Poly Diallyldimethylammonium Chloride Research Articles

Enhanced Aramid/Al2O3 interfacial properties by PDDA modification for the preparation of composite insulating paper

To further improve the electrical insulation properties of meta-aramid paper, polydimethyldiallyl ammonium chloride (PDDA) was used for the modification of nano-Al2O3 in this work. The modified products were characterized by means of transmission electron microscopy, Fourier transform infrared spectrometer and liquid Zeta potential. The original and PDDA-modified nano-Al2O3 was doped into the aramid fiber composite, and the effects of PDDA and filler mass fraction on several properties such as electrical conductivity, breakdown strength and surface charge dissipation rate of insulating paper were studied. Finally, the interfacial properties of the composites were investigated using molecular dynamics. The results showed that PDDA was successfully coated on the surface of nano-Al2O3, and its surface potential was changed from negative to positive, which could improve the interface characteristics between filler and matrix and enhance the dielectric strength of aramid paper. Besides, saturation effect of PDDA modification was observed, and when the amount of PDDA was 10% and the content of modified nano-Al2O3 was 3%, the breakdown strength of aramid paper was increased by 20%, and the volume conductivity was decreased by 68%. The simulation result revealed that PDDA could improve the insulation performance of aramid paper by reducing the interfacial binding energy between aramid and filler.

Non-iridescent and Wide-Color-Range Structural Coloration Enabled by Cellulose Nanocrystals with a Controlled Long-Range Photonic Structure and Helical Pitch

Bioinspired coloration of cellulose nanocrystals (CNCs) has advanced a new era of wide applications for decoration, sensing, and anti-counterfeiting. However, the solid structural color films suffer from strong angle-dependent iridescence and a limited color range due to the spatial arrangement caused by kinetic arrest during evaporation-induced self-assembly of CNCs. Here, a ternary co-assembly approach is demonstrated to prepare CNC films with weak/non-angular optical response and wide-range colors. Structural coloration is enabled by the long-range and short-range ordered photonic structure of CNCs. A cationic polymer, poly(dimethyl diallyl ammonium chloride), is introduced to influence the CNC self-assembly through electrostatic attraction, inducing the structural transition to the long-range disordered/short-range ordered structure as well as presenting the gradual change from iridescent structural colors to non-iridescent colors. Additionally, a hydrophilic small compound, glycerol, is used to adjust the helical pitch of nanostructured CNC arrays, offering the broad-range coloration. The CNC-based composite material is further used as an optical coating for anti-counterfeiting and realizing color patterning and angle-dependent selective color changes.

Advanced treatment of microplastics and antibiotic-containing wastewater using integrated modified dissolved air flotation and pulsed cavitation-impinging stream processes

Livestock and poultry breeding wastewater is a major reservoir of antibiotic resistance genes (ARGs) and antibiotics residues, and it is also a potential reservoir of microplastics (MPs). In this work, a novel system consisting of modified dissolved air flotation (MDAF) and self-excited oscillating pulsed cavitation-impinging (SOPC) processes was established to explore the removal performance of ARGs, antibiotics and MPs. Polydimethyldiallyl ammonium chloride (PDAC) showed better performance than cetyltrimethylammonium bromide (CTAB) in MDAF. At a saturation pressure of 0.4 MPa and 0.8 mg/L of PDAC, 88.3% of MPs was removed by MDAF. More than 97% of antibiotics and 100% ARGs were removed during the SOPC treatment, and 99.2% of antibiotics were removed by the combined system. The SOPC can stably generate hydroxyl radicals (•OH) in wide pH ranges without additional chemicals. This study demonstrates that the hybrid system has the potential to be applied for the advanced treatment of wastewater containing ARGs and MPs.

