Acryloyloxyethyl Trimethyl Ammonium Chloride Research Articles

Reversibly Adhesive, Anti-Swelling, and Antibacterial Hydrogels for Tooth-Extraction Wound Healing.

Oral wound treatment faces challenges due to the complex oral environment, thus, sealing the wound quickly becomes necessary. Although some materials have achieved adhesion and sterilization, how to effectively solve the contradiction between strong adhesion and on-demand removal remains a challenge. Herein, a reversibly adhesive hydrogel is designed by free radical copolymerization of cationic monomer [2-(acryloyloxy) ethyl] trimethylammonium chloride (ATAC), hydrophobic monomer ethylene glycol phenyl ether acrylate (PEA) and N-isopropylacrylamide (NIPAAm). The cationic quaternary ammonium salts provide electrostatic interactions, the hydrophobic groups provide hydrophobic interactions, and the PNIPAAm chain segments provide hydrogen bonding, leading to strong adhesion. Therefore, the hydrogel obtains an adhesion strength of 18.67KPa to oral mucosa and can seal wounds fast within 10s. Furthermore, unlike pure PNIPAAm, the hydrogel has a lower critical solution temperature of 40.3°C due to the contribution of ATAC and PEA, enabling rapid removal with 40°C water after treatment. In addition, the hydrogel realizes excellent anti-swelling ratio (≈80%) and antibacterial efficiency (over 90%). Animal experiments prove that the hydrogel effectively reduces inflammation infiltration, promotes collagen deposition and vascular regeneration. Thus, hydrogel as a multi-functional dressing has great application prospects in oral wound management.

Preparation of the modified chitosan flocculant introduced acryloyloxyethyl trimethyl ammonium chloride and 2-acrylamido-2-methyl propane sulfonic acid for the treatment of papermaking wastewater

To solve the shortcomings of poor solubility, low cationic strength, and small molecular weight of chitosan (CTS), acryloyloxyethyl trimethyl ammonium chloride (DAC) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were introduced into the amino group of chitosan by graft copolymerization, and the modified chitosan flocculant CTS-DAC-AMPS was successfully prepared. The performance of CTS-DAC-AMPS in the treatment of papermaking wastewater was investigated, and the mechanism of the flocculation process was analyzed. The results showed that the crystal habit of CTS-DAC-AMPS was reduced, and the solubility range was broadened compared with CTS due to the introduction of DAC and AMPS. In addition, CTS-DAC-AMPS with quaternary ammonium and sulfonic groups prompted its cationic strength stronger than CTS. In addition to high thermal stability, CTS-DAC-AMPS, composed of two CTS molecules, one DAC molecule, and one AMPS molecule, had a long molecular chain. The results of flocculation experiments showed that the performance of CTS-DAC-AMPS in treating papermaking wastewater was better than that of unmodified CTS and commercially available flocculants. Based on the experimental results, the mechanism of CTS-DAC-AMPS treatment of papermaking wastewater was mainly charge neutralization.

Preparation of Cationic Composite Hydrogel Improved by Activated Carbon and Its Use in Removal of Anionic Dye

Water-insoluble p(AETAC)/AC composite hydrogels containing quaternary ammonium were prepared by free-radical polymerisation method with [2-(Acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and activated carbon (AC). The composite hydrogel was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) methods. In addition, the swelling behavior of p(AETAC)/AC composite hydrogels containing 50 mg, 75 mg, 100 mg, and 150 mg AC in deionized water was investigated. The swelling capacity of the p(AETAC)/AC75 composite hydrogel containing 75 mg AC in various waters was determined. Initial dye concentration, contact time, pH of dye solution, amount of adsorbent, and temperature parameters affecting MO adsorption of p(AETAC)/AC75 composite hydrogel were investigated. The obtained adsorption data agree with the Langmuir isotherm model and the PFO kinetic model. It was determined that the maximum adsorption ability of p(AETAC)/AC75 composite hydrogel according to Langmuir isotherm was 909.09 mg/g. ΔH° and ΔS° values for the adsorption of MO dye-stuff of p(AETAC)/AC75 composite hydrogel were calculated as 22.25 ± 1.43 and 85.40 ± 4.60, respectively. In addition, the value of ΔG° less than zero at four different temperatures indicates that the dye adsorption is spontaneous. According to all the data obtained, p(AETAC)/AC75 composite hydrogel can be considered a promising candidate for the removal of anionic dyestuffs from water.

