Diallyldimethylammonium Chloride Research Articles

A facile method for carbon nanotube/carbon fiber‐reinforced polylactic acid composites

AbstractThe mechanical strength of polylactic acid (PLA) can be improved by carbon fiber (CF) compositing to expand its application in tissue engineering scaffolds. However, the mechanical strength of CF‐reinforced polylactic acid (CFRPLA) composites is compromised due to weak interfacial interaction resulting from the chemically inert surface of CF. In the article, carbon nanotube (CNT) with poly(diallyldimethylammonium chloride) (PDDA) as a coupling agent was covered on CF to improve the chemical activity and roughness of the surface of CF, and then the as‐prepared CF‐PCNT were further incorporated into PLA via melt compounding. The yield strength, modulus, and thermal conductivity of PLA/CF‐PCNT were 14.09%, 7.65%, and 5.24% higher than those of PLA/CF, respectively, and the volume resistivity was 99.74% lower at a 10 wt% loading. The enhancement for the mechanical properties of PLA/CF‐PCNT composites could be ascribed to the mechanical locking, hydrogen bonds and covalent bonds between CF and matrix through the interface modulation of CNT and PDDA. This facile and non‐destructive method offers a novel strategy for the modification of CF fillers.Highlights CF was modified by PDDA and CNT through a facile and non‐destructive method. The active functional groups and roughness on the surface of CF were increased. The surfaces of CFs were characterized by FT‐IR, Raman spectra, XPS and SEM. The interface was improved by mechanical locking, covalent, and hydrogen bonds. The mechanical strength, electrical and thermal conductivity of composites were improved.

Preparation of grafted starch‐based cationic flocculants and its removal of reactive and disperse dyes

AbstractIn this paper, a starch‐based flocculant (ADSt) with medium and low temperature solubility and enhanced flocculation effect was synthesized using corn starch, acrylamide, and dimethyldiallyl ammonium chloride as main materials by the ethanol‐alkali method and grafting method. The main mechanism of ADSt's flocculation was electrical neutralization and bridging. The flocculation performance of ADSt was verified by using it along with polymeric aluminum chloride (PAC) as coagulant/flocculant, dispersible dye (dispersible yellow RGFL), and reactive dye (active trimeric blue KN‐G) to simulate dye wastewater. For the dispersed yellow water sample and active emerald blue water sample, the dosage of PAC was 40 and 35 mg/L respectively. When the dosage of ADSt was 10 mg/L with a dye content of 100 mg/L, the decolorization rates for both dyes reached up to 96.2% and 94.4% respectively. The properties of the flocs such as size and two‐dimensional fractal structure were described. The prepared ADSt maintained a good flocculation effect in the pH range of 5–9 due to its excellent water solubility achieved through the ethanol‐alkali preparation process, where its solubility reached 86.7% at 30°C. Overall, the preparation process for ADSt is simple, cost‐effective, while providing an effective solution for treating printing and dyeing wastewater.

Dual signal amplification strategy-based electrochemical aptasensor utilizing redox molecule/MOF composites for multi-pesticide detection

Electrochemical aptasensor is a great tool for simultaneously assessing harmful pesticide residues in agricultural products and foods. This study ingeniously designed an electrochemical aptasensor based on dual signal amplification strategies for concurrent detection of various pesticide residues. Firstly, poly(diallyldimethylammonium chloride)-functionalized reduced graphene oxide (PR) and Au-Pt-Pd trimetallic nanoflowers supported on HP-UiO66-NH2 were creatively employed together as substrates to load more aptamers, ascribed to the improved conductivity, abundant sites and a large electrochemical effective surface area. Secondly, ferrocene-cysteine gold nanoparticles supported on CeMOF(Ⅲ, Ⅳ) and methylene blue-loaded MOF235 were innovatively engineered to build two distinctive signal labels, which displayed comparable large and stable signal currents among other redox molecule/MOF composites. Additionally, PR contributed further signal amplification. Consequently, the constructed aptasensor showed superior performance for simultaneous detection of acetamiprid (AD) and malathion (ML), with linear ranges from 10 pM to 0.1 μM and detection limits of 4.8 pM for AD and 0.51 pM for ML. Moreover, the aptasensor performed well in the assay of AD and ML in Chinese cabbage samples with high accuracy compared with a high-performance liquid chromatography-tandem mass spectrometry method. Overall, the strategies proposed herein provided a useful and potential route for general development of electrochemical aptasensors to simultaneously detect multiple pesticide residues.

