaussian software, and the surface electrostatic potential polarity and area distribution, charge change, adsorption energy, and transferred charge of each molecular fragment were calculated. Moreover, cell models of OGs with the same dimensions were constructed to simulate the adsorption amount, heat of adsorption, interaction energy, radial distribution function, and hydrogen-bonding interactions for methane at room temperature and pressure. The results were consistent with the DFT simulations.

Adsorption and desorption characteristics of flavonoids from white tea using macroporous adsorption resin.

White tea contains the highest flavonoids compared to other teas. While there have been numerous studies on the components of different tea varieties, research explicitly focusing on the flavonoid content of white tea remains scarce, making the need for a good flavonoid purification process for white tea even more important. This study compared the adsorption and desorption performance of five types of macroporous resins: D101, HP20, HPD500, DM301, and AB-8. Among the tested resins, AB-8 was selected based on its best adsorption and desorption performance to investigate the static adsorption kinetics and dynamic adsorption-desorption purification of white tea flavonoids. The optimal purification process was determined: adsorption temperature 25 °C, crude tea flavonoid extract pH 3, ethanol concentration 80 %, sample loading flow rate and eluent flow rate 1.5 BV/min, and eluent dosage 40 BV. The results indicated that the adsorption process followed pseudo-second-order kinetics. Under the above purification conditions, the purity of the total flavonoids in the purified white tea flavonoid increased from approximately 17.69 to 46.23 %, achieving a 2.61-fold improvement, indicating good purification results. The purified white tea flavonoid can be further used for nutraceutical and pharmaceutical applications.

Phenotypic characterization and genomic analysis of Limosilactobacillus fermentum phage.

Limosilactobacillus (L.) fermentum is widely utilized for its beneficial properties, but lysogenic phages can integrate into its genome and can be induced to enter the lysis cycle under certain conditions, thus accomplishing lysis of host cells, resulting in severe economic losses. In this study, a lysogenic phage, LFP03, was induced from L. fermentum IMAU 32510 by UV irradiation for 70 s. The electron microscopy showed that this phage belonged to Caudoviricetes class. Its genome size was 39,556 bp with a GC content of 46.08%, which includes 20 functional proteins. Compared with other L. fermentum phages, the genome of phage LFP03 exhibited deletions, inversions and translocations. Biological analysis showed that its optimal multiplicity of infection was 0.1, with a burst size of 133.5 ± 4.9 PFU/infective cell. Phage LFP03 was sensitive to temperature and pH value, with a survival rate of 48.98% at 50 °C. It could be completely inactivated under pH 2. The adsorption ability of this phage was minimally affected by temperature and pH value, with adsorption rates reaching 80% under all treated conditions. Divalent cations could accelerate phage adsorption, while chloramphenicol expressed little influence. This study might expand the related knowledge of L. fermentum phages, and provide some theoretical basis for improving the stability of related products and establishing phage control measures.

The Characteristics of Adsorption of Di-n-Butyl Phthalate by Surface Sediment from the Three Gorges Reservoir.

Phthalic acid esters (PAEs), recognized as endocrine disruptors, are identified as predominant organic pollutants in the Three Gorges Reservoir (TGR). Di-n-butyl phthalate (DBP), a representative PAE, has been extensively studied for its sources, distribution and ecological risks. However, there are few studies on the adsorption of DBP by sediment from the TGR, and the adsorption characteristics of surface sediment on DBP are not clear. Therefore, based on the actual sediment contents and particle sizes in the TGR, the kinetics and isothermal adsorption characteristics of surface sediment on DBP were investigated in this study. The results showed that the equilibrium time was 120 min, the adsorption kinetics were more in line with the pseudo-second-order kinetic model, and the sediment in water from the Yangtze River exhibited a higher adsorption rate and maximum adsorption amount on DBP than that observed in deionized water. Additionally, a decrease in DBP adsorption was observed with increasing sediment content, while sediment particle size and specific surface area had a slight influence. Analysis using SEM, TGA and FTIR revealed that organic matter on the sediment surface significantly contributed to DBP adsorption. This study contributes valuable insights into the adsorption characteristics of DBP by the surface sediment from the TGR, providing a scientific foundation for understanding the migration and transformation of DBP in this critical reservoir in China.

Study on the adsorption of Zn(II) and Cu(II) in acid mine drainage by fly ash loaded nano-FeS.

