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This research paper focuses on the removal of the nonsteroidal anti-inflammatory drug, ibuprofen, from an aqueous solution using a dissolved air flotation process. The comparison of different types of cationic surface-active agents such as cetyltrimethyl ammonium bromide (CTAB), tetrabutyl ammonium bromide (TBAB), and octyltrimethyl ammonium bromide (OTAB) have been employed to scrutinize the effective removal of the ecotoxic pharmaceutically active compound. The work included the influencing parameters such as pressure, contact time, surfactant dosage, pH, flow rate, and initial concentration owing to the best-optimized conditions. The maximum removal rate of 96.09% was achieved at 15 min for CTAB, TBAB had 62.36% at 45 min, and 89.6% was obtained for OTAB at 30 min, with 50 mg L−1 as the initial concentration and pH = 4. The removal rate was better with the optimized dosage of CTAB at 0.6 g, TBAB at 1.2 g, and OTAB at 1.0 g. It was observed that the geometric shape of the surface-active agents had greater impacts on the contaminants' efficiency. CTAB and OTAB were combined to find out the best possible removal rate of contaminants. The synergistic effect augments surfactant-based occurrence to be better in forming a good foaming effect and tends to have a lower critical micelle concentration (CMC). From the evaluation of kinetic models, pseudo-second-order flotation kinetics fitted the experimental data best. Furthermore, the formed metabolites that had been identified using gas chromatography-mass spectrometry were found to be less toxic than the parenting compounds. [ABSTRACT FROM AUTHOR]

Tailings sand is the dam-building material of the tailings dam accumulation sub-dam, and its mechanical properties directly affect the safety and stability of the whole tailings dam. With the improvement of mineral sorting technology, the content of fine and ultrafine particles in the tailings gradually increases, which will affect the mechanical strength of tailings accumulation sub-dam. To improve the settling effect of tailings accumulation in the Chengchao iron ore mine (China), the effect of iron tailings flocculation and settling law on the mechanical properties of tailings sand was studied. Polymerized iron sulfate (PFS) as an inorganic polymer flocculant, compared with the traditional flocculant, has a stronger flocculation and adsorption capacity, is widely used in drinking water, industrial wastewater, and domestic sewage treatment, is an anionic polyacrylamide (APAM-800) for polymer compounds, mainly divided into nonionic, cationic, and anionic three, and is commonly used mine flocculant at home and abroad. Through different flocculants, PFS, and APAM-800 compound flocculation and settling experiments, the effect of the flocculant-dosing scheme on the settling rate and turbidity of clarified liquid was determined, and the change in tailings consolidation shear strength of the best dosing scheme was measured. The experimental results showed that the settling rate of iron tailings was the fastest when PFS was used in combination with APAM-800 at 1.2 g L−1 and 0.20 g·L−1 dosages, respectively. The direct shear test results showed that the internal friction angle of tailings sand increased by 2.18°, the cohesion increased by 5.814 kPa, and the shear resistance of flocculated settled tailings increased, which can effectively improve the safety factor of tailings sand pile sub-dam. [ABSTRACT FROM AUTHOR]

Various chemicals were explored in chemical combinations with two selected agrowastes in order to optimize, enhance, and improve their biosorption potential for the optimal and effective eradication of noxious, carcinogenic, and malignant cationic and basic dyes from wastewater. In this project, environmentally safe, economic, inexpensive, and widely available peels of Trapa natans (TP) and Citrullus lanatus (CP) were collected, dried, and pretreated with citric acid, revealing promising results. FT-IR and SEM characterizations of chemically changed biosorbents (C-TP and C-CP) have evidenced the presence of more secondary adsorption sites on their surfaces. These acid-modified biosorbents were employed to eliminate the hazardous and toxic basic dyes such as Rhodamine B (RAD) and Brilliant Green Dye (BLG) in batch mode processing. The Langmuir model was best fitted to equilibrium experimental data as compared to Freundlich and Temkin isothermal mathematical models with Qmax of 15.63 and 27.55 mg/g for RAD using C-TP and C-CP, respectively, whereas, for BLG on C-TP and C-CP, it was 128 and 189 mg/g, respectively. Therefore, the mechanism is related to chelation and ion exchange modes between adsorbate molecules and adsorbent surfaces, leading to homogeneous and monolayer adsorption and following pseudo-2nd-order kinetics in the best way. Thermodynamic parameters such as ΔG0, ΔS0, ΔH0, and ΔE0 are determined statistically for the adsorption performance of both novel chemically mutant biosorbents, which reflect that biosorption mechanisms are exothermic as well as spontaneous. [ABSTRACT FROM AUTHOR]