Anti-swelling P(DAC-co-NaSS-co-VDT) polyampholyte hydrogel with solvent displacement and salinity enhanced wet strength and adhesion

Polyampholyte (PA) hydrogels in general possess excellent mechanical properties, but their underwater applications are largely limited due to swelling induced dramatically reduced strength and poor wet adhesion, especially in high salinity environments. Here, we report our approach to fabricating an anti-swelling poly(acryloyloxyethyltrimethyl ammonium chloride (DAC)-co-sodium p-styrenesulfonate (NaSS)-co-2-Vinyl-4,6-diamino-1,3,5-triazine (VDT), or P(DAC-co-NaSS-co-VDT), PA hydrogel by introducing multi-hydrogen bonding capable functional VDT moieties into the DAC/NaSS coexisting and cation/anion ratio easily tunable PA network. The mechanical properties of the P(DAC-co-NaSS-co-VDT) hydrogel in bulk and at interface were controllable with dimethyl sulfoxide (DMSO)/H2O solvent displacement and Hofmeister effect in a wide salinity range, exhibiting maximum tensile strength, Young's modulus, and wet adhesion toughness of 7.6 MPa, 200 MPa, and 350 J m−2, respectively. The anti-swelling and strong P(DAC-co-NaSS-co-VDT) PA hydrogel developed in this work may find great potential in underwater sensing and sewage treatment as well as for many biomedical applications.

Mussel-inspired cationic chitosan-based flocculants with floc enlarging capacity for efficient removal of anionic dye

Biomass-based flocculants have been widely studied and applied to wastewater treatment due to their environmental friendliness. However, these flocculants tend to generate flocs with small size and lead to difficult solid-liquid separation after the flocculation. The key to solving the floc size problem is enhancing intermolecular or intramolecular interaction forces by changing the molecular structure and functional groups of flocculants. Herein, we developed a mussel-inspired cationic biomass flocculant by functionalizing chitosan (CS) with cation component acryloyloxyethyltrimethyl ammonium chloride (DAC) and mussel-inspired monomer N-2-(3, 4-dihydroxyphenethyl) acrylamide (DAA) through free radical polymerization. The prepared flocculant could provide multiple interaction forces such as electrostatic interaction, cation-π interaction, π −π stacking, and hydrogen bonding to pollutants. As a result, the spent CS-g-p (DAC-co-DAA) flocculant generate dye-containing flocs with dramatically increased size when compared with its counterpart CS-g-pDAC without catechol groups and are capable to realize more than 95% removal efficiency towards organic dyes such as MB and CR over a broad pH range from 3 to 9. This study provides some insights in how to apply this mussel-inspired strategy to develop environmentally friendly biomass-derived flocculants with floc enlarging capacity to treat organic wastewaters in wide pH range.

1H DOSY analysis of high molecular weight acrylamide-based copolymer electrolytes using an inverse-geometry diffusion probe

Copolymers of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and acrylamide (AAm) (AETAC-co-AAm) are polyelectrolytes used as flocculants in wastewater purification. Diffusion-ordered two-dimensional NMR spectroscopy (DOSY) experiments for AETAC-co-AAm samples with Mw ranging from 1.9 to 3.9 million and a polyacrylamide sample with Mw of 1.3 million were carried out in pure D2O and in D2O containing 0.1 or 1 M NaCl using an inverse-geometry diffusion probe system. Projections of the DOSY contour plots onto the diffusion coefficient (D) dimension gave distributions of D for the AETAC and AAm units in the samples. The D values at the maximum point of the distribution (Dp) agreed fairly well with those determined by dynamic light scattering.

