Poly Diallydimethylammonium Chloride Research Articles

Pd-loaded hierarchical titanosilicalite-1 catalysts on CO2 cycloaddition with epoxides: Experimental and DFT investigations

This work presents the synthesis of Pd-loaded microporous titanosilicalite-1 (Pd/TS-1) and Pd-loaded hierarchical titanosilicalite-1 (Pd/HTS-1) with abundant mesopores (2–30 nm) inside the framework via hydrothermal method using polydiallydimethyl ammonium chloride as the non-surfactant mesopore template. XRD, N2 sorption, FT-IR, FESEM-EDX, TEM, XPS, and DR-UV techniques were used to characterize the morphological and physicochemical properties of the synthesized materials. These materials were tested as heterogeneous catalysts, along with tetrapropylammonium bromide as co-catalyst, for cycloaddition reactions of CO2 with epoxides to produce cyclic carbonates. It was found that the epoxide conversions were influenced by acidity and pore accessibility of the catalysts. Using Pd/HTS-1 facilitated bulky substrates to access active sites, resulting in higher conversions than Pd/TS-1. Over 85 % conversions were achieved for at least five consecutive cycles without significant loss in catalytic activity. The interaction between the Pd active surfaces and epichlorohydrin (ECH) was further studied by DFT calculations. The existence of Pd(200) was more influential on adsorbing epichlorohydrin (ECH) and subsequent formation of dissociated ECH (DECH) intermediate than Pd(111) surface. However, Pd(111) was dominant in enhancing the activity of DECH species for capturing CO2. Therefore, the co-existence of Pd(200) and Pd(111) surfaces was needed for cycloaddition of CO2 with ECH.

Water vapor adsorption on metal-exchanged hierarchical porous zeolite-Y

The development of efficient zeolite-based adsorbents with high water uptake capacity is an essential requirement for water adsorption and moisture removal technologies. In the present study, zeolite-Y samples with interconnected hierarchical micro-mesoporous network were synthesized by employing a bifunctional cationic polymer (namely, polydiallydimethyl-ammonium chloride, PDDA), and ion-exchanged with several metal salts (such as Zn, Mg, Li) targeting high capacity water adsorption. We systematically investigated water adsorption behavior of hierarchically porous NaY (HP–NaY) samples and studied the influence of their distinct metal exchange analogues on water affinity and total adsorption capacity. The water affinity and water uptake increased for the HP-NaY samples compared to conventional NaY. HP-NaY samples demonstrating a high water adsorption capacity (17.32–17.98 mmol/g) at 303 K and 0.7 relative pressure (P/Po) when compared to commercial zeolite-Y (CBV-400, 14.83 mmol/g). A further improvement in water uptake was attained by introduction of distinct metal ions into the hierarchical porous zeolite-Y. HP-LiY exhibited the highest water adsorption capacity (19.08 mmol/g at 0.7 P/Po) amounting to 28% and 15% improvement when compared to CBV-400 and CBV-Li respectively. The observed improvements in water adsorption capacity are attributed to (i) the existence of interconnected micro-mesoporous channel network and higher total pore volume and (ii) the enhancement in accessibility of adsorption sites by H2O molecules. The adsorption data of the samples were also fitted using various adsorption models. Hierarchically porous zeolites displayed site heterogeneity, the latter being rendered by the existence of varying chemical environments between sites within the micropores and the mesopores and the nature of the host metals.

The capacity of mesoporous fly ash grafted with ultrathin film of polydiallyldimethyl ammonium for enhanced removal of phenol from aqueous solutions