A cationic polyelectrolyte for enhancing dewatering of montmorillonite-containing coal slime: adsorption and modification mechanism

ABSTRACT In this study, a cationic polyelectrolyte (Poly dimethyl diallyl ammonium chloride, PDADMAC) was introduced as a filter aid to enhance the dewatering effect of montmorillonite (MT)-containing coal slime, and compared with cationic polyacrylamide (CPAM). The dewatering performance of PDADMAC and CPAM was evaluated based on vacuum filtration experiments. The modification mechanism of PDADMAC on Mt particle surface was revealed by filter cake pore distribution, zeta potential, contact angle and Atomic Force Microscopy (AFM). The adsorption difference between PDADMAC and CPAM on Mt surface was studied by Density Functional Theory (DFT). In addition, DLVO theory further explains the mechanism of PDADMAC enhancing dewatering from the perspective of interaction force. The optimal dosage of PDADMAC was 125 g/t, and the filter cake moisture content was reduced by 3%. Compared to CPAM, PDADMAC achieves efficient dewatering at a lower dosage. PDADMAC has a more prominent ability to neutralize charge, and its effect on interparticle interactions was a potential mechanism to promote dehydration.

Polymerizable deep eutectic solvent enables flexible gel formation for motion sensor and anti-UV film

Specific applications of gels can raise multiple demands, including low cost, elasticity, adaptability to wide temperature ranges, conductivity, and reduced hazards, thereby presenting diverse challenges for one material. Deep eutectic solvents (DESs) offer unexpected solutions to tackling the challenging task. Here, we mixed anhydrous diallyldimethylammonium chloride (DMDAAC) and urea to synthesize a polymerizable DES with a wide range of solubility. It can polymerize to form versatile DES gel upon photoinitiation. The gel exhibited high transparency (∼94 %), a wide range of temperature tolerance (−40 ∼ 100 °C), outstanding elastic properties (ε > 2400 %), good conductivity (0.05 mS·cm−1) and self-healing capability. The pristine gel film was successfully applied to motion sensors, while the DES gel with lignin was also employed as an elastic anti-UV film. Moreover, its water-solubility and non-hazardous compositions suggest the minimize environmental impact of the DES gel. This polymerizable DES can not only boost the development of electronic devices like motion sensors, but also inspire more creative ideas in promising applications of DESs and DES gels.

Synergistic enhancement of dewatering of montmorillonite-containing coal slime by novel combined filter aid: an experimental and simulation study

ABSTRACT The efficient dewatering of montmorillonite (Mt)-containing coal slime is still an urgent problem to be solved in coal preparation plant. In this study, the dewatering effect of poly(o-phenylenediamine)/Poly dimethyl diallyl ammonium chloride (POPD/PDADMAC) combined filter aid on Mt-containing coal slime was studied. The dewatering performance of combined filter aid was investigated by vacuum filtration test. The action mechanism of combined filter aid was revealed by contact angle, zeta potential, cake pore and atomic force microscope (AFM). The co-adsorption principle of the combined filter aid was elucidated based on density functional theory (DFT) and molecular dynamics simulation (MD). Compared to PDADMAC, the combined filter aid has better performance for dewatering of Mt-containing coal slime, and has the advantage of low reagent dosage. The combined filter aid can greatly reduce the Mt potential, increase the Mt contact angle, and increase the porosity of the filter cake. There was a co-adsorption effect between the combined filter aid. Specifically, there were ion–dipole interaction, cation–π interaction and Cl ions bridged electrostatic interaction between POPD and PDADMAC. This study has developed a novel combined filter aid, which provides theoretical and technical support for the high-efficiency pressure filtration dewatering of Mt-containing coal slime in coal preparation plants.