Preparation of ultra-thin sandwich Cu-Cu/CNTs-Cu composite foil with high tensile strength by electrodeposition

In this experiment, CNTs were co-deposited with Cu2+ in the acid electrolyte by acidizing sulfuric and nitric acid and protonating cationic surfactant poly diallyldimethylammonium chloride (PDDA). Subsequently, Cu-Cu/CNTs-Cu composite copper foil (1) with a sandwich thickness of 8 μm was prepared by combining additives of 3-mercapto-1-propanesulfonate (MPS) and Cl−. The results show that the resistivity of the composite foil is 1.89 × 10−8 Ω·m, which increased only 2%. The tensile strength σ is 582 MPa, the elongation ε is 3.27%, and the elastic modulus and hardness of the nano-indentation test are 97.5 GPa and 2.38 GPa respectively. These are due to the uniform distribution of CNTs as enhanced phases in the crystal, and importantly, nano twins appear in size smaller than 10 nm, thereby constructing a micro-nano organizational structure and greatly improving the mechanical properties of the composite foil. In addition, the main peak of XRD is shifted from (1 1 1) to (2 2 0) crystal plane, which shows reduced stress in grains, effectively inhibits the phenomenon of self-annealing, and ensures long-term stability of copper foil microstructure.

Study on the Relationship between the Relative Molecular Mass of a Polymer Clay Stabilizer and the Permeability of a Tight Reservoir.

Water-sensitivity damage is inevitable during hydraulic fracturing for tight reservoir stimulation. A polymer clay stabilizer is the most effective and commonly used agent for reducing this kind of permeability damage. However, due to the small pore throat radii of tight reservoirs, polymers may be captured and detained, resulting in secondary permeability damage caused by polymer plugging. Therefore, it is necessary to clarify the matching relationship between the relative molecular mass of the clay stabilizer and the permeability of tight cores, which has not been reported yet. In response to this problem, the residual resistance factor and the permeability damage rate of PDMDAAC (poly dimethyl diallyl ammonium chloride, a kind of commonly used polymer clay stabilizer) to tight cores from Xinjiang Oilfield were investigated in cores with permeabilities of 0.10 × 10–3 μm2 (0.08–0.17 × 10–3 μm2), 0.05 × 10–3 μm2 (0.035–0.065 × 10–3 μm2), and 0.01 × 10–3 μm2 (0.007–0.020 × 10–3 μm2) through flow experiments. It was found that the relative molecular masses of PDMDAAC, which did not cause obvious core permeability damage, should be less than 10 000, 5000, and 2000, respectively. In addition, the bridging flocculation principle between the hydrodynamics radius of the clay stabilizer and the radius of the tight core pore throat can be used to explain the matching relationship between the relative molecular mass of the polymer clay stabilizer and the permeability of the tight reservoir. This study points out the direction for the optimization of the polymer clay stabilizer used in tight reservoir hydraulic fracturing and provides some references for the construction of hydraulic fracturing fluid systems for the efficient development of unconventional oil and gas resources.

Flocculation of Chlorella vulgaris-induced algal blooms: critical conditions and mechanisms.

Algal blooms have posed great threats to livestocks and human health. Although flocculation is effective, its efficiency may hinder the direct application for algal blooms. In this study, critical (optimal) conditions and mechanisms for AlCl3, FeCl3, poly-aluminum chloride (PAC), chitosan, and polydimethyldiallylammonium chloride (PDADMAC)-induced flocculation of Chlorella vulgaris (C. vulgaris) were studied. Results identified the critical conditions which can cause flocculation efficiencies over 90% in 45 min for the five flocculants. Specifically, 4~10-mg/L doses of PDADMAC were proved to be appropriate for the treatment of C. vulgaris-induced algal blooms at pH 6.0~12.0. To probe the underlying mechanisms, functional groups involved in flocculation, zeta potential, and species distribution were analyzed during flocculation. FT-IR results indicated that N-H stretching in amine and C-H deformation in aliphatics were involved in algal flocculation with FeCl3, and C-H deformation played an important role with PDADMAC, PAC, and chitosan. For AlCl3, zeta potential and species distribution results suggested that charge neutralization and adsorption bridging were responsible for algal flocculation at pH 6~8. However, adsorption bridging and sweeping effects were the main mechanisms at pH >3 for FeCl3. The flocculation mechanisms for the rest of the three polymers were charge neutralization, adsorption bridging, and sweeping. Meanwhile, all the flocculation processes followed second-order kinetics. Strong linkages were found between the rate constant, fractal dimension, and flocculation efficiency (P < 0.05). The results of critical flocculation conditions and mechanisms indicated that PDADMAC was an excellent flocculant for C. vulgaris removing and recycling, especially in water bloom treatment.

