Ammonium Research Articles

A Facile One-Step Self-Assembly Strategy for Novel Carbon Dots Supramolecular Crystals with Ultralong Phosphorescence Controlled by NH4.

A new methodological design is proposed for carbon dots (CDs)-based crystallization-induced phosphorescence (CIP) materials via one-step self-assembled packaging controlled by NH4 +. O-phenylenediamine (o-PD) as a nitrogen/carbon source and the ammonium salts as oxidants are used to obtain CDs supramolecular crystals with a well-defined staircase-like morphology, pink fluorescence and ultralong green room-temperature phosphorescence (RTP) (733.56ms) that is the first highest value for CDs-based CIP materials using pure nitrogen/carbon source by one-step packaging. Wherein, NH4 + and o-PD-derived oxidative polymers are prerequisites for self-assembled crystallization so as to receive the ultralong RTP. Density functional theory calculation indicates that NH4 + tends to anchor to the dimer on the surface state of CDs and guides CDs to cross-arrange in an X-type stacking mode, leading to the spatially separated frontier orbitals and the through-space charge transfer (TSCT) excited state in turn. Such a self-assembled mode contributes to both the small singlet-triplet energy gap (ΔEST) and the fast inter-system crossing (ISC) process that is directly related to ultralong RTP. This work not only proposes a new strategy to prepare CDs-based CIP materials in one step but also reveals the potential for the self-assembled behavior controlled by NH4 +.

Synthesis of Al-enriched beta zeolite nanocrystals by using DABCO di-cationic quaternary ammonium as organic structure directing agent

Al-enriched Beta zeolite nanocrystals with densely populated acid sites and enhanced mass transfer efficiency have been demonstrated to show promising catalytic performance. In this work, low Si/Al ratio (8–9) Beta nanocrystals (about 20 nm) was synthesized by using DABCO based di-cationic quaternary ammonium salts as organic structure directing agent with high solid yield (＞95 %). The hydrothermal synthesis process was followed by monitoring the intermediate products at different time intervals, through which the key role of the di-cationic quaternary ammonium for the formation of Beta nuclei was identified. The promising catalytic performance of the Al-rich Beta nanocrystals in 1,3,5-triisopropylbenzene transalkylation with benzene was attributed to the high density and enhanced accessibility of acid sites.

Quaternized oxidized sodium alginate injectable hydrogel with high antimicrobial and hemostatic efficacy promotes diabetic wound healing

In this paper, a hydrogel material with efficient antibacterial, hemostatic, self-healing, and injectable properties was designed for the treatment of diabetic wounds. Firstly, quaternary ammonium salts were grafted with oxidized sodium alginate, and quaternized oxidized sodium alginate (QOSA) was synthesized. Due to the introduction of quaternary ammonium group it has antibacterial and hemostatic effects, at the same time, due to the presence of aldehyde group it can be reacted with carboxymethyl chitosan (CMCS) to form a hydrogel through the Schiff base reaction. Furthermore, deer antler blood polypeptide (DABP) was loaded into the hydrogel (QOSA&CMCS&DABP), showing good swelling ratio and bacteriostatic effect. In vitro and in vivo experiments demonstrated that the hydrogel not only quickly inhibited hepatic hemorrhage in mice and reduced coagulation index and clotting time in vitro, but also significantly enhanced collagen deposition at the wound site, accelerating wound healing. This demonstrates that the multifunctional hydrogel materials (QOSA&CMCS&DABP) have promising applications in the acceleration of skin wound healing and antibacterial promotion.