Self-assembled conductive coating and bifacial microstructures Collaboratively Adjusting the sensing performance and high reliability of the flexible pressure sensors

Flexible pressure sensors are being studied intensively for applications such as smart wearables and health monitoring. While ensuring the excellent sensing performance, the reliability (durability and environmental resistance) of the sensors are also key indicators that determine whether they can be used in practice. In this research, a strategy to adjust the sensing performance and high reliability of the flexible pressure sensors by self-assembled conductive coating and bifacial microstructures (BM) is proposed. Polydimethylsiloxane/carbon nanotube films with BM are first modified to reduce the surface contact angle. Then poly(dimethyl diallyl ammonium chloride) (PDAC) and hydroxylated carbon nanotubes/carboxylated cellulose nanofibers/glycerol (CNT-OH/CNF-C/GL) are successively assembled on the BM surface to construct conductive coatings (PCCG). The sensor based on PCCG and BM (the PCCG-BM sensor) shows a high sensitivity (9.97 kPa−1), a wide detection range (0–330 kPa), and a fast response time (59 ms). The PCCG-BM sensor has excellent repeatability, and it still outputs stable current change signals after 240,000 pressure cycles. What’s more, the PCCG-BM sensor is treated with extreme environments such as bending, stretching, washing, and high pressure, and the sensor still maintains excellent performances. This preparation strategy provides a new perspective for the fabrication of high-performance and high-reliability flexible sensors.

Exploring the dyeing potential of annatto dye on linen substrate: An inquiry into the effects of different mordants

AbstractThis study aimed to compare the dyeing capacity of annatto dye on linen textile substrates under the influence of different mordants, such as ferrous sulphate, alum, chitosan, and poly(diallyldimethylammonium chloride) (PDDACl). Annatto dye was extracted in an alcoholic medium, and the concentrations of the dye compounds bixin and norbixin were determined using ultraviolet‐visible spectrophotometry. Dyeing experiments were conducted with 10% and 20% weight of material (s.p.m.) concentrations, both on mordant‐treated substrates and on substrates pre‐bleached only. The colour evaluation indicated better colour yields for substrates pretreated with alum and PDDACl, with colour strength (K/S) values of 41.14 and 38.74, respectively, for dyeing with 20% s.p.m. However, these substrates exhibited the highest colour deviation (∆E) values in washing and lightfastness tests. The substrate pretreated with ferrous sulphate and the substrate pre‐bleached only showed K/S values of 25.99 and 18.68, respectively, with the ferrous sulphate‐treated substrate exhibiting the lowest ∆E values in washing and lightfastness tests among all evaluated substrates. Chitosan‐cationised samples showed the lowest colour yield, with a K/S of 12.51. Regarding washing and lightfastness, the pre‐bleached only substrate and the chitosan‐pretreated substrate displayed intermediate ∆𝐸 values. The dyeing kinetics of pre‐bleached substrates exhibited pseudo‐first‐order behaviour, while for ferrous sulphate‐pretreated samples, pseudo‐second‐order behaviour was observed. Langmuir's adsorption model was suitable for pre‐bleached substrate dyeing and ferrous sulphate‐pretreated sample dyeing in adsorption isotherms. However, for mordanted samples, higher adsorption intensity was observed.