Coacervation between Two Positively Charged Poly(ionic liquid)s.

Complex coacervates are usually formed through electrostatic attraction between oppositely charged polyelectrolytes, with a few exceptions such as coacervates of like-charge proteins and polyelectrolytes, both in vivo and in vitro. Understanding of the preparation and mechanisms of these coacervates is limited. Here, a positively charged poly(ionic liquid), poly(1-vinyl-3-benzylimidazolium chloride) (PILben), is designed that bears benzene rings in repeating units. Fluidic coacervates are prepared by mixing the PILben aqueous solution with a like-charge poly(ionic liquid) named poly(dimethyl diallyl ammonium chloride) (PDDA). The effects of polymer concentration, temperature, and ionic strength in the PILben-PDDA coacervate are studied. Raman spectroscopy and 2D 1 H-13 C heteronuclear single quantum coherence (1 H-13 C HSQC) characterizations verify that the coacervate formation benefits from the cation-π interaction between PILben and PDDA. This work provides principles and understandings of designing coacervates derived from like-charge poly(ionic liquids) with high charge density.

Acid-regulated hydrolysis and condensation of titanium cation toward controllable synthesis of multiphase mesoporous TiO2 for effectively enhance photocatalytic H2 evolution

Titanium dioxide (TiO2) polymorphs photocatalysts containing two or more crystal phases have customarily been synthesized at high temperature using complicated procedures or expensive equipment, accompanied by the formation of by-products. Therefore, here, we propose an effective acid-regulated hydrolysis and condensation of titanium cation strategy to directly synthesize mesoporous TiO2 with controllable phase junctions. In the method, poly dimethyl diallyl ammonium chloride (PDADMAC) is used as the structure directing agent to produce mesostructure, and hydrochloric acid (HCl) is used as the acid regulator and coordination agent to adjust the hydrolysis and condensation modes of Ti4+, thereby controlling the crystal structure and phase junctions of synthesized mesoporous TiO2 polymorphs. Furthermore, since the heterophase junctions and mesostructure effectively improve the separation and transfer of photo-generated electron-holes, the obtained R74B26 with unique brookite and rutile phase junctions owns the highest photocatalytic activity among all obtained samples, the evolution rate of H2 is 8.98 mmol h‐1−1 g−1. This work will open up new perspectives toward the synthesis of mesoporous polycrystalline material for various potential applications.

An electrostatic self-assembly approach to prepare tebuconazole nanoparticles with improved sustained release and enhanced antifungal activity

Compared with the traditional pesticides, the nanopesticides (NPs) exhibit better sustained release performance, higher utilization efficiency and reduction of environmental pollution. In this study, the antifungal tebuconazole (TEB) loaded nanoparticles (TEB NPs) were prepared by electrostatic self-assembly of the positively charged poly dimethyl diallyl ammonium chloride (PDADMAC) and sulfobutylether-β-cyclodextrin (SCD) inclusion complex (TEB-SCD) with negative charge. The water solubility and thermal stability of TEB were significantly improved after forming the inclusion complex. The blank NPs and TEB NPs were both characterized by particle size, zeta potential, scanning electron microscopy (SEM), sustained release and antifungal activity. The average particle size of the TEB NPs were 411.75 ± 61.65 nm, and the polydispersity index (PDI) showed low values (< 0.3). The TEB NPs were stable for at least 28 days at 25 °C. Compared with pure TEB, TEB NPs showed the sustained release properties. In addition, TEB NPs exhibited better antifungal activity than TEB industrial concentrate (TC, 98%) and commercially available TEB suspension concentrate (SC) with the 96.33 ± 13.52% antifungal rate of fusarium graminearum. The results indicated that the TEB NPs can improve the antifungal activity and reduce environmental pollution.