A Step towards CO2 Sequestration through Mineral Carbonation: Using Ammonium-Based Lixiviants for the Dissolution of Calcium from Iron-Making Blast Furnace Slag

In recent years, technical processes for the sequestration of CO2 through industrial waste mineral carbonation have been explored and developed. There is a large portfolio of carbon capture, utilisation, and storage (CCUS) techniques that have been employed in laboratories and at pilot scale. These include geological storage, ocean storage, and mineralisation by carbonate ores. In view of this, the main purpose of this research was to investigate and explore chemical variables, particularly ammonium salts as lixiviants for calcium mineral extraction from iron-making slag. The slag in use was acquired from a steel mill in the Vaal Triangle Region in Gauteng, South Africa. The experimental test work was conducted using different ammonium lixiviants, namely, NH4NO3, NH4Cl, and CH3COONH4, to understand the influence of anion type as well as possible differences in mechanisms of interactions. Lixiviant concentration as well as reaction time were varied in this research study. The three selected ammonium-based lixiviants showed different extents of calcium extraction owing to differences in the anion groups. NH4NO3, NH4Cl, and CH3COONH4 were found to be capable of dissolving 50% to 80% of the calcium from the selected slag for different molar concentrations. Anion type and leaching time also had significant influences on the leaching of calcium from the slag. Rapid pH degradation resulted in better calcium extraction capabilities. This work has shown that the selected ammonium salts have the potential to be lixiviants for calcium dissolution from iron-making blast furnace slags. These lixiviants would, therefore, be important to consider during calcium mineral carbonation for CO2 sequestration.

Palladium-Catalyzed Amination of Aryl Halides with Aqueous Ammonia and Hydroxide Base Enabled by Ligand Development.

The conversion of aryl halides to primary arylamines with a convenient and inexpensive source of ammonia has been a long-standing synthetic challenge. Aqueous ammonia would be the most convenient and least expensive form of ammonia, but such a palladium-catalyzed amination reaction with a high concentration of water faces challenges concerning catalyst stability and competing hydroxylation, and palladium-catalyzed reactions with this practical reagent are rare. Further, most reactions with ammonia to form primary amines are conducted with tert-butoxide base, but reactions with ammonium hydroxide would contain hydroxide as base. Thus, ammonia surrogates, ammonia in organic solvents, and ammonium salts have been used under anhydrous conditions instead with varying levels of selectivity for the primary amine. We report the palladium-catalyzed amination of aryl and heteroaryl chlorides and bromides with aqueous ammonia and a hydroxide base to form the primary arylamine with high selectivity. The palladium catalyst containing a new dialkyl biheteroaryl phosphine ligand (KPhos) suppresses both the formation of aryl alcohol and diarylamine side products. Mechanistic studies with a soluble hydroxide base revealed turnover-limiting reductive elimination of the arylamine and an equilibrium between arylpalladium amido and hydroxo complexes prior to the turnover-limiting step.

A Step towards CO2 Sequestration through Mineral Carbonation: Using Ammonium-Based Lixiviants for the Dissolution of Calcium from Iron-Making Blast Furnace Slag

In recent years, technical processes for the sequestration of CO2 through industrial waste mineral carbonation have been explored and developed. There is a large portfolio of carbon capture, utilisation, and storage (CCUS) techniques that have been employed in laboratories and at pilot scale. These include geological storage, ocean storage, and mineralisation by carbonate ores. In view of this, the main purpose of this research was to investigate and explore chemical variables, particularly ammonium salts as lixiviants for calcium mineral extraction from iron-making slag. The slag in use was acquired from a steel mill in the Vaal Triangle Region in Gauteng, South Africa. The experimental test work was conducted using different ammonium lixiviants, namely, NH4NO3, NH4Cl, and CH3COONH4, to understand the influence of anion type as well as possible differences in mechanisms of interactions. Lixiviant concentration as well as reaction time were varied in this research study. The three selected ammonium-based lixiviants showed different extents of calcium extraction owing to differences in the anion groups. NH4NO3, NH4Cl, and CH3COONH4 were found to be capable of dissolving 50% to 80% of the calcium from the selected slag for different molar concentrations. Anion type and leaching time also had significant influences on the leaching of calcium from the slag. Rapid pH degradation resulted in better calcium extraction capabilities. This work has shown that the selected ammonium salts have the potential to be lixiviants for calcium dissolution from iron-making blast furnace slags. These lixiviants would, therefore, be important to consider during calcium mineral carbonation for CO2 sequestration.