Polyelectrolyte modified Ag-nanosphere: A Practical Approach for Sensitive and Selective SERS-based Detection of Organic Dye Pollutants

This study presents a cost-effective method for fabricating surface-enhanced Raman spectroscopy (SERS) substrates using Ag-nanospheres (AgNS) capped with Poly(diallyldimethylammonium chloride) (PDADMAC) and poly(styrene sulfonate) (PSS). AgNS synthesis involves immersing Ag-nanocrystals in a nonaqueous solution, mixed with PEs in an aqueous solution via ultrasonic disturbance. Resulting aggregates form stable spherical assemblies with diameters ranging from 150 nm to 450 nm, and various characterization techniques, including scanning electron microscopy with energy-dispersive X-ray, UV-visible spectrophotometry, dynamic light scattering, and zeta potential analysis, were employed to analyze their fundamental chemical and physical properties. These qualified AgNSs serve as SERS substrates for sensitive and selective identification of charged organic dye contaminants, such as rhodamine 6G (R6G) and rose bengal (RB). Sensitivity assessments with the optimized quantities of either PDADMAC or PSS-capped AgNSs demonstrate successful detection down to concentrations of 10-14 M for RB and 4 x 10-13 M for R6G. The same SERS substrates also enable electrostatically driven selective detection even in analyte mixtures, and an additional variation of the SERS substrate comprising a complex of PDADMAC-capped and PSS-capped AgNSs exhibited distinct SERS spectra influenced by both positively and negatively charged analytes. Finally, successful detection of two oppositely charged pesticides was achieved through electrostatic attraction, so theses polyelectrolytes capped AgNS-based SERS substrate presents a promising avenue for efficiently and selectively detecting charged organic contaminants.

Insight into the corrosion inhibition performance of dimethyldiallylammonium chloride acrylamide copolymer for mild steel in acidic solution

Dimethyldiallylammonium chloride acrylamide (DADMAC-AAM) copolymer was firstly applied as a novel corrosion inhibitor for carbon steel in acidic solution. Electrochemical, theoretical and computational methods were performed to illustrate the corrosion inhibition mechanism of DADMAC-AAM. Results of electrochemical tests indicated that DADMAC-AAM effectively slowed down corrosion rate of mild steel in HCl solution as a mixed-type corrosion inhibitor. Its corrosion inhibition efficiency increased with dosage, and the maximum value reached about 92.44 % with adding 100 mg/L. In-situ scanning vibration electrode technique illustrated that the corrosion inhibition performance of DADMAC-AAM increased with immersion time. Metal surface was covered with a dense hydrophobic film due to the physical-chemical adsorption of DADMAC-AAM molecules, and the adsorption behavior obeyed to the Langmuir adsorption isothermal model. Theoretical calculations were carried out to explain the corrosion inhibition mechanism, and the increase of active energy indicated that the strong inhibitive action of DADMAC-AAM molecule could be due to the increase of activation energy barrier of corrosion reaction. Results obtained from computational simulations proved that DMDMAC-AAM molecules adsorbed on metal surface through interactions between N or O and Fe atoms. This adsorption film could retard the invasion of corrosive species, thus protecting metal from corrosion.

A cathodic photoelectrochemical self-powered aptasensor for ratiometric detection of cortisol based on PCN-224@graphene nanocomposites

Cathodic photoelectrochemical (PEC) sensors have garnered considerable research interest in bioanalysis for their ability to mitigate interference from photogenerated holes in concomitant reducing substances, but there remains a challenge to improve detection accuracy with rational strategies. In this study, a ratiometric assay was developed for cathodic PEC aptasensing of cortisol (COR), a stress hormone. Under visible-light exposure, porphyrin-based metal organic framework (PCN-224) and poly(diallyldimethylammonium chloride)-modified reduced graphene oxide (PrGO) composites were utilized as photoactive materials, enabling cathodic photocurrent production at 0 V. The spatially resolved dual photocathodes were combined with a COR-binding aptamer to selectively recognize the COR target, with one serving as the control. The ratio of the concentration-dependent inhibited photocurrent response (PI1) to the reference signal (PI2) from the control photocathode was employed for the sensitive COR bioassay. The proposed aptasensor revealed a broad linear range toward COR concentration from 0.4 nM to 800 nM, with a detection limit (3S/N) of 0.14 nM. The proposed sensor was successfully applied to real human serum samples, demonstrating promise in detecting disease markers in medical diagnostics.

