Poly Diallyldimethylammonium Chloride Research Articles

Polydimethyldiallylammonium chloride inhibits dark fermentative hydrogen production from waste activated sludge

Polydimethyldiallylammonium chloride (PDDA) is an excellent flocculant for wastewater purification and sludge dewatering, but whether it poses a threat to hydrogen production from waste activated sludge is not known. In this study, the effect and underlying mechanism of PDDA on the dark fermentation of sludge was investigated. The results showed that PDDA reduced cumulative hydrogen production from 3.8±0.1 to 2.4±0.1 mL/g volatile suspended solids at 40 g/kg total suspended solids. PDDA impeded the dark fermentation process by inhibiting the activity of key enzymes, presenting a stronger inhibitory effect on the hydrogen production process than the hydrogen consumption process. Additionally, PDDA inhibited Firmicutes by enriching other microorganisms, thereby impeding hydrogen production via the acetate pathway. This study deepens the understanding of the potential effects of PDDA on sludge treatment and provides a theoretical basis for alleviating the negative effects of quaternary ammonium-based cationic flocculants.

Polycation-Intercalated MXene Membrane with Enhanced Permselective and Anti-Microbial Properties.

Two-dimensional (2D) nanomaterial-based membranes feature attractive properties for molecular separation and transport, which exhibit huge potential in various chemical processes. However, the low permeability and bio-fouling of the MXene membrane in water treatment become huge obstacles to its practical application. Herein, a highly permselective and anti-bacterial 2D nanofiltration membrane is fabricated by intercalating a polycation of polydiallyldimethylammonium chloride (PDDA) into the Ti3C2Tx MXene laminar architecture through a facile and patternable electrostatic assembly strategy. As a result, the as-fabricated Ti3C2Tx/PDDA composite membrane exhibits higher water permeance up to 73.4 L m-2 h-1 with a rejection above 94.6% for MgCl2. The resultant membrane simultaneously possesses good resistance to swelling and long-term stability in water environments, even after 8 h. Additionally, the Ti3C2Tx/PDDA membrane also demonstrates a high flux recovery ratio of nearly 96.1% to bovine serum albumin proteins after being cleaned. More importantly, the current membrane shows excellent anti-adhesive and anti-microbial activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), with inhibition rates of 90% and 95% against E. coli and S. aureus, respectively. This holds great potential for the application of the polyelectrolyte-intercalated MXene membrane in serving as a promising platform to separate molecules and/or ions in an aquatic environment.

Molecular dynamic modeling of EPS and inorganic/organic flocculants during sludge dual conditioning

Extracellular polymeric substances (EPS) are the key components determining the dewatering behavior of wastewater sludge. However, current technical optimization of sludge conditioning for dewatering is limited by the poor understanding of the conditioner-EPS interactions at molecular levels. Herein, a combination of molecular dynamic (MD) simulations, dewaterability assessment and EPS characterization was used to reveal the sludge dewatering mechanisms using dual conditioning processes (prevalent inorganic (poly aluminum chloride (PAC)) and organic (poly dimethyl diallyl ammonium chloride (PDDA)). Results suggested that PAC and PDDA bridged the biopolymers mainly through electrostatic interactions, promoting the agglomeration of biopolymers and reducing their contact probability with water molecules. Water molecules were tightly bound to EPS mainly through hydrogen bonding with polar oxygen-containing functional groups. The adsorption of PAC and PDDA on hydrophilic components reduced the molecular polarity of biopolymers and altered the conformation of water molecules in the hydration shell, resulting in a decreased hydration capacity of EPS and the release of bound water, and sludge dewaterability was improved. PAC was found to be more effective than PDDA in disrupting the hydrogen bonding between water molecules and EPS, especially the protein β-sheet structure inside the molecular clusters with its high charge strength and diffusivity. Sludge bound water decreased by 73.16 % after PAC conditioning. In addition, PDDA exhibited superior agglomeration ability to biopolymers and promoted the electrostatic interaction between PAC and polar groups during dual conditioning. The strength and hydrophobicity of EPS molecular clusters were thus enhanced, and the conditioning efficiency was improved. This study offers molecular-level insights into the coagulation treatment process of sludge and provides theoretical references for process optimization and new conditioner development.