On the other hand, in the case of polymer matrices, biodegradable polymers such as cellulose, polylactic acid (PLA), and chitosan have relevance in the packaging and biomedical sectors. Polymer-based nanocomposites have received considerable interest in research for the last three decades. Figure 2 shows the most used nanofillers and polymer matrices in the last decade to prepare polymer nanocomposites among the different application fields. [Extracted from the article]

In order to investigate the influences of emulsifier types on properties of cement bitumen emulsion mortars (CBEM), anionic and cationic emulsifiers were used to prepare CBEM in this work. Influences of anionic and cationic bitumen emulsions on workability, mechanical properties, and viscoelastic property of CBEM were studied. The workability of CBEM was evaluated by fluidity and extensibility tests. The mechanical properties were assessed by compressive strength and flexural strength tests. XRD was used to analyze the phase before and after bitumen emulsion was added. The viscoelastic property was studied by a dynamic mechanical analyzer (DMA). The results show that CBEM prepared by cationic bitumen emulsion (CBE) has better workability. The mechanical properties of CBEM are negatively affected by bitumen emulsion. The impact on the compressive strength of CBEM prepared by CBE is higher. Bitumen emulsion can significantly improve the viscoelastic property of CBEM. With the increase of bitumen emulsion dosage, the loss factor of CBEM increases. The viscoelastic property at low frequency is better than that at high frequency. In contrast to CBEM prepared by CBE, CBEM prepared with anionic bitumen emulsion (ABE) possesses better viscoelastic property. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp) has been synthesized by a hydrothermal treatment in the presence of a Gemini cationic surfactant. This process is a new strategy of synthesis and mainly consists of two parts, i.e., an ordinary hydrothermal treatment and a liquid-solid-solution reaction (LSS strategy). Crystalline HAp nanorods or nanogranules with length of 50-180 nm and width of 30-40 nm were produced by ordinary hydrothermal treatment. By contrary, HAp spheres with a 3D architecture were fabricated with Gemini cationic surfactant by LSS strategy. For Gemini cationic surfactant concentration of 0.05%, spherical HAp particles with an average diameter of 1.7 μm were obtained. [ABSTRACT FROM AUTHOR]

A series of fluorine-containing polyacrylic epoxy (FPAE) prepolymers with different fluorine content and molecular weight are synthesized by solution free radical polymerization of hexafluorobutyl methacrylate (HFBMA), butyl acrylate (BA), and glycidyl methacrylate (GMA). The synthesized prepolymers show high conversion and low volume shrinkage. The effect of different types of active diluent for the cationic UV curing of FPAE was investigated, among which oxetane exhibits better comprehensive property than epoxy and vinyl ether. The formulations with the optimal ratio of different functionality oxetane combination show good flexibility, adhesion, hydrophobicity, and antistain property. [ABSTRACT FROM AUTHOR]