Getting the Best out of Capillary Electrophoresis and Capillary Electrophoresis-Mass Spectrometry by Quantifying Sources of Peak Broadening for Proteins Using Polyelectrolyte Multilayer Coated Fused Silica Capillaries.

Capillary electrophoresis (CE) has emerged as a relevant technique for protein and biopharmaceutical analysis, as it combines high separation efficiency, sensitivity, and versatility. The use of capillary coatings, including successive multiple ionic-polymer layers (SMILs), reduces interactions between analytes and the capillary, further improving the CE performance. Nevertheless, separations done on SMIL coatings rarely surpass 500 × 103 plates/m. To obtain the best out of the CE, it is interesting to have a detailed look at the sources of peak dispersion. Separations of a mix of model proteins were performed on (poly(diallyldimethylammonium chloride)/poly(styrenesulfonate))2.5-coated capillaries at different electrical field strengths, leading to plate height H against migration velocity u plots that enabled a quantitative analysis of each contribution. Using this model, capillary lengths and injected volumes were systematically varied. For the first time, the contribution of sample electrophoretic heterogeneity to the total peak dispersion was deciphered for model proteins and a monoclonal antibody. Dispersion due to electromigration was seen to have an impact on plate heights in the case of triangular peaks of small molecules but not for proteins under the present conditions. UV and mass spectrometry detections were compared on the same capillary, providing valuable information on the impact of the detection type on separation efficiency. Close to 1 million plates/m were reached in the best conditions.

Effects of Dye Addition on the Rheological Properties of Aqueous Polymer Solutions.

In many commercial applications, polymer-dye interactions are frequently encountered from food to wastewater treatment, and while shear rheology has been well characterized, the extensional properties are not well known. The extensional viscosity ηE and relaxation time λE are the extensional rheological parameters that provide valuable insights into how aqueous polymers respond during deformation, and this study investigated the effect of dyes on the extensional rheology of three different aqueous polymer solutions (e.g., anionic, cationic, and neutral) paired with two different dye salts (e.g., anionic and cationic) using drop pinch-off experiments. We have found that the influence of dyes on the pinch-off dynamics is complex but generally leads to a decrease in, for example, the apparent extensional relaxation time. We have utilized the dripping-onto-substrate method to probe the uniaxial deformation of widely used polymers such as xanthan gum (XG), poly(diallyldimethylammonium chloride) (PDADMAC), and poly(ethylene oxide) (PEO) as the anionic, cationic, and neutral polymers, respectively, paired with either fluorescein (Fl) or methylene blue (MB) as the anionic and cationic dyes, respectively. Polymer-dye pairs with opposite charges (e.g., XG-MB and PDADMAC-Fl) displayed a pronounced decrease in pinch-off times, but even PEO, which is a neutral polymer, resulted in decreased pinch-off times, which was restored by the addition of NaCl. The pinch-off times for the Boger fluid (mixture of poly(ethylene glycol) and PEO), however, were surprisingly uninfluenced by dyes. These results showed that not only did the small addition of dyes strongly decrease the polymer relaxation times, but the relative importance of the dye salts on the polymer pinch-off dynamics was also different from that of pure salts such as NaCl.

Assessment of poly(diallyl dimethyl ammonium chloride) and lime for surface water treatment (pond, river, and canal water): seasonal variations and correlation analyses.