Aiming at the acid mine drainage (AMD) in zinc, copper and other heavy metals treatment difficulties, severe pollution of soil and water environment and other problems. Through the ultrasonic precipitation method, this study prepared fly ash-loaded nano-FeS composites (nFeS-F). The effects of nFeS-F dosage, pH, stirring rate, reaction time and initial concentration of the solution on the adsorption of Zn(II) and Cu(II) were investigated. The data were fitted by Lagergren first and second-order kinetic equations, Internal diffusion equation, Langmuir and Freundlich isotherm models, and combined with SEM, TEM, FTIR, TGA, and XPS assays to reveal the mechanism of nFeS-F adsorption of Zn(II) and Cu(II). The results demonstrated that: The removal of Zn(II) and Cu(II) by nFeS-F could reach 83.36% and 70.40%, respectively (The dosage was 8 g/L, pH was 4, time was 150 min, and concentration was 100 mg/L). The adsorption process, mainly chemical adsorption, conforms to the Lagergren second-order kinetic equation (R2 = 0.9952 and 0.9932). The adsorption isotherms have a higher fitting degree with the Langmuir model (R2 = 0.9964 and 0.9966), and the adsorption is a monolayer adsorption process. This study can provide a reference for treating heavy metals in acid mine drainage and resource utilization of fly ash.

[Adsorption Characteristics of Fluoride in Low-Concentration Water by Aluminum and Zirconium-Modified Biochar].

To deal with problems such as the difficult treatment of low-concentration fluoride-containing water and water pollution caused by excessive fluoride (F-) discharge, aluminum and zirconium-modified biochar (AZBC) was prepared and its adsorption characteristics and adsorption mechanism for low-concentration fluoride in water were studied. The results showed that AZBC was a mesoporous biochar with uniform pore structure. It could rapidly adsorb F- from water and reach adsorption equilibrium within 20 min. When the initial ρ(F-) was 10 mg·L-1and the AZBC dosage was 30 g·L-1, the removal rate was 90.7%, and the effluent concentration was lower than 1 mg·L-1. The pHpzc of AZBC was 8.9, and the recommended pH in practical application was 3.2-8.9. The adsorption kinetics accorded with pseudo-second order kinetics, and the adsorption process accorded with the Langmuir model. The maximum adsorption capacities at 25, 35, and 45℃ were 8.91, 11.40, and 13.76 mg·g-1, respectively. Fluoride could be desorbed by 1 mol·L-1 NaOH. The adsorption capacity of AZBC decreased by approximately 15.9% after 5 cycles. The adsorption mechanisms of AZBC were the combination of electrostatic adsorption and ion exchange.Taking actual sewage as theexperimental object, when the AZBC dosage was 10 g·L-1, the ρ(F-) was reduced to below 1 mg·L-1.

Phosphorus fractions and iron oxides responsible for the variations in the Cd retention capacity in tropical soil aggregates under different cropping patterns.

The environmental behavior of Cd in soil has been widely studied because of its close relationship with food security and soil environmental pollution. In this study, the roles of P fractions and Fe oxides in the retention of Cd in typical tropical soil from five cropping patterns were investigated. Although there was no evident relationship between the Cd adsorption capacity and soil aggregate particle sizes, strong spatial associations of P, Fe, and Cd at the soil aggregates were observed via energy dispersive spectroscopy analysis. Among five cropping patterns, citrus plantations exhibited highest ratios (calculated by pixel area) of P overlapped with Cd (8.61%) and Fe overlapped with Cd (9.53%) in the microaggregates. Furthermore, the random forest model revealed that humic P and labile organic P greatly contributed to the sorptivity of Cd2+ by < 0.053 mm (13.3%) and 0.25-0.053 mm (13.4%) soil aggregates, respectively. Compared with the P fractions in different-sized soil aggregates, the contribution of Fe oxides to the sorption of Cd2+ by soil aggregates was more significant. Amorphous ferric oxide had the most significant contribution to the sorptivity of Cd2+ by < 0.053 mm (26.0%), 0.25-0.053 mm (23.0%), 2.0-0.25 mm (25.1%), and > 2.0 mm (33.9%) soil aggregates.

Adsorption Characteristics between Ti Atoms of TiO2(100) and Corrosive Species of CO2-H2S-Cl- System in Oil and Gas Fields.

The service environment of OCTG (Oil Country Tubular Goods) in oil and gas fields is becoming more and more severe due to the strong affinity between ions or atoms of corrosive species coming from solutions and metal ions or atoms on metals. While it is difficult for traditional technologies to accurately analyze the corrosion characteristics of OCTG in CO2-H2S-Cl- systems, it is necessary to study the corrosion-resistant behavior of TC4 (Ti-6Al-4V) alloys based on an atomic or molecular scale. In this paper, the thermodynamic characteristics of the TiO2(100) surface of TC4 alloys in the CO2-H2S-Cl- system were simulated and analyzed by first principles, and the corrosion electrochemical technologies were used to verify the simulation results. The results indicated that all of the best adsorption positions of corrosive ions (Cl-, HS-, S2-, HCO3-, and CO32-) on TiO2(100) surfaces were bridge sites. A forceful charge interaction existed between Cl, S, and O atoms in Cl-, HS-, S2-, HCO3-, CO32-, and Ti atoms in TiO2(100) surfaces after adsorption in a stable state. The charge was transferred from near Ti atoms in TiO2 to near Cl, S, and O atoms in Cl-, HS-, S2-, HCO3-, and CO32-. Electronic orbital hybridization occurred between 3p5 of Cl, 3p4 of S, 2p4 of O, and 3d2 of Ti, which was chemical adsorption. The effect strength of five corrosive ions on the stability of TiO2 passivation film was S2- > CO32- > Cl- > HS- > HCO3-. In addition, the corrosion current density of TC4 alloy in different solutions containing saturated CO2 was as follows: NaCl + Na2S + Na2CO3 > NaCl + Na2S > NaCl + Na2CO3 > NaCl. At the same time, the trends of Rs (solution transfer resistance), Rct (charge transfer resistance), and Rc (ion adsorption double layer resistance) were opposite to the corrosion current density. The corrosion resistance of TiO2 passivation film to corrosive species was weakened owing to the synergistic effect of corrosive species. Severe corrosion resulted, especially pitting corrosion, which further proved the simulation results mentioned above. Thus, this outcome provides the theoretical support to reveal the corrosion resistance mechanism of OCTG and to develop novel corrosion inhibitors in CO2-H2S-Cl- environments.