Electron Tunneling Fosters Solar-to-Hydrogen Energy Conversion.

Transition-metal chalcogenide quantum dots (TMCs QDs) exhibit emerging potential in the field of solar energy conversion due to large absorption coefficients for light harvesting, quantum size effect, and abundant active sites. However, fine-tuning the photoinduced charge carrier over TMCs QDs to manipulate the directional charge-transfer pathway remains challenging, considering their ultrashort charge lifetime and slow charge-transfer kinetics. To this end, herein, MoSx/PDDA/TMCs QDs heterostructures were exquisitely designed by a simple and green electrostatic self-assembly strategy under ambient conditions, wherein tailor-made negatively charged TMCs QDs stabilized by mercaptoacetic acid (MAA) were precisely self-assembled on the positively charged polydiallyl dimethylammonium chloride (PDDA)-modified MoSx nanoflowers (NFs), forming a well-defined three-dimensional heterostructured nanoarchitecture. As an electron trapping agent, an MoSx NFs cocatalyst benefits the unidirectional electron transfer from TMCs QDs to the ideal active centers on the MoSx NFs surface by tunneling the ultrathin insulating polymer interim layer, thereby boosting the charge separation efficiency and endowing self-assembled MoSx/PDDA/TMCs QDs heterostructures with considerably increased photocatalytic hydrogen evolution activity (1.96 mmol·g-1·h-1) and admirable stability under visible light irradiation. Our work will provide new insights into smart regulation of directional charge transfer over TMCs QDs-based photosystems for solar energy conversion.

Mechanical Properties of Palygorskite Clay Stabilized with Polyelectrolytes

Two polyelectrolytes of opposite charges, sodium polystyrene sulfonate (PSS) and polydiallyldimethylammonium chloride (PDADMAC), were investigated to stabilize palygorskite clay at varying dosages of 0.2, 0.8, 1.6, and 3.2 % by the dry weight of the soil. Both PSS and PDADMAC improved the unconfined compressive strength of the palygorskite clay. PSS was effective at all the polymer contents studied after 7 days of dry curing and the strength increased with the dosages of PSS added, ranging from 2 MPa (0.2 % PSS) to 3.1 MPa (3.2 % PSS), compared with 1.5 MPa of the untreated soil. PDADMAC, on the other hand, showed comparable strength improvements as PSS did at the high polymer contents of 1.6 and 3.2 % but did not work at 0.2 and 0.8 % dosages. Under wet curing at 100 % relative humidity, PSS improved the strength of the clay by 40 % (620 kPa at 0.2 % PSS) to 77 % (764 kPa at 1.6 % PSS) compared to the untreated clay (440 kPa). PDADMAC exhibited less improvement than PSS under wet conditions but still worked at dosages of 0.8 and 1.6 %. Besides strength, the resilient modulus and fracture toughness of the treated specimens increased by approximately 10 % and 66 %, respectively, when treated with 1.6 % PSS, which was the optimum content based on the strength results. PDADMAC-treated palygorskite, however, exhibited cracking during curing for both tests, showing potential drying crack issues. The adsorption of PSS and PDADMAC on palygorskite clay were also measured using ultraviolet–visible spectroscopy, and binding between these polymers and palygorskite has been confirmed. The measured adsorption capacities of PSS and PDADMAC were comparable (2.9 and 2.7 mg/g, respectively), while the PSS was somewhat more efficient in improving soil mechanical properties.

Dynamic Properties of Pulmonary Lipid Monolayers on the Surfaces of Sodium Polystyrene Sulfonate and Polydiallyldimethylammonium Chloride Solutions

Dynamic Properties of Pulmonary Lipid Monolayers on the Surfaces of Sodium Polystyrene Sulfonate and Polydiallyldimethylammonium Chloride Solutions

Mof-based basswood nanocomposite membrane of PDDA framework for ultrafast recognition and separation of ribavirin