Influence of phosphomolybdate modified with quaternary ammonium salts on enhancing the flame retardancy and antibacterial characteristics of epoxy resin/aluminum diethylphosphinate composites

In this work, we synthesized a series of compounds, denoted as xCTAB@AMP, by incorporating varying different molar fractions of cetyltrimethylammonium bromide (CTAB) into ammonium phosphomolybdate (AMP). The effects of CTAB modification on the surface characteristics, morphology and hygroscopicity of AMP were studied. Moreover, we explored the combined flame-retardant impact between xCTAB@AMP and aluminum diethylphosphinate (ADP) when incorporated into epoxy resin (EP), as well as the resulting composite's mechanical properties, thermal stability and antibacterial properties. The EP composite containing 50 molar percent CTAB-modified AMP (EP/50CTAB@AMP/ADP) demonstrated remarkable flame retardancy, achieving a UL-94 V-0 rating and increasing limiting oxygen index (LOI) to 30.0%. This formulation significantly lowered the peak heat release rate (PHRR) to 452 kW/m2, a 65% reduction to that of EP, and the total heat release (THR) to 68 MJ/m2, a 24% decrease to that of EP. Additionally, compared to EP, the peak smoke production rate (PSPR) of this composite was decreased by 30% (0.28 m2/s), the total smoke production (TSP) was reduced by 25% (30.2 m2), and peak carbon monoxide release rate (PCOP) was diminished by 34% (0.038 g/s). The combination of 50CTAB@AMP and ADP in the EP matrix exhibited an exceptional synergistic flame-retardant effect. Concurrently, the CTAB modification bolstered the interfacial interactions between AMP and the EP matrix, which enhanced the mechanical properties of EP/AMP/ADP composites. As a result, the tensile strength and elongation at break of the EP/50CTAB@AMP/ADP composite increased by 13% and 15%, respectively, compared to the EP/AMP/ADP. Moreover, the 50CTAB@AMP maintained its inherent antibacterial activity, which endowed the EP/50CTAB@AMP/ADP composite with a potent inhibitory effect against Staphylococcus aureus, a common pathogenic bacterium.

Fabrication of multifunctional polyimide foams with co-polymerized benzimidazole moieties for excellent thermal insulation and flame retardancy applications

In this study, heterocyclic diamine 2-(4-aminophenyl)-5-aminobenzimidazole (APBIA) was employed as a co-polymerization component to improve the properties of polyimide foams (PIFs) which were synthesized from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) and 4,4′-diaminodiphenyl ether (ODA). The rheological behavior of polyester ammonium salt (PEAS) precursors was regulated by introducing APBIA moieties to the chain backbones, which affected the foaming behavior of PEAS and the microstructure of corresponding PIFs. Anisotropic porous structure was constructed with the help of microwave-assisted foaming strategy due to the directional growth of foam pores, which led to anisotropic mechanical and thermal insulation performance of resultant PIFs. PIFs demonstrated robust mechanical performance in the vertical direction (i.e., parallel to pore growth direction) and mechanical flexibility (compression response rate of 97.1–99.0 %) in the horizontal direction (i.e., perpendicular to the pore growth direction). The co-polymerized PIFs also presented excellent thermal insulation performance, with thermal conductivity ranging from 0.0266 to 0.0517 W/(m·K) within a temperature range of 25∼300 °C. In addition, PIFs exhibited exceptional thermal stability and flame retardancy performance, which demonstrate a great potential for high-temperature thermal protection applications. To summarize, multifunctional PIFs with excellent mechanical, thermal insulation and flame retardancy were successfully prepared by adopting co-polymerization strategy and microwave-assisted foaming technique, which have promising applications in high-end engineering sectors.

Dual Strategy of Morphology Optimization and Interlayer Expansion in VS2 Cathode Toward High-Performance Mg-Li Hybrid Ion Batteries.