This study investigates the feasibility of coating cationic polydiallydimethyl ammonium chloride (PDDA) onto mesoporous acid-treated fly ash (AFA) and its capacity to adsorb phenol from aqueous solution. The PDDA-FA and its AFA substrate were characterized using a scanning electron microscope with energy-dispersive x-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and thermogravimetric analysis (TGA) to ascertain successful film coating. Batch adsorption studies were carried out to evaluate the effects of solution pH, initial concentration, adsorbent dosage, contact time, shaking speed and temperature on the removal of phenol using PDDA-FA and AFA. Characterization revealed that the coating of cationic polyelectrolyte film onto FA introduced surface polarity which enhanced the mass transfer of phenol to the PDDA-FA surfaces. Importantly, the results showed that synthesized PDDA-FA is 4-fold more efficient than precursor AFA in removing phenol from aqueous solution. The sorption equilibrium isotherm of adsorbent was described by Freundlich, Langmuir and Temkin models. The adsorption rate of both adsorbents followed the pseudo-second-order kinetic model, while the thermodynamic studies of PDDA-FA sorption of phenol indicated a favorable endothermic and physical adsorption mechanism. The PDDA-FA also has a higher adsorption capacity than other reported modified FA. In conclusion, an ultrathin coating of fly ash with cationic polyelectrolyte offers a viable potential as an alternative adsorbent from waste. This work has the advantages of cleaner production of adsorbents from waste, and wastewater decontamination.

Effect of PDDA surfactant on the microstructure and properties of electrodeposited SiO2/Ni nanocomposites

In this study, SiO2/Ni nanocomposite coatings were electrodeposited from a sulphate bath with and without the addition of polydiallydimethylammonium chloride (PDDA) as a cationic surfactant. The surface morphology and microstructure on the cross-sections of the deposited nanocomposites were examined by scanning electron microscopy. More detailed microstructure characterization was performed using transmission, scanning-transmission and high-resolution transmission electron microscopy. It was determined that the addition of 2 and 3 mL/L of PDDA allows the incorporation of well-dispersed SiO2 nanoparticles in the crystalline nickel matrix. The distribution of SiO2 nanoparticles in the nanocomposite was visualized on elemental maps using energy dispersive X-ray spectroscopy in scanning-transmission mode. The size of nickel grains was determined by means of XRD, as well as image analysis of TEM images. The volume fraction of SiO2 clusters in the SiO2/Ni+PDDA nanocomposites with the addition of 2 and 3 mL/L of PDDA was equal to 16 and 27%, respectively. It was determined that improved quality nanocomposites electrodeposited in the presence of 3 mL/L of PDDA and 8 g/L of SiO2 exhibit high nanohardness, as well as good tribological properties and corrosion resistance.

Evaluation of the removal of phenol from contaminated water by graphene oxide functionalized with poly diallydimethyl ammonium chloride (GPDADMAC)

Evaluation of the removal of phenol from contaminated water by graphene oxide functionalized with poly diallydimethyl ammonium chloride (GPDADMAC)

Rapid Desorption of Polyelectrolytes from Solid Surfaces Induced by Changes of Aqueous Chemistry.

The short-term desorption induced by changes of aqueous chemistry of predeposited polyelectrolyte layers on solid surfaces was studied with reflectometry. The behavior of a strong polycation, polydiallydimethylammonium chloride (PDADMAC), interacting with flat silica was investigated in detail. Results showed that partial desorption of preadsorbed polymer chains can be quickly triggered by changes in ionic strength and pH. When lowering these parameters in the PDADMAC-silica system, the increased lateral repulsive potential of neighboring chains drove the desorption of some of the polymer. Furthermore, layer desorption was favored when electrostatic interactions between a polyelectrolyte and the underlying surface became less attractive or switched to being repulsive. At the investigated timescales (<1 h), adlayer desorption was always partial and often incomplete. When initiating desorption from a condition of large adsorbed mass, desorption effects did not result in the plateau mass obtained by adsorption on a clean surface: an excess mass remained deposited. The results thus suggest that a relatively large energy barrier needs to be overcome to induce redissolution of predeposited chains and that this barrier may be a function of the number of polymer-surface interactions, which are in turn correlated with polymer molecular mass. These mechanisms have important implications for environmental processes and colloidal systems because they imply that, once adsorbed, polymeric chains may be redissolved but only to a limited degree at typical engineering timescales.

Optical studies of the solution phase reduction and stabilization of indigo tetrasulfonate in polyelectrolyte complexes.