Polydimethyldiallylammonium chloride induces oxidative stress in anaerobic digestion of waste activated sludge

The effects and key mechanisms of polydimethyldiallylammonium chloride on anaerobic digestion of waste activated sludge were investigated. Polydimethyldiallylammonium chloride at 38.1 g/kg total solids substantially reduced cumulative methane production from 138.2 ± 5.5 to 49.4 ± 5.0 L CH4/kg volatile solids added, a reduction of 64.3 ± 0.2%. The quaternary ammonium groups on polydimethyldiallylammonium chloride agglomerated sludge flocs by neutralizing negatively charged amino groups in in extracellular polymeric substances, which hindered the release of organic matter. Quaternary ammonium groups induce oxidative stress by inducing the production of reactive oxygen species, thereby inhibiting the activity of anaerobic digestive enzymes. In addition, quaternary amine groups reduced the abundance of hydrolyzing bacteria, acidifying bacteria, and acetylotrophic methanogens. Oxidative stress could be an underappreciated mechanism that quaternary ammonium groups deteriorate anaerobic digestion, which could be transformative for understanding the potential risks of quaternary ammonium cationic flocculants in biological sludge treatment.

Combined organic reagents for co-conditioning of sewage sludge: High performance in deep dewatering and significant contribution to the floc property

In this study, we have examined a new all-organic conditioning method for sewage sludge pretreatment, featuring the combined use of poly dimethyldiallylammonium chloride (PDMD) and tannic acid (TA). The impact of the reagents and the specific dosing order were identified for process optimization. Results showed that TA + PDMD mode (i.e., TA addition followed by PDMD) has better sludge filterability and dewaterability. With the optimal dosage, it decreased specific resistance of filtration by 90.60%, capillary suction time by 65.08%, and reduced moisture content of dewatered sludge cake to 53.46%, giving the highest dewatering performance reported so far. In addition, a significant positive correlation was found between viscosity and dehydration performance (Rp = 0.9898, p < 0.05). The explanation was the enhanced interparticle interaction and structural strength, indicated by higher apparent viscosity and yield stress, thixotropic hysteresis loop, solid-like viscoelastic property, and higher fractal dimension (Df) value as well. The enhanced compressibility (0.69 versus 1.06 of raw sludge) and SEM image further confirmed the compact and permeable structure of the conditioned sludge. And for dosing order, it was proved that TA-first conditioning method led to full reaction of protein precipitation, which produced increasingly compact flocs consequently. In conclusion, the floc property played an important role in condensed sludge formation and in deep dewatering process, which offset the side effect of undesirably higher equilibrium viscosity of the conditioned sludge.

An Improved Approach to Manufacture Carbon Nanotube Reinforced Magnesium AZ91 Composites with Increased Strength and Ductility

Multiwalled carbon nanotubes (MWCNTs) are decorated with Pt nanoparticles by a “layer-by-layer” approach using poly (sodium 4-styrene sulfonate) (PSS) and poly (diallyl dimethylammonium chloride) (PDDA). Transmission electron microscopy (TEM) images and Energy Dispersive X-ray (EDX) analysis of the samples confirm Pt deposition on surfaces of CNTs. Dispersibility and dispersion stability of MWCNTs in the solvents are enhanced when MWCNTs are coated with Pt nanoparticles. Mg AZ91 composites reinforced with MWCNTs are then produced by a melt stirring process. Compression tests of the composites show that adding 0.05% wt Pt-coated MWCNTs in AZ91 improves the composite’s mechanical properties compared to the pure AZ91 and pristine MWCNT/AZ91. Fracture surface analysis of the composite using a scanning electron microscope (SEM) shows individual pulled out MWCNTs in the case of the Pt-coated MWCNT/AZ91 composites. This finding can be attributed to the uniform dispersion of Pt-coated MWCNTs in Mg due to the improved wettability of Pt-coated MWCNTs in Mg melts. The study of the pull-out behaviour of pristine and Pt-coated CNTs from an Mg matrix using molecular dynamics simulation supports this interpretation.