Surface hydrolysis-anchored eugenol self-polishing marine antifouling coating

Traditional self-polishing antifouling coatings kill surface organisms by releasing toxic substances, which are damaging to the ecosystem. As a natural antimicrobial substance, eugenol is environmentally friendly and has been proven by different research teams to be effective in enhancing the anti-fouling effect of coatings in the real sea. While in these previous research works, the eugenol was released directly into the seawater thus cannot further serve as surface antifouling effect, leading to a limited antifouling effect of the coating. In this work, the quaternary ammonium component was introduced into the butyl ester-based resin - poly (eugenol methacrylate - acryloyloxyethyltrimethyl ammonium chloride - hexafluorobutyl methacrylate - methyl methacrylate - butyl methacrylate - ethylene glycol methyl ether acrylate) (EMQFP) coating for the first time by simple one-step free radical polymerization method. On the one hand, the eugenol produced by hydrolysis is anchored to the quaternary ammonium on the coating surface for a period of time due to the cationic-π interaction, instead of being released into seawater immediately after hydrolysis, thus increasing the utilization rate of eugenol; on the other hand, the negatively charged carboxylate groups generated after hydrolysis in the coating are mutually attracted to quaternary ammonium through electrostatic effect, so the resin chain segment conformation on the coating surface adjusted to produce zwitterionic-like structure, and the hydration of zwitterionic inhibits primary fouling adhesion.

Effect of temperature and inorganic salts concentration on syneresis rate of AM/DAC hydrogel

Compared with ordinary polyacrylamide, acrylamide copolymer of acryloyloxyethyl trimethylammonium chloride (AM/DAC) hydrogel is easier to reside in large pores and fractures in sandstone formation through electrostatic adsorption. However, the syneresis mechanism of AM/DAC hydrogel caused by high temperature and inorganic salts has not been clear. In this paper, the type of water in gelling solutions and hydrogels was analyzed by the DSC method, the results showed that the bound water in the hydrogel was transformed into free water and then the free water was separated from the hydrogel during the syneresis of AM/DAC hydrogel. Experimental investigations, including dynamic light scattering (DLS), differential scanning calorimetry (DSC), high-performance liquid chromatography (HPLC), phase-analysis light-scattering (PALS), and scanning electron microscope (SEM), have been conducted to elucidate the mechanism of temperature and inorganic salts on syneresis rate of AM/DAC hydrogel. The result showed that with the increase of temperature, the polymer in the AM/DAC hydrogel degraded and the molecular chain broken, which destroyed the grid of hydrogel and reduced the water holding capacity. At the same time, the formation of the hydrophobic group in the molecular chain led to the decrease of the hydrophilicity so that the AM/DAC hydrogel was easy to syneresis. In addition, the increase of temperature will promote the formation of crosslinking intermediate (di/trimethylol), improve the crosslinking rate between crosslinking intermediate and polymer, which makes the AM/DAC hydrogel easy to over crosslink. Inorganic salts diffused the electric double layer by compressing the polymer and competed with the hydrophilic groups on the polymer to absorb water, which will reduce the elongation and hydrophilicity of the polymer molecular chain. This will lead to the decrease of the hydrodynamic radius of polymer molecules in AM/DAC hydrogel, which is the main reason why inorganic salts promote hydrogel dehydration. Besides, inorganic salts had little effect on the formation rate and crosslinking rate of di/trimethylol. Therefore, reducing the molecular hydrodynamic radius of AM/DAC is the main reason why inorganic salts promote the syneresis of AM/DAC hydrogel. The research demonstrated the mechanism of high temperature and inorganic salts on syneresis rate of AM/DAC hydrogel. This study also provides technical guidelines for inhibiting hydrogel syneresis.