Ultraviolet-visible (UV-vis) and fluorescence spectroscopy have been used to characterize the polyelectrolyte complexes (PECs) formed when potassium indigo tetrasulfonate (ITS) interacts with poly diallydimethylammonium chloride (PDADMAC) through columbic attraction in the presence of the reducing agent sodium bisulfite, NaHSO3. The PDADMAC facilitates both the reduction of the ITS and the stabilization of the reduced state of the ITS in an atmospheric oxygen environment. Dilutions of the dye solution show that the PEC is stable to dilutions of at least 1 to 1000. UV–vis studies indicate that the reduced ITS (ITSred) forms what is likely a J-aggregate in the presence of PDADMAC with an absorbance band red shifted from the normal absorbance band of reduced ITS by roughly 130 nm, 390 nm to 520 nm. Excitation of the PEC solution at either 390 nm or 520 nm produces an emission spectrum of the aggregated complex with an emission maximum near 534 nm. Monomer emission at 480 nm of ITSred represents only 3.0 ± 0.5% of the emission signal of the aggregated complex. Kinetic studies using fluorescence spectroscopy over a temperature range of 30 to 70 °C and dilutions of dye solutions ranging from 1:10 to 1:1000 yield data for the oxidation of ITSred that is best fit by a first order rate constant. Kinetic data displays two distinctive regimes, a short time rate and a long time rate. These two distinct kinetic regimes are likely due to the reduced ITS interacting with an outer PEC environment and an inner PEC environment. First order rate constants could be used to estimate Δ‡H and Δ‡S of the oxidation reaction. Fluorescence data was used to calculate the partitioning of reduced ITS molecules between the outer and inner PEC environments. Partitioning from the inner to outer PEC environment was found to be entropically driven. Addition of NaCl to the diluted dye solutions could alter the kinetics of the oxidation but the significance of the effect depended on the initial dye solution preparation.

Catalytic cracking of n-dodecane over hierarchical HZSM-5 zeolites synthesized by double-template method

Hierarchical HZSM-5 zeolites have been prepared by a double-template method with tetrapropylammonium hydroxide and polydiallydimethylammonium chloride (PDDA) as micro- and meso-scale template, respectively, and Al(NO3)3 as aluminum source. The as-prepared zeolites were characterized by XRD, SEM, TEM, N2-adsorption–desorption, TGA, ICP, in situ FT-IR and NH3-TPD. The hierarchical HZSM-5 zeolite prepared at the PDDA/TEOS weight ratio of 0.2 in the synthesis gel (HZ-0.2P) had uniform mesopores (11–13 nm) and high acid site accessibility. An increase of the PDDA/TEOS resulted in enlargement of mesopore size and broadening of size distribution, together with appearance of some non-uniform accumulation pores. Moreover, the accessibility of acid sites in hierarchical HZSM-5 decreased. Catalytic cracking of n-dodecane carried out at 500 °C and 4 MPa in a wall-coated tubular reactor with HZSM-5 zeolites showed that HZ-0.2P exhibited the superior catalytic activity and stability, with the increase higher than 20% in the conversion of n-dodecane and reduction to ca. 1/2 in the deactivation rate compared with micro-porous HZSM-5 zeolite. This could be ascribed to its highest acid site accessibility, which improves the diffusion of n-dodecane and its cracking product molecules inside pore channels of catalyst.

Differentiating Process Performance of Various Coagulants in Removal of Congo red and Orange G Dyes

Abstract Two refractory azo dyes- Congo red and Orange G, especially at high concentrations were subjected to coagulation with different conventional coagulants and newer formulations developed from Aluminum sulfate, Iron (III) chloride, Aluminium chloride, Poly diallydimethylammonium chloride (Poly DADMAC) and Poly Aluminium Chloride (PAC). The highest COD reduction of 99 % was obtained with PAC SAB 18 (Powder Grade PAC) for Congo red at pH 4.5 while the color removal of 99 % was achieved with almost all the coagulants in the present study at specific pH within 3–8. The optimum dose for the iron-based coagulant is 200 mg/L while that of aluminum-based coagulants and PAC is 150–200 mg/L. Results showed that Orange G was more difficult to remove with a maximum COD removal of 65 % and 35 % color removal using various formulations. The combinational formulations of inorganic-inorganic and inorganic-organic produced a substantial enhancement in COD and color removal and reduced sludge. PAC-Fe30/70 produces the minimum sludge of 50 mL/g on Congo red. pH in the range 3–9 showed high reductions in COD and color (90–99 %) for Congo red while jerky rise in COD and color reduction was observed in the case of Orange G after pH 9. An attempt to understand the dye coagulation mechanism has been made based on the specific difference in dye structure and cation speciation.

Combination of in situ preconcentration and on-site analysis for phosphate monitoring in fresh waters.

Excess nutrients of phosphorus and nitrogen would lead to adverse impacts on a water body. It is important that their concentrations in a dynamic water ecosystem are measured accurately and constantly for an early warning before occurrences of algal blooms and for environmental management. Nevertheless, on-site measurements by existing technologies are often limited by the inherent sensitivities. In this study, a portable system for dissolved phosphate monitoring in freshwater based on the diffusive gradients in thin films (DGT) technique was developed. A polydiallydimethylammonium chloride (PDA) aqueous solution and a dialysis membrane were used as a binding phase and a diffusive layer in this preconcentration device, respectively. The binding properties of the PDA solution were evaluated in solutions of different pH (3 to 9) and varying concentrations of anions (2.0-20 mM). The amount of phosphates preconcentrated in the devices was measured by ultraviolet-visible (UV) spectroscopy to obtain the concentrations in waters without elution steps. The devices were validated in synthetic river water with good agreement with the theoretical prediction and in natural river water. A system combining this preconcentration device and a compact detection chamber equipped with a pair of light emitting diodes (LED) was studied in lab synthetic solutions for on-site monitoring of phosphate concentrations and their fluctuations.

Self-assembled multilayer films containing 1,8,15,22-tetrakis (8-quinolineoxy-5-sulfonic acid)-phthalocyanine copper: Preparation, and third order nonlinear optical properties

Composite film with alternating layers containing anionic 1,8,15,22-tetrakis (8-quinolineoxy-5-sulfonic acid)-phthalocyanine copper and cationic polydiallydimethylammonium chloride was fabricated by electrostatic self-assembled layer-by-layer (LBL) technique. The microstructure of the film was characterized by a series of techniques. The third-order nonlinear optical properties of the film were measured using 4f coherent imaging system with phase object (NIT-PO) with laser duration of 20ps at the wavelength of 532nm. The film exhibited excellent nonlinear absorption and self-focusing effect. The second-order molecular hyperpolarizability γ value of the film reaches as high as 1.54×10−29esu.

Modification of GCC with Poly-DADMAC and PSS with Different Molecular Weights and its Effect on the Paper Properties

In this study, we modified the surface of ground calcium carbonate (GCC) with polyelectrolytes with different molecular weight using Layer-by-Layer (LbL) multilayering technique and investigated its effect on the paper properties. Polydiallydimethylammonium chloride (poly-DADMAC) and poly sodium 4-styrene sulfonate (PSS) which have different molecular weights were used for LbL multilayering. Zeta potential and particle size of the LbL modified GCC were measured. After preparation of handsheets, their structural and mechanical properties were evaluated. The zeta potential and average particle size of the modified GCC were affected by the molecular weight of anionic polyelectrolyte (PSS). The zeta potential was higher and the particle size was smaller when GCC was treated by PSS with high molecular weight compared to the case with low molecular weight of PSS. The tensile and internal bond strength of the handsheets was increased with an increase in the number of layers on GCC particles, but the molecular weight of polyelectrolyte did not significantly affect the paper strength.

PolyDADMAC and polyacrylamide as a hybrid flocculation system in the treatment of pulp and paper mills waste water

The flocculation performance of polydiallydimethylammonium chloride (polyDADMAC) coupled with polyacrylamide for treating pulp and paper mill wastewaters was studied. The flocculation performance tests were carried out in jars with polyDADMAC and polyacrylamide (PAM) dosages of 0.4–2.0 mg L −1 and 0.4–8.0 mg L −1, respectively. The tests were conducted at a rapid mixing rate of 200 rpm for 2 min, followed by a slow mixing rate at 30 rpm for 10 min, and settling time of 5 min. Polyacrylamide was introduced into the wastewater samples 45 s after the addition of polyDADMAC. The reduction efficiency of turbidity, chemical oxygen demand (COD) and total suspended solids (TSS) were the main evaluating parameters. It was found that poyDADMAC incorporated with PAM was efficient in treating pulp and paper mills wastewater. Increasing dosages of polyDADMAC increased the destabilization of particles and produced small flocs, while the addition and increasing of PAM increased the size of flocs for a better synergistic flocculation process.

Combined humic substance and heavy metals coagulation, and membrane filtration under saline conditions

Membrane retention was investigated with the aid of poly diallydimethylammonium chloride and copolymer of dimethyl aminoethyl acrylate polyelectrolyte coagulants. The membranes used were P005F ultrafiltration (UF) and NF270 nanofiltration (NF) membranes and the studied conditions were salinity level, humic substances (HS) concentration, heavy metals concentration and polyelectrolytes type and concentration. Results showed that with the aid of polyelectrolytes, HS retention reached a maximum point where further increase in polyelectrolytes degraded membrane retention. This study showed also that at low polyelectrolyte concentration, salinity reduced membrane retention. While at optimum polyelectrolytes dose, membrane performance was not affected by salinity. In addition, HS binding capacity for heavy metals was reduced considerably at high salinity levels.

Third-order nonlinear optical properties of self-assembled thin films containing tetracarboxylic copper phthalocyanine

Films with alternating layers containing anionic tetracarboxylic copper phthalocyanine [ CuPc(COONa)4 ] and cationic polydiallydimethylammonium chloride (PDDA) were fabricated by electrostatic self-assembled layer-by-layer (LBL) technique. The delicate structure of the film was characterized by a series of techniques. The third-order nonlinear optical properties of the film were measured by the Z-scan technique with laser duration of 4 ns and 21 ps at the wavelength of 532 nm. The film exhibited excellent nonlinear absorption and self-focusing effect. The second-order molecular hyperpolarizability γ value of the film was much larger than that of CuPc(COONa)4 aqueous solution under the irradiation of whether ns or ps pulses. A series of damage experiments of the film for the intense laser pulses were conducted to prove the reliability of the experimental results under the conditions.

Nanoscale Coatings on Wood: Polyelectrolyte Adsorption and Layer-by-Layer Assembled Film Formation

Surface chemistry of wood is based on the exposed surface that is the combination of the intact and cut cellular wall material. It is inherently complex and changes with processing history. Modification of wood surfaces through noncovalent attachment of amine containing water soluble polyelectrolytes provides a path to create functional surfaces in a controlled manner. Adsorption of polyethylenimine (PEI) and polydiallydimethylammonium chloride (PDDA) to wood was quantified as a function of solution conditions (pH and ionic strength). Polycation adsorption was maximized under basic pH without the addition of electrolyte. Added salt either had marginal influence or decreased adsorption of polycation, indicating interactions are strongly influenced by Coulombic forces. PEI adsorption could be modeled by both a Langmuir and Freundlich equations, although the wood surface is known to be heterogeneous. After adsorption of polycations, layer-by-layer assembled films were created on the wood surface. Layered films masked ultrastructural features of the cell wall, while leaving the microscale features of wood (cut lumen walls and openings) evident. These findings revealed for the first time that nanoscale films on wood can be deposited without changing the microscopic and macroscopic texture. Functionalized wood surfaces created by nanoscale films may have a future role in adhesives systems for wood composites, wood protection, and creating new functional features on wood.

Combined humic substance coagulation and membrane filtration under saline conditions

The effects of poly diallydimethylammonium chloride (PDADMAC) and copolymer of dimethyl aminoethyl acrylate (CoAA) coagulants on membrane performance are investigated under different conditions using ultrafiltration (UF) and nanofiltration (NF) membranes. It is evident that PDADMAC performance is better than CoAA in removing humic substances (HS) with both membranes, P005F and NF270, having equal fouling potential. Salinity results showed reduction in HS retention and increase in fouling with increasing salinity from 10,000 to 25,000 ppm NaCl using P005F UF membrane. No further reduction in retention or increase in fouling was experienced when salinity was increased to 35,000 ppm NaCl, while NF270 NF membrane experienced reduced retention and increased fouling throughout the studied salinity range. Finally, TMP did neither affect HS retention nor NF270 fouling, but increased P005F fouling.

Preparation and Characteristics of MWNT/SnO₂Nanocomposites Anodeby Colloidal Heterocoagulation for Li-ion Battery

Through the electrostatic interaction between the poly-diallydimethylammonium chloride (PDDA) modified Multi-walled carbon nanotube (MWNT) and suspension in 1mM solution, MWNT- nanocomposites (MSC) for anode electrodes of a Li-ion battery were successfully fabricated by colloidal heterocoagulation method. TEM observation showed that most of the nanoparticles were uniformly deposited on the outside surface of the MWNT. Galvanostatic charge/discharge cycling tests showed that MSC anodes exhibited higher specific capacities than bare MWNT and better cyclability than unsupported nano- anodes. Also, after 20 cycles, the MSC anode fabricated by heterocoagulation method showed more stable cycle properties than the simply mixed MSC anode. These improved electrochemical properties are attributed to the MWNT, which adsorbs the mechanical stress induced from volume change and increasing electrical conductivity of the MSC anode, and suppresses the aggregation between the nanoparticles.

Characterization and retention of UF membranes using PEG, HS and polyelectrolytes

Molecular weight cut-off (MWCO) of two different types of membranes (polyether sulfone (PES) and regenerated cellulose (RC) ultrafiltration (UF) membranes) has been investigated using 2, 4 and 6 kDa polyethylene glycol (PEG) solutes. The retention results of humic acid (HA), fulvic acid (FA), copolymers of dimethyl aminoethyl acrylate (CoAA) and poly dially dimethylammonium chloride (PDADMAC) is also presented in this paper. Retention of PEG solutions produced MWCO lower than stated by the manufacturers. The MWCO of P005F, C005F and P020F was 3.75, 3.35 and 12.1 kDa, respectively. The manufacturer values were 5 kDa for P005F and C005F and 20 kDa for P020F. The rejection of PDADMAC and CoAA was found to be lower than expected with respect to the MW specified by the supplier. The MW of PDADMAC and CoAA is 60–200 kDa and 10–12 intrinsic viscosity, respectively. The retention of such high MW substances should be ≫90%, but the results show a maximum retention of 91% and the other results are <90%. Nevertheless, the retention of HA and FA was as expected. The humic substances (HA and FA) were extracted from soil, which has a low MW i.e. <6 kDa. The maximum rejection of HA and FA was ~93 and ~84%, respectively. The lower rejection of FA is attributed to the lower MW of FA compared to HA. The observed rejection of PDADMAC and CoAA decreases with increasing the pressure, but the real rejection is constant. This is attributed to the increase in concentration at the wall of the membrane, hence increasing the mass transfer coefficient. The same trend is achieved when filtering HA and FA. The rejection of P005F is always higher than the rejection of C005F for all substances. Although the manufacturer stated the same MWCO of both membranes, the P005F MWCO was higher than C005F producing a higher rejection.

Dispersion of aqueous nano-sized alumina suspensions using cationic polyelectrolyte

In this paper, we investigate and report the effects of a cationic polyelectrolyte, polydiallydimethylammonium chloride (PDADMAC), on the stability of nano-sized alumina (α-Al 2O 3) suspension. Due to the static electrical repulsion interactions, PDADMAC show significant adsorption on α-Al 2O 3 only at alkaline pH. Considerable amount of non-adsorbed free PDADMAC exist in α-Al 2O 3 suspensions dispersed by PDADMAC at acidic and neutral pH. At 1.0 wt.% PDADMAC addition, α-Al 2O 3 became highly positively charged (>50 mV) in the entire pH range contrast with that the stability of α-Al 2O 3 suspension is enhanced only over the basic pH range in the presence of anionic polyelectrolyte. Free PDADMAC electrolyte in suspension results in increasing viscosity of α-Al 2O 3 suspensions dispersed with PDADMAC at alkaline and neutral pH. However, non-adsorbed free PDADMAC in suspension do not contribute to viscosity increase in acidic α-Al 2O 3 suspensions and α-Al 2O 3 suspensions dispersed with PDADMAC show the best flow behavior at acidic pH.