Breeding, Biosorption Characteristics, and Mechanism of a Lead-Resistant Strain.

To effectively carry out the bioremediation of a Pb2+ polluted environment, a lead-tolerant strain named D1 was screened from the activated sludge of a factory in Hefei, and its lead removal in a solution with Pb2+ concentration of 200 mg/L could reach 91% under optimal culture conditions. Morphological observation and 16S rRNA gene sequencing were used to identify D1 accurately, and its cultural characteristics and lead removal mechanism were also preliminarily studied. The results showed that the D1 strain was preliminarily identified as the Sphingobacterium mizutaii strain. The experiments conducted via orthogonal test showed that the optimal conditions for the growth of strain D1 were pH 7, inoculum volume 6%, 35 °C, and rotational speed 150 r/min. According to the results of scanning electron microscopy and energy spectrum analysis before and after the D1 exposure to lead, it is believed that the lead removal mechanism of D1 is surface adsorption. The Fourier transform infrared spectroscopy (FTIR) results revealed that multiple functional groups on the surface of the bacterial cells are involved in the Pb adsorption process. In conclusion, the D1 strain has excellent application prospects in the bioremediation of lead-contaminated environments.

Improving the adsorption characteristics and antioxidant activity of oat bran by superfine grinding.

Oat bran (OB) is a by-product of oat, which is rich in ß-glucan. As a new food processing technology, ultrafine powder can improve the surface properties of samples. OB with different grinding times was prepared, and its functional components, physical properties, adsorption properties, and antioxidant properties were evaluated. Results showed that with increased grinding times, the average particle size of OB decreased significantly (p < .05). And the water-holding capacity, swelling capacity, and water solubility index of OB increased significantly (p < .05), whereas the animal and vegetable oil-holding capacities decreased. Oat bran could adsorb cholic acid and glucose, which was related to the time of superfine grinding. In addition, the antioxidant capacity of OB was improved after superfine grinding. Related analysis shows that there was significant positive relationship between ß-glucan, polyphenols and soluble dietary fibers and antioxidant indicators (p < .05). The Fourier transform infrared (FTIR) results showed that the FTIR spectra of OB powder with different crushing times were similar. On the basis of the above analyses, it is suggested that OB prepared by superfine grinding for 5 min had good physical and chemical properties and antioxidant properties and is widely used in food.

Adsorption characteristics of sulfonamide antibiotic molecules on carbon nanotube and the effects of environment.

CONTEXT: In this paper, the adsorption characteristics of five sulfonamide antibiotic molecules on carbon nanotubes were investigated using density functional theory (DFT) calculations. The adsorption configurations of different adsorption sites were optimized, and the most stable adsorption configuration of each sulfonamide molecule was determined by adsorption energy comparison, and the relative adsorption stability of five sulfonamide molecules on carbon nanotubes was determined by comparing their adsorption energies, i.e., sulfamethazine > sulfadiazine > sulfamerazine > sulfamethoxazole > sulfanilamide. The electron densities of the adsorption configurations were then calculated to confirm that the adsorption of five sulfonamide drug molecules on carbon nanotubes should be physical adsorption. Moreover, the adsorption energy of five sulfonamide molecules on carbon nanotubes in the aqueous environment was larger than that in the vacuum even though the adsorption process remain to be physical adsorption. The adsorption characteristics of the five sulfonamide molecules in various acid-base environments were finally investigated. In contrast, the adsorption energies of the five drug molecules in acid-base environments were significantly reduced, indicating that carbon nanotubes may need to have a suitable pH range to achieve the optimal adsorption effect when they are used for the treatment of sulfonamide antibiotics. METHODS: In this paper, we use density functional theory (DFT) with PBE functional to study the adsorption properties of five sulfonamides on carbon nanotubes. The structural optimization and the calculation of electronic structural properties are carried out by CP2K package (version 7.1), adopting the DZVP-MOLOPT-SR-GTH basis set and Goedeck-Teter-Hutter (GTH) pseudo potential. Grimme's D3 correction is used to during all the calculations to correctly capture the influence of the van der Waals interactions.