Hydrodynamic alignment and self-assembly of cationic lignin polymers made of architecturally altered monomers

Cationic kraft lignin (CKL) polymers with different degrees of grafting (35.2–125.5 mol%) were synthesized via polymerizing kraft lignin (KL) and [2-(acryloyloxy)ethyl]trimethylammonium chloride (ATAC) or [2 (methacryloyloxy)ethyl]trimethylammonium methyl sulfate (METAM) to investigate the impact of the chain extension of the polymers on the physicochemical behavior of CKL in an aqueous solution. It was observed that, at the same grafting ratio, the structural difference of CKLs influenced their hydrophilicity, in which the contact angle of KL-METAM and KL-ATAC solution (1 g/L) reached 9.4° and 11.8° on a glass slide, respectively, at the maximum degree of grafting of ~125 mol%. KL-METAM had a more three-dimensional and flexible structure than KL-ATAC in solution, which promoted its self-assembly (with the aggregate diameter of 235–532 nm) and sedimentation (with the TSI value of 16.8). The rheological studies confirmed the more elasticity of KL-METAM than KL-ATAC with the elastic modulus of 9.3 and 8 Pa at the highest frequency. Quartz crystal microbalance (QCM) adsorption studies illustrated that KL-METAM adsorbed more greatly and generated a bulkier and more viscoelastic adlayer than KL-ATAC did on a rigid surface, below saturation (ΔD/Δf slope of 0.13–0.45) and at equilibrium (ΔD/Δf slope of 0.02–0.17). For the deposited adlayer, the alterations in the slope of dissipation/frequency (ΔD/Δf) between the early and late stages of adsorption were claimed to be related to the conformational changes of CKLs upon adsorption. The findings of this study showed that the architecture of cationic monomers could affect the structure of CKLs so significantly that the lignin polymers would have different chain conformations and flexibility in solution, varied rheological properties, and adsorption performance on a solid surface. The significance of the monomer architecture on the properties and performance of CKLs was more observable at a higher grafting ratio.

Synthesis of a new polyunsaturated cationic crosslinker by a new micro‐polycondensation reaction as a critical modifier of polycationic flocculant for purifying dyeing wastewater

AbstractBACKGROUNDThis work explored a complete evolutionary process, from discovering a new reaction and synthesizing a new crosslinker intermediate, to product application in the purification of dyeing wastewater.RESULTSA new micro‐polycondensation reaction between propylacryloyloxypropyldimethylamine and epichlorohydrin was first observed, forming a new polyunsaturated cationic crosslinker (poly (2‐hydroxypropylacryloyloxypropyldimethylammonium chloride) (PHPAC), abbreviating HPAC unit as the repeating unit); meanwhile, this new PHPAC crosslinker was just a critical modifier of a polycationic flocculant. When the thimbleful of PHPAC crosslinkers containing only 0.2% molar percentage of HPAC units were incorporated into a polycationic skeleton of poly (acryloyloxyethyltrimethylammonium chloride) (PDAC), the application properties of the obtained modified product (known as SC‐PDAC) were greatly improved compared to the unmodified product of PDAC. The cost for preparing the modified product of SC‐PDAC was hardly increased because the quantity of HPAC modifier used was minimal. The multi‐dimension flocculation interactions of SC‐PDAC with the anionic dyes allowed the SC‐PDAC to realize a more efficient purification of dyeing wastewater than the unmodified PDAC. The obtained SC‐PDAC could remove 99.10% of the dyes Reactive Scarlet 3BS and 96.69% of the dyes Methyl Blue when used for purifying the dyeing wastewater. In real engineering applications, the further complex interactions of SC‐PDAC with certain inorganic flocculants and coagulant aids would allow the flocs to be quickly formed, condensed, and aggregated, so as to realize a fast purification of dyeing wastewater within 10 s. The successful implementation of a simulation amplification experiment for treating a 4.0 L dye solution further confirmed that the SC‐PDAC had good potential to be applied in real water treatment engineering.CONCLUSIONSTherefore, as expected, it could be regarded as an economic and facile modification way to obtain the efficient organic cationic flocculant by selecting the PHPAC crosslinker as a critical modifier. © 2021 Society of Chemical Industry (SCI).