Unleashing Insulating Polymer as Charge Transport Cascade Mediator

AbstractCrafting spatially controllable charge transfer channels at the nanoscale level remains an enduring challenge in solar‐to‐chemical conversion technology. Despite the advancements, it still suffers from sluggish interfacial charge transport kinetics and scarcity of strategies to finely modulate charge transport pathways. Herein, this article demonstrates the unexpected charge modulation property of non‐conjugated insulating polymer assisted by a universal layer‐by‐layer self‐assembly tactic. Oppositely charged poly(dimethyl diallyl ammonium chloride) (PDDA) and Ti3C2 MXene quantum dots (MQDs) are periodically attached to the wide bandgap metal oxides (WMOs) to design multilayered heterostructured photoanodes. The intermediate PDDA layer acts as an efficacious charge relay medium to access directional electron flow from WMOs to Ti3C2 MQDs, while Ti3C2 MQDs serve as the electron extractor. Charge transfer cascade is thus stimulated on account of the simultaneous electron‐trapping capabilities of interim PDDA layer and Ti3C2 MQDs, which synergistically favors the conspicuously boosted charge separation over WMOs, affording the WMOs/(PDDA/MQDs)n photoanodes with considerably enhanced photoelectrochemical (PEC) water oxidation performances. Moreover, PEC performances of such photoanodes can be tuned by interface configuration via assembly number and sequence. This work will provide an insightful perspective to craft a directional charge transfer pathway through insulating polymer for solar energy conversion.

Unraveling the Simultaneous Enhancement of Selectivity and Durability on Single-Crystalline Gold Particles for Electrochemical CO2 Reduction.

Electrochemical carbon dioxide reduction is a mild and eco‐friendly approach for CO2 mitigation and producing value‐added products. For selective electrochemical CO2 reduction, single‐crystalline Au particles (octahedron, truncated‐octahedron, and sphere) are synthesized by consecutive growth and chemical etching using a polydiallyldimethylammonium chloride (polyDDA) surfactant, and are surface‐functionalized. Monodisperse, single‐crystalline Au nanoparticles provide an ideal platform for evaluating the Au surface as a CO2reduction catalyst. The polyDDA‐Au cathode affords high catalytic activity for CO production, with >90% Faradaic efficiency over a wide potential range between −0.4 and −1.0 V versus RHE, along with high durability owing to the consecutive interaction between dimethylammonium and chloride on the Au surface. The influence of polyDDA on the Au particles, and the origins of the enhanced selectivity and stability are fully investigated using theoretical studies. Chemically adsorbed polyDDA is consecutively affected the initial adsorption of CO2 and the stability of the *CO2, *COOH, and *CO intermediates during continuous CO2 reduction reaction. The polyDDA functionalization is extended to improving the CO Faradaic efficiency of other metal catalysts such as Ag and Zn, indicating its broad applicability for CO2 reduction.