The application system for membrane separation technology has been enlarged thanks to research and development into new technologies, however membrane separation still confronts many difficulties. This study uses vacuum self-assembly technology for the first time to combine in-situ grown metal–organic framework (MOF) basswood with poly dimethyl diallyl ammonium chloride (PDDA) ring framework to adsorb and separate ribavirin (RBV). The resulting imprinted film exhibits excellent adsorption capacity (49.2 mg g−1) and selectivity (better than 4.6) thanks to the numerous accessible imprinting sites provided by MOF that had previously been grown in situ on basswood and the synergistic effect of the PDDA ring framework. Dynamic permeation was utilized in this study to assess the membrane's stability, and the findings revealed that it consistently has a high separation factor (superior to 9) under specific pressure and time conditions. Furthermore, the synthesis process of MOF/layered PDDA framework-basswood membranes (MLFBMs) is facile and has little environmental impact. Last but not least, the aforementioned experimental findings and synthetic procedure demonstrate that the domains of selective separation, chemical engineering, and environmental protection can greatly benefit from the use of our MLFBMs synthesis technique.

Multi-objective optimization of a novel microalgae harvesting method based on buoy-bead flotation and feasibility analysis by life cycle assessment

Highly efficient microalgae harvesting is crucial for promoting the industrial application of microalgae bioenergy. In this study, positively charged sodium alginate microspheres (PCSAMs) were prepared, and the efficient harvest of Chlorella vulgaris (C. vulgaris) was realized based on the buoy-bead floatation method. A multi-objective optimization model was established to optimize the harvesting process, and the method’s feasibility was analyzed through life cycle assessment. The optimal harvesting efficiency and biomass concentration were 95.34% and 5.80%, respectively, and the corresponding costs were 5.13–5.16$/m3 and energy consumption was 0.065–0.066 kW h/m3. PCSAMs and C. vulgaris could form adhesion through electrostatic complementation, and poly dimethyl diallyl ammonium chloride (PDDA) long chain molecules formed “traps” on the surface of PCSAMs, improving the ability of PCSAMs to carry C. vulgaris. CO2 emissions during the harvesting process were only 0.065–0.066 kg/m3, which conforms to the carbon reduction policy and is more suitable for large-scale microalgae harvesting.

Surface-immobilized cross-linked cationic polyelectrolyte enables CO2 reduction with metal cation-free acidic electrolyte

Electrochemical CO2 reduction in acidic electrolytes is a promising strategy to achieve high utilization efficiency of CO2. Although alkali cations in acidic electrolytes play a vital role in suppressing hydrogen evolution and promoting CO2 reduction, they also cause precipitation of bicarbonate on the gas diffusion electrode (GDE), flooding of electrolyte through the GDE, and drift of the electrolyte pH. In this work, we realize the electroreduction of CO2 in a metal cation-free acidic electrolyte by covering the catalyst with cross-linked poly-diallyldimethylammonium chloride. This polyelectrolyte provides a high density of cationic sites immobilized on the surface of the catalyst, which suppresses the mass transport of H+ and modulates the interfacial field strength. By adopting this strategy, the Faradaic efficiency (FE) of CO reaches 95 ± 3% with the Ag catalyst and the FE of formic acid reaches 76 ± 3% with the In catalyst in a 1.0 pH electrolyte in a flow cell. More importantly, with the metal cation-free acidic electrolyte the amount of electrolyte flooding through the GDE is decreased to 2.5 ± 0.6% of that with alkali cation-containing acidic electrolyte, and the FE of CO maintains above 80% over 36 h of operation at −200 mA·cm−2.

Electrostatic self-assembled MXene@PDDA-Fe3O4 nanocomposite: A novel, efficient, and stable low-temperature phosphating accelerator

In this study, MXene@PDDA-Fe3O4 binary hybrid (MPF) was synthesized by electrostatic self-assembly and incorporated into the low-temperature phosphating as an accelerator. MXene@PDDA-Fe3O4 with a large specific surface area exhibited excellent dispersion stability, structural stability, and the ability to selectively attract metal ions in the phosphating bath, which was conducive to the formation of the dense phosphating coating. The phosphate coating obtained from a phosphating bath containing 0.12 g/L MXene@PDDA-Fe3O4 (12-MPF coating) had the lowest porosity among all samples, which was decreased by 99.07% in comparison to the blank coating. Moreover, the EIS test revealed that 12-MPF coating exhibited the highest low-frequency impedance among all samples, which is more than an order of magnitude higher than that of blank coating, indicating that 12-MPF coating has excellent corrosion resistance. This notable improvement can be attributed to several factors, including the large specific surface area of MXene, the synergistic inhibitory effect of poly (dimethyl diallyl ammonium chloride) (PDDA) and Fe3O4 on agglomeration tendency of MXene, as well as the selective adsorption of Fe3O4 on metal ions. This study demonstrates the significant potential of the 0D/2D binary hybrid in phosphating treatment.