Effect of fine structure of chitosan-based flocculants on the flocculation of bentonite and humic acid: Evaluation and modeling

The fine molecular structure of a flocculant fundamentally determines the internal flocculation mechanism and the final application property. In this work, three series of chitosan-based polymers (CTS-g-PAMD) with divergent charge densities and graft chain distribution were synthesized by graft copolymerization using acrylamide (AM) and acryloyloxyethyltrimethylammonium chloride (DAC). Meanwhile, flocculant with linear chain structure (CTS-CTA) was prepared by etherification using 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA). The characterization results confirmed that various monomers had been successfully introduced into chitosan. The reaction basically happened on —NH2 at C2 of chitosan, and the ring structure of chitosan was destroyed by free radical reaction. The obtained flocculants were used to flocculate bentonite and humic acid solution. Besides dose, the effects of chain structure, charge density and chain distribution on flocculation performance were systematically studied. Based on the fractal theory and flocculation kinetics, the effects of structural factors on floc characteristics were also investigated. The results showed that, flocculant with abundant graft chains exerts better flocculation performance and floc characteristic due to enhanced adsorption electrical neutralization and adsorption bridging effect. The effects of charge density and chain distribution on the flocculation performance were disparate in the range of insufficient and excessive doses. Furthermore, on the basis of the quadratic polynomial model, quantitative structure-effect relationships were established, which has guiding significance for the development and utilization of flocculants.

Synthesis of magnetic nanoparticles-decorated halloysite nanotubes/poly([2-(acryloyloxy)ethyl]trimethylammonium chloride) hybrid nanoparticles for removal of Sunset Yellow from water

Magnetite nanoparticles (MNPs) were synthesized on the surface of halloysite nanotubes (HNTs) through co-precipitation approach and the achieved nanocomposites were employed as the support of surface polymerization of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) to obtain a hybrid adsorbent for removal of Sunset Yellow from wastewater. The resulting magnetic nanocomposite was assessed by several characterizations. The X-ray diffraction (XRD) pattern confirmed the synthesis of Fe3O4 MNPs on HNTs. The field emission scanning electron microscope (FESEM) images showed that spherical Fe3O4 MNPs were successfully synthesized and the energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of Fe element in nanocomposite structure. The solid adsorbent was prepared by the aid of the magnetic HNTs as the support. The vibrating sample magnetometer (VSM) was employed for assessment of the magnetic properties of the magnetic HNTs and the solid polymeric adsorbent. The Freundlich isotherm model was fitted the experimented data better than Langmuir isotherm model, indicating the multi-layer adsorption of the dye to the polymeric adsorbent. The polymeric adsorbent had facile elution procedure by the aid of NaCl solution of 1 M. The prepared adsorbent showed fast separation kinetic, reaching equilibrium in about 15 min. and high absorption capacity of 33.8 µmol/g at room temperature, which made this adsorbent a good candidate for industrial wastewater treatment procedures.

Synthesis and characterization of a novel cationic polyacrylamide-based flocculants to remove Congo red efficiently in acid aqueous environment