Impact of polymeric stabilisers on the reaction kinetics of SrBr2

Thermochemical heat storage (TCHS) in salt hydrates attracts increasing interest due to the high energy density combined with loss-free storage. Strontium bromide hexahydrate (SBH), and composites thereof, are often suggested as suitable materials for this application. Although many aspects of SBH composites have been thoroughly investigated, very little has been done on the fundamental aspects of the hydration reaction and interactions between composite components on a molecular level. In this paper, we examine the interaction between SBH and polymeric additives polydiallyldimethylammonium chloride (PDAC), sodium carboxymethyl cellulose (CMC), and polyacrylic acid (PAA) in previously developed TCHS composites. The primary function of the polymeric additives is enhanced mechanical integrity however this study investigates potential implications on reaction temperature and speed the addition of such components might have. Focus is given to the interaction between SrBr2 and PDAC since such composites showed (de)hydration behaviour deviating from pure SrBr2. The reaction kinetics are investigated at several points in the phase diagram through thermogravimetric analysis (TGA), supplemented by powder x-ray diffraction (XRD) studies. Our findings show that there exists an interaction between SrBr2 and PDAC which manifests itself through shrinkage of crystallite size and increased lattice strain induced by preferential binding of PDAC to SrBr2. Depending on the PDAC content in the composite we have found out that 1) at excessive amounts PDAC inhibits hydration due to its sequestering properties 2) at low amounts it an enhances reaction kinetics due its hydrophilic nature.

Ultrafast crystallization of mesoporous Sn-MFI single crystals achieved by addition of the cationic polyelectrolyte in starting gels

Heteroatoms substituted zeolites (HSZ) are important absorbents/catalysts for many industrial processes. However, precisely locating the heteroatoms in the desired zeolite frameworks is still challenged by the low crystallization rate. Herein, we report that poly dimethyl diallyl ammonium chloride (PDDA) can greatly accelerate the HSZ crystallization with the simultaneous creation of mesopores. Significantly, highly crystallized Sn-MFI single crystals are obtained within 6 h, which is over one hundred times faster than that of the available methods (∼720 h). The addition of PDDA is revealed to speed up the in-situ depolymerization and re-condensation of nanosized silica precursors, leading to the rapid crystallization of MFI framework with the concomitantly homogeneous incorporation of tetra-coordinated Sn atoms. The obtained Sn-MFI mesoporous zeolites exhibit excellent catalytic performance for the hydration of epichlorohydrin to 1, 2-diol. More importantly, the realization of Sn-MEL, ZSM-11, Ga-MFI and ZSM-5 zeolites with prominently short time and the diversity of the cationic polyelectrolyte make the thus developed strategy a highly efficient and general method for synthesizing HSZ.

SERS detection of negatively charged molecules by interface-induced self-assembly of PDDA modified Ag nanoparticles

Some noble metal colloids with negative charges were mostly used as surface-enhanced Raman scattering (SERS) substrates, that the Raman signals of negatively charged molecules are hard to be detected because of the electrostatic repulsion among them and the negatively charged metal nanoparticles. Herein, Ag nanoparticles (Ag NPs) with positive charges and its Ag nanofilm were prepared by poly dimethyl diallyl ammonium chloride (PDDA) to realize the SERS detection of negatively charged molecules directly. The zeta potential and its particle sizes were characterized to select the optimum condition of PDDA. In addition, the morphology of positive Ag NPs and Ag nanofilm was characterized by UV–Vis spectroscopy and transmission electron microscopy. The SERS effect of negatively charged thiamphenicol on positively charged Ag nanofilm was significantly enhanced at the optimum condition and its sensitivity was significantly improved compared with normal Ag nanofilm. The proposed novel positively charged Ag nanofilm can be further applied to detect other negatively charged molecules by SERS.

Preparation and Characterizations of PSS/PDADMAC Polyelectrolyte Complex Hydrogel.

Polyelectrolyte complex (PEC) hydrogel, formed via physically electrostatic crosslinks between polyanion and polycation, is an interesting hydrogel in terms of its nontoxicity and solvent-free technique. In this work, poly (sodium 4-styrenesulfonate) (PSS)/poly (diallyl dimethyl ammonium chloride) (PDADMAC) complex hydrogels were prepared. Firstly, the PSS/PDADMAC complex aggregates using various PSS/PDADMAC mole fractions that were prepared in the presence of NaCl solution. Then, the aggregates were resolubilized under stirring at 70 °C for 2 h to obtain a homogeneous PEC solution. Finally, the PEC solution was dialyzed using a dialysis membrane with 3500 molecular cut-off for 1 day. The dialysis bath was changed every interval period of 2 h to control the rate of reversible electrostatic interaction, resulting in the homogenous PEC hydrogel with porous morphology as revealed by SEM and BET investigations. The dimensional stability and viscoelasticity of the PEC hydrogel was studied by DMA experiment, which showed the viscoelastic behavior at a compressive force ranging from 0 to 0.1 N. Finally, PSS/PDADMAC hydrogels showed a high water absorbency property and excellent affinity to textile anionic dyes.