The present study deals with the assessment of different physicochemical parameters (pH, electrical conductivity (E.C.), turbidity, total dissolved solids (TDS), and dissolved oxygen) in different surface water such as pond, river, and canal water in four different seasons, viz. March, June, September, and December 2023. The research endeavors to assess the impact of a cationic polyelectrolyte, specifically poly(diallyl dimethyl ammonium chloride) (PDADMAC), utilized as a coagulation aid in conjunction with lime for water treatment. Employing a conventional jar test apparatus, turbidity removal from diverse water samples is examined. Furthermore, the samples undergo characterization utilizing X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The study also conducts correlation analyses on various parameters such as electrical conductivity (EC), pH, total dissolved solids (TDS), turbidity of raw water, polyelectrolyte dosage, and percentage of turbidity removal across different water sources. Utilizing the Statistical Package for Social Science (SPSS) software, these analyses aim to establish robust relationships among initial turbidity, temperature, percentage of turbidity removal, dosage of coagulant aid, electrical conductivity, and total dissolved solids (TDS) in pond water, river water, and canal water. A strong positive correlation could be found between the percentage of turbidity removal and the value of initial turbidity of all surface water. However, a negative correlation could be observed between the polyelectrolyte dosage and raw water's turbidity. By elucidating these correlations, the study contributes to a deeper understanding of the effectiveness of PDADMAC and lime in water treatment processes across diverse environmental conditions. This research enhances our comprehension of surface water treatment methodologies and provides valuable insights for optimizing water treatment strategies to address the challenges posed by varying water sources and seasonal fluctuations.

Identifying Root Origin of Insulating Polymer Mediated Solar Water Oxidation.

Rational construction of high-efficiency photoelectrodes with optimized carrier migration to the ideal active sites, is crucial for enhancing solar water oxidation. However, complexity in precisely modulating interface configuration and directional charge transfer pathways retards the design of robust and stable artificial photosystems. Herein, a straightforward yet effective strategy is developed for compact encapsulation of metal oxides (MOs) with an ultrathin non-conjugated polymer layer to modulate interfacial charge migration and separation. By periodically coating highly ordered TiO2 nanoarrays with oppositely charged polyelectrolyte of poly(dimethyl diallyl ammonium chloride) (PDDA), MOs/polymer composite photoanodes are readily fabricated under ambient conditions. It is verified that electrons photogenerated from the MOs substrate can be efficiently extracted by the ultrathin solid insulating PDDA layer, significantly boosting the carrier transport kinetics and enhancing charge separation of MOs, and thus triggering a remarkable enhancement in the solar water oxidation performance. The origins of the unexpected electron-withdrawing capability of such non-conjugated insulating polymer are unambiguously uncovered, and the scenario occurring at the interface of hybrid photoelectrodes is elucidated. The work would reinforce the fundamental understanding on the origins of generic charge transport capability of insulating polymer and benefit potential wide-spread utilization of insulating polymers as co-catalysts for solar energy conversion.

Microstructural Tuning of High‐Performance Bacterial Cellulose Anion Exchange Membranes via Constrained In Situ Polymerization and Double Chemical Cross‐Linking

AbstractHigh electrochemical and durability anion exchange membranes (AEMs) are a vital material for Flexible zinc‐air batteries (F‐ZAB) and AEM water electrolysis (AEMWE) to achieve green economy and environmental protection. However, the existing AEMs possess the disadvantages of a complicated preparation process, poor homogeneity, and unsatisfactory electrochemical performance. Here, a novel alkaline exchange membrane is synthesized using bacterial cellulose (BC) as the matrix, incorporating constrained in situ Poly (diallyldimethylammonium chloride) (PDDA) polymerization and double chemical cross‐linking techniques. By adjusting the microstructure, a unique long‐range order and dense internal structure to address the issue of loose bonding between PDDA and BC is established and achieve the purpose of rapid OH− conduction. The membranes exhibit excellent application properties, with excellent ionic conductivity (145.12 mS cm−1) and superb mechanical strength (73.26 MPa). Consequently, the membrane is assembled into the F‐ZAB, and the unprecedented power density of 258.7 mW cm−2 can be achieved at room temperature. Moreover, the membrane also can reach 3.0 A cm−2 at 2.3 V, indicating good prospects in the field of water electrolysis in 6 m KOH. The approach paves a new path for manufacturing AEMs for green energy and environmental applications.