Dye treatments in industrial wastewaters causes numerous obstacles while stains exist normally constant to radiance as well as corrosion and thus, aerobic digestion. The removal of Congo red dye in low concentration from acidic aqueous solution is the main objective of present work. Synthesis of Acrylamide (AM), Diallyl Dimethyl Ammonium Chloride Propylene (DADMAC) and Acryloyloxyethyltrimethyl ammonium chloride (DAC) (PADD) were carried by UV-initiated polymerization, and polyacrylamide (PAM) as contrast sample. Several analytical techniques existed employed to characterization and demonstrate the productive synthesize of PADD, characteristics and composition of the flocculants was studied through FTIR, 1HNMR while thermal stability of PADD in addition PAM was studied by TGA. In addition, the strong structure of surface morphology was confirmed by scanning electronic microscopy (SEM). Established effective process was used to evaluate the flocculation behaviour with special characteristics. Measuring the parameters, dosage of flocculants, flocculation time, temperature, flocculants initial concentration of Congo red dye, stirring speed and zeta potential in removal of Congo red efficiently in acid aqueous environment. These factors presented that in the condition of strong acidity, low concentration and charge neutralization, the adsorption and bridging effect of PADD on Congo red dye was dominant. Under the idyllic conditions concentration of dye 3.0 mg L−1 and pH 6.0, the maximum removal rates of Congo red dye have been 96.45% and 81.10%, PADD and PAM, respectively. PADD provides a scientific basis platform for the removal of Congo red dye efficiently.

Preparation of a hydrophobically associated cationic polyacrylamide and its regulation of the sludge dewatering performance

A hydrophobically associating cationic polyacrylamide (HACPAM) was prepared by using a micellar polymerization method with V-50 (azobisisobutyramidine hydrochloride) as the initiator and acrylamide, acryloyloxyethyl trimethylammonium chloride and butyl methacrylate as substrates under ultraviolet light irradiation. Structural analysis using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance and X-ray photoelectron spectroscopy analyses showed that the substrates were successfully polymerized. HACPAM was used to condition sludge to improve its dewatering performance, and the results showed that as the amount of HACPAM increases, the sludge dewatering performance is significantly improved, and 3.532 kg/t dry solids of HACPAM is regarded as the optimal amount. Compared with the commercially available cationic polyacrylamide (CPAM), HACPAM has a stronger hydrophobic group association effect, with better promotion of the conversion of bound water in sludge flocs into free water, thereby improving the sewage dewatering performance. The 3D spatial structure of dewatered sludge cakes analyzed by computed tomography technology showed that the number of pores of the dewatered sludge cake treated by HACPAM 3 was smaller than that of the cake treated by CPAM, with a reduction in the porosity of 68.8%, resulting in a better hydrophobic effect. In addition, the mechanism of HACPAM improving the dewatering performance is discussed.

Synthesis of ion-conductive polymers by radical polymerization of deep eutectic monomers bearing quaternary ammonium groups with urea

We describe the synthesis of three novel deep eutectic monomers (DEMs) by reacting cationic monomers bearing quaternary ammonium groups with urea. These DEMs can be used for the synthesis of ion-conductive polymers by radical polymerization. The reaction of methacroylcholine chloride (MC-Cl) with urea in a 1:2 M ratio at 80 °C for 1 h afforded the methacrylate-type DEM, MC-Cl-2Urea, as a transparent viscous liquid. Similarly, an acrylate- and a diallyl-type DEMs, ATMA-Cl-1Urea and DADMA-Cl-2Urea, were obtained through simple mixing of the quaternary-ammonium-containing monomers, 2-(acryloyloxy)ethyl trimethyl ammonium chloride (ATMA-Cl) and diallyl-dimethyl ammonium chloride (DADMA-Cl), respectively, with urea. Free radical polymerization of the DEMs afforded the corresponding polymers, which were characterized using NMR, viscosity, DSC, and TGA measurements. Among the three poly(DEM)s, the diallyl-type poly(DADMA-Cl-2Urea) exhibited the highest ionic conductivity of 5.3 × 10−3 S cm−1 at 25 °C under ambient humidity condition (relative humidity = 30–50%). The polymeric products obtained from liquid DADMA-Cl-2Urea via in situ polymerization without using any volatile organic solvent exhibited an ionic conductivity of 1.6 × 10−6 and 7.5 × 10−5 S cm−1 at 25 and 50 °C under anhydrous condition.