Enhanced sludge dewatering by PDMDAAC coupled with Fenton-like reaction initiated by Fe-rich sludge biochar with in-situ generation of H2O2: Fe/C structure as an electron shuttle

Fenton-like reaction has been used to enhance sludge dewaterability effectively. However, the unstable characteristic, ignitability, and corrosivity of H2O2 make it difficult for application. To address this challenge, a novel process of in-situ H2O2 generation by Fe-rich sludge biochar under aeration condition combined with poly-diallyldimethylammonium chloride (PDMDAAC) was proposed to enhance sludge dewaterability. Under optimized conditions, the capillary suction time and specific resistance to filterability of the conditioned sludge were reduced significantly compared with raw sludge (54.2 vs. 351 s, 0.249×1013 vs. 2.68×1013 m/kg, respectively). The carbon skeleton in Fe-rich sludge biochar can reduce the charge transfer impedance between Fe and O2, promoting in-situ generation of H2O2. The degradation of hydrophilic organics in extracellular polymeric substances of sludge floc and the PDMDAAC coagulation effect promoted the release of bound water. This study provides a strategy to enhance sludge dewaterability by Fenton-like reaction initiated by Fe-rich biochar with no H2O2 addition.

Sulu Çözeltide Arseniğin Nanokompozit Tabanlı Elektrokimyasal Algılanmasının Geliştirilmesi

Contamination of drinking water with heavy metals is a serious threat to the global environment and public health. Currently, approximately 20 countries have been reported for arsenic levels present in drinking water that are higher than the EPA guidelines. Arsenic is highly toxic, widely dispersed and found in the earth’s crust. It can be found in inorganic as well as organic compounds in water. Arsenic is released into the environment in a variety of ways, including industrial effluents, pesticides, wood preservative chemicals, combustion of petroleum and coal, and mining operations. Currently, Arsenic is determined using a wide variety of methods that include inductively coupled plasma mass spectrometry (ICPMS), high-performance liquid chromatography (HPLC) with ICPMS and graphite furnace atomic absorption spectrometry (GFAAS). Nevertheless, these methods are slow, expensive and require skilled people to operate. Alternatively, electrochemical sensors have been potentially recognized as a powerful analytical method for the detection of heavy metals at very low concentrations. It also allows on-site and continuous monitoring of heavy metals. A nanocomposite consisting of gold nanoparticles and conducting polymers (polydiallyldimethylammonium chloride (PDDA) and polystyrene sulfonate (PSS)) functionalized graphene was used in this study to detect arsenic, which causes major environmental and health concerns.

Dynamic Properties of Pulmonary Lipid Monolayers on the Surfaces of Sodium Polystyrene Sulfonate and Polydiallyldimethylammonium Chloride Solutions

Pulmonary surfactant, which is a complex mixture of lipids and proteins, plays a key role in the functional properties of the respiratory system. Lipids form complexes with proteins to maintain low values of surface tension at continuous compression/expansion deformations. However, interactions that lead to the complexation still remain to be unknown thus significantly hampering the development of synthetic analogs of the natural pulmonary surfactant. In this work, the methods of surface rheology and ellipsometry have been employed to study the dynamic properties of model phospholipid monolayers applied onto the surfaces of synthetic polyelectrolyte solutions. It has been shown, that electrostatic or hydrophobic interactions between lipids and macromolecules are insufficient for the efficient complexation and maintenance of low surface tension values.