A Hygroscopic Janus Heterojunction for Continuous Moisture-Triggered Electricity Generators.

Moisture-triggered electricity generator (MEG) harvesting energy from the ubiquity of atmospheric moisture is one of the promising potential candidates for renewable power demand. However, MEG device performance is strongly dependent on the moisture concentration, which results in its large fluctuation of the electrical output. Here, a Janus heterojunction MEG device consisting of nanostructured silicon and hygroscopic polyelectrolyte incorporating hydrophilic carbon nanotube mesh is proposed to enable ambient moisture harvesting and continuous stable electrical output delivery. The nanostructured silicon with a large surface/volume ratio provides strong coupling interaction with water molecules for charge generation. A polyelectrolyte of polydiallyl dimethylammonium chloride (PDDA) can facilitate charge selective transporting and enhance the effectiveness of moisture-absorbing in an arid environment simultaneously. The conductive, porous, and hydrophilic carbon nanotube mesh allows water to be ripped through as well as the generated charges being collected timely. As such, any generated charge carriers in the Janus heterojunction can be efficiently swept toward their respective electrodes, because of the device asymmetric contact. A MEG device continuously delivers an open-circuit voltage of 1.0 V, short-circuit current density of 8.2 μA/cm2, and output power density of 2.2 μW/cm2 under an ambient environment (60% relative humidity, 25 °C), which is a record value over the previously reported values. Furthermore, the infrared thermal measurements also reveal that the moisture-triggered electricity generation power is likely ascribed to surrounding thermal energy collected by the MEG device. Our results provide an insightful rationale for the design of device structure and understanding of the working mechanism of MEG, which is of great importance to promote the efficient electricity conversion induced by moisture in the atmosphere.

Synthesis and evaluation of cationic polyacrylamide and polyacrylate flocculants for harvesting freshwater and marine microalgae

• Cationic PAETAC & PAmPTAC were synthesized by UV-induced radical polymerization. • New polymers showed good flocculation performance of freshwater & marine microalgae. • Optimal doses of PAETAC were 50 and 4.8 mg/g for C. vulgaris & P. purpureum. • PAETAC and PAmPTAC produced stable flocs, supporting simple dewatering step. This study addresses the challenge of microalgae harvesting through the development of flocculants. Two positively charged cationic polymers including poly[2 (acryloyloxy)ethyl]trimethylammonium chloride (PAETAC) and poly(3 acrylamidopropyl)trimethylammonium chloride (PAmPTAC) were synthesized using the UV-induced radical polymerization, for harvesting both freshwater and marine microalgae. The results show that the synthesized polymers have excellent flocculation performance for both freshwater green microalgae ( Chlorella vulgaris) and marine red microalgae ( Porphyridium purpureum). PAETAC outperformed PAmPTAC for both Chlorella vulgaris and Porphyridium purpureum microalgae. The optimal PAETAC doses for Chlorella vulgaris and Porphyridium purpureum microalgae were 50 and 4.8 mg/g of dry biomass while the optimal PAmPTAC doses were 252 and 35 mg/g of dry biomass respectively. Additionally, the floc formation with the PAETAC was more stable than PAmPTAC, which supported the dewatering step via sieving. The superior performance can be attributed to the higher molecular weight of the PAETAC polymer when compared to the PAmPTAC polymer. In comparison to commercially available polydiallyldimethylammonium chloride (PolyDADMAC), the newly synthesised PAETAC and PAmPTAC polymers demonstrated superior flocculation efficiency at a lower dose. The findings of this study established a platform technology for designing and synthesising cationic flocculants for use in microalgae harvesting.