Interaction of poly dimethyl diallyl ammonium chloride with sludge components: Anaerobic digestion performance and adaptive changes of anaerobic microbes

The wide utilization of poly dimethyl diallyl ammonium chloride (polyDADMAC) in industrial conditions leads to its accumulation in waste activated sludge (WAS), thereby affecting subsequent WAS treatment processes. This work investigated the interaction between polyDADMAC and WAS components from the perspective of anaerobic digestion (AD) performance and anaerobes adaptability variation. The results showed that polyDADMAC decreased the content of biodegradable organic substrates (i.e., soluble protein and carbohydrate) by binding with the functional groups and then settling to the solid phase, thus impeding the subsequent utilization. Higher concentrations of polyDADMAC prompted an initial protective response of excreting organic substrates into extracellular environment, but its toxicity to archaea was irreversible. Consequently, polyDADMAC inhibited the processes of AD and induced a 30 % reduction in methane production with 0.05 g polyDADMAC/g total suspended solid (TSS) addition. Changes in microbial community structure indicated that archaea involved in methane production (e.g., Anaerolineaceae sp. and Methanosaeta sp.) were inhibited when exposed to polyDADMAC. However, several adaptive bacteria with the ability of utilizing complex organics and participating in nitrogen cycle (e.g., Aminicenantales sp. and Ellin6067 sp.) were enriched with the above dosage. Specifically, the decreased abundance of genes relevant to methane metabolism pathway (i.e., mer and cdh) and increased abundance of genes involved in metabolism of cofactors and vitamins (e.g., nad and thi) indicated the toxicity of polyDADMAC and the irritant response of microflora. Moreover, polyDADMAC underwent degradation in AD system, resulting in a 12 % reduction in 15 days, accompanied by an increase in the -NO2 functional group. In general, this study provided a thorough understanding of the interaction between polyDADMAC and WAS components, raising concerns regarding the elimination of endogenous pollutants during AD.

Mesoporous carbon hollow spheres based sensitive SPME probes for in vivo sampling analysis of selected plant hormones in Chinese aloes

Phytohormones are a class of endogenous substances that separately or synergistically regulate the growth, development, and differentiation of plants. Accurately and efficiently detecting and monitoring the concentration of plant hormones in living plants is of significant importance. Herein, a novel mesoporous carbon hollow spheres (MCHS)-based in vivo solid phase microextraction (SPME) probe was designed for in vivo sampling of plant hormones. The designed MCHS features the advantages of high surface area, porous shells, and large hollow spaces, facilitating the dynamic adsorption and enrichment of target phytohormone. In addition, a cationic polyelectrolyte, (poly (diallyl dimethyl ammonium chloride) (PDDA), was further modified onto the MCHS to expedite the extraction process by electrostatic interaction. Utilizing the MCHS@PDDA probe in combination with HPLC-MS/MS facilitated the continuous monitoring of three plant hormones (abscisic acid (ABA), indole-3-acetic acid (IAA), and gibberellin (GA3)) in Chinese aloe. The detection limit of this method was 0.016–0.090 μg/L, the linear range was 10–1000 μg/L, and both the RSD of the single probe (n = 6) and probe-to-probe test (n = 6) were less than 7.2 %. This method had excellent accuracy and good reproducibility comparable to the traditional sample pretreatment method. Ultimately, this established in-vivo SPME method was successfully adopted to quantify three selected plant hormones in living Chinese Aloes, providing a new method for the long-term monitoring of endogenous active substances in living system.