Insights into the control mechanism of different coagulation pretreatment on ultrafiltration membrane fouling for oily wastewater treatment

Oily wastewater treatment is necessary to reduce environmental pollution. Herein, a coagulation-ultrafiltration integrated process was used to remove emulsified oil. AlCl3, FeCl3, polyaluminum chloride (PAC), polyferric chloride (PFC), and polydimethyl diallyl ammonium chloride (PDMDAAC) were used in coagulation process. It was found that PAC was more effective than AlCl3 and Fe based coagulants in treating oil/water emulsions. Flocs formed in PAC+PDMDAAC, PDMDAAC+PAC, and PAC-PDMDAAC coagulation systems had different size, resistance, structure, and recovery ability, which was due to the changes in the dominant coagulation mechanism. The flocs formed by PAC-PDMDAAC composite coagulant were large and loose, indicating that bridging action and entrapment dominated the removal of oil droplets. PAC-PDMDAAC was efficient in reducing irreversible membrane fouling, while the PAC+PDMDAAC dual coagulation system performed well in controlling reversible fouling. The PDMDAAC+PAC system had a large adsorption resistance and a small cake layer resistance. The PAC-PDMDAAC system had a large polarization resistance. The different membrane resistance distribution was closely related to the discrepancy in coagulation behaviors. Therefore, the enhancement in coagulation performance is the key factor to alleviate membrane fouling. This study will provide theoretical guidance for the treatment of actual oily wastewater.

Laser-direct-writing assisted preparation of flexible humidity sensors based on semi-interpenetrating polymer network for applications in non-contact human-machine interaction

Flexible sensors for non-contact human-machine interaction (HMI) received great attention recently due to increasing requirements for cross-infection of bacteria or virus, which is prominent considering the disaster brought about by COVID-19. Herein, a semi-interpenetrating network of poly(dimethyl diallyl ammonium chloride)/crosslinked poly(vinyl alcohol)/graphene oxide (PDDA/c-PVA/GO) was deposited on polytetrafluoroethylene membrane with interdigital electrodes constructed by reducing GO with laser-direct-writing technology to prepare a flexible humidity sensor (FHS). As-prepared PDDA/c-PVA/GO FHS showed excellent sensing performance, including high response magnitude over wide range of relative humidity (RH) (impedance change of three orders of magnitude between 10 % and 90 % RH), good sensing linearity (R2 = 0.991) on a semi-logarithmic scale, small hysteresis (∼ 4.4 % RH) and resistance to humid environment. Moreover, the FHS exhibited good performance in various scenarios of non-contact HMI, including prompt differentiation of respiration status, speech recognition, accurate measurement of fingertip movement (as small as 2 mm). Specially, a 3 × 3 FHS sensor array could realize accurate non-contact positioning. This work provides a new approach for developing high performance flexible sensors with great application potentials in non-contact HMI.

Self-powered, durable and high fire-safety ionogel towards Internet of Things

It is of great importance but full of challenge to construct intelligent materials with self-powered, durable and high fire-safety to meet the requirements of the intelligent fire protection towards Internet of Things (IoT). In this work, phosphorous-containing ionic liquid (PIL)-based ionogels (PILGs) were fabricated with acrylamide, low melting point polyanionic polystyrene sulfonate sodium and polycationic polydiallyl dimethyl ammonium chloride via ultraviolet initiated polymerization. PILGs showed good ionic conductivity (1.33 S·m−1) and high ionic thermoelectric effect (1.31 mV·K−1), which endowed flammable materials with accurate temperature-sensing, sensitive fire-warning performance and outstanding flame retardancy. When being burned, PILGs triggered the fire-warning system at about 1 s and rapidly self-extinguished. Besides, due to the good thermostability and low volatility of PIL, PILGs displayed high durability in extreme environments. More importantly, PILGs were designed as thermoelectric capacitors and high output power galvanic cells, which could power fire-warning circuits and electronics. Our work provides new insights for the development and application of self-powered intelligent fire protection materials.

Intrinsic mechanism for the removal of antibiotic pollution by a dual coagulation process from the perspective of the interaction between NOM and antibiotic