In this research, a kind of 2-acrylamido-2-methylpropanesulfonic acid sodium salt- (AMPS-Na-) type copolymer additive, the fluid loss additive (FLA), named as FLA A additive, was used for research. The performance of FLA A was tested and found to fail in the effective control of free water and to hinder the hydration process for delaying the breaking of the early hydration shell. The reason for it was the absorbed behavior and chelating effect of the AMPS-Na unit to Ca2+ hydrating cement particles. Thus, a cationic polyvinyl alcohol (PVA) polymer, modified by glyoxal and boric acid, was discovered due to its excellence in associating with the FLA A additive for controlling the free cement-based material water amount and preventing the chelating effect of FLA A chains on the surface of the cement-based material. Glyoxal/boric acid-modified polyvinyl alcohol, abbreviated as PVAGB or PVA-G-B, was with special molecular properties, i.e., positive ZETA (ζ) potential characteristics and cross-linked molecular structure. Due to competitive absorbed behavior of glyoxal-modified hydroxyl groups and free Ca2+ released by the hydration product, the chelating effect of AMPS-Na units to Ca2+ was weakened and the possibility of FLA A chains being absorbed to the surface of the cement-based material was decreased. Then, the formation of a complete fluid loss system was obtained; i.e., the fluid loss volume decreased to less than 50 mL at 30°C and 108 mL at 80°C with 0.2 percentage by weight of cement (%BWOC) of PVAGB and 0.50%BWOC (percentage by weight of cement) of FLA A. Besides, the hydration process of cement-based material was accelerated due to formation of more C-S-H gels in the early hydration period. As a result, the cement-based material not only showed no worse compressive-strength retrogression but also showed a stable 28-day compressive strength of 28 MPa. [ABSTRACT FROM AUTHOR]

Cationic and zwitterionic polyelectrolytes are synthesized through atom transfer radical polymerization (ATRP), comprising a polyfluorene backbone with a small fraction of 2,1,3-benzothiadiazole and poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) side chains. Due to higher charge density generated from grafted side chains, two polymers show higher water solubility and higher quantum yield. In comparison with cationic polyelectrolytes, zwitterionic polyelectrolytes are stable over a broad pH range from 1 to 13, even in 1 M NaCl solution. The absence of FRET between zwitterionic polymers and dye-labeled ssDNA indicates their ultralow nonspecific adsorption, while cationic polymer shows much stronger nonspecific interactions. The MTT assay of zwitterionic polymers exhibits their minimal cytotoxicity and potential in long-term clinical application. Most importantly, zwitterionic polymer could be efficiently taken up by cells, whereas cationic polymer stains the surface of cell due to membrane disruption generated from positive charges. The results illustrate that conjugated zwitterionic polymer could serve as a novel type of highly efficient ultralow fouling material with low cytotoxicity for labelling cell or potential biomedical applications. [ABSTRACT FROM AUTHOR]

Due to continuous improvements in the beneficiation process, the size of tailings has decreased. In many mines, more than 50% of the total tailings are finer than 74 μm. Ultrafine tailings exhibit a slow settling velocity and uneven settling, which pose new challenges to the safety and stability of tailings dams. In this paper, ultrafine iron tailings from the Makeng Iron Mine in Longyan City, Fujian Province, were used as the research object. A four-factor, three-level orthogonal test method was used to study the sedimentation characteristics of ultrafine tailings with four common curing agent materials, including polyacrylamide, polyaluminum chloride, polyaluminum sulfate, and polyferric sulfate. The results show that when the pulp concentration is 30%, the polyacrylamide is cationic and the molecular weight is 10 million, the optimal content of the flocculant is 3‰, the optimum dose of the polyaluminum chloride with a content of 28 is 0.1‰, the optimum dose of polyaluminum sulfate is 1‰, and the optimum dose of polymeric ferric sulfate is 1‰. When the flocculant is mixed according to the proportion of 2‰ polyacrylamide, 0.05‰ polyaluminum chloride, 1‰ polyaluminum sulfate, and 1.0‰ polyferric sulfate, the sedimentation speed of the ultrafine tailings is fast, and the supernatant liquid is clear. The results of multivariate nonlinear regression analysis of the sedimentation curve show that the primary and secondary factors affecting sedimentation are polyacrylamide > polyaluminum sulfate > polyaluminum chloride > polyferric sulfate. When the optimal ratio is applied, the cohesion (c) of ultrafine tailings increases from 27 kPa to 68.75 kPa and the internal friction angle (φ) increases from 25.53° to 27.53°, which shows that the shear strength improves and the stability of the tailings dam increases. The economic analysis of the composite flocculant with the optimal ratio shows that the flocculant with the optimal proportion has an obvious economic advantage over polyacrylamide alone. [ABSTRACT FROM AUTHOR]

Abstract: A novel hydrophilic cationic chain extender, 1,4‐butanediol di(3‐diethylamino‐2‐ hydroxylpropyl alcohol) ether (BDE), was successfully prepared, and then a series of lateral‐chain‐type cationic waterborne polyurethanes (CWPUs) with high solid content was synthesized. Compared with the traditional cationic chain extender, N‐methyl diethanol amine (MDEA), BDE with lateral amino groups shows more efficient hydrophilicity and ionization properties. CWPUs prepared from BDE possess lower viscosity, smaller particle size, and larger zeta‐potential. As predicted, stable CWPU latexes with higher solids content (≥50%) and lower hydrophilic group content were achieved. Further study indicated that other properties, including the molecular weight, glass transition temperature, thermal stability, and mechanical properties, of lateral‐chain‐type CWPUs were similar or superior to those of main‐chain‐type ones; no negative effect could be observed. [ABSTRACT FROM AUTHOR]

A ternary cationic polyacrylamide (CPAM) with the hydrophobic characteristic was prepared through ultraviolet- (UV-) initiated polymerization technique for the estrone (E1) environmental estrogen separation and removal. The monomers of acrylamide (AM), acryloyloxyethyl-trimethyl ammonium chloride (DAC), and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) were used to synthesize the ternary copolymer (PADA). Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) were employed to characterize the structure, thermal decomposition property, and morphology of the polymers, respectively. FT-IR and 1H NMR results indicated the successful formation of the polymers. Besides, with the introduction of hydrophobic groups (phenyl group), an irregular and porous surface morphology and a favorable thermal stability of the PADA were observed by SEM and TG/DSC analyses, respectively. At the optimal condition (pH = 7, flocculant dosage = 4.0 mg/L and E1 concentration = 0.75 mg/L), an excellent E1 flocculation performance (E1 removal rate: 90.1%, floc size: 18.3 μm, and flocculation kinetics: 22.69×10-4 s−1) was acquired by using the efficient flocculant PADA-3 (cationic degree = 40%, and intrinsic viscosity = 6.30 dL·g−1). The zeta potential and floc size analyses were used to analyze the possible flocculation mechanism for the E1 removal. Results indicated that the charge neutralization, adsorption, and birding effects were dominant in the E1 removal progress. [ABSTRACT FROM AUTHOR]

A novel bioinspired molecule, 1,3-bis(vinylbenzyl)thymine (bisVBT), was isolated as a by-product during the synthesis of 1-(4-vinylbenzyl)thymine (VBT) and analyzed with various techniques: NMR, IR, and Single-Crystal X-ray Diffraction. In addition to embodying all the desired characteristics of VBT (i.e., having the ability to undergo a 2π+2π photodimerization reaction upon UV irradiation, a derivatization site, hydrogen bonding sites, and aromatic stacking ability) the bisVBT monomer has the added benefit of having two vinyl groups for cross-polymerization. Copolymerizing the bisVBT monomer with the charged monomer vinylbenzyl triethylammonium (VBA) chloride, different copolymers/terpolymers/cross-linked network were obtained, as it was shown by the absence of the vinyl resonance in the NMR spectra. Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) showed an indication of materials with low degree of cross-linking. A Gel Permeation Chromatography (GPC) method was improved to better characterize the molecular weight distributions of the cationic structures. Preliminary qualitative cross-linking studies were performed on bisVBT-VBA copolymers, and a comparison with VBT-VBA copolymers is presented. [ABSTRACT FROM AUTHOR]

A new siRNA delivery system using a cationic glyco-star polymer is described. Spermine-modified 8-arm amylose star polymer (with a degree of polymerization of approximately 60 per arm) was synthesized by chemoenzymatic methods. The cationic star polymer effectively bound to siRNA and formed spherical complexes with an average hydrodynamic diameter of 230 nm. The cationic 8-arm star polymer complexes showed superior cellular uptake characteristics and higher gene silencing effects than a cationic 1-arm polymer. These results suggest that amylose-based star polymers are a promising nanoplatform for glycobiomaterials. [ABSTRACT FROM AUTHOR]

Owing to its hydrophilicity, negative charge, small size, and labile degradation by endogenous nucleases, small interfering RNA (siRNA) delivery must be achieved by a carrier system. In this study, cationic copolymers composed of low-molecular-weight polyethylenimine and polythiophenes were synthesized and evaluated as novel self-tracking siRNA delivery vectors. The concept underlying the design of these copolymers is that hydrophobicity and rigidity of polythiophenes should enhance the transport of siRNA across the cell membrane and endosomal membrane. A gel retardation assay showed that the nanosized complexes formed between the copolymers and siRNA were stable even at a molar ratio of 1 : 2. The high cellular uptake (>80%) and localization of the copolymer vectors inside the cells were easily analyzed by tracking the fluorescence of polythiophene using fluorescent microscopy and cytometry. An in vitro luciferase knockdown (KD) assay in A549-luc cells demonstrated that the siRNA complexes with more hydrophobic copolymers achieved a higher KD efficiency of 52.8% without notable cytotoxicity, indicating protein-specific KD activity rather than solely the cytotoxicity of the materials. Our polythiophene copolymers should serve as novel, efficient, low cell toxicity, and label-free siRNA delivery systems. [ABSTRACT FROM AUTHOR]

Papermaking has been using high quantities of retention agents, mainly cationic substances and organic compounds such as polyamines. The addition of these agents is related to economic and environmental issues, increasing contamination of the effluents. The aim of this work is to develop a cationic polymer for papermaking purposes based on the utilization of alpha-cellulose. The cationization of mercerized alpha-cellulose with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) is governed by a pseudo-second-order reaction. The initial amorphous fraction of cellulose is reacted with CHPTAC until the equilibrium value of nitrogen substitution is reached. Nitrogen is incorporated as a quaternary ammonium group in the polymer. Also, the kinetic constant increased with decreasing crystallinity index, showing the importance of the previous alkalization stage. The use of modified natural polysaccharides is a sustainable alternative to synthetic, nonbiodegradable polyelectrolytes and thus is desirable with a view to developing new products and new processes. [ABSTRACT FROM AUTHOR]

Cationic polymer, hydroxy aluminum, and clay minerals are three flocculants with different action mechanisms and a more cost-efficient multiple flocculant can be prepared by compositing them through appropriate technology. All of attapulgite (ATP), clay minerals containing magnesium, aluminum, and silicate, are porous environmental mineral material with good absorbability and have found wide applications in industrial sewage treatment. With polyaluminum chloride (PAC), poly(dimethyl diallyl ammonium chloride) (PDMDAAC), and attapulgite (ATP) clay being the main raw materials, multiple flocculant CMHa (liquid) with good storage stability was prepared and its optimized blending mass percent was PDMDAAC of 2%-3%, ATP of 4%–6%, and PAC of 20%–30%. The liquid poly(dimethyl diallyl ammonium chloride) (PDMDAAC) was firstly loaded on solid material in kneader and then mixed in certain proportion with PAC and ATP to prepare solid CMHa convenient for storage and transportation. The optimized mass ratio is PAC : ATP : PDMDAAC = 80 : 10 : 2.4. When this multiple flocculant was used to treat domestic sewage, coal washing sewage, dyeing wastewater, and papermaking wastewater, its equivalent dosage was just 50% of PAC, while overall production cost has been reduced to about 40%, viewing showing broad application prospect. [ABSTRACT FROM AUTHOR]

A designated bioactive peptide "Hispidalin" purified from the seeds of Benincasa hispida, which is a medicinal plant, belongs to Cucurbitaceae family. Purification was achieved by using a procedure consisting of extraction from potassium phosphate buffer followed by FPLC and HPLC steps. Based on amino acid residue, this peptide is amphipathic and basic with one net positive charge having isoelectric pH 8.1. This peptide is without sulphur containing amino acid suggesting its extended conformation lacking double bond secondary structure. The results obtained from MALDI-TOF suggested that Hispidalin is of molecular mass 5.7KDa with 49 amino acid residues and confirmed SDS-PAGE resolved ~6.0KDa protein band. This novel and unknown peptide "Hispidalin" showed broad and potent inhibitory effects against various human bacterial and fungal pathogens; its growth inhibition was significantly comparable with commercial antibacterial and antifungal drugs. The Hispidalin at 40 μg/mL concentration exhibited 70.8% DPPH free radical-scavenging activity and 69.5% lipid peroxide inhibition. Thus, in the present study, Hispidalin demonstrated remarkable antimicrobial and antioxidant potentials from the seeds of B. hispida. [ABSTRACT FROM AUTHOR]

The roles of novel reactive cationic copolymers (P(CMDA-DMDAAC)s) of 3-chloro-2-hydroxypropylmethyldiallylammonium chloride (CMDA) and dimethyldiallylammonium chloride (DMDAAC) in fixing anionic dyes on cotton fabric were studied by modern instrumental analysis technologies such as FT-IR spectra and SEM analysis, to achieve the new theoretical guides for the wide applications of those dye fixatives. The FT-IR spectra of the obtained insoluble-water color lakes verified that they could be formed from the electrostatic interactions of the P(CMDA-DMDAAC)s with anionic dyes, which were further confirmed by the FT-IR analysis of the anionic dyes on dyeing cotton sample fixed by P(CMDA-DMDAAC)s. The FT-IR spectra of cotton samples fixed by P(CMDA-DMDAAC)s showed the absorptions of P(CMDA-DMDAAC)s and the signs similar to the formation of new ether linkage on cotton fabric even after being repeatedly washed, which were further confirmed by the SEM analysis of the fixed dyeing cotton samples. Thus, the reactive units (CMDA) of the obtained P(CMDA-DMDAAC)s could be expected to bring about the covalent bonds with the hydroxyl groups of cotton (cellulose) to form an ether linkage when fixing, resulting in the stronger interactions of P(CMDA-DMDAAC)s with cotton fabric, as well as their electrostatic forces with anionic dyes to produce the insoluble-water color lakes, for the development of fastness of anionic dyes on cotton fabric. [ABSTRACT FROM AUTHOR]

In this research, organozeolite filled ethylene vinyl acetate (EVA) composites were prepared in a melt-mixing process and followed by compression molding using hot press machine according to standard test specimen. Prior to mixing process, zeolite was modified via cationic exchange of alkylammonium ions. The effect of zeolite or organozeolite loading from 5 up to 25 volume percentages on the properties of EVA/zeolite composites was evaluated. A combination of Fourier Transform Infrared Radiation (FTIR) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) analysis were done to characterize the resultant organoclay. Tensile test was performed in order to study the mechanical properties of the composites. EVA filled with organozeolite showed better tensile properties compared to EVA filled with unmodified zeolite, which might be an indication of enhanced dispersion of organophilic clay in the composites. Meanwhile, morphological study using SEM revealed the fibrillation effect of organozeolite. Besides, thermal properties of the composites were also characterized by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed that the application of the cation exchange treatment increases both decomposition and melting temperature of EVA/zeolite composites. [ABSTRACT FROM AUTHOR]

Background. The expression term of the gene transfected in cells needs to belong enough inorder to make a gene therapy clinically effective. The controlled release of the transfected gene can be utilized. The new biodegradable hydrogel material created by 20 w/w% aldehyded dextran and 10 w/w% ε-poly(L-lysine) (ald-dex/PLL) was developed. We examined whether it could be as a nonviral carrier of the gene transfer. Methods. A plasmid (Lac-Z) was mixed with ald-dex/PLL. An in vitro study was performed to assess the expression of Lac-Z with X-gal stain after gene transfer into the cultured 293 cells and bone marrow cells. As a control group, PLL was used as a cationic polymer. Results. We confirmed that the transfection efficiency of the ald-dex/PLL had a higher transfection efficiency than PLL in 293 cells (plasmid of 2 μg: ald-dex/PLL 1.1%, PLL 0.23%, plasmid of 16 μg: ald-dex/PLL 1.23%, PLL 0.48%). In bone marrow cells, we confirmed the expression of Lac-Z by changing the quantity of aldehyded dextran. In the groups using ald-dextran of the quantity of 1/4 and 1/12 of PLL, their transfection efficiency was 0.43% and 0.41%, respectively. Conclusions. This study suggested a potential of using ald-dex/PLL as a non-carrier for gene transfer. [ABSTRACT FROM AUTHOR]