Novel cationic polymer modified magnetic chitosan beads for efficient adsorption of heavy metals and dyes over a wide pH range

Wastewater containing highly toxic and non-biodegradable heavy metals and organic dyes poses a serious threat to ecological environment and human health. Adsorption has been regarded as a promising technology to purify this kind of wastewater. Therefore, it is of great importance to develop efficient adsorbents. Herein, a magnetically recyclable adsorbent Fe3O4-CS/PDAC was facilely fabricated by coating poly(acryloyloxyethyltrimethyl ammonium chloride)-modified chitosan on the surface of Fe3O4 nanoparticles. The morphology, physical-chemical and magnetic properties of as-prepared Fe3O4-CS/PDAC was fully characterized by various techniques. Its adsorption behaviors towards heavy metal Cr(VI) and organic dye sunset yellow (SY) were systematically investigated. Evidently, Fe3O4-CS/PDAC exhibited adsorption capacities of 163.93 and 769.23 mg/g for Cr(VI) and SY respectively, much higher than other reported adsorbents. Besides, batch experiment results showed that adsorption capacities decreased slightly with pH increasing from 2.0 to 10.0. Furthermore, Fe3O4-CS/PDAC could be easily separated and effectively regenerated after adsorption. The superior adsorption performance of Fe3O4-CS/PDAC could be attributed to the electrostatic interaction and ion exchange between target pollutants and the grafted cationic polymer. Owing to its high adsorption capacity over a wide pH range, rapid separation, easy regeneration and good reusability, Fe3O4-CS/PDAC has great potential for practical application in water treatment.

Enhanced municipal sludge dewaterability using an amphiphilic microblocked cationic polyacrylamide synthesized through ultrasonic-initiation: Copolymerization and flocculation mechanisms

Flocculation is an important pretreatment technique for sludge dewatering, the performance of employed flocculants is the key factor determine the flocculation efficiency. Herein, an amphiphilic cationic polyacrylamide (CPAM) with microblock structure was synthesized through template copolymerization initiated by ultrasonic. The chemical components and cationic microblock structure of copolymers were confirmed through comparative characterization by Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (1H NMR) spectrum. The copolymerization mechanism was investigated through kinetics study and association coefficient (KM) determination. The results indicated that the reaction followed free radical copolymerization and terminated mainly through bimolecular termination. The pre-adsorption between acryloyloxyethyltrimethylammonium chloride (DAC) and sodium polyacrylate (NaPAA) before reaction confirmed the template polymerization met the type I (ZIP) mechanism. Cationic microblocks and hydrophobic association together contributed to the optimal dewaterability (FCMC=67.2 %, SRF=3.84×1012 m·kg−1) using TP(AM-DAC-LA). Hydrophobic association enhanced bridging and sweeping effect to promote the floc size growth. Cationic microblocks produced compacter flocs with stronger mechanical strength through enhanced charge neutralization and patching effects, which acted as skeletons to make filter cakes less compressible and more permeable in mechanical dewatering. This work developed a highly effective flocculant for sludge dewatering, the synthesis and working mechanism of which were also given.

Study on Preparation and properties of low sensitive polycarboxylate superplasticizer

Esterified macromonomers (P1) were obtained from methacrylic acid(MAA), maleic anhydride(MAn) and methoxy polyethylene glycol monomethyl ether (MPEG). A low sensitive polycarboxylate superplasticizer (P-DMG) was prepared by copolymerization of Esterified macromonomers (P1) with acrylic acid (AA), hydroxyethyl acrylate (HEA), acryloyloxyethyl trimethyl ammonium chloride (DAC) and 4-hydroxybutyl vinyl polyoxyethylene ether (VPEG). Compared with the conventional polycarboxylate superplasticizer, P-DMG can reduce the sensitivity to concrete dosage, water consumption, temperature and raw materials, and has good workability. It can be widely used in various concrete projects.

Cellulose nanocrystals-based flocculants for high-speed and high-efficiency decolorization of colored effluents

Abstract The modified cellulose nanocrystals (CNCs) are expected to achieve fast and efficient decolorization of colored effluents. In this study, CNCs were surface-modified by grafting polymerization of acryloyloxyethyltrimethyl ammonium chloride (AETMAC) with the initiator of ceric ammonium nitrate (CAN). The optimum scheme to synthesize poly acryloyloxyethyltrimethyl ammonium chloride) (PAETMAC)-grafted CNCs (PAETMAC-g-CNCs) with the highest cationicity of 31.2% was determined from the orthogonal test as 4/1 (w/w) of AETMAC/CNCs, 0.01 mg/L of CAN, 50 °C and 5 h. Zeta potential, particle size, FT-IR and 13C-NMR characterizations manifested the successful introduction of PAETMAC on CNCs. XRD proved the same cellulose I of PAETMAC-g-CNCs as CNCs. As new eco-friendly flocculants, PAETMAC-g-CNCs were tested to decolorize 100 mg/L of neutral reactive blue 19 (RB 19) solutions. The results show that the higher the cationicity of PAETMAC-g-CNCs is, the less amount is needed for getting the maximum color removal. The widest flocculation window from 30 to 100 mg/L is acquired using PAETMAC-g-CNCs2 with the medium cationicity of 21.1%. Moreover, PAETMAC-g-CNCs2 is less sensitive to the pH and ion concentration of dye solutions due to its increased colloidal stability in electrolytes, acids and/or bases. It can work on a wide pH range and is applicable to treat high salt concentration effluents. The color removal efficiency is over 80% at pH 3–9 and NaCl concentration up to 60 g/L. The high crystallinity of PAETMAC-g-CNCs2 and the PAETMAC grafts promote the growth of dye-containing flocs and accelerate the flocs’ precipitation. PAETMAC-g-CNCs2 can rapidly decolorize the RB 19 solutions, which is desirable for industrial applications.

Viscosity Behavior of P(DAC-AM) with Serial Cationicity and Intrinsic Viscosity in Inorganic Salt Solutions.

The poly(acryloyloxyethyl trimethyl ammonium chloride–co–acrylamide), P(DAC-AM), is a kind of cationic polyelectrolyte usually applied in a solution form, and its performance is affected by its structure and the environment where it is used. In particular, its viscosity properties in salt solutions are directly related to its efficacy in various applications, and the performance is one of the most important solution properties. Therefore, in this paper, the effects of the salt concentration and valence of seven kinds of inorganic salts, NaCl, LiCl, KCl, MgCl2, AlCl3, Na2SO4, and Na3PO4, on the values of apparent viscosity (ηa) of P(DAC-AM) samples with cationicity of 10%, 50%, and 90%, and intrinsic viscosity ([η]) of 5, 10, and 15 dL/g were investigated. The ηa was determined using a rotational viscometer. The interaction mechanism between the polymers and salt ions was also investigated. The results showed that depending on the salt concentration, the ηa firstly decreased sharply to the inflection point which indicated the minimum volume of the molecule shrinking, and then either maintained the value unchanged or increased. The salt concentration corresponding to the inflection point decreased with the increase of the salt ion valence but with the reduction of the cationicity of the polymer. The ηa at the inflection point increased as the [η] of the polymer grew. This indicated that the salt concentration and the salt ion valence had a notable impact on the stretch of the cationic polymer molecule in the salt solutions. It was discovered that the phenomenon of the increase of the ηa of P(DAC-AM) samples in the multivalent salt solutions after the inflection point was caused by not only the increase of the ηa of the complexes formed from the pure salts, but also the viscosity resistance of the charge and volume between the polymer molecules and salt ions, as well as the complexes themselves. The linear relationship between the increased ηa and the salt concentration, representing the interaction both among the complexes themselves and between the polymer and complexes, was obtained. Furthermore, the interaction model between the salt ions and P(DAC-AM) molecules in a wide range of salt concentrations was illustrated.