Novel poly(2-ethyl-2-oxazoline) and poly(diallyldimethylammonium chloride) polymer functionalized montmorillonite: Physicochemical aspects and near-IR study of hydration properties

The novel functionalized montmorillonites (Mts) with non-ionic poly(2-ethyl-2-oxazoline) (PEtOx) and cationic poly(diallyldimethylammonium) (PDDA) were created via an intercalation method with different loading ratio of both polymers. A comprehensive investigation into their physicochemical properties was conducted using Carbon analysis (CA), Powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), Simultaneous thermal analysis (TGA/DSC) and BET-N2 adsorption analysis. The impact of hydration on PEtOx-Mts and PDDA-Mts was assessed through gravimetric analysis and near-infrared spectroscopy (NIR) spectroscopy. PXRD analysis revealed a significant increase in 001 diffraction of PDDA-Mt corresponding to a PDDA interlayer with a basal spacing ranging from 1.47 to 1.49 nm. Conversely, the basal spacing exceeding 2 nm for PEtOx suggested, that the PEtOx polymer was intercalated in a larger amount and packed in a less compact manner compared to PDDA. After modification of Na-Mt with PEtOx polymer, FTIR spectroscopy confirmed the presence of the carbonyl CO group (3265 and 1641 cm-1) and the stretching (2982, 2942 and 2883 cm-1) and bending (1480–1200 cm-1) vibrations of the CH2 and CH3 groups. The vibrations of CH groups were further verified following PDDA modification. NIR spectroscopy also confirmed the vibrational bands attributed to both modifiers after intercalation of PEtOx and PDDA. The results of BET-N2 adsorption revealed a significant decrease in the specific surface area (SSA) after intercalation with a non-ionic PEtOx polymer. On the contrary, in the case of saturation of Na-Mt with polycation PDDA, SSA increased slightly in two instances. TGA analysis confirmed greater weight loss for PEtOx-Mts compared to PDDA-Mts. Derivative thermogravimetry (DTG) revealed the release of physisorbed bound water around 100 °C, decomposition of the organic phase within the 250–550 °C range and dehydroxylation of OH groups around 550–800 °C in both cases. The results obtained from the gravimetry and NIR analysis indicated a greater hydrophobic nature for PEtOx-Mts compared to PDDA-Mts. These findings hold substantial potential for enhancing the properties of novel organo-montmorillonites, thereby facilitating their application as adsorbents for pollutants, surface coatings, biodegradable materials, fillers in polymer nanocomposites, drug carriers, anticancer agents and various other significant applications.

Poly(dimethyldiallylammonium chloride)-modified magnetic bentonite for removal of polystyrene nanoplastics

Nanoplastics (NPs) can contaminate water sources and living organisms, posing significant challenges for removal due to their small size and complex surface properties. There is a need to develop efficient technologies for the removal of NPs. In this study, bentonite was magnetically modified and loaded with Poly(dimethyldiallylammonium chloride) (PDMDAC) to enhance the adsorption for NPs, and improve separation and recovery efficiency. The synthesized PDMDAC-modified magnetic bentonite (PDMMB) had a high specific surface area of 49.386 m2/g and a maximum adsorption capacity of 250.50 mg/g for polystyrene nanoplastics (PS-NPs). The incorporation of PDMDAC increased the surface charge of magnetic bentonite from −39.50 mV to +37.7 mV, generating strong electrostatic attraction to the negatively charged PS-NPs (-64.3 mV). The PDMMB exhibited a saturation magnetization of 17.619 emu/g and an S-type hysteresis curve, indicating strong superparamagnetism that facilitating magnetic separation and recovery. Characterization analysis revealed that the adsorption was driven by electrostatic attraction and the Fe-O functional group. Kinetics and adsorption model analyses indicated that the adsorption mechanism involved electrostatic attraction, complexation, and single/multilayer adsorption, the adsorption process was exothermic and thermodynamically favorable. The adsorption rate remained at 86.41 % after 5 adsorption-desorption cycles. PDMMB exhibited high removal efficiency over a wide range of pH (3−10), ionic strength (0.01–0.5 mol/L), and in the presence of various anion types, indicating its potential for flexible application. The high efficiency, easy operation and excellent regeneration of PDMMB demonstrate its potential for effective removal of NPs from wastewater.