Antibiotics bring potential risks to human health and ecosystem, and their coexistence with natural organic matters (NOMs) could have harmful impacts on the environment. Herein, a polyaluminium chloride (PAC)-polydimethyl diallyl ammonium chloride (PDMDAAC) dual coagulation process was designed to remove the co-pollutants of chlortetracycline (CTC) and humic acid (HA), representing antibiotics and NOMs, respectively. The main research strength was given to understand molecular interactions and their mechanisms associated with the coagulation and flocculation. We found that the co-existing HA and CTC increased the hydrophily and stability of contaminants, and generated HA@CTC complexes with large particles size. The interaction mechanism between CTC and HA was mainly hydrogen bonding, hydrophobic association action, n−π* electron donor-acceptor interaction, and π−π* conjugation. Lewis acid-base interaction was the main force between HA and CTC. The bonding energies of OH…N, OH…O, and hydrophobic association were −12.2 kcal/mol, −13.1 kcal/mol, and −11.4 kcal/mol, respectively, indicating that hydrogen bonding was stronger than hydrophobic association. The interactions between HA and CTC could improve their removal efficiency in the coagulation process. This is due to that the functional groups (COOH and OH) in the HA@CTC could be adsorbed by Al based hydrolysates. Polar interaction dominated the CTC and HA removal, and PAC was more efficient than PDMDAAC to remove HA@CTC complexes due to its higher complexing capacity. Thanks to the low concentration of residual contaminants and the formation of large and loose flocs, the interaction of HA and CTC could alleviate membrane fouling during ultrafiltration process. This study will provide new insight into the efficient removal of combined pollution and membrane fouling control.

Thin Cationic Polymer Coatings against Foodborne Infections

Biocidal coatings are known to minimize or terminate development of bacterial and fungicidal infections. In this paper, biocidal activity of seven cationic (co)polymers with amino groups—polyethyleneimine, polyallylamine, polydiallyldimethylammonium chloride/polyhexamethylene guanidine copolymer, diallyldimethylammonium chloride/SO2 copolymer, linear and hyperbranched epichlorohydrin/dimethylamine copolymers, polydiallyldimethylammonium chloride—were tested toward Gram-positive and Gram-negative cells. The polymers showed a significant biocidal effect in both aqueous solution and after formation of polymer films on the hydrophilic glass plates. Polymer films were almost completely removed by water during 10 wash-off cycles, that finally resulted in the ultrathin monolayers with a thickness of several nanometers. A polyethyleneimine film showed the most resistance to water with a 50% loss after three wash-off cycles and 75% loss after six wash-off cycles. Binding and subsequent deactivation of pathogenic microorganisms occurs on the outer surface of cationic polymer films. It is expected that a gradual polymer wash-off will allow renewal of the outer film surface and thereby restore the biocidal properties of the polycationic coatings, including those with a nanoscale thickness.

Parametric study of the silver nanoparticles deposition on polyelectrolyte supporting layers

Colloidal nanoparticles deposition on polyelectrolyte (PE) supporting layers is a widespread technique to achieve high density nanoparticle coatings, however the choice of the parameters is often not consistent and varies in different reports. Frequently the obtained films suffer from the aggregation and non-reproducibility. Here, we addressed the main variables in silver nanoparticles deposition—the immobilization time; concentration of the PE in the solution; the thickness of PE underlayer and overlayer; the concentration of salt in the PE solution during the formation of a underlayer. We report on the formation of the high-density silver nanoparticle films and ways to tune their optical density in the wide range using the immobilization time as well as the thickness of PE overlayer. Silver colloidal films with maximum reproducibility were obtained by adsorption of nanoparticles on 1 underlayer of 5 g l−1 polydiallyldimethylammonium chloride with 0.5 M NaCl concentration. The results are promising for the fabrication of the reproducible colloidal silver films for multiple applications, such as plasmon enhanced fluorescent immunoassays and surface enhanced Raman scattering sensors.

Electrodeposition of FeW-graphene composites: Effect of graphene oxide concentration on microstructure, hardness and corrosion properties

Graphene has emerged as excellent reinforcement for electrodeposited metallic composites. The poor stability of graphene in electrochemical baths makes it challenging to obtain uniform composite coatings. In this work, we investigate the possibility to electrodeposit FeW-graphene coatings with organic stablizers. Polydiallyldimethylammonium chloride is selected to stabilize the graphene oxide which is added into the electrolyte in various concentrations. Scanning electron microscopy and Raman analysis confirmed the successful co-deposition of graphene in all the coatings. The composition of the FeW matrix remained unaffected by the addition of graphene, while an increase in the crystallinity of the structure of the compositeswas observed. Graphene was retained even after the coatings were heat treated at 400 °C for 1 h. The hardness and the corrosion resistance of the FeW-graphene composite were largely improved: a22% increase in hardness and an 80% increase in corrosion resistance were measured compared to the graphene-free coating.