Combining the merits of the dendrite-free formation of a Mg anode and the fast kinetics of Li ions, the Mg-Li hybrid ion batteries (MLIBs) are considered an ideal energy storage system. However, the lack of advanced cathode materials limits their further practical application. Herein, we report a dual strategy of morphology optimization and interlayer expansion for the construction of hierarchical flower-like VS2 architecture coated by N-doped amorphous carbon layers. This tailored hierarchical flower-like structure coupled with homogeneous N-doped amorphous carbon layers cooperatively provide more active sites and buffer volume changes, thus realizing the enhancement of capacity and structural stability. Moreover, the enlarged interlayer spacing caused by the cointercalation of polyvinylpyrrolidone and ammonium ions can effectively promote the charge transfer rate and facilitate the rapid ion diffusion, as further demonstrated by electrochemical results and theoretical calculations. These features endow the hierarchical flower-like VS2 cathode with superior specific energy density (644.4 Wh kg-1, average voltage of 1.2 V vs Mg2+/Mg) and excellent rate capability (181.1 mAh g-1 at 2000 mA g-1). Systematic ex situ characterization measurements are employed to reveal the ion storage mechanism, which confirms that Li+ storage plays a leading role in the capacity contribution of MLIBs. Our strategy is in favor of providing useful insights to design and construct MLIBs with high energy density and excellent rate performance.

Tribological Effects of Quaternary Ammonium-Functionalized Montmorillonite as Water-Based Additives.

In this study, a water-soluble quaternary ammonium salt (QAS)-functionalized montmorillonite (MMT) was fabricated using a mechanochemical method as a high-performance water lubrication additive. The intercalation of QAS into the MMT layer expands the layer spacing of MMT, but does not affect the hydrophilicity of MMT. The ultrathin layer QAS-functionalized montmorillonite (QAS-MMT) demonstrated excellent water-stable dispersion and can be used as a water-based lubrication additive. Only 0.1% addition can reduce the friction coefficient by more than 71.4% and the wear volume by about 58.8% when compared to water, demonstrating its excellent friction reduction and antiwear performance. The frictional mechanism indicates that the physical adsorption film, together with the chemical reaction film, endows the QAS-MMT additives with outstanding tribological performance, provides excellent lubrication for the contact of steel/steel pairs, and prevents the steel surface from being further worn.

Acetate-based ionic liquid immobilized Fe-MIL-101-NH2: A highly efficient heterogeneous catalyst for the conversion of CO2 into oxazolidinones with N-aryl epoxy amines

A novel acetate-based ionic liquid immobilized metal organic frameworks catalyst, Fe-MIL-101-N(Bnme2)OAc, was synthesized using a straightforward ion exchange strategy. Initially, Fe-MIL-101-N(Bnme2)Br was prepared by condensing a quaternary ammonium salt ionic liquid (N(BzBnme2)Br) with Fe-MIL-101-NH2. Subsequently, the Br- ions were exchanged with OAc- ions from potassium acetate to produce the desired catalyst. The morphology, structure and physicochemical properties of the catalyst were comprehensively characterized by XRD, SEM, FT-IR, DRS UV−vis, TGA, BET, and EA, which confirmed both the successful preparation of the catalyst and the integrity of the MOFs framework. The heterogeneous catalyst Fe-MIL-101-N(Bnme2)OAc demonstrated high activity in catalyzing the reaction of N-aryl epoxy amines with CO2 to form oxazolidinone compounds under optimal conditions (80 °C, 8 h, 1 mL of MeCN, 1.0 MPa CO2 and 5 mg catalyst), achieving a yield of up to 99 % with almost no production of the by-product cyclic carbonate. Moreover, this catalyst displayed excellent recyclability and extensive substrate applicability, maintaining its catalytic activity for at least five consecutive uses. Substrates with various substituents also produced the corresponding oxazolidinone products in high yields.

Quaternization-based graft modification of straw fibers for conditioning the sludge dewatering performance.

Extracellular polymeric substances (EPS) are a critical influencing factor in sludge dewatering. Disrupting such EPS contributes to the release of bound water in sludge, enhancing the sludge dewatering performance. In This study, quaternized straw fibers that are destructive to the EPS structure and components in active sludge were prepared useing heterogeneous free radical graft polymerization. Straw fibers, dimethyl diallyl ammonium chloride (DMDAAC), ammonium persulfate (APS), and acrylamide (AM) were taken as the substrate, grafting monomer, catalyst, and cross-linking agent, respectively.The optimal processing conditions determined for the DMDAAC-based quaternization and graft modification of straw fibers were as follows: reaction temperature of 60 °C, reaction time of 5 h, 0.100 g of catalyst APS dosage per gram of straw, and 3.000 ml of DMDAAC dosage per gram of straw. The optimal processing conditions yielded 1.335 g of modified straw fibers per gram of straw, 33.67% grafting rate, and 31.70% substitution of the quaternary ammonium groups. The capillary suction time (CST) was conditioned from 243.3 ± 22.6 s in the original sludge to 134.5 ± 34.45 s. The specific resistance to filtration (SRF) was reduced from 8.82 ± 0.51 × 1012 m/kg in the original sludge to 4.59 ± 0.23 × 1012 m/kg.

A clean metallurgical process for vanadium precipitation from vanadium-rich solutions

Ammonium salt vanadium precipitation process has excellent performance in industrial production, but its shortcomings such as high cost and environmental impact are not conducive to sustainable development. In this paper, ethylenediamine was selected as the precipitant, and vanadate was precipitated from acidic simulated vanadium-rich solutions by the ammonium salt precipitation process. The high purity V2O5 product was obtained after calcination. Under optimal conditions, the precipitation rate of vanadium reached 94.8 %, and the purity of vanadium was as high as 99.1 %. The vanadium precipitation product was hexamethyl ammonium, and the vanadium product was V2O5. It can be derived by the differential method that the reaction order was n = 2.4, the reaction rate equation was CV-1.4=kt+a, and the apparent activation energy was 27.8097 kJ/mol, which can be classified as the diffusion-controlled reaction. This innovative process enables a savings of 5050 yuan per ton of V2O5. On this basis, a complete V2O5 production process with zero waste discharge was designed.

Electrochemical degradation of acetaminophen in urine matrices: Unraveling complexity and implications for realistic treatment strategies

Urine has an intricate composition with high concentrations of organic compounds like urea, creatinine, and uric acid. Urine poses a formidable challenge for advanced effluent treatment processes following urine diversion strategies. Urine matrix complexity is heightened when dealing with pharmaceutical residues like acetaminophen (ACT) and metabolized pharmaceuticals. This work explores ACT degradation in synthetic, fresh real, and hydrolyzed real urines using electrochemical oxidation with a dimensional stable anode (DSA). Analyzing drug concentration (2.5 - 40 mg L−1) over 180 min at various current densities in fresh synthetic effluent revealed a noteworthy 75% removal at 48 mA cm−2. ACT degradation kinetics and that of the other organic components followed a pseudo-first-order reaction. Uric acid degradation competed with ACT degradation, whereas urea and creatinine possessed higher oxidation resistance. Fresh real urine presented the most challenging scenario for the electrochemical process. Whereas, hydrolyzed real urine achieved higher ACT removal than fresh synthetic urine. Carboxylic acids like acetic, tartaric, maleic, and oxalic were detected as main by-products. Inorganic ionic species nitrate, nitrite, and ammonium ions were released to the medium from N-containing organic compounds. These findings underscore the importance of considering urine composition complexities and provide significant advancements in strategies for efficiently addressing trace pharmaceutical contamination.

Regulation of Asymmetric Bimetallic NiFe Sites Boost Fast Desolvation Kinetics for Long-cycling Ammonium-Ion Storage

Aqueous ammonium ion battery (AAIB) is a new type of energy storage device with non-metallic ion (NH4+) as the carrier, possessing the apparent advantages of low cost, high safety, and long-term sustainability. However, the sluggish kinetics of the electrolyte-electrode interface often results in a slow NH4+ transport within the host structure, leading to poor cycling stability, especially in the type of cathode material with open frameworks represented by Fe-based Prussian blue analogues (PBAs). In this work, a NiFe-PBA (NiFe) cathode material with asymmetric bimetallic sites is purposely designed to regulate and improve the NH4+ desolvation kinetics at the electrolyte-electrode interface. Theoretical simulations first reveal that regulating the asymmetric bimetallic site effectively reduces the energy barrier of NH4+(H2O)4 desolvation at the electrolyte-electrode interface, and thus the NH4+(H2O)4 can be desolvated into NH4+ into host material. The electrochemical study results further show that the successful introduction of asymmetric bimetallic sites largely improves the diffusion kinetics and structural stability of FeFe-PBA (FeFe), realizing stable cycling performance (97% retention after 700 cycles at 0.25 A g-1) and high-rate capability. Finally, in-situ characterizations in combination with theoretical calculations demonstrate that the insertion/extraction of NH4+ is attributed to the charge storage mechanism of reversible interactions in association with the coordination of N atoms in the NiFe-PBA.

Evaluating the impact of control measures on sulfate-nitrate-ammonium aerosol variations and their formation mechanism in northern China during 2022 Winter Olympic Games

Sulfate, nitrate, and ammonium (SNA) significantly contribute to fine particulate matter (PM2.5). To ensure good air quality during 2022 Winter Olympic Games (WOG), stringent control measures were implemented in northern China. In this study, comprehensive atmospheric observations were conducted from 2022 January to March in four representative cities to investigate the changes in SNA and its formation mechanism in response to these control measures. The SNA concentrations obviously decreased (29.45%–42.83%) during the control periods in the four cities, but their proportion of PM2.5 remained relatively stable (>50%). SNA was the key factor driving the decrease and increase in the PM2.5 concentration during WOG, with nitrate making the most prominent contribution. The formation of SNA was largely dominated by aqueous heterogeneous chemistry instead of gas-phase oxidation. However, the aerosol liquid water content (ALWC) decreased while odd oxygen (OX) increased during the control periods. Such a variation influenced the role of aqueous heterogeneous and gas-phase reactions in SNA formation, with the former's dominant role being replaced by the latter. After the control periods, the aqueous heterogeneous reactions were enhanced again due to the increased ALWC. Among the cities in the study region, SNA formation became more intense from north to south with increased air temperature and relative humidity (RH). Moreover, ISORROPIA-II thermodynamic modelling revealed notable impacts of sulfate, ammonium, and nonvolatile cations (NVCs) on variations in particle acidity throughout WOG. These results provide a more comprehensive understanding of SNA responses to pollution control on a regional scale and insight into future conventional control.

Evaluating the impact of control measures on sulfate-nitrate-ammonium aerosol variations and their formation mechanism in northern China during 2022 Winter Olympic Games

Sulfate, nitrate, and ammonium (SNA) significantly contribute to fine particulate matter (PM2.5). To ensure good air quality during 2022 Winter Olympic Games (WOG), stringent control measures were implemented in northern China. In this study, comprehensive atmospheric observations were conducted from 2022 January to March in four representative cities to investigate the changes in SNA and its formation mechanism in response to these control measures. The SNA concentrations obviously decreased (29.45%–42.83%) during the control periods in the four cities, but their proportion of PM2.5 remained relatively stable (>50%). SNA was the key factor driving the decrease and increase in the PM2.5 concentration during WOG, with nitrate making the most prominent contribution. The formation of SNA was largely dominated by aqueous heterogeneous chemistry instead of gas-phase oxidation. However, the aerosol liquid water content (ALWC) decreased while odd oxygen (OX) increased during the control periods. Such a variation influenced the role of aqueous heterogeneous and gas-phase reactions in SNA formation, with the former's dominant role being replaced by the latter. After the control periods, the aqueous heterogeneous reactions were enhanced again due to the increased ALWC. Among the cities in the study region, SNA formation became more intense from north to south with increased air temperature and relative humidity (RH). Moreover, ISORROPIA-II thermodynamic modelling revealed notable impacts of sulfate, ammonium, and nonvolatile cations (NVCs) on variations in particle acidity throughout WOG. These results provide a more comprehensive understanding of SNA responses to pollution control on a regional scale and insight into future conventional control.

Brønsted acidity of bis(trifluoromethanesulfonyl)amide and trifluoromethanesulfonic acid in ionic liquids of ternary ammonium

Bis(trifluoromethanesulfonyl)amide (Tf2N−) and triflate (TfO−) are commonly used anions of protic ionic liquids (PILs). They are the conjugate anions of strong acids, Tf2NH and TfOH, whose Brønsted acidities crucially influence the performance of the PILs. In this study, the Brønsted acidity of Tf2NH and TfOH was compared directly through potentiometric titrations carried out in the ionic liquids of ternary ammonium salts. As a result, Tf2NH exhibits stronger Brønsted acidity than TfOH by approximately 2 pH units. Furthermore, calorimetric titrations revealed that this difference originates from differences in their entropy states. This suggests that the solvation state, rather than the properties in their isolated state, has a more significant impact on the acidities of Tf2NH and TfOH. Besides, ionization thermodynamics turned out to be governed by both the constituent cations and anions of the PILs. Therefore, once the acid-base natures of the constituent ions are characterized, the overall acid-base behavior of the PIL may become predictable.

Immobilization of multilayer sodium alginate/polysaccharide antibacterial material composite beads as glufosinate controlled release matrices

To find a new way to slow down the release of glufosinate (GA) pesticide and to solve the susceptibility to decomposition by soil microorganisms, a series of novel antibacterial polysaccharide-based sustained release beads (PSRB) were prepared. The PSRB was prepared by immobilization of GA loaded polysaccharide-based chitosan quaternary ammonium salt (PS-HACC) microcapsules in the core and layers of the multilayer sodium alginate beads. The PSRB was characterized by FI-IR spectroscopy, XRD, SEM, and BET to reveal their composition and surface morphology. The optimal conditions of the slow release beads were as follows, the concentration of Ca2+, pH, temperature and the coating layer number was 0.1 mol/L, 7, 25 °Cand 3, respectively. The kinetic study showed that the slow release of PSRB was in accordance with the Higuchi kinetic model, and the FI-IR and XRD analyses revealed that the PS-HACC and GA were successfully cross-linked to the PSRB. BET showed that PSRB were greater than PSRB3 at surface area, pore volume and pore size. Inhibition circles experiments demonstrated that WPSRB3 has good antibacterial activity. The weed control in soybean with PSRB3 application is perfect and the weed control cycle is long. Therefore, this technology can provide a potential way to control GA release, improve utilization efficiency, reduce pesticide use and environmental pollution, and at the same time, provide a potential way to achieve ecological agriculture.

Effect of the structure of chitosan quaternary ammonium salts with different spacer groups on antibacterial and antibiofilm activities

In this study, three types of dodecyl chitosan quaternary ammonium salts, each with different spacer groups were synthesized. These chitosan derivatives are N′,N′-dimethyl-N′-dodecyl-ammonium chloride-N-amino-acetyl chitosan (DMDAC), N′-dodecyl-N-isonicotinyl chitosan chloride (DINCC) and N′,N′-dimethyl-N′-dodecyl-ammonium chloride-N-benzoyl chitosan (DMDBC). The synthesized products were characterized using Fourier transform infrared spectrometers, nuclear magnetic resonance, thermogravimetric analysis, and elemental analysis. The antibacterial and antibiofilm activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were investigated. The experimental results indicated that the introduction of hydrophobic groups of spacer groups could enhance the antibacterial and antibiofilm activities of the chitosan derivatives. The antibacterial rates of the chitosan derivatives were over 90 % for both E. coli and S. aureus at a concentration of 0.5 mg/mL. The chitosan derivatives removed >50 % of the mature biofilm of E. coli and over 90 % of the mature biofilm of S. aureus at a concentration of 2.5 mg/mL. Further, the synthesized chitosan derivatives were determined to be non-toxic to L929 cells. Among them, DMDBC exhibited the most promising overall performance and show potential for wide-ranging applications in food preservation, disinfectants, medical, and other fields.