Cationic Degree Research Articles

Energetic and configurational mechanisms to facilitate mica nanosheets synthesis by organo-ammonium cation intercalation

It is currently challenging to synthesis large, high-quality mica nanosheets to exploit nanoelectronics based on 2D mica. We carried out a first-principles investigation of the crystal and electronic structure as well as the interlayer interaction of mica intercalated with various organo-ammonium cations. The long-chain organo-ammonium cation intercalation expands interlayer spacing more efficiently, while the branched organo-ammonium cation intercalation is more effective in reducing exfoliation energy to facilitate exfoliation. Two exfoliation mechanisms are proposed as M1 (by increasing configurational entropy to destabilize interlayer structure, e.g., the interlayer spacing rises from 3.31 Å to 6.27 Å) and M2 (by increasing enthalpy to destroy interlayer structure, e.g., the exfoliation energy reduces from 2.51 eV to 1.13 eV). In addition, the intercalated mica shows remarkably narrowed bandgap attributed to ionic H-O bonds between mica tetrahedral sheets and organo-ammonium cations, which are dependent on the cation's degree of branching. Applying the energetic and structural analysis of organo-ammonium cation intercalated mica, our research furthers the understanding of cation intercalation and exfoliation of layer structured materials, opening the way for the effective massive production of nanosheets.

Optimizing the Flocculation Effect of Cationic Polyacrylamide Prepared with UV-Initiated Polymerization by Response Surface Methodology

Cationic polyacrylamide (CPAM) is a commonly used flocculant for water treatment. Factors that affect the flocculation effect and can be controlled manually include the type and dosage of CPAM, wastewater pH, stirring time and settling time, and their reasonable setting is critical to the flocculation effect of CPAM. In this paper, the optimal flocculation conditions of a novel CPAM were studied. First, single-factor tests were conducted to preliminarily explore the optimal range of factors that influence CPAM flocculation, and then response surface methodology (RSM) tests were performed to accurately determine the optimums of the influencing factors. The results showed that the flocculation effect was better when the intrinsic viscosity was larger or the cationic degree of CPAM was higher. The CPAM dosage, wastewater pH and stirring time significantly impacted the flocculation effect, and inflection points were observed. A model that could guide CPAM-8.14-40.2 flocculation was obtained by RSM tests. The model optimization showed that the optimal flocculation conditions of CPAM-8.14-40.2 for treating wastewater prepared with kaolin were as follows: the CPAM dosage, wastewater pH and stirring time were 5.83 mg·L−1, 7.28, and 5.95 min, respectively, and the turbidity of the treated wastewater was reduced to 6.24 NTU.

Facile Synthesis of Cyclic Polyamidine with High Cationic Degree Using Environmentally Benign Approach

An environmentally benign approach was developed to fabricate cyclic polyamidine via polymerization in supercritical carbon dioxide (SCCO2) and subsequently amidinization in water. Synthetic parameters were evaluated using response surface methodology. In comparison with aqueous solution polymerization for the fabrication of PNVF-co-PAN, polymerization using SCCO2 is favorable to promote the yield and viscosity of PNVF-co-PAN and diminished reaction time on account of excellent solvation capacity and transport property of SCCO2. Replacing the traditional water solution with SCCO2 as a green solvent could heighten the purity of PNVF-co-PAN by virtue of the excellent extraction of SCCO2. The cationic degree (5.66 mmol/g) of polyamidine fabricated by environmentally benign approach was significantly higher than that in previous reported studies.

Size Effect of Electrolyte Ions on the Electric Double-Layer Structure and Supercapacitive Behavior

Finding a viable electrolyte for next-generation supercapacitors is of primary importance for developing supercapacitors with high power and energy densities. Herein, we synthesized a conducting salt, tetramethylphosphonium tetrafluoroborate (TMPBF4), and compared the electrochemical characteristics of supercapacitor devices containing TMPBF4 or 1,1-dimethylpyrrolidinium tetrafluoroborate (DMPBF4). The TMPBF4 salt was selected based on the generally accepted design rule that smaller ions and solvation shells contribute to higher energy and power densities. However, at a low current density (0.1 A g–1), supercapacitors with TMPBF4 in acetonitrile (AN) exhibited a slightly lower capacitance (24.6 ± 0.1 F g–1) than those with DMPBF4 (25.0 ± 0.2 F g–1). Clarification of this behavior using electrochemical and theoretical methods revealed that the total capacitance is influenced by not only the size of the ions but also the degree of cation–anion interactions near the electrodes. By contrast, at a high current density of 10 A g–1, supercapacitors with TMPBF4 showed an 18% increase in capacitance relative to those with DMPBF4. Supercapacitors with TMPBF4 exhibited both high capacitance and a remarkably long cycle life (10,000 cycles) at a high working voltage (3.2 V) and high current density (10 A g–1). Furthermore, supercapacitors utilizing TMPBF4/AN provided a sufficiently fast frequency response for 60 Hz alternating current (ac) line filtering. These insights into the influence of the investigated electrolyte salts on the formation of electric double-layer structures offer design rules for developing electrolytes for supercapacitors.

Nano aluminum-based hybrid flocculant: Synthesis, characterization, application in mine drainage, flocculation mechanism

Given the characteristics of high turbidity and trace emulsified oil in mine drainage, which leads to the problems of low settling efficiency and poor treatment efficiency in the coagulation/flocculation treatment process, there is an urgent need to develop efficient, economical, and stable flocculants. In this study, a new hybrid flocculant Al-P(AM-DMDAAC-BA) was synthesized by the solution copolymerization method, and its viscosity, molecular weight, and cationic degree were 1492.93 mL/g, 7.44 × 106 Da and 16.97%, respectively. The physical and chemical properties of Al-P(AM-DMDAAC-BA) were characterized by Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (1H and 13C NMR), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermogravimetric (TG), and Zeta potential. SEM, Zeta potential, and laser particle size measurement characterized the properties of flocs. Batch wastewater treatment experiments analyzed the flocculation treatment efficacy. The results of the analysis are as follows. Aluminum hydroxyl complexes were attached to organic polymers via -Al-O-C- bonds. Acrylamide (AM), dimethyl diallyl ammonium chloride (DMDAAC) and butyl acrylate (BA) were linked to each other by Carbon-carbon double bond (-CC-). The aluminum-based complex is dispersed as nano-microspheres in the hybrid flocculant and cross-linked to the organic branched chains. Al-P(AM-DMDAAC-BA) is thermally stable and less susceptible to thermal decomposition. It possesses strong electrical neutralization ability and rapid floc growth ability. It has excellent turbidity removal (reduced to 7.96 ± 1.15 NTU) and emulsified oil removal (reduced to 0.23 ± 0.01 mg/L) performance. The flocculation mechanism is mainly attributed to the electro-neutralization of the hybrid flocculants and the adsorption bridging effect of organic branched chains.

The novel chitosan-amphoteric starch dual flocculants for enhanced removal of Microcystis aeruginosa and algal organic matter

A novel flocculation strategy for simultaneously removing Microcystis aeruginosa and algal organic matter (AOM) was proposed using chitosan-amphoteric starch (C-A) dual flocculants in an efficient, cost-effective and ecologically friendly way, providing new insights for harmful algal blooms (HABs) control. A dual-functional starch-based flocculant, amphoteric starch (AS) with high anion degree of substitution (DSA) and cation degree of substitution (DSC), was prepared using a cationic moiety of 3-chloro-2-hydroxypropyltrimethylammonium chloride (CTA) coupled with an anion moiety of chloroacetic acid onto the backbone of starch simultaneously. In combination of the results of FTIR, XPS, 1H NMR, 13C NMR, GPC, EA, TGA and SEM, it was evidenced that the successfully synthesized AS with excellent structural characteristics contributed to the enhanced flocculation of M. aeruginosa. Furthermore, the novel C-A dual flocculants could achieve not only the removal of >99.3 % of M. aeruginosa, but also the efficacious flocculation of algal organic matter (AOM) at optimal concentration of (0.8:24) mg/L, within a wide pH range of 3–11. The analysis of zeta potential and cellular morphology revealed that the dual effects of both enhanced charge neutralization and notable netting-bridging played a vital role in efficient M. aeruginosa removal.

Synthesis, structure and photoluminescence properties of NIR phosphor LiAlSi2O6:Cr3+

A novel Cr3+-doped LiAlSi2O6 phosphor was synthesized by a solid-state reaction. Details of first-principles calculation, structural studies, spectroscopic, crystal field calculations along with photoluminescence thermal stability for Cr3+ doped LiAlSi2O6 are given in the present paper. First-principles calculations show β-LiAlSi2O6 has the lowest formation free energy in α1-, α2-, β- and γ-LiAlSi2O6 and is the indirect band gap. The XRD pattern indicates that the sample is β-LiAlSi2O6. The excitation spectrum of LiAlSi2O6:Cr3+ peaking at 254, 411 and 561 nm corresponded to three spin-allowed Cr3+ d–d intra-shell transitions of 4A2g-4T1g(4P), 4A2g-4T1g(4F) and 4A2g-4T2g(4F), respectively. The reason for the change of the emission peak observed between the ultra-trace doping sample and the actively doped sample is discussed. Cr doping increases the disorder degree of cations in LiAlSi2O6 and makes the possible emission of Cr due to mainly N line emission. The Tanabe–Sugano diagram shows that Cr doping increases the strength of LiAlSi2O6 crystal field. The emission intensity of LiAlSi2O6:0.15%Cr3+ at 423 K (150 °C) maintains ≈ 70.0% of its initial value at 303 K (30 °C). Only the sharp emission line of the 2Eg-4A2g related transitions even at high temperatures (T = 523 K) and no large increase of the PL intensity caused by the odd-parity phonon gaining over the wide range of temperature from T = 303 K–523 K.

Effect of cationic, anionic and non-ionic surfactants on transport of microplastics: Role of adhesion of surfactants on the polyethylene surface

• Anionic, cationic, and nonionic surfactants all promote PE transport. • The greater adhesion of surfactants on the PE surface cause stronger PE transport. • Adhesion of surfactant on PE is related to the minimum single molecule adsorption area. In view of the amphiphilicity of surfactants, which can improve the hydrophilicity of polyethylene (PE) microplastics and increase the mobility of PE microplastics, the research on the transport behavior of PE microplastics under the coexistence of surfactants is still lacking and necessary. In this work, column experiments were carried out on the suspensions made of 15 surfactants mixed and dispersed with PE microplastics to explore the promoting effect of various surfactants on the transport of PE in saturated porous media. The dynamic contact angle of surfactant on PE surface and the surface tension and zeta potential of PE / surfactant dispersion system were measured. The interaction energy between PE / surfactant and medium, the adhesion of surfactant on PE surface were calculated respectively according to DLVO theory and Young's equation. The experimental results showed that different surfactants promoted the transportation of PE in the column to different degrees. The promotion degree of cationic, anionic and nonionic surfactants on PE transport from large to small were BG > PQ28 > CTAB > BLB > TLB, SDS > SLDED > DSS > SL > SDBS, POES > T40 > T80 > X100 > TX20, respectively. The recovery of PE in the column ranged from 17% to 99.93% under the surfactants. The calculation results of the adhesion of surfactant on PE surface also showed the same law. The minimum single molecule adsorption area (A sL ) of surfactant on PE surface was negatively correlated with the recovery of PE in the column under the same type of surfactant. The high adhesion of surfactant on PE surface was caused by the small adsorption area of single molecule, which finally made PE obtain higher stability and penetration. These findings provide new insights and methods for the fate and transport of microplastic and surfactant coexisting systems in soil and the prediction of their potential risk of groundwater pollution.

Synergistic catalytic effect of zirconium chloride and Brønsted acid salt for conversion of agarose to 5-hydroxymethylfurfural in aqueous media

A facile and highly efficient method for converting seaweed-derived agarose to 5-hydroxymethylfurfural (HMF) in aqueous media using combined metal salts as catalysts is proposed. A series of combined metal salts were investigated under different conditions. The combination of ZrCl4 and KHSO4 was the most efficient catalyst; it was capable of achieving a high HMF yield of 71.4% under optimized conditions. The charge density or counter anion possibly affected the ionization degree of the metal cations in the aqueous solution, thereby influencing the HMF yield. ZrCl4 promoted the cleavage of the C–O–C bond in agarose and galactose to ketose isomerization, which is the key step for HMF formation. KHSO4 increased the conversion rate of ketose to HMF. This work offers a convenient method for converting seaweed-derived agarose to HMF and improve the utilization of marine biomass.

Molecular dynamics study on the impacts of cations in sea salt aerosol on transport performance of Nafion Membranes for PEMFCs in marine application

The application of polymer electrolyte membrane fuel cells (PEMFCs) in marine industry receives a widespread attention, due to the severe emission regulations. However, cationic contaminants in sea salt aerosol have detrimental effects on the transport performance of polymer electrolyte membranes, which are the core components of PEMFCs. In this study, the effects of K+ and Mg2+ in marine atmosphere on the transport performance of Nafion 117 membranes were evaluated by molecular dynamics simulations. Moreover, the influence of temperature is considered for the first time. The mean square displacements are used to evaluate the diffusion coefficients of water molecules (H2O) and hydronium ions (H3O+). In addition, the effect mechanisms are analyzed using radial distribution functions, water clusters distribution and relative concentration distribution. Results show that the diffusion of H3O+ and H2O is significantly weakened by K+ and Mg2+. Moreover, the impact of Mg2+ is more serious. The difference in the influence of these two kinds of cations on the transport performance of Nafion membranes is discussed by hydrated radius, hydration degree of cations, and the interaction between cations and sulfonic groups. The diffusion coefficients increase significantly with the increase of temperature. The increase of the temperature can also increase the interaction between the cations and the sulfonic groups. In contrast, the interaction between the sulfonic groups and water molecules is decreased.

Study on the transport performance degradation of Nafion membrane due to the presence of Na+ and Ca2+ using molecular dynamics simulations

Foreign cations have detrimental effects on the transport performance of polymer electrolyte membranes. In this study, the effects of two typical kinds of cations (Na+ and Ca2+) on the diffusion of hydronium ions (H3O+) and water molecules (H2O) in Nafion 117 membranes are investigated using molecular dynamics simulations, at the same time the effects of temperature are considered. The mechanisms of effects are analyzed using radial distribution functions, water clusters distribution and relative concentration distribution. Results show that the diffusion coefficients of H3O+ and H2O are significantly reduced by the presence of Na+ and Ca2+. Moreover, the impact of Ca2+ is more serious. Further investigations show that cations affect intramembrane transport properties by occupying sulfonic groups and disrupting the connectivity of water clusters. The difference in the effects of these two kinds of cations is discussed by hydrated radius, hydration degree of cations, and the interaction between cations and sulfonic groups. Increasing temperature can increase not only the diffusion coefficients, but also interaction between the cations and the sulfonic groups. However, the interaction between the sulfonic groups and H2O is decreased by the increasing temperature.

The effect of molecular structure on the properties of cationic polyacrylate and its flocculation‐flotation performance of oilfield oily wastewater treatment

AbstractWith the increasing amount of oily wastewater produced in the offshore oilfield, more efficient air flotation agent is needed to be developed. Cationic polyacrylate with amphiphilic structure has been found to be a type of potential efficient air flotation agent. However, the effect of molecular structure on its properties and performance was lack of research. In this paper, copolymers with tertiary amine as side group were synthesized by copolymerization of ethyl acrylate (EA) and tertiary amine monomers, and then a series of cationic polyacrylates were prepared by quaternization of tertiary amine with quaternization reagent. The effects of tertiary amine monomer type (including dimethylaminopropyl methacrylamide (DPM) and dimethylaminoethyl methacrylate (DEM)), quaternization reagent type (including 3‐Chloro‐1,2‐Propanediol and 3‐chloro‐2‐hydroxytrimethylammonium chloride) and quaternization degree on the cationic polyacrylate properties and its flotation performance were investigated. The experimental results showed that the flotation performance increased with the increasing hydrophilicity and cation degree of the hydrophilic unit in the cationic polyacrylate. When the tertiary amine monomer was DPM, quaternization reagent was 3‐chloro‐2‐hydroxytrimethylammonium chloride, and theoretical quaternization degree was 100%, the oil removal of product PE‐M‐1.0 was the highest. When PE‐M‐1.0 dosage was 50 mg/L, gas flow was 1 L/min, flotation time was 10 min, its oil removal rate was higher than 95% in the range of 20‑60°C. The results of zeta potential measurement and microfluidic experiment showed that PE‐M‐1.0 can increase the size of oil droplets by destroying the electric double layer on the surface of oil droplets and maintain the stability of bubbles, which was helpful for the improve of gas bubble‐oil droplet collision probability and adhesion efficiency.

A Cobalt Enrichment Strategy for Suppressing the 4.2 V Adverse Phase Transition in Ni-Rich Layered Materials

In this study, a Co-rich Ni-rich layered material with a core–shell structure is designed, in which LiNi0.82Co0.12Mn0.06O2 (NCM-Ni82) is used as the core wrapped in the shell by doping Al into LiNi0.735Co0.15Mn0.1Al0.015O2 to form the hybrid particle LiNi0.795Co0.13Mn0.07Al0.005O2 (NCM-HA). NCM-HA is divided modularly into the core part NCM-Ni82 and the single hybrid part without doped Al (NCM-HS), and then all modules were compared with the pristine LiNi0.8Co0.1Mn0.1O2 via various characterization methods to reveal the superiority of the design. The core–shell structure, which prevents the diffusion of microcracks caused by the lattice shrinkage of a high content of cobalt, is used to improve the morphological strength of the material so that the cathode material is capable of fully playing the excellent stable cycling performance brought by the remarkable cationic order degree of Co-rich treatment. The excellent cathode material NCM-HA still has a capacity retention rate of 83.35% after 200 cycles, while the pristine material has a rate of 55.42%. Moreover, NCM-HA successfully inhibits the unsteady phase transition of layered materials at 4.2 V and reduces the degree of polarization during the cycling process. This study provides a new strategy for the modification of Cobalt-enriched Ni-rich layered materials.

Cationization of Eucalyptus Kraft LignoBoost Lignin: Preparation, Properties, and Potential Applications.

Current changes toward a more biobased economy have recently created tremendous renewed interest in using lignin as a valuable source for chemicals and materials. Here, we present a facile cationization approach aiming to impart kraft lignin water-solubility, with similar good features as lignosulfonates. Eucalyptus globulus kraft lignin obtained from a paper mill black liquor by applying the LignoBoost process was used as the substrate. Its reaction with 3-chloro-2-hydroxypropyl-trimethylammonium chloride (CHPTAC) in an aqueous alkaline medium was studied to assess the impact of different reaction conditions (temperature, time, educt concentration, molar CHPTAC-to-lignin ratio) on the degree of cationization. It has been shown that at pH 13, 10 wt % lignin content, 70 °C, and 3 h reaction time, a CHPTAC-to-lignin minimum molar ratio of 1.3 is required to obtain fully water-soluble products. Elemental analysis (4.2% N), size-exclusion chromatography (Mw 2180 Da), and quantitative 13C NMR spectroscopy of the product obtained at this limit reactant concentration suggest introduction of 1.2 quaternary ammonium groups per C9 unit and substitution of 75% of the initially available phenolic OH groups. The possible contribution of benzylic hydroxyls to the introduction of quaternary ammonium moieties through a quinone methide mechanism has been proposed. Since both molecular characteristics and degree of substitution, and hence solubility or count of surface charge, of colloidal particles can be adjusted within a wide range, cationic kraft lignins are promising materials for a wide range of applications, as exemplarily demonstrated for flocculation of anionic dyes.

Effect of Different Cationic Polyacrylamide Organic Dehydrating Agents on Sludge Dewatering Performance

To study the effect of different cationic polyacrylamide organic dehydrating agents on sludge dewatering performance, eight commercially available cationic polyacrylamides of the same series with different properties were used. Based on the different cationic degree, they were named 9101, 9102, 9103, 9104, 9106, 9108, 9110, and 9112, respectively. Their properties were characterized by instruments and chemical analysis, and the indexes of sludge after treatment were also measured. The results showed that the properties of the eight organic dehydrants were different, among which the charge density, cationicity, viscosity, and Zeta potential had homologous trends, which all increased gradually from 9101 to 9112. The four indexes of 9112 were as high as 2.98 meq·L-1, 17.42%, 85.07 mPa·s, and 67.10 mV, respectively. The dewatering performance of sludge was improved by improving the specific resistance of filtration (SRF), floc properties, viscosity, Zeta potential, the bound water content, and the distribution of extracellular polymeric substances (EPS) after dosing organic dewatering agents. The results showed that the viscosity, charge density, cationic degree, and Zeta potential of the dewatering agents had a great influence on the sludge dewatering performance. The SRF of sludge was negatively correlated with the viscosity of the organic dewatering agent, and the correlation coefficient was as high as 0.92025, indicating that the sludge dewatering performance was improved mainly through the adsorption bridging effect of the organic dewatering agent in sludge dewatering.

Study on preparation of cationic flocculants by grafting binary monomer on cellulose substrate by γ-ray co-irradiation

Carboxymethyl cellulose (CMC) and wood flour cellulose (WFC) graft copolymers were prepared from acrylamide/dimethyl diallyl ammonium chloride (AM/DMDAAC) by γ-ray co-irradiation graft copolymerization method. CMC could obtain an excellent grafting effect at the absorbed dose of 6 kGy and CMC/AM/DMDAAC ratio of 0.2 g:2 g:1 ml, and the grafting rate, grafting efficiency, cationic degree and grafting efficiency of DMDAAC monomer were 790%, 46.01%, 20.17% and 64.56% respectively. Relatively, when the ratio of AM and DMDAAC was 3 g:1 ml and the absorbed dose was 8 kGy, the grafting effect of WFC was the optimum, and the more WFC added, the better graft copolymerization effect. The flocculation effect of the products and cationic polyacrylamide on kaolin wastewater was investigated, and the maximum turbidity removal rate of CMC graft copolymer on kaolin wastewater reached 86.0%, showing an excellent flocculation effect. The flocculation effect under different conditions was WFC graft copolymer＞CMC graft copolymer＞Cationic Polyacrylamide.

Improving the microwave dielectric properties of Ga2[LiGa3]O8 inverse spinel by enhancing B-site ordering degree

A series of inverse spinel ceramics, Ga 2 [Li 1+ x Ga 3 ]O 8+δ (0.05 = x ≤ 0.125), were synthesized by the conventional solid-phase reaction. The addition of Li ( x ≤ 0.1) increased the order degree of octahedra cations and caused an expansion in cell volume, and the maximum solution was located at 0.1–0.125. The dielectric constant of Ga 2 [Li 1+ x Ga 3 ]O 8+δ ceramics increased with the ionic polarizability of primitive unit cell, and the optimum microwave dielectric performances were obtained at x = 0.1 sample sintered at 1260 °C with ε r = 10.78 ± 0.1, Q × f = 171,171 ± 500 GHz, and τ f = −56.47 ± 1.0 ppm/°C. The τ f showed an opposite variation trend to that of the Ga1 bond valence and octahedron distortion. The Q × f was determined by the packing fraction and FWHM of 424 cm −1 Raman mode. In addition, the intrinsic dielectric properties of Ga 2 [Li 1+ x Ga 3 ]O 8+δ ceramics were evaluated by infrared reflectivity spectra. The results show that Ga 2 [Li 1+ x Ga 3 ]O 8+δ ceramic is a promising substrate material.

Some soil factors constraining buffel grass (

Buffel grass (Cenchrus ciliaris L.) has passionate grazing industry advocates and biodiversity conservation detractors around the world due to its ability to readily establish and spread on certain soil types. A more detailed understanding of what soil factors influence the success of seedling establishment will offer guidance to anyone wishing to either encourage or discourage buffel grass establishment in a particular area. Twenty soils from land types where buffel grass had a varied history of successful establishment and persistence in south western Queensland, Australia were assessed in a pot trial for their influence on early seedling growth rate of buffel grass. Some currently had buffel grass growing there. Aspects of the chemistry of each soil were compared against the rate of seedling growth of buffel grass cv. Biloela that was sown with or without a phosphate coating on the seed. Available soil phosphorus had a major influence on seedling growth in the absence of a phosphate fertiliser coating, but levels of other factors such as exchangeable aluminium and calcium were also critical. Several multiple regression equations with differing soil parameters included proved equally good at predicting buffel seedling growth but they did not greatly improve on the strong correlation with available soil phosphorus. This seemed due to the interchangeability amongst soil pH, cation exchange capacity and degree of clay as controlling factors, over and above available phosphorus. Thus, where available soil phosphorus is marginal for rapid buffel seedling growth, soil pH, exchangeable aluminium and total exchangeable cation levels could have similar importance in determining whether buffel grass colonised or failed to gain a foothold in that area.

A green approach to starch modification by solvent-free method with betaine hydrochloride

In this study, a novel simple and eco-efficient, semi-dry method with a spray system for starch modification has been developed. Compared to conventional semi-dry methods, this method does not use solvents so that no slurry or semi-liquid mixture is obtained, the material is in a moisted/semi-moisted state. The modification of starch was performed using betaine hydrochloride (BHC) as the cationic reagent, and the characteristics of such starch derivates were compared with cationic starches obtained using glycidyltrimethylammonium chloride (GTMAC). Due to the instability, toxicity, and high cost of the most commonly used GTMAC, it should be replaced with more eco-friendly reagents, such as BHC, which is derived from betaine found in most green plants (e.g., spinach - Spinacia oleracea, beets - Beta vulgaris). The influence of processing conditions such as temperature, concentration of cationic reagents, presence and concentration of natural plasticizers/catalyst on physico-chemical and structural properties of cationic starches have also been studied. The cationic degree varied from 0.045–0.204 for the starch–BHC samples and within the range of 0.066–0.245 for the starch–GTMAC samples. The modification of starch with cationic reagents resulted in an increased solubility and swelling capacity, followed by decreased viscosity of the modified starches.

Investigation on the Electrochemical Deposition of Nanocrystalline Zinc with Cationic Polyacrylamide (CPAM)-ZnSO4 Electrolyte.

The electrochemical deposition of nanocrystalline zinc has high potential to deposit zinc coatings, which have improved wear and corrosion properties compared to conventional coating methods. Conventionally, two or more additives are used in the electrolyte for the formation nanocrystalline zinc; these electrolyte components are complex, and their maintenance is inconvenient, making it unstable and not suitable for industrial scale production. This paper proposes an electrochemical deposition technique for nanocrystalline zinc using a ZnSO4 solution with cationic polyacrylamide (CPAM) as the unique additive. The results reveal that the cationic degree of CPAM has a significant influence on the deposition process and that the cationic degree of 20% enhances the electrolyte conductivity and improves the density of the deposited coating. The concentration of CPAM affects the electrolyte viscosity and conductivity. CPAM with a concentration of 20 g/L could simultaneously improve the electrolyte conductivity and maintain the viscosity at a low value, which promotes the formation of a bright deposited coating with a grain size of 87 nm. Additionally, the current density affects the grain structure of the deposited coating. With a current density of 0.5 A/dm2, a dense coating with lamellar grains and a grain size of 54.5 nm was obtained, which has, and the surface roughness was reduced to 0.162 μm. Moreover, the corrosion resistant property of the deposited